PPH RN 11 JUN 2015

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Policy and procedure handbook Ident. : NOTE-DS-EM-533-858-94-EN - A.5

© ATR - 2015 ATR Note page 1/209

POLICY AND PROCEDURES

HANDBOOK

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0 - TABLE OF CONTENTS/RECORD OF REVISIONS

0 - TABLE OF CONTENTS/RECORD OF REVISIONS .........................................................................................2

0-1 REASON OF REVISION....................................................................................................................4

0-2 RECORD OF INITIAL ISSUE (DEC 1994) ............................................................................................60-3 RECORD OF REVISION 1 (OCT 1998)...............................................................................................70-4 RECORD OF REVISION 2 (MAY 2005)...............................................................................................80-5 RECORD OF REVISION 3 (OCT 2005)...............................................................................................90-6 RECORD OF REVISION 4 (MAR 2007) ............................................................................................100-7 RECORD OF REVISION 5 (MAR 2008) ............................................................................................110-8 RECORD OF REVISION 6 (JUN 2009) .............................................................................................120-9 RECORD OF REVISION 7 (FEB 2010) .............................................................................................130-10 RECORD OF REVISION 8 (JAN 2011) ...........................................................................................140-11 RECORD OF REVISION 9 (JUN 2012) ...........................................................................................150-12 RECORD OF REVISION 10 (NOV 2013).........................................................................................160-13 RECORD OF REVISION 11 (JUN 2015) .........................................................................................17

1- INTRODUCTION...............................................................................................................................................18

2- POLICIES..........................................................................................................................................................18

2-1 GENERAL ORGANIZATION .........................................................................................................192-1-1 INDUSTRY STEERING COMMITTEE ..........................................................................................................192-1-2 WORKING GROUPS ...............................................................................................................................20 2-1-3 MAINTENANCE REVIEW BOARD ..............................................................................................................20 2-1-4 MEETINGS / SCHEDULES.........................................................................................................................20 2-1-5 COMMUNICATIONS / MINUTES ................................................................................................................23

2-2 SPECIFIC RESPONSIBILITIES .....................................................................................................242-2-1 AIRCRAFT MANUFACTURER ...................................................................................................................242-2-2 AIRWORTHINESS AUTHORITIES' ADVISORS .............................................................................................24

2-2-3 REGULATORY AUTHORITIES OTHER THAN EASA AND FAA.........................................................................242-3 TRAINING REQUIREMENTS ........................................................................................................262-3-1 SPECIFIC TECHNICAL TRAINING .............................................................................................................26 2-3-2 MAINTENANCE PROGRAM DEVELOPMENT PROCESS ( MSG-3) TRAINING ....................................................26

2-4 MRB ACTIVITY WORKSCOPE .....................................................................................................272-4-1 REVISION OF EXISTING PROGRAMS........................................................................................................27 2-4-2 MODIFICATION STANDARD.....................................................................................................................27 2-4-3 BASIC WORKSCOPE ..............................................................................................................................27 2-4-4 BASIC WORKSCOPE CHANGE .................................................................................................................27

2-5 APPLICABLE MSG-3 STANDARD.................................................................................................282-5-1 HISTORICAL FOLLOW -UP .......................................................................................................................28 2-5-2 REVISION OF EXISTING MSG-3 ANALYSES...............................................................................................28 2-5-3 DEVELOPMENT OF NEW MSG-3 ANALYSES .............................................................................................28

2-5-4 ATR SPECIFIC RULES............................................................................................................................28 2-6 MRB REPORT CONTENT............................................................................................................29

2-6-1 MAINTENANCE TASKS ...........................................................................................................................292-6-2 INDIVIDUAL TASK T HRESHOLD / INTERVAL ...............................................................................................32

2-6-2-1 INTERVAL...................................................................................................................................................322-6-2-2 THRESHOLD ...............................................................................................................................................322-6-2-3 SUBSEQUENT THRESHOLD/INTERVAL ESCALATION/ REDUCTION ........................................................................322-6-2-4 PROGRAM NOTES .......................................................................................................................................32

2-6-3 TASK EFFECTIVITY / REMARKS ................................................................................................................332-6-4 PACKAGING OF MAINTENANCE TASKS ....................................................................................................33

2-6-4-1 GENERAL PRINCIPLE ...................................................................................................................................332-6-4-2 APPROPRIATE USEAGE PARAMETERS FOR CHECK INTERVALS...........................................................................34

2-7 SAMPLING PROGRAMS ............................................................................................................35

2-7-1 SAMPLING PROGRAM FOR STRUCTURE ..................................................................................................35 2-7-1-1 SSIS CONCERNED:.....................................................................................................................................352-7-1-2 AIRCRAFT SELECTION FOR SAMPLING PURPOSE:.............................................................................................352-7-1-3 DEFECT REPORTING AND PROGRAM ADJUSTMENT:..........................................................................................352-7-1-4 INSPECTIONS ARRANGEMENT: ....................................................... ............................................................... 35

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2-8 MRB REPORT APPROVAL..........................................................................................................382-8-1 MINIMUM REVIEW / APPROVAL PERIOD.....................................................................................................38 2-8-2 APPROVAL OF INCOMPLETE MRB REPORT .............................................................................................38 2-8-3 NON APPROVAL OF MRB REPORT ...........................................................................................................38

2-9 MRB REPORT REVISION............................................................................................................392-9-1 TEMPORARY REVISIONS .......................................................................................................................39

2-9-1-1 MINOR TEMPORARY REVISIONS...................................................... ............................................................... 392-9-1-2 SIGNIFICANT TEMPORARY REVISIONS ....................................................... ..................................................... 39

2-9-1-3 APPLICABILITY ............................................................................................................................................392-9-2 MAJOR REVISION ..................................................................................................................................40

2-9-2-1 SCOPE, APPROVAL......................................................................................................................................402-9-2-2 APPLICABILITY ............................................................................................................................................40

3- PROCEDURES .................................................................................................................................................41

3-1 GENERAL PROCEDURES FOR ALL MRB ACTIVITIES ......................................................................423-1-1 PROGRAM DEVELOPMENT PROCEDURE .................................................................................................42 3-1-2 SYSTEMS ANALYSIS..............................................................................................................................43

3-1-2-1 MSI SELECTION...........................................................................................................................................433-1-2-2 BASIC METHODOLOGY .................................................................................................................................443-1-2-3 SUPPLEMENTARY SYSTEMS METHODOLOGY....................................................... ........................................... 55

3-1-3 STRUCTURES ANALYSIS........................................................................................................................57

3-1-3-1 DEFINITIONS...............................................................................................................................................573-1-3-2 SSD DOCUMENT..........................................................................................................................................583-1-3-3 SSI ANALYSIS .............................................................................................................................................583-1-3-4 NOTES ON ENVIRONMENTAL DETERIORATION ON NON-METALLIC MATERIALS .....................................................653-1-3-5 TEMPLATE OF SSI ANALYSIS ........................................................... .............................................................. 66

3-1-4 ZONAL ANALYSIS ( INCLUDING EZAP AND L / HIRF ) .....................................................................................77 3-1-4-1 INTRODUCTION ...........................................................................................................................................773-1-4-2 ZONAL ANALYSIS SELECTION PROCESS................................................................ .......................................... 77

3-1-5 DESCRIPTION OF TRANSFER PROCEDURES ..........................................................................................115 3-1-5-1 EXTERNAL TRANSFER: TRANSFER TO ZONAL WORKING GROUP ............................................................ ........... 1153-1-5-2 INTERNAL TRANSFER: TRANSFER OF FAILURE CAUSES BETWEEN MSI ..............................................................115

3-1-6 APPROVAL PROCEDURE OF MRB REPORT PROPOSAL OR MAJOR REVISIONS. ..........................................116

3-2 ADDITIONAL PROCEDURES FOR SOME SPECIFIC MRB ACTIVITIES...............................................1173-2-1 MRB REPORT REVISION ......................................................................................................................117

3-2-1-1 TEMPORARY REVISIONS.............................................................................................................................1173-2-1-2 MAJOR REVISION ......................................................................................................................................1193-2-1-3 EVOLUTION PROCESS FOR C CHECKS AND MULTIPLES (BEFORE IP44) ............................................................120

3-2-2 DEVELOPMENT OF DERIVATIVE AIRCRAFT PROGRAMS...........................................................................129

APPENDIX A: SPECIFIC MRB ACTIVITY .........................................................................................................131

A-1 SPECIFIC SCOPE ...................................................................................................................132 A1-1 COMPLETE REDESIGN OF THE SYSTEMS / POWERPLANT PROGRAMME (ALL MODELS ) ....................................132 A1-2 CORROSION PREVENTION AND CONTROL PROGRAMME ( ALL MODELS ).........................................................133 A1-3 ENHANCED ZONAL ANALYSIS PROGRAM ( EZAP ) .........................................................................................134 A1-4 EVOLUTION PROCESS FOR C CHECK AND MULTIPLES .................................................................................135 A1-5 TBO LANDING GEAR EVOLUTION ...............................................................................................................136 A1-6 AVIONICS SUITE MODIFICATION ................................................................................................................137

A-2 SCHEDULE OF ACTIVITIES ......................................................................................................138 A2-1 MAINTENANCE REVIEW BOARDS AND INDUSTRY STEERING COMMITTEES .....................................................138 A2-2 WORKING GROUPS ..................................................................................................................................143

APPENDIX B: SAMPLE ANALYSIS ..................................................................................................................147

APPENDIX C: ACRONYMS/MSG-3 GLOSSARY..............................................................................................158

C-1 ACRONYMS ..............................................................................................................................159C-2 MSG-3 GLOSSARY ....................................................................................................................161

APPENDIX D: LIST OF OTHER STRUCTURE..................................................................................................167

APPENDIX E: CORROSION SENSITIVITY RATINGS DOCUMENT ................................................................191

APPENDIX F: POLICY AND PROCEDURE DOCUMENT (PPD)......................................................................209

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0-1 REASON OF REVISION

INITIAL ISSUE –DEC 1994

Initial issue of Note DS-EM 533-5858/94.

REVISION 1 –OCT 1998

The revision 1 has for main purpose revision of paragraphs §2-6-1, §2-6-2, complete review of §2-7,introduction of new digital template for MSG-3 systems analyses in §3-1-2-2-2 and revision of annexes with objectives of future MRB activities: redesign of systems/powerplant program anddefinition of CPCP requirements.

REVISION 2 - M AY 2005

The revision 2 has for main purpose the introduction of Ageing Aircraft Structure Programme policiesthrough the addition of the:

- Corrosion Prevention and Control Program policies (section 3) and the- Structural Task Group policies through the Policy and Procedures Document (PPD in appendix D).

The global content of the PPH has not been changed, only editing updating has been introduced in

order to clarify, as much as possible, the presentation of the PPH.The table of contents has been detailed a little bit more trying to enhance the clarity of the document.

REVISION 3 - OCT 2005

The revision 3 has for main purpose the:

- updating of the in-service findings reporting form (section 3) and the

- updating of Policy and Procedure Document (see details of revision in appendix D).

REVISION 4 - M AR 2007

The revision 4 has for main purpose the:

- introduction of Enhanced Zonal Analysis Program (EZAP) principles,

- C check evolution methodology and the

- TBO landing gear evolution objectives and principles.

The wording “DGAC” has been replaced by “EASA”, when necessary, and the EASA acronym hasbeen added in the appendix C-1.

REVISION 5 - M AR 2008

The purpose of revision 5 is the updating of MSG-3 structure analyses templates further totransfer of structure analyses from paper to electronic format.The organization of pages 32 to 81 of Section 3-Procedures has been reviewed at this occasion.

-REVISION 6 - JUN 2009

The purpose of revision 6 is the updating of methodology for C check evolution further to ISC of NOV08 and the updating of list of participants to EZAP and C check working groups.FAA AC reference for EWIS has been updated and MMEL reference in MSG-3 analyses has alsobeen indicated.

REVISION 7 - FEB 2010

The purpose of revision 7 is the updating of §3-1-2-6 for indication of delay of ninety days for MRBRapproval as well as updating of § 3-1-2-2-5 for size/density ratio table in accordance with FAA AC 25-27 values

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REVISION 8 - J AN 2011

The purpose of revision 8 is the introduction of methodology for New Avionics suite consideration inMSG-3 analyses with § 3-1-2-2-2 and appendix A updating and the introduction of L/HIRFconsideration in the EZAP dossier, with § 3-1-2-2-4 updating and new § 3-1-2-2-6.

REVISION 9 - JUN 2012

The purpose of revision 9 is mainly the introduction of methodology for transfer procedures further toISC NOV 2011. New templates for zonal analyses have been added.Re- organization of some paragraphs (2, 3) has been made for more clarity.

REVISION 10 - NOV 2013

The purpose of revision 10 is the clarification of vendor recommendations consideration. An update of the task selection procedure in second level of MSG-3 systems analysis has beenmade. CPCP tagging process has been modified. Empty appendix A-4 is deleted.

REVISION 11 –JUN 2015

The main purpose of revision 11 is the introduction of new templates for MSG-3 structure analyses as

well as complete review of §3-1-3 structures analysis section.Updating of §2.5 for applicable MSG-3 standard for revised and new analyses has been realized withupdating of C-2 MSG-3 Glossary.Definitions in glossary have been updated to be in line with ATA MSG-3 2007.1, except for detailedinspection in line with ATA MSG-3 Rev.2 and walkaround inspection ATR approach maintained,based on original ATA MSG-3 and derived from GVI definition.

Miscellaneous:§2-1-1: Precision on ISC participants

Annexes: Harmonization writing of A-1. A-3 appendix inclusion in empty A-2, follow-up of appendix A1-5 for TBO evolution, new appendix D for other structure, new appendix E for Corrosion sensitivityratings, previous appendix D for PPD renamed appendix F.Typo corrections on some pages.

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-

0-2 RECORD OF INITIAL ISSUE (DEC 1994)

Prepared by : Date :C. JOLIVETMAINTENANCE SERVICES MANAGER

AVIONS DE TRANSPORT REGIONAL

Approved by : Date :O. MADSENCIMBER AIR

Accepted by : Date :F. COUDONMRB ChairmanDGAC

Accepted by : Date :

T. NEWCOMBEMRB ChairmanFAA

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0-3 RECORD OF REVISION 1 (OCT 1998)

Prepared by : Date :H.TALFUMIER

ATR Maintenance Engineering manager

Approved by : Date :O. MADSENCIMBER AIR

Accepted by : Date :F. LEBLONDMRB ChairmanDGAC

Accepted by : Date :T. NEWCOMBEMRB ChairmanFAA

Accepted by : Date :M. PAINCHAUDMRB ChairmanTRANSPORT CANADA

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0-4 RECORD OF REVISION 2 (MAY 2005)

Prepared by : Date :

N. GUALINA ATR Maintenance Planning Manager

Approved by : Date :

O. MADSENCIMBER AIRISC Chairman


F. JOUVARDMRB ChairmanDGAC/EASA


G. LAYTONMRB ChairmanFAA

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0-5 RECORD OF REVISION 3 (OCT 2005)




M. CAJANI ATR Structure Data and Justification

(limited to Appendix D)


O. MADSENCIMBER AIRISC Chairman


F. JOUVARDMRB ChairmanEASA


G. LAYTONMRB Chairman

FAA

Accepted by : Date :(limited to Appendix D)

H. HERESON Airworthiness LimitationDGAC/EASA

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0-6 RECORD OF REVISION 4 (MAR 2007)




D. SIMS AIR NEW ZEALANDISC Chairman




MRB ChairmanFAA

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0-7 RECORD OF REVISION 5 (MAR 2008)








H. W. THARPSMRB ChairmanFAA

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0-8 RECORD OF REVISION 6 (JUN 2009)


N. GUALINA ATR Maintenance Engineering Director






MRB ChairmanFAA

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0-9 RECORD OF REVISION 7 (FEB 2010)






F. JOUVARDMRB Chairman

EASA


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0-10 RECORD OF REVISION 8 (JAN 2011)






F. JOUVARDMRB Chairman

EASA


K. E. MILLERMRB ChairmanFAA

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N. FIGUE-DEGROUTTE ATR Maintenance Engineering Manager


D. DUGGANFEDEX EXPRESSISC Chairman


F. JOUVARD

MRB ChairmanEASA



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0-12 RECORD OF REVISION 10 (NOV 2013)


N. FIGUE-DEGROUTTE ATR Maintenance Engineering Manager




J. NEVEUXMRB Chairman

EASA



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Prepared by: Date:

N. FIGUE ATR Maintenance Engineering Manager

Approved by: Date:


Accepted by: Date:

J. NEVEUXMRB ChairmanEASA

Accepted by: Date:

MILTON C. HUNTERMRB ChairmanFAA

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1- INTRODUCTION

This policy and procedures handbook (PPH) is meant to describe the organisational structures, theresponsibilities, policies and procedures, which will apply in the various cases of maintenanceprograms development and revision.

Such policies and procedures insure compliance with the following regulations:

EASA CS /FAR 25-1529 instructions for continued airworthiness.

EASA CS /FAR 25-571 damage tolerance and fatigue evaluation.

EASA CS /FAR 25-611 accessibility provisions.

EASA CS /FAR 25-1309 equipment, systems and installations.

There are basically three broad categories of activities covered by this policy and procedureshandbook:

development of new aircraft initial maintenance programs.

development of derivative aircraft maintenance programs.

revision of existing aircraft maintenance programs.

2- POLICIES

Unless otherwise indicated, the same policies apply to the different maintenance program activities,from minor revision to complete new program development.

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2-1 GENERAL ORGANIZATION

2-1-1 INDUSTRY STEERING COMMITTEE

The industry steering committee (ISC) shall:

be comprised of representatives from aircraft, engine, propeller, appliance manufacturers and

operators, as may be required depending on the scope of activities. Operators can delegate their representation to a lessor, a contractor or other, providing they are involved in the maintenanceprocess of the operator.

have its activities directed by two chairpersons, one from operators, the other from the aircraftmanufacturer.

review and approve the policy and procedures handbook (PPH) and forward it to the MRBchairpersons (EASA/FAA) for acceptance.

determine the number and type of working groups that will be necessary, organise themaccording to expertise (i.e. electrics/avionics, hydro mechanical, propulsion, structure/zonal) andcontrol their activities.

request from the aircraft manufacturer all supporting technical data necessary for the workinggroup activities.

provide technical and MSG-3 training of all steering committee and working group members andairworthiness authority advisors.

invite the MRB chairpersons and selected MRB members to ISC meetings.

promote participation of other airworthiness authorities to ISC meeting through the EASA MRBchairperson.

provide the MRB chairpersons with a list of working groups and working group members andnotify them of any changes.

review the proposals from the working groups and document any required changes to suchproposals in the ISC meeting minutes.

provide all reports and ISC meeting minutes to the MRB chairpersons and participatingairworthiness authorities.

submit the MRB report proposal, with all appropriate justifications, to the type certificate holder.

be represented by its chairpersons at the MRB meetings, when invited.

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2-1-2 WORKING GROUPS

The working groups (WGs) shall:- be comprised of representatives from the manufacturers and operators and be chaired by an

industry representative (preferably operator).

- review and validate, in accordance with their respective area of expertise, the analyses and

justification documents presented by the manufacturers.- make appropriate corrections and recommendations in the minutes of each working group

meeting and forward them in a timely manner to the ISC.

2-1-3 MAINTENANCE REVIEW BOARD

The maintenance review board (MRB):- is primarily comprised of qualified personnel from EASA and FAA.

- is jointly chaired by one EASA and one FAA representative.

- invites other airworthiness authorities to participate in the MRB and coordinate their activities.- reviews and accepts the policy and procedures handbook.

- determines the number of representatives from the authorities to be involved at all levels of theMRB process (MRB, ISC, WGs) and notify the ISC chairpersons accordingly.

- controls the activities of its advisors to the working groups and ensure their regular attendance.

- coordinates all MRB activities and associated matters with the ISC chairpersons.

- reviews ISC and working groups activity reports, offer guidance and assistance and providetimely notification of potential problems to all concerned.

- attends ISC meetings, when invited.- may invite the ISC chairpersons and selected ISC members to specific MRB meetings.

- approves the MRB report and revisions.

2-1-4 MEETINGS/SCHEDULES

Based on its understanding of the scope of the MRB activity being Considered, the aircraftmanufacturer will propose a specific number and type of meetings to the industry steering committee.

The first meeting will normally be an industry steering committee Meeting primarily dedicated to

- reviewing the objectives, extent and tentative schedule of the proposed MRB activity.- defining the number and type of working groups.

Working groups shall be classified in the following categories:

+ electric/avionics working group (EWG)

+ hydro mechanical working group (HWG)

+ power plant working group (PWG)

+ structure working group (SWG)

+ zonal working group (ZWG)

Working groups may be combined if judged appropriate by the ISC.For example, a combined electric/avionics/hydromechanical working group would be identifiedas "EHWG".

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- finalizing the number and location of all meetings (ISC and WG).Numbering of meetings will be in chronological order.

- setting up the working groups structures and defining responsibilities.

- providing training on the technical features being evaluated for maintenance requirements.

- reviewing any relevant changes to the policy and procedures handbook.

The subsequent meetings will follow the pattern of the accepted initial schedule:

- the working group meetings will assess the various maintenance tasks proposals and justificating data:

+ the working group will either accept the task and justificating data as proposed or request additional information or reanalysis.

+ all accepted tasks will be presented to the ISC by the working group chairperson.

- the industry steering committee meetings will review proposals from previous working groups,monitor progress and revise the initial schedule as necessary:

+ whenever working group proposals are found unacceptable by the ISC, the ISC

chairperson shall clearly instruct the WG chairperson(s) on the additional justificationor reanalyses required from the WG(s).

+ ISC non acceptance of a significant number of tasks, related justificating data andMSG-3 analyses will inevitably lead to a complete reassessment of the affectedworkpackage at the next suitable working group. If none is planned, an additionalworking group may need to be scheduled by the ISC.

+ ISC non-acceptance of only a few tasks, due to minor errors in the related justificatingdata or analyses, should, if at all possible, be resolved within the current ISC meetingtimeframe. Failing that, it should be postponed to the following suitable WG meeting.If such WG meeting is no longer scheduled at that point in time, reassessment shallpreferably be carried out by the ISC to avoid unnecessary burden on the MRB activity.

An attendees’ list shall be compiled for each meeting.

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WORKING GROUPCODE

DESIGNATION RESPONSIBILITIES

EWG AVIONICS/ELECTRICS 20 Electrical WiringInterconnection system (EWIS)22 Auto flight23 Communications24 Electrical power 26 Fire protection31 Indicating/RecordingSystems33 Lights34 Navigation42 Integrated Modular Avionics(IMA) and Avionics DataCommunication Network45 Onboard maintenancesystems46 Information systems

PWG POWERPLANT 61 Propellers71-80 Engine and enginesystems

HWG HYDROMECHANICAL 21 Air Conditioning &Pressurization25 Equipment & Furnishings27 Flight controls

28 Fuel29 Hydraulic power 30 Ice and Rain Protection32 Landing Gear 35 Oxygen36 Pneumatic38 Water and waste52 Doors

SWG STRUCTURES 52 Doors53 Fuselage54 Nacelles/Pylons55 Stabilizers

56 Windows57 Wings

ZWG ZONAL Complete airplane

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2-1-5 COMMUNICATIONS/ MINUTES

The working language shall be English. For any original document written in another language, anEnglish translation shall be provided.

The aircraft manufacturer shall notify the MRB chairpersons at least three months prior to theintended beginning of any MRB activity.

Invited foreign authorities shall indicate the degree of their involvement to the MRB chairpersons.

The EASA MRB chairperson shall inform the aircraft manufacturer on:

- which foreign authority intends to participate.

- the degree of participation of each (attending ISC meetings or only on distribution for ISCminutes).

For new or derivative programs, notification shall be given immediately following official program

launch.Simultaneously, a tentative schedule of activities shall be issued by the aircraft manufacturer to theMRB chairpersons, prospective operators and vendors invited to participate.

Response from authorities, operators and vendors with respect to MRB and ISC chairmanship or other levels of participation shall be given no later than one month prior to the first scheduledmeeting.

An agenda outlining the topics to be discussed at any specific meeting will be issued to allparticipants by the aircraft manufacturer no later than three weeks before that meeting.

All correspondence related to general organization (changes to schedules, chairmanships, attendeesetc...), whether or not originating from the ISC, shall pass through the ISC and be distributed to all

concerned by the ISC.It shall be kept in a master file by the ISC chairmanship.

All technical material, justificating data and MSG-3 analyses shall be distributed by the aircraftmanufacturer no later than two weeks (10 working days) prior to any meeting.

All working group and ISC meetings activities and decisions, regarding general topics and individualtasks, shall be documented in minutes:

- written by the aircraft manufacturer.

- corrected and accepted by the appropriate MRB, ISC or working group chairperson(s).

- distributed by the ISC to all concerned, normally two weeks after the related meeting and no

later than two weeks before the meeting at which they are scheduled for review.- kept in a master file by the ISC chairperson from the aircraft manufacturer.

The minutes record all changes made to the analysis as well as action items.

It must contain the reference to MSI and analysis item, and for each meeting :

- records of all decisions taken with respect to this analysis.

- justifications for such decisions (technical explanations, reference to technical documents).

- follow-up actions, deadlines and responsibilities to resolve open issues.

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2-2 SPECIFIC RESPONSIBILITIES

2-2-1 AIRCRAFT MANUFACTURER

The aircraft manufacturer will be relied upon to:

- develop a policy and procedures handbook for presentation to the ISC and the MRB.- provide general familiarisation training for the MRB, ISC and working groups.

- provide the ISC with an initial list of maintenance significant items (MSIs) and structuralsignificant items (SSIs) with sufficient data to justify this selection.

- provide the ISC with a daily utilisation rate for the aircraft concerned by this MRB activity andspecifically quote this rate in the PPH.

- provide the working groups with sufficient technical data to support the analysis of MSIs/SSIs.Provide engineering support during all meetings.

- provide the ISC and appropriate working groups, in a timely manner with information

concerning certification issues and resolutions regarding proposed tasks originating from thecertification process (airworthiness limitation items or certification maintenance requirements).

- ensure that the manufacturer's manuals contain information covering those on-aircraftsystems/power plant tasks in the MRB report.

- participate in the ISC and working group activities.

- present the MRB report proposal to the MRB for approval.

2-2-2 AIRWORTHINESS AUTHORITIES' ADVISORS

The airworthiness authorities advisors are expected to:- attend working group meetings related to their specific area of expertise as observers/advisors

and provide guidance to the working group members.- provide progress reports to the MRB members prior to the next ISC meeting, assessing

working group activities and highlighting potential problem areas.

- attend MRB meetings.

2-2-3 REGULATORY AUTHORITIES OTHER THAN EASA AND FAA

Following notification of the MRB process by EASA, it is the function and responsibility of the other regulatory authorities to:

- indicate to the MRB and ISC their level of participation, if any, to the various meetings and,subsequently, be properly represented at such meetings.

- notify the ISC, through the MRB, of their disagreement with its decisions or conclusions or of their specific national requirements which may affect the MRB report proposal.

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MRB ACTIVITYRESPONSABILITIES

Approve MRB Report

- - - - - - - - - - - - - - - - - - - Attend ISC meetings. Accept PPH. Review/finalise MRB Report

proposal

- - - - - - - - - - - - - - - - - - - Co-ordinate all activities

between authorities andindustry.

Approve PPH.

- - - - - - - - - - - - - - - - - - - Control WG’s activities in

accordance with PPH. Revise PPH as required. Review WG’s decisions.

- - - - - - - - - - - - - - - - - - Guide individual Working

Group activities. Report to ISC.

- - - - - - - - - - - - - - - - - - Review all technical data and

MSG-3 analyses. Request changes or additional

data from A/C manufacturer.

- - - - - - - - - - - - - - - - - - Gather all technical data. Perform MSG-3 analyses. Present MRB report proposal to

MRB.

MRB CHAIRMANSHIP

EASA/FAA

MRB MEMBERSHIP

EASA/FAA advisors

Other authorities

ISC CHAIRMANSHIP

A/C manufacturer/airline

A UT H ORI T I E S

ISC MEMBERSHIP

Airlines (WG chairpersons)

Manufacturers

WG CHAIRMANSHIP

Airline

WG MEMBERSHIP

Airlines

Manufacturers

MRB Advisors

A/C MANUFACTURER

I ND U S T RY

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2-3 TRAINING REQUIREMENTS

2-3-1 SPECIFIC TECHNICAL TRAINING

Specific technical training will be provided prior to the Working group and ISC activities on:- any new maintenance significant item (MSI):

- existing MSI for which the functions have been redefined, thus altering its initial MSG-3analysis.

This technical training will focus on clearly identifying the normal functions, the back-up functions andthe consequences of failures on the MSI itself or the systems interfacing with it.

Explanations and descriptions not contributing to the MSG-3 analysis (i.e. details on the internalfunction of complex components), will not be provided.

Except for simple mechanical features, schematics will mostly remain at the block diagram level.

For each MSI, specific information on expected or known reliability, accessibility, inspectability will beprovided.

2-3-2 MAINTENANCE PROGRAM DEVELOPMENT PROCESS (MSG-3) TRAININGSince participants to the WGs and ISC may not all have sufficient understanding of the MSG-3process, familiarisation training will be provided prior to ISC and WGs activities.

This training is not intended to give participants the level of working knowledge required to produceMSG-3 analyses, but simply provide sufficient guidelines to allow them to review and detect errors inthe proposed analyses.

This training will focus on:

the objective of MSG-3 and the fundamental concepts surrounding the definition of this objective:

- inherent reliability. Safety and economic impact. Reliability follow-up.

- definition and selection of MSIs/SSIs.- applicability and effectiveness of maintenance tasks/ maintenance programs. Design

implications.

explaining the meaning of the different statements found in the decision logic flow charts,particularly:

- crew normal duties

Refer to glossary for definition of "operating crew" and "normal duties".- hidden/evident failure modes

- direct adverse effect on safety

which tend to be the most conflicting issues when reviewing specific analyses. familiarisation with the current ATR analysis sheets lay-out.

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2-4 MRB ACTIVITY WORKSCOPE

2-4-1 REVISION OF EXISTING PROGRAMS

The basic work scope shall be determined by the accumulated in-service experience and the designstandard of the aircraft being considered at the date of the first ISC meeting.

For development of derivative or new aircraft programs, the MRB activity shall begin whenever themanufacturer indicates that there is a firm project.

2-4-2 MODIFICATION STANDARD

The work scope shall be defined in terms of modification standard whenever such modifications affectthe maintenance requirements.

2-4-3 BASIC WORKSCOPE

The basic work scope must be ready for presentation at the first ISC meeting to enable the ISC todetermine the type and number of working groups.

2-4-4 BASIC WORKSCOPE CHANGEIn the course of the MRB process, depending on the availability of essential information, the ISC may,with appropriate notification and justification to the MRB, request authorisation for expansion or reduction of the basic work scope.

Such request shall be given careful consideration by the MRB.

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2-5 APPLICABLE MSG-3 STANDARD

2-5-1 HISTORICAL FOLLOW-UP

Original MSG-3 analyses were developed using ATA MSG-3 initial issue of 1980 for ATR42 and ATR72.

Structural analyses for ATR42-400/-500 were derived from the ATR42 and ATR72 ones. Wherenecessary, new structural analyses were developed using ATA MSG-3 Rev.2 of 1993.

In 2001, all systems and powerplant analyses were completely revised using MSG-3 Rev. 2.

2-5-2 REVISION OF EXISTING MSG-3 ANALYSES

Existing MSG-3 analyses are revised:- to correct obvious errors or omissions overlooked during previous review and acceptance.

- to account for changes prompted by product modifications and in-service experience.

Except for ATR specific rules (see §2-5-4), the ATA MSG-3 revision 2007.1 is used for revision of allMSG-3 analyses.

2-5-3 DEVELOPMENT OF NEW MSG-3 ANALYSES

All new analyses (systems, structures and zonal) shall be performed using MSG-3 revision 2007.1except for ATR specific rules (see §2-5-4).

For systems and powerplant analyses, technical descriptions are required on all new aircraft systemsfeatures to provide guidance both in the making and understanding of the associated MSG-3 analysis.

Technical descriptions must focus on:

- explaining the general architecture of a given system (block diagrams, simple electricalschematics).

- defining the essential functions of each key component within that system.

- explaining, for each key component, what effect the loss of one of its functions has on the restof the system (loss of redundancy, proper indication/warning, safety implications etc...).

Refer to appendix B for sample technical descriptions

2-5-4 ATR SPECIFIC RULES

In ATA MSG-3 rev 2001, the detailed inspection definition was changed with deletion of term “visual”.For practical reason, ATR keeps using visual in detailed inspection definition and associated DVI

acronym in both structural and systems/powerplant analyses. As far as zonal analyses are concerned, ATR approach of walkaround inspection, based on original ATA MSG-3 issue, is maintained with definition derived from GVI. L/HIRF analysis is developed onlyfor aircraft fitted with new avionics suite (POST 5948).

As per MSG-3 rev 2007.1, Fatigue Damage requirements for PSE should go to AirworthinessLimitations only. Instead they are also included in the Structure Program section of the MRBRfollowing the ATR block maintenance concept.

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2-6 MRB REPORT CONTENT

The MRB report format shall follow the general guidelines provided in Advisory Circular AC 121-22B.

Besides the three programs (systems/power plant, structure, zonal) and associated program rules itshall contain:

- the list of MSIs for which no tasks were found to be applicable or effective.

- the cross reference list of systems/structure tasks transferred to specific zonal tasks.

- the list of zones not specified in the zonal program.

- the list of modifications having an impact on maintenance, with cross reference to servicebulletins when applicable.

2-6-1 MAINTENANCE TASKS

Refer to sample MRB pages in this section.

The tasks contained in the MRB report shall be primarily derived from MSG-3 analyses.

For each systems/power plant program task, the failure consequence "route number" (5 to 9) shall beindicated in the "Rte" column.

After accumulation of fleet service experience, the ISC or MRB chairpersons may request changes tothe requirements of the MRB report.

The proposed new or revised tasks shall normally be defined through reassessment of the initialMSG-3 analyses.

ATR monitors vendor recommendations changes through internal process.

All documentations coming from vendors and having an impact on maintenance data (task,procedure, interval) are taken into consideration at each MSI revision and submitted to design officespecialist when necessary.

Additional tasks issued from airworthiness directives or CMR need not to be incorporated in the MRBreport, if not already derived from MSG-3 analysis; task interval is the one selected in the analysisand may be more or less restrictive than the AD or CMR limit.

The list of CMRs and airworthiness limitations may be appended to the MRB report.

Tasks issued from systems and structure analyses, which are found acceptable for transfer to thezonal, program must be accounted for on the appropriate transfer sheet and be deleted in theprogram from which they originated.

Alternative tasks may be included in the following MRB sections:- systems/power plant programme : when the failure effect category is either 6, 7 or 9,

- structure programme : when an alternative method of inspection is applicable and effective for a given SSI (fatigue damage only) provided it is adequately justified by certificationdocuments.

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2-6-2 INDIVIDUAL TASK THRESHOLD/INTERVAL

2-6-2-1 INTERVAL

The interval for a task shall be determined by:- the safety critical nature of the item or system involved.

- the calculated or estimated reliability of the item or system involved

- the known reliability of comparable items or systems on existing aircraft (service experience).

- the complexity of the task and its impact on aircraft downtime.

- engineering judgement.

The unit of measurement for a given task interval (flight hours, Cycles or calendar period) will dependon which, of the aircraft operating hours/cycles or age, has most effect on the failure mode beingconsidered.

The selected intervals and units of measurement are applicable for an average daily utilization of 5.5flight hours and 8.3 flights. For daily utilization, which significantly deviate from the above values,specific tasks may need to have their intervals and/or units of measurement reconsidered.

2-6-2-2 THRESHOLDThresholds are mainly used in the structure program for fatigue and environmental damage source.However, they can be used in the systems / power plant section provided it is demonstrated that aunit or component rate of deterioration is very low up to a certain limit (threshold) where it starts todeteriorate faster and requires thereafter more frequent inspections (engine components for instance).

Initial threshold determination follows the same guidelines listed in 2-6-2-1.

2-6-2-3 SUBSEQUENT THRESHOLD/INTERVAL ESCALATION/ REDUCTION

On the occasion of periodic MRB report revisions, accumulated service experience in the form of:- fleet reliability data compiled by the aircraft manufacturer.

- inspection findings, for "on-wing" tasks, as reported by operators.

- shop findings, for major components restoration tasks, as reported by the appropriatevendor/repair shop performing such restorations.

shall be reviewed to optimize individual task thresholds and/or intervals.

2-6-2-4 PROGRAM NOTES

Program notes must sometimes be substituted to task intervals whenever one or several specificrequirements dictate the frequency of accomplishment of a given task, making it impossible toexpress the task interval in the normally accepted units.

Program notes apply mostly to systems program tasks and shall be incorporated in the "programrules" section.

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2-6-3 TASK EFFECTIVITY/REMARKS

When task effectivity is a function of a specific modification standard, PRE/POST modificationreference shall be clearly indicated in the effectivity/remarks column of the MRB report.

When task effectivity relates to a specific aircraft model or derivative covered by a multi model MRB

report (such as the ATR-72 MRB report), it should be identified:- either by a single type modification reference or generic modification

- or by aircraft / engine / propeller model reference in case of complex combination of modifications.

2-6-4 PACKAGING OF MAINTENANCE TASKS

2-6-4-1 GENERAL PRINCIPLE

Under the MSG-3 "task oriented" philosophy, optimized and effective tasks tend to all have differentintervals which usually fit in three broad timeframes:

- less than a week.- between one week and one year.

- over one year.

While it had been common industry practice for years to package tasks in "check" labelled "line", "A","B", "C" for systems and "D" for structure, most maintenance programs developed under MSG-3 haveno longer been able to follow this earlier pattern:

- systems analyses have rarely identified a characteristic "B" interval, but rather a scatter of multiples of "A".

- similarly, there is no longer a single "C" check, but a basic "C" check with additional tasks at

various multiples of the basic interval.- structural analyses for three types of damages (environmental, fatigue, accidental) and

classification of structural items analyzed for fatigue in two categories (damage tolerant andsafe-life) have resulted in a significant scatter of structural inspection tasks. There is no longer an identifiable "D" check.

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2-6-4-2 APPROPRIATE USEAGE PARAMETERS FOR CHECK INTERVALS

CHECK INTERVAL DEFINITION/REMARK

DAILY (DY) 1 CALENDAR DAY1 calendar day means that nextdue time is any time in day 2, if previous accomplishment doneany time in day 1

LINE CHECK (LC) 2 CALENDAR DAYS2 calendar day means that nextdue time is any time in day 3, if previous accomplishment doneany time in day 1

WEEKLY (WY) 7 CALENDAR DAYS7 calendar day means that nextdue time is any time in day 8, if previous accomplishment doneany time in day 1

SPECIFICCOMPONENT TASK

FLIGHT HOUR (FH)YEAR (YE)

Inspection, restoration or discardof specific components

A(multiples up to 4A) 500 FH

Visual checks, bite checks,lubrication/servicing, operationaltests

C(multiples up to 4C)

5000 FH Inspections, operational and

functional checks of a/c systems

STRUCTURAL TASK

FLIGHT CYCLEF (multiples up to 36000 F)

Fatigue/accidental damageinspections

YEARYE (multiples up to 12YE)

Environmental/accidentaldamage inspections

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2-7 SAMPLING PROGRAMS

2-7-1 SAMPLING PROGRAM FOR STRUCTURE

As fatigue deterioration can be considered as a systematic process linked with the operatingage/usage of the aircraft, a sampling program is used for all SSI’s where a directed inspection for fatigue damage is necessary.

2-7-1-1 SSIS CONCERNED:

Any SSI for which a systematic fatigue damage characteristic has been analysed.

Inspections where sampling program rules apply are identified with a letter "S" in the "FSP"column (Fatigue Sampling Program).

2-7-1-2 AIRCRAFT SELECTION FOR SAMPLING PURPOSE:

For each operator, the sampled aircraft are those, which have accumulated the highest number of flight cycles, and represent 1/5 of the fleet.

If the number of sampled aircraft is not a round figure, it has to be increased to the next roundnumber.

In the case the fleet has changed, a review of the sampling program has to be carried out.

2-7-1-3 DEFECT REPORTING AND PROGRAM ADJUSTMENT:

Significant defects in terms of fatigue deterioration evidenced on any aircraft must be reported tothe airframe manufacturer; appropriate corrective actions such as design change, specificinspection recommendations (inspection service bulletin, airworthiness limitation...) will then berequired.

Based on the criticality of the defect found, it may be necessary to inspect other aircraft 100%upon reaching the threshold (to be confirmed by the airframe manufacturer)

2-7-1-4 INSPECTIONS ARRANGEMENT:

(refer to enclosed illustrations)

Sampled aircraft are inspected 100% at threshold and repeat interval as indicated in this structureprogram section.

Other aircraft must be inspected not later than the 100% limit, which is defined as the calculatedthreshold through damage tolerance evaluation, and at each subsequent interval (as indicated inthis section); this limit is an airworthiness limitation and listed in the "Time Limits" section.

Operators electing not to follow the fatigue sampling program, must perform the inspections at thethresholds and repeat intervals stated in the MRBR structure program, on all their aircraft.

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2-8 MRB REPORT APPROVAL

2-8-1 MINIMUM REVIEW/APPROVAL PERIOD

The MRB report proposal shall be submitted to the authorities for review and approval no lessthan ninety days before issuance of the related aircraft type certificate.

2-8-2 APPROVAL OF INCOMPLETE MRB REPORT

On new or derivative aircraft, it might not be practical to delay the approval of the MRB report untilcompletion of the fatigue damage tolerance calculations used as a basis for MSG-3 analyses. Insuch a case, as long as the aircraft manufacturer proposes an acceptable plan for completion of the MSG-3 fatigue damage analyses before the forecasted dates of the first fatigue damageinspections. The ISC should propose and the MRB should accept partial approval of anincomplete MRB report containing:

- the systems/power plant program,

- the structural inspection program for corrosion (from environmental or accidental damagesources),

- the zonal program,

but exclusive of the structural inspection program for fatigue damage.

2-8-3 NON APPROVAL OF MRB REPORT

Although major difficulties associated with an MRB activity should be identified and reported bythe MRB advisors as early as possible, point of contentions which cannot be resolved by the MRBchairpersons might still arise just prior to MRB report final approval.

The MRB chairpersons’ direct management shall attempt to resolve the situation failing that aconsensus on a final decision shall be reached between EASA's upper management and the FAAMRB policy board's chairperson.

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2-9 MRB REPORT REVISION

Since the MRB report is intended to remain a current document. It will be subject to periodicrevisions of different magnitude.

2-9-1 TEMPORARY REVISIONS

2-9-1-1 MINOR TEMPORARY REVISIONS

The following changes are considered as minor revisions:

making non policy editing changes to the text part of the MRB report (introductions,programs rules, glossaries, definitions, etc...).

updating sampling programs thresholds.

error corrections to task numbering, descriptions, zones, accesses, effectivity/remarks.

- There is no need to call up a meeting.

- The proposal for changes is directly submitted by mail to the MRB chairpersons by the aircraft

manufacturer.

2-9-1-2 SIGNIFICANT TEMPORARY REVISIONS

The following changes are considered as significant revisions:

changing the nature of the scope of one or several tasks (i.e. going from inspection torestoration, DVI to SDI, etc...).

changing the interval and/or the route of one or several tasks.

adding/deleting one or several tasks.

making policy changes to the text part of the MRB report.

- There is no need to call up meetings. Change proposals are distributed by mail to allconcerned.

- Such significant changes must be reviewed at all decision levels (working group, ISC andMRB chairpersons) of the MRB organization before final approval.

2-9-1-3 APPLICABILITY

Temporary revisions are particularly well suited to address:

- on-going changes from service experience.

- product improvement modifications.

- specific systems changes to an existing aircraft type. Any single temporary revisions shall not contain more than 20 different proposed changes.

There shall not be more than five temporary revisions in any twelve months period.

Once a year, all temporary revisions shall be consolidated into a normal revision.

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2-9-2 MAJOR REVISION

2-9-2-1 SCOPE, APPROVAL

A major revision is one which affects a large portion of a given aircraft MRB report.

A major revision may require working group meetings and will always require one or moresteering committee meetings before submission of the final proposal to the MRB.

2-9-2-2 APPLICABILITY

A major revision is primarily required when sufficient accumulated service experience justifies aproposal for an overall increase in the "A" and "C" checks intervals of the systems program.

A major revision may also be justified if, through a yearly assessment, the aircraft manufacturer,the ISC and the MRB have determined the need for specific changes to a significant portion of theMRB report that could not be handled through temporary revisions.

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3- PROCEDURES

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3-1 GENERAL PROCEDURES FOR ALL MRB ACTIVITIES

3-1-1 PROGRAM DEVELOPMENT PROCEDURE

This section is not intended to rephrase the MSG-3 pamphlet, but rather to highlight the maindifficulties encountered by analysts and working group members in the interpretation and practicaluse of MSG-3 logic.

The objective of MSG-3 is to produce a package of appropriate tasks which will maintain maximumreliability of the various components and systems of an aircraft.

Maximum inherent reliability is achieved by design and only redesign can change it.

Most mechanical features of aircraft systems require some form of maintenance to remain at their maximum reliability level.

MSG-3 is a process, which essentially assesses the consequences of unreliability (failure) of individual components or subsystems on the overall reliability of the complete aircraft. Depending onthe system involved, such consequences may be of a safety, operational or purely economic nature.

With the severity of the consequences in mind, the likely causes are carefully reviewed to determine if

maintenance can eliminate them. All single failures considered to have safety consequences must be preventable first by design(redundancy), second by maintenance.

Significant changes to MSG-3 analyses shall be identified by a revision number and date.

Revised MSG-3 analyses shall be kept in the aircraft manufacturer's master file and distributed to theMRB.

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3-1-2 SYSTEMS ANALYSIS

3-1-2-1 MSI SELECTION

MSG-3 defines a maintenance significant item as an item whose failure could affect safety and/or could go undetected for some time and/or could have significant operational or economic impacts.This is a very broad description. In actual fact, a MSI is generally at the level of "on aircraft"replaceable components.

The finalized MSI list shall be endorsed by the ISC and later appended to the MRB report.

Although MSG-3 recommends a "top-down" approach to define a list of MSIs and their functions,before finalizing such a list, it is essential to review all components of each system and subsystem (asdefined by the ATA breakdown) in order not to miss important functions, particularly hidden ones.

For each component, the following additional information should be provided when available:

vendor name and part number.

estimated MTBUR.

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3-1-2-2 BASIC METHODOLOGY

Basic systems MSG-3 analysis is based on three phases according to the following process:

3-1-2-2-1 PREPARATION PHASE

A- Identification of MSIs normal functions

This is the most difficult phase of the MSG-3 analysis process.

A well prepared technical description will be of great help in properly identifying all the normalfunctions of the various MSIs.

MSG-3 defines "function" as the normal characteristic actions of an item.

In a less abstract way, the functions of a MSI are basically the various operating modes for which ithas been designed.

All functions of a given MSI are not always obvious to the analyst.

Example: An oil cooler has one obvious function, to control the oil temperature. However it alsohas two less obvious functions:

to contain the oil.

to allow unrestricted flow of the oil.

Selecting a large MSI may result in less obvious functions being missed.

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B- Identification of MSIs single functional failures

Unlike failure mode and effect analyses (FMEAS), which attempt to account for all the failure modesof individual sub-components and arrive at MTBUR estimates for higher level components, or safetyanalyses which assess the probability of safety critical aircraft operation resulting from the combinedeffect of multiple failures, MSG-3 focuses primarily on single failures, and will only consider a secondfailure whenever the initial one is hidden.

Consequently, FMEAS and safety analyses failure modes can only be used as useful information, butmust not be confused with MSIs functional failures.

According to MSG-3 the general definition of failure is "the inability of an item to perform withinpreviously specified limits".

Thus, a single functional failure is the inability of a component or subsystem to perform one specificfunction.

Consequently, the term "functional failure" applies only to aircraft systems, not operating conditions(i.e. "aircraft in icing conditions" or "aircraft stalling" are not failures).

Functional failures should not be confused with functional failure consequences.

Only single failures can be either of the evident or hidden category.Too broadly defined failures, derived from broadly defined functions, may encompass several singlefailures from both categories, thus leading to an improper analysis.

C- Assessment of the failure effects and consequences

A failure always has some effects, rarely a single one but rather a combination of several (visualindications, vibration, unusual flight control loads, noise, odors or, simply, loss of redundancy).

Proper assessment of the effects is essential to determine the severity of the failure. It is the startingpoint of the first level of MSG-3 analysis (level 1).

For back up or safety systems such as fire protection, emergency oxygen etc..., analysed for hiddenfailures, events such as fire, smoke, depressurization, which are not the result of many multiple

failures, can be considered as valid second failures for the purpose of the analysis.

However, emergency situations such as crash landing, ditching... should not be taken as realisticsecond single failures, since they are the consequence of pilot error or a series of several major failures.

D- Determination of the failure causes

The cause of a functional failure is also a specific failure (mechanical breakdown due to wear, fatigueor corrosion, leaks, electrical circuit failures etc...), often termed as "potential failure", which takesplace at the component or sub component level.

Proper determination of failure causes leads to a good MSG-3 analysis at the second level (level 2).

Confusion between failure and cause often exists when MSIs selection is improperly done.The level of selection of a MSI is correct when its failure causes are defined precisely enough toenable selection of the most effective maintenance tasks.

MSI selection may need to be reassessed if tasks coming out of from level 2 logic seeminappropriate.

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3-1-2-2-2 FIRST LEVEL OF MSG-3 ANALYSIS

This is the assessment of the severity of the failure consequences.

A level 1 analysis form (form 5) should be used for each functional effect.

Question 1- Evident versus hidden single failures

The effects of a single functional failure may or may not be detectable by the crew immediately.

When the effects of a failure are felt by the crew through normal sensory means (visual indications,physical efforts, vibrations, sounds, odors etc...), Such a failure can be considered as evident.

Hidden failures apply to components or subsystems: which are continuously working in parallel with another component or subsystemperforming the same function (i.e. each element of a dual push rod mechanism).

which are part of a back-up or emergency system which is rarely activated.

From an MSG-3 standpoint, a failure is considered as genuinely hidden only if not detectable by theoperating crew during "normal duties", defined as those duties associated with the routine operationof the aircraft on a daily basis.

Normal duties do not include any crew activity outside the aircraft while parked on the ramp, such asPre-flight walk around.

"Routine operation" can be considered to be the period during which the flight crew performs its

normal activities in the flight compartment.Confusion between failure and failure cause due to poor choice of MSI level often leads tounnecessary hidden failures analyses.

Assuming a well-designed aircraft and properly defined MSIs, the majority of functional failures should

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be evident, while their causes (potential failures) will remain discrete (hidden) and only detectable bymaintenance.

Allowing the crew to monitor degradation (failure cause) is not cost effective in terms of design and,therefore, rarely implemented, which explains why crew monitoring is no longer in level 2 MSG-3analysis.

Question 2 or 3- Safety impact of functional failuresOnce the failure is identified as being either evident or hidden, its consequences on operating safetymust be assessed.

Unlike safety analyses, MSG-3 is not concerned with the probability of failure occurrence, justwhether safety is an issue or not.

According to MSG-3, a functional failure affects safety if it puts the aircraft operating characteristicsoutside of the certificating conditions.

The crew's ability to control the aircraft is significantly reduced and serious damage to the aircraft andinjuries to occupants are likely.

In certification terminology, such failures are rated "catastrophic" or "hazardous".

Question 4- operational impact of evident functional failures

The assessment of whether or not a failure has an effect on operating capability may requireconsultation of the MMEL and/or other documentation with operational procedures, such as AFM.Whenever reference is made to the MMEL in answering this question, an MMEL item should be notedon the analysis FEC form in the MMEL Ref. space as needed.

Failure Effect Category (FEC)

Category 5: Evident single functional failures with direct safety consequences

These should be primarily prevented by incorporation of appropriate redundancy in systems design.When redundancy is not applicable (i.e. to prevent blade separation from a propeller or rupture of keystructural elements of a landing gear), safety must be assured by very high design life limit objectivesand suitable maintenance in between (inspection and/or discard).This situation should apply to few MSIs.MSG-3 analyses producing a significant number of evident failures with safety consequences(category 5) are likely flawed and should be questioned by the working groups.

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Category 6: Evident single functional failures with economic (operational) consequences

Determining the impact of an evident functional failure on the operating capability of the aircraft isusually quite straightforward.To fall in this category, either:

the failure must be corrected before next flight, or

operating limitations must be implemented.

Category 7: Evident single functional failures with economic (non-operational) consequences

Such failures usually apply to systems and subsystems where, at the same time, redundancy existsand loss of function is known to the crew (i.e. flight compartment instruments, radio equipment, non-essential or ground operated devices with manual back-ups).

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Category 8: Hidden single functional failures with potential safety consequences

By definition, hidden failures cannot have safety consequences by themselves (they wouldn't behidden if they did).They can only reduce the design safety margin in a given system or subsystem.The analysis must consider all the possible second single failures and find, at least, one which willfurther reduce the safety margin of the system in which the initial hidden failure occurred to the pointwhere safe aircraft operation is jeopardized.Second single failures, when analysed as first failures, should be evident and, of course, have nosafety impact on their own, but only in combination with the first failure.Example: The failure of the landing gear normal extension system is an evident failure with no safetyconsequences since there is an emergency extension system.But the failure of the emergency extension system is a hidden failure with safety consequences whenassociated with the failure of the normal system.When second failures, analysed as first failures, are found to be hidden, the analysis or, possibly, thedesign should be questioned. If they are found to affect safety, the analysis is definitely wrong.

Category 9: Hidden single functional failures with potential economic consequences

In this case no difference is made between potential operational and non operational consequences.

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3-1-2-2-3 SECOND LEVEL OF MSG-3 ANALYSIS

This is the treating of the causes by appropriate maintenance tasks. A level 2 analysis form (form 6) should be used for each cause unless it was transferred to another MSI.

Task selection criteria

Depending on the effect category, different types of tasks or tasks combinations are evaluated in

terms of: applicability.

effectiveness.

The above criteria are very precisely defined for each task in the task selection criteria table(described in this paragraph).For all consequences (categories 5, 6, 7, 8 and 9) the first level 2 question on lubrication (question"A") is always asked.For safety related consequences (categories 5 and 8), all level 2 questions following question "A"must be asked and either a task must be found or redesign is mandatory.For non-safety related consequences (categories 6, 7 and 9), the analyst is allowed to stop at the first"yes" answer following question "A" or to go through all questions until the cost of the tasks is equal tothe cost of the failure.The sentence “previous selected task allows exiting the logic” will be written in the justification fields of next questions, when exiting the logic.If all answers are "no", no task is generated.If economic penalties are severe, redesign may be desirable.Whenever some doubts exist on the outcome of level 2 analysis, in terms of most effective taskselection, the initial choice of the MSI should be questioned.

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TASK SELECTION CRITERIA

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TASK APPLICABILITY SAFETY

EFFECTIVENESSOPERATIONAL

EFFECTIVENESSECONOMIC

EFFECTIVENESS

LUBRICATION

OR

SERVICING

The replenishment of the consumable mustreduce the rate of functional

deterioration.

The task must reducethe risk of failure.

The task must reducethe risk of failure to anacceptable level.

The task must be costeffective.

OPERATIONAL

OR

VISUAL CHECK

Identification of failuremust be possible.

The task must ensureadequate availabilityof the hidden functionto reduce the risk of amultiple failure.

Not applicable. The task must ensureadequate availabilityof hidden function inorder to avoideconomic effects of multiple failures andmust be cost effective.

INSPECTION

OR

FUNCTIONAL

CHECK

Reduced resistance tofailure must bedetectable, and there

exists a reasonablyconsistent intervalbetween adeterioration conditionand functional failure.

The task must reducethe risk of failure toassure safe operation.


The task must be costeffective; i.e., the costof the task must be

less than the cost of the failure prevented.

RESTORATION The item must show

functional degradationcharacteristics at anidentifiable age, and alarge proportion of units must survive tothat age. It must bepossible to restore theitem to a specificstandard of failureresistance.

The task must reducethe risk of failure toassure safe operation.


The task must be costeffective; i.e., the costof the task must beless than the cost of the failure prevented.

DISCARD The item must show

functional degradationcharacteristics at anidentifiable age and alarge proportion of units must survive tothat age.

The safe life limit mustreduce the risk of failure to assure safeoperation.


An economic li fe limitmust be cost effective;i.e., the cost of thetask must be less thanthe cost of the failureprevented.

Task description

The task descriptions should follow the MSG-3 terminology as closely as possible:

lubrication/ servicing

operational/ visual check

inspection/ functional check

restoration

discard.It should briefly and precisely describe what to do on which system, subsystem or component, but nothow to do it, the latter being the purpose of the job instruction card.

Whenever task descriptions make reference to items normally designated by abbreviations (i.e. GCU,PCU, MFC etc...) such items shall be spelled out in full with their respective abbreviation betweenbrackets.

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Example: "visual check of propeller control unit (PCU) ball screw spline."Visual checks whose purpose is to detect obvious abnormalities, not to measure a specific level of degradation, can usually be transferred to the zonal program.In this case, a “Yes” is written in the zonal flag field and the MRBR zonal task reference is indicated inthe task description column of the level 2 sheet (form 6).

Establishing the initial task interval

MSG-3 only provides broad guidelines on how to determine the most appropriate initial task intervaland/or threshold when applicable. Determination of a suitable interval cannot be done on probabilityalone. Sound engineering judgement must be used at all decisions levels (working group, ISC, MRB).For a given design standard, an individual component's reliability is fairly predictable and can beconfirmed by qualification/endurance tests.However, installation may significantly alter individual components reliability or wear pattern andreduce the overall subsystem or system reliability.The results of safety analyses shall be taken into account when setting task intervals for someoperational/visual checks selected to detect hidden failures with potential safety consequences. For this category of hidden failure, both the probability of occurrence and the severity of the potentialeffect (loss of control of the aircraft in the air being likely the worst one) should be reflected in theinterval.

For major components restoration tasks, each component manufacturer shall establish theappropriate initial restoration interval and propose it to the ISC.In some cases, interval may refer to vendor documents such as CMMv, SIL… and the acronym VR isused in place of interval value. Then, the corresponding vendor document reference will be written inthe remark effectivity column of the selected task in the MSI dossier.

Correspondence between MSG-3 tasks and MRBR tasks references

In order to ensure cross-reference between MRBR and MSG-3 analyses, the corresponding MRBRtask reference is written in the task description column of the analyses. In addition, section 8 of MRBRprovides for each MRBR task transferred to zonal program, the corresponding MRBR zonalreference.

3-1-2-2-4 T ASK SUMMARY SHEET

Following the selection of all applicable and effective tasks, a task summary sheet (form 7) is issued,grouping all the tasks selected for a given MSI.

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3-1-2-3 SUPPLEMENTARY SYSTEMS METHODOLOGY

3-1-2-3-1 PRINCIPLE OF THE INTEGRATED MODULAR AVIONICS SYSTEMS

Traditional aircraft systems have an organisation where each system is composed of a number of dedicated hardware units. These applications are physically separated from one another and MSG-3analyses are therefore undertaken individually.

“Integrated Modular Avionics” (IMA) is a term used to describe a set of generic, modular andintegrated computers connected to a network. An important characteristic of the IMA is that the samecomputing modules are shared by several aircraft systems to run applications.

MSG-3 analysis has to take into account that the shared hardware can have functions, and be apotential failure cause, in several systems/ATA-chapters, because the system functions that arecontained in IMA software are hosted by IMA hardware.

Hardware corresponds to the IMA system components physically identifiable.Software term represents the applications contained in the IMA hardware equipment.

The ATA breakdown repartition of the IMA system functions is as follow:- ATA 42 System section covers the IMA system.- Each software application hosted by IMA hardware is dispatched in the ATA section

corresponding to the software proper functions.

3-1-2-3-2 MSG-3 APPROACH OF IMA SYSTEMS FUNCTIONS

The dispatch of the IMA functions in the MSG-3 System analyses are described below:

The Hardware functions of the IMA Hardware components are analysed in the MSI that includes the

hardware equipments.The hardware functions are those functions that are not specific to one of the software functions fromthe other ATA chapters.The hardware functions are the functions that allow:

- the software support and operation (resources sharing)- the network communication (routing)

It’s considered that:- the ATA HARD is the ATA section that covers the hardware functions- the MSI HARD is the MSI analysis that analyses the hardware functions

The software functions are hosted by the processing part of the IMA hardware components but realizeaircraft functions in accordance with other ATA chapters (different from the ATA that covers the

hardware).The software functions are to be covered by the MSI related to the ATA functions realized by theSoftware application.It’s considered that:

- the ATA SOFT are the different ATA sections that cover the software functions- the MSI SOFT are the MSI analyses that analyse the software functions

Note: In some case, the introduction of new aircraft functionalities by software can lead to a new MSIdevelopment that will only cover a software application.

As the software application is removable from the Aircraft, it’s considered as an LRU and analysed onthe same principle in the MSG-3 analyses.

The analysis method of the Software / hardware functional failures is described hereafter:

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Consideration of the software Functional Failures in the MSI SOFT

The Failure Causes related to a software functional failure, will incriminate the software applicationand the hardware equipment that hosts the software application.The software functional failures are analysed with usual MSG-3 logic Level 1 and Level 2

Consideration of the hardware Functional Failures in the MSI HARD

Due to the design principle of the IMA systems based on two redundant parts, theoretically thesystem is fully redundant.But based on a conservative approach of these systems, a preliminary analysis has to be realized inorder to define and verify the redundancy properties of the IMA systems.Two cases can be possible:

- the IMA system is fully redundant:In this case, all the functions performed by one hardware equipment are in case of failureassumed by the redundant equipment and the system is able to perform the samefunctionalities.

- the IMA system is not fully redundant:In this case, a specific analysis has to be performed in order to identify the non-redundantfunctions and the associated impact in case of loss due to a hardware equipment failure.The result of this specific analysis has to be included in the description part of the analysisand taking into account during the MSG-3 logic level 1 development.

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3-1-3 STRUCTURES ANALYSIS

3-1-3-1 DEFINITIONS

AIRCRAFT STRUCTURE

According to MSG-3, the aircraft structure consists of all load carrying members of the fuselage, wing,empennages, engine nacelle, landing gear, flight control surfaces, including all attachment fittings for actuating devices found on flight controls, doors, and landing gears but excluding such actuatingdevices which are analysed as part of their related systems.

SIGNIFICANT STRUCTURAL DOSSIERS (SSD)

SSD are ATR internal working units and correspond to the major sub-assemblies of the aircraftstructure, based on the first 4 digits of ATA 100 chapter numbering

SIGNIFICANT STRUCTURAL ITEMS (SSI)

The MSG-3 glossary defines SSI as "any detail, element or assembly, which contributes significantlyto carrying flight, ground, pressure or control loads and whose failure could affect the structural

integrity necessary for the safety of the aircraft". This definition applies to most of the aircraftstructure.

The size and boundaries of an SSI depend on the function and design of the concerned structure, theconsequences of its failure, the type and size of the possible damage.

Figure 1: aircraft structure breakdown

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The finalised list of selected SSIs is endorsed by the ISC and included in the MRB report.

NUMBERING OF SSI

SSI numbering follows the ATA breakdown, with the first three digits identifying ATA and sub-ATA.The fourth digit corresponds to the aircraft manufacturer's own breakdown of the sub-ATA. The lasttwo digits are sequential.

"OTHER STRUCTURE"

All structural items that are not part of an SSI are defined as “other structure”. This category, to whichbelongs most of the aircraft’s secondary structure, does not require dedicated maintenanceinspections. Detection of possible defects or damage is entrusted to the zonal program.

The list of “other structure” is given in appendix D and is obtained by eliminating all SSI from thecomplete list of structures described in the SRM - Structural Repair Manual.

At some time and for any reason, “Other structure” requiring a dedicated inspection is removed fromthe list and is covered by a new SSI or included in an existing one.

3-1-3-2 SSD DOCUMENT

For each SSD, a dedicated document describes the concerned structure, its components and thebasic design features. All SSI belonging to the SSD are listed and located on figures. All the resultingmaintenance tasks are listed as well, with their MRBR reference.

Note: the SSD concept was introduced with the STG of November 2014. Not all SSD documents areavailable at this time and will be produced progressively.

3-1-3-3 SSI ANALYSIS

Each SSI is assessed following the MSG-3 process. The analysis and its results are included in the ATR Structure MSG-3 analysis report, which has 4 sections:

- administrative section: cover sheet, sheets i and ii

- SSI description section: sheet 1 (SSI data) and sheet 2 (figures)

- analysis section: sheet 3a and 3b (Accidental Damage analysis - “AD”, metallic and non-metallic),sheet 4 (Environmental Deterioration and CPCP analysis - “ED”) and sheet 5 (Fatigue Damageanalysis - “FD”)

- results section: sheet 6 (task summary) and sheet 7 (individual task information)

A blank template is provided in §3-1-3-5.

Note: the current template was introduced with STG of November 2014 and will be used for all newand revised MSG-3 analyses.

3-1-3-3-1 COVER SHEET

The cover sheet mentions the type of aircraft (ATR42, ATR42-400/-500 or ATR72), the SSI number and title. “ATR42” is short for ATR42-200/-300/-320.

3-1-3-3-2 LIST OF REVISIONS (SHEET I)

This section lists all the known revisions of the analysis, with issue number, date and reason for revision. Tracking of older revisions is sometimes difficult and is done as far as possible.

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3-1-3-3-3 LEP - LIST OF EFFECTIVE P AGES (SHEET II)

The MSG-3 analysis report is made of sheets rather than pages. Sheet numbers correspond to thedifferent sections of the analysis. For example, sheet 5 always contains the fatigue damage analysis.

A sheet can span over multiple physical pages: 5.1, 5.2…

Sheets with no information are removed from the document and are not listed in the LEP. Somesheets contain pieces of information (e.g. “covered by another SSI”) but no actual analysis; these are

considered “not active” and the corresponding box in sheet ii is left un-checked.

3-1-3-3-4 SSI DATA (SHEET 1)

Sheet 1 identifies the SSI: description, zone, effectivity (aircraft for which the document is valid) and

type of material - metallic or non-metallic; provides a numbered list of the items that compose the SSI.

3-1-3-3-5 FIGURES (SHEET 2)

The figures show the location and boundaries of the SSI and the item it is composed of.

Note: in sheets 3a to 5, the “applies to” field indicates to which items or to which sub-set of aircraft theanalysis applies. For example: “items 1, 2 and 5”, or “post mod 3715”. Often: “all”.

3-1-3-3-6 ACCIDENTAL D AMAGE ANALYSIS - METALLIC (SHEET 3 A)

Accidental damage analysis for metallic parts is given on sheet 3a.

For each possible source of accidental damage, it is determined whether it is likely or unlikely to occur on the concerned structure. When likely, the type and size of expected damage is given.

figure 2: structure analysis flowchart

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Accidental Damage on metallic structures does not generate an inspection task by itself. If at leastone likely source of accidental damage has been identified, it is indicated if it has an impact on the EDanalysis or the FD analysis.

3-1-3-3-7 ACCIDENTAL D AMAGE ANALYSIS - NON-METALLIC (SHEET 3B)

The design of non-metallic (composite) primary structures on ATR is damage tolerant and is based onthe no-growth concept: possible production defects or damage that may be caused by accidentalimpacts occurring during aircraft operation and maintenance do not propagate, as demonstrated bytest. However, they reduce the residual strength of the structure.

For damage that reduces the static strength below ultimate loads, an inspection program isestablished so that the resulting level of safety is acceptable and not lower than that, which isexpected from a damage tolerant metallic structure (figure 3).

The inspection program is based on a probabilistic evaluation of the risk of failure, which is a functionof:

- the probability of occurrence of a damage

- the probability to encounter a load exceeding the residual strength of the damaged structure

- the probability to detect the damage.

The analysis is performed by the Design Office.

Sheet 3b summarizes the analysis results, mentioning the sources of damage and providing theidentified inspection tasks. For each task, type and size of the damage to be detected are given,along with the inspection level and interval.

3-1-3-3-8 ENVIRONMENTAL DETERIORATION AND CPCP ANALYSIS (SHEET 4)

Sheet 4 applies to metallic materials only.

The inspections requirement for ED detection are the result of an initial analysis, possibly adjustedwith data from in-service experience according to the CPCP - Corrosion Inspection and ControlProgram.

The ED/CPCP analysis for an SSI can be “covered by another SSI”. This is the case when theconcerned structural items (for example fatigue critical details) are also part of a larger assembly,addressed by another SSI.

figure 3: damage tolerance on metallic and composite structure

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a) Initial assessment

The initial assessment is a function of the SSI’s sensitivity to environmental deterioration, the level of exposure to aggressive environment and the quality of protection.

A rating factor is assigned to each of the three parameters, as follows:

1. corrosion sensitivity rating

The following elements are considered:

- material rating: values from 1 (highest sensitivity) to 3 (lowest) for the different metallicmaterials to different types of corrosion (stress, intergranular, pitting and uniform) are takenfrom the document “Corrosion Sensitivity Ratings Document” (refer to Appendix E). Thelowest rating of all the materials composing the SSI is selected. For quick reference, thetable in sheet 4 lists a selection of most common materials used on ATR aircraft.

Note: the ED analysis is made by using the sensitivity ratings available at the time. Later changes are not retroactively applied to existing analyses.

- filiform, crevice, fretting and microbiological corrosion are not linked to the material butdepend on surface conditions, geometry, design and environment. When occurrence of these types of corrosion is likely, a sensitivity rating of 1 is selected.

- galvanic corrosion may occur when different materials are in contact. Materials that are part

of the SSI must be considered, as well as the materials of other structure in contact with theSSI. Figure 5 gives the ratings for the different combinations. When insulation and sealingprevent electrical conductivity between dissimilar materials, the rating can be increases by1 unit, without exceeding 3.

figure 4: ED on metallic structures flowchart

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The lowest rating from the above considerations and its source are mentioned in the corrosionsensitivity rating table in sheet 4.

2. environment:rating 1 = probable exposure to highly corrosive agents (toilet or galley spillage, batteryelectrolyte…)rating 2 = probable exposure to corrosive agents (runway water, cabin condensation, fluidspillage from cargo, fuel, microbiological growth, alkaline or acid dust…)rating 3 = no probable exposure to corrosive environment

3. protection:

ratings 1 (average protection) to 3 (high protection) are assigned to the different materials and

protection schemes as shown in figure 6.It is considered that an accidental damage reduces the protection level to “average”.

figure 5: galvanic corrosion ratings (for material 1 in contact with material 2)

figure 6: protection ratings

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b) Interval

The three ratings are combined to determine the inspection interval of the initial requirement: 2, 4 or 8years. In the most adverse cases (“NOTE”), inspection only is considered inadequate and a designmodification is necessary. In the most favorable cases (“NT”, No Task), no inspection is required.Nonetheless, it is verified that a zonal task covers the area.

c) Threshold

If the ED is systematic in nature, a threshold can be selected, based on in-service data or experienceon similar structural items or on similar aircraft. No threshold is selected for ED of random nature.

d) Inspection level

The appropriate inspection level (GVI, DVI or SDI) is related to the size and location of the damage tobe detected. Most types of corrosion are detectable through a general visual inspection. A detailedinspection level may be required for stress, galvanic, intergranular, fretting, pitting and crevicecorrosion types. Difficult access areas may require the use of boroscopic or video equipment (SDI).

e) Corrosion Prevention and Control Program (CPCP)

The objective of the CPCP is to maintain corrosion to level 1 or better. Corrosion levels are defined in

EASA AMC-20-20.During periodic reviews, ATR compares the existing inspection program with the latest in-servicefindings. Corrosion cases > level 1 are critically analysed. Age and operating history of the affectedaircraft, nature and importance of the deteriorated structure, severity of the corrosion cases are takeninto account. Should the existing inspection program prove to be inadequate, ATR will proposecorrective actions and submit them to the STG. The STG may decide:

- to request a new SSI be created, or an existing one be modified to cover a new structural area

- to tag the SSI and the corresponding ED inspection task as “CPCP”; a “YES” is then added inthe CPCP column of the MRB Report

- to increase the inspection frequency of a task or to modify its inspection level

Where applicable, the escalation (reduction of inspection frequency) of ED inspection tasks can beproposed following the guidelines of IP44, or to correct a too conservative impact of previous CPCPreviews.

In-service experience and CPCP considerations are reported in sheet 4, along with the finalinspection requirements.

3-1-3-3-9 F ATIGUE D AMAGE ANALYSIS (SHEET 5)

Structural items that are designed following the Safe Life concept are not inspected for fatiguedamage. The applicable life limit is mentioned.

For Damage Tolerant SSI, the inspection program is based on fatigue and crack propagation

calculations and tests and provides a high probability of detecting fatigue damage before the residualstrength drops below acceptable levels.

Inspection thresholds and intervals are a function of fatigue and crack propagation lives, which areevaluated by the responsible design office and transmitted to the Maintenance Engineering Group,along with a proposed suitable inspection method.

The following is taken into account:

- material properties and surface condition

- design characteristics and applied loads

- initial crack length, introduced during the production process or consequence of a possibleaccidental damage (see sheet 3a)

- critical crack length: when the structure is no longer able to provide the required residualstrength

http://easa.europa.eu/system/files/dfu/Annex%202-3-4-5%20to%20Decision%202007-019-R.pdf#page=116

http://easa.europa.eu/system/files/dfu/IP%2044%20Evolution-Optimization%20Guidelines%20%20issue%203.pdf

http://easa.europa.eu/system/files/dfu/IP%2044%20Evolution-Optimization%20Guidelines%20%20issue%203.pdf

http://easa.europa.eu/system/files/dfu/Annex%202-3-4-5%20to%20Decision%202007-019-R.pdf#page=116

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- the detectable crack length, that depends on the chosen inspection level: 150 mm for WA, 75mm for GVI, 15 mm for DVI, less than 15 mm for SDI.

Based on the calculated thresholds and intervals, fatigue inspection tasks are usually groupedtogether at pre-determined values, following a block maintenance concept.

The most significant data are mentioned in sheet 5: possible impact from AD, the description and afigure of the fatigue damage to be detected, initial and critical crack lengths and the selectedinspection level. When an SDI is required, the chosen NDT method is mentioned, along with the

corresponding detectable crack length.The FD analysis for an SSI can be “covered by another SSI”: calculations performed and inspectionrequirements defined for a similar, but more critical, structural detail (the “covering” SSI), areextended to the “covered” SSI.

When the fatigue damage is of systematic nature, the fatigue damage inspection task is eligible for the sampling program. Refer to §2-7.

Non-metallic structures on ATR aircraft are designed so that fatigue damage is not expected.

3-1-3-3-10 SSI TASK SUMMARY (SHEET 6)

All maintenance tasks resulting from the MSG-3 analysis are listed. The table contains all the

information needed to compile the MRB report:- <task>: sequential number. This value does not appear in the MRBR.- <MRBR task>: the task reference used in the MRBR- <zone>: the list of zones concerned by the task, separated by commas- <description>: type and location of damage to be detected- <access and preparation>: the list of accesses to be opened/removed, separated by commas,

followed by the list of preparations- <I/L>: Inspection Level, "DVI", "GVI" or "SDI (xx)". "xx" is the code of the inspection method,

one of the following:TT = tap testUT = ultrasonicEC = eddy current

XR = x-rayFPI = fluorescent penetrantMP = magnetic particleBO = boroscope

Figure 7: FD on metallic structure flowchart

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- <DS>: damage source: "FD" (fatigue), "ED" (environmental) or "OD" (other damage)- <AD>: to be checked if accidental damage impacts the task. In the MRBR, this results

in “’AD” for non-metallic materials, “AD/ED” or “AD/FD” for metallic materials.- <threshold> and <interval>: the task threshold/interval with the units: "FL" for flights, "FH" for flight

hours, "YE" for years- <FSP>: fatigue sampling program, to be checked if applicable- <CPCP>: to be checked for tasks affected by the CPCP program

- <effectivity>: the aircraft configurations for which the task is applicable. "all" if applicable toall aircraft

- <TTZ>: to be checked if the task is transferred to the zonal program

3-1-3-3-11 INDIVIDUAL TASK INFORMATION (SHEET 7)

This sheet (basically, one page for each task listed in sheet 6) provides additional information relatedto the inspection. Specific instructions are mentioned here, together with references of applicableNDT manual or JIC.

For tasks that are transferred to the zonal program, the selected zonal tasks are mentioned here.

3-1-3-4 NOTES ON ENVIRONMENTAL DETERIORATION ON NON-METALLIC MATERIALS

Several factors contribute to the deterioration of non-metallic materials in time.

a) Moisture. The resins used with composite materials tend to absorb moisture, especially under high temperature and humidity. This has a negative impact on the strength and stiffness of thematerial. The effects of moisture absorption are taken into account during design and certification: thereduced mechanical properties are used for calculations and artificial ageing is performed on selectedtest articles.

b) Ultraviolet light. An intact paint system effectively protects from the effects of UV radiation.Should the paint system be damaged, UV radiation may degrade the resin used in compositematerials. Such degradation is very slow and limited to a thin superficial layer. The GVI inspections of the zonal program are considered adequate to cover this aspect.

c) Aggressive fluids. Composite structures do not show particular susceptibility to products usedin aircraft (hydraulic fluid, fuel, de-icing product…).

d) In-service ageing. The ATR72 was the first civil aviation aircraft to feature a composite primarystructural part (outer wing box). Possible long term effects of ageing in an operating environment havenot been fully documented for composite structures. So far, neither in-service findings nor testexperience have highlighted any significant reduction of strength or stiffness due to the process of ageing.

No dedicated inspections are necessary to cover the above aspects. The zonal program is consideredadequate to verify the integrity of the paint system.

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3-1-3-5 TEMPLATE OF SSI ANALYSIS

A blank template of SSI analysis is given as example in the following pages.

Figure 8: one page of the structure program section of the MRBR

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3-1-4 ZONAL ANALYSIS (INCLUDING EZAP AND L/HIRF)

3-1-4-1 INTRODUCTION

The analysis selection provides an overview of the Zonal analysis for the aircraft.The aircraft is broken down into 8 major zones (100 to 800) each of them being divided in major sub-zones and zones.

The zones numbering and identification is based on ATA iSpec 2200 (formerly ATA Spec 100).

A general description of the aircraft zones and access doors/panels is given in ATR Zone/AccessPanels and Doors Identification document (ZAPDI).

A three-digit number identifies all zones:- Major zones: 100, 200…- Major sub-zones: 110, 120…- Specific zones: 121, 122…

Each access panel/door or fairing is identified in relation to the aircraft zone in which it is located by athree digit zone number followed by a two-letter suffix to indicate the location within the zone (e.g.125AL).

3-1-4-2 ZONAL ANALYSIS SELECTION PROCESS

All the major zones, major sub-zones and specific zones shall be listed in a top-down approach.

For each zone, the relevant analysis type to be established is selected by applying the followingcriteria:

- Standard Zonal analysis: All zones (zones containing: structure items and/or equipment

and/or wiring and/or L/HIRF protection elements).- Enhanced Zonal analysis: Zones with wiring.- L/HIRF Zonal analysis: Zones with L/HIRF protections installed

NOTA: L/HIRF zonal analysis applies only to protections added or modified through themodification 5948.

3-1-4-2-1 GENERAL

This section contains guidelines for developing:- Standard Zonal analysis- Enhanced Zonal Analysis Procedure (EZAP)- L/HIRF Zonal Analysis Procedure

The Zonal Analysis covers the following sub-processes:- Administrative data- Zone description- Standard Zonal Analyses- Enhanced Zonal Analyses- L/HIRF Zonal Analyses- Consolidation

Zone description:By means of the zone description (structure items, systems installation, wiring installed in the zone), itis possible to determine the subsequent analysis procedure to be followed (Standard, Enhanced)

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Standard Zonal Analysis:The Standard Zonal Analysis allows to identify General Visual Inspections (GVI) which aim is todetect degradation of structural and systems items, particularly those not classified as MSI (Systemsinstallations) and SSIs.

Enhanced Zonal Analysis:The Enhanced Zonal Analysis allows appropriate attention to be given to safety related deterioration

of wirings, particularly in zones having the potential for combustible material being present.

L/HIRF Zonal Analysis:The L/HIRF Zonal Analysis allows identification of maintenance tasks to detect degradation of L/HIRFprotection features that was identified during L/HIRF certification as having an adverse effect onsafety.

Consolidation:Once the relevant maintenance requirements have been identified, a consolidation process willdetermine if the General Visual Inspections (GVIs) coming either from:

- Enhanced Zonal Analysis and/or,- L/HIRF Zonal Analysis,

- Systems and Powerplant Analysis and /or - Structure Analysis,

are adequately covered by the inspections identified within the Standard Zonal Analysis. Tasksadequately covered by the Standard Zonal Inspections will not appear as dedicated ones in other sections of the scheduled maintenance.The stand-alone tasks arising from the Enhanced Zonal Analysis and L/HIRF Zonal Analysis will beintroduced as dedicated tasks in ATA Chapter 20 of the System and Powerplant section under theresponsibility of the Zonal Maintenance Working Group.Other GVI arising from System & Powerplant and the Structure analysis not adequately covered bythe Zonal will remain in the respective sections.

3-1-4-2-2 ZONE DESCRIPTION

GENERAL

The purpose of this description is to identify the content and condition of the zone, that is to say:- Installed structure items- Installed equipment- Installed wiring- Location (ceiling, under floor, sidewalk, etc.)- Route identification:- Installed L/HIRF protection

- Possible combustible material accumulation (to be listed on the Enhanced Zonal analysis –Evaluation sheet 1.)

DESCRIPTION DATA

1-Identification and description of the Zone and boundaries

The zones shall be defined in accordance with the aircraft zoning.The zone, wherever possible, shall be defined by actual physical boundaries such as wing spars,major bulkheads, cabin floor, skin, etc.

2- List details of zone

An evaluation will be carried out to identify:- Significant structure components

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- Installed equipment- Wiring installed- L/HIRF protection installed

Some components (fuel piping, anti-ice ducting...) are identified on the empty form sheets in order toprovide a clear understanding of what is in the zone and how it could potentially affect wiring or firepropagation. For these items the installation information “YES/NO” must be given in the dedicated

column. In case of further structure/equipment/wiring of interest for the Zonal analysis inside the zone,these should be listed in the dedicated tables below the already identified items.

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3- Illustration Sheets

For each zone:- on appropriate diagrams, identify all accesses by a reference number - compile a zone inventory: list all items located in it (MSIs, SSIs, ducting,piping, wiring,

mechanical controls, "other" structure, insulation blankets) with their respective accesses andmaintenance requirement.

For each access, determine:- the size- the number and type of fasteners.

Pertinent wiring identification should be conducted in order to pay particular attention to:- the potential for wire bundle failure to cause fire ignition (high power arcing)- the potential for loss of multiple functions to the extend that continued safe operation may not

be possible (wiring failure as a consequence of ageing, adjacent arcing or fire).

A general view of the wiring routes present in the analyzed zone is necessary without individual wiringassessment as the relevant functional failures are covered in System analysis.

Illustrations have to be provided to mainly indicate sensitive areas (wiring, flight controlcomponents...) within their environment, thus making easier the analysis process.

Current photo or drawing may be used. (e.g. photos from aircraft zones in order to describe in-serviceconditions for similar installation and environment)

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3-1-4-2-3 STANDARD ZONAL ANALYSIS PROCEDURE

The intent of the Standard Zonal Analysis is to develop effective general visual inspection tasksallowing timely detection of obvious degradation or hidden failures of system and structuralcomponents.

Consequently, for each zone, the zonal analysis must be able to determine:- the degree of accessibility to all the items in it,- the potential for damage,- suitable inspection intervals, consistent with the opening of specific accesses (short intervals

should relate to accesses easy to open).

The purpose of the Standard Zonal analysis is to identify GVIs to detect damage or deterioration of structure items and systems installations including wirings and L/HIRF protections, for which nospecific task was created. The density of components within the zone, the importance of thesecomponents and the environment of the zone are to be taken into consideration.

Any cleaning that is considered necessary should be performed before the Zonal inspection tofacilitate discrepancy identification.

The interval determination will be carried out taking the following factors into consideration:

DENSITY

This rating is a measure of how close the various systems components and wiring are packed in thezone being. Thus the density rating gives an idea of how much the failure of a particular item in thezone can affect adjacent installations and particularly if this include wiring. It also indicates the degreeof inspectability of the system installation and structure in the zone.

IMPORTANCEThis rating is a measure of how important the components (systems, structure, wiring, L/HIRFprotection) in the zone are to the safe and/or economic operation of the aircraft. When rating theimportance of a zone, account should also be taken of whether or not components in the zone havefunctional failures which could damage surrounding systems or structure (e.g. hydraulic leakage canpossibly lead to corrosion of adjacent structure).

The following zones will be considered as high level of importance:- adjacent fuel tank zones where failure of components could cause localized heating of tank

surfaces and consequently auto-ignition of the fuel.- fuel leakage zones where temperature as a result of failure could increase (e.g. overloaded

electric motors or transformers, failures in the pneumatic system and/or ducting) and wherepossible ignition sources exist (electrical arcs, friction sparks resulting from mechanicalcontact of rotating equipment).Fuel tank zones should be considered as moderate level of importance: service experienceidentified accidental and foreign object damage, microbiological contamination and corrosionas main concerns for fuel tank internal areas.

ENVIRONMENTAL

This rating is a measure of how much the zone is subject to temperature, vibration, atmosphericexposure, moisture, contamination and the possibility of accidental damage to systems and structurein the zone.

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The density, importance and environment factors shall be combined to an overall rating according tothe following figure:

To justify rating selection a brief explanation must be given for each characteristic in the box providedon the evaluation sheet.

The following sheet should be applied for each individual zone evaluation:

NOTE: This rating table is used as a guideline. If another interval is selected by engineering judgement, justification for inspection interval falling outside of Zonal guidance interval must be writtenin the relevant box.

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The determination of the appropriate task scope and interval should be based on :- the various intervals of tasks proposed for transfer (refer to zone inventory).- the task complexibility level according to accesses.

Standard zonal evaluation – Final Question: “Is there an additional specific access/area to beanalysed?”

This question selects supplementary GVIs when additional accesses (panels, doors, lining, fairingetc.) need to be opened to gain proximity to some specific areas within the zone.

As different interval can be selected for each GVI a separate evaluation sheet is to be compiled.

A negative answer directs to the Enhanced Zonal Analysis.

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3-1-4-2-5 ENHANCED ZONAL ANALYSIS PROCEDURE

The Enhanced Zonal Analysis procedure allows appropriate attention to be given to electrical wiringinstallation within a zone.The logic provides a means to identify applicable and effective tasks to minimise combustible materialaccumulation and to address significant wiring discrepancies that may not be reliably detected

through Standard Zonal inspections.

The changes in maintenance regulations have been addressed by the FAA through an AgingTransport Systems Rulemaking Advisory Committee (ATSRAC). An Enhanced Zonal AnalysisProcedure was developed in order to assess age related deterioration of systems installations andnotably to permit appropriate attention to be given to potential safety related deterioration of wiring.

The methodology used to develop the requirements includes a means that must lead to minimize:- Local accumulation of combustible material that could cause a fire to be sustained,- Wiring degradation likelihood to turn into fire ignition source,- Wiring fire occurrence adjacent to flight controls systems able to adversely affect more than

one redundant channel. This concern is raised if design directives and Certification Basis arenot constraining enough regarding separation and segregation between redundant criticalsystems.

For additional information on the Enhanced Zonal analysis see also the EASA CS-25 Amendment 5subpart H decision 2008-006 and FAA AC25-27 (issue date 23rd November 2007).

The Enhanced Zonal Analysis Procedure must be performed for all zones containing wiring whereboth of the following criteria are met:

- Presence of combustible material- Potential for arcing in case of wiring insulation damage prone to cause fire ignition.

Wiring identification will be made by means of the Aircraft Wiring Manual (AWM).For zones without wiring installation no Enhanced Zonal Analysis is required: the Standard Zonal Analysis is adequate.

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Enhanced Zonal Analysis Flow Chart

Continue with EnhancedZonal Analysis

Zone contains wiring

YES NO

1. Accumulation of combustible material in zone

YES NO

3. Describe combustible material

YES NO

5. Define Task and Interval

6. Effective INSPECTION LEVEL for all wiring in the zone

GVI GVI + Specific Task

YES NO

7. Using AD/ED rating tables, assess likelihood of damage to wiringin the zone to determine an appropriate GVI Task and Interval

8. Description of specific Items/Areas in the zonefor which Stand-Alone GVI or DVI is justified

9. Select Inspection Level of specific Area/Wiring inthe zone using Rating Table

10. Using AD/ED Rating Tables determine an

appropriate Interval for each Inspection Task

11. Is an additional specific area to be inspected

13. Continue with L/HIRF Zonal AnalysisEvaluation Sheet 1

Enhanc ed Zonal

A n a l y s i s

12. L/HIRF protection elements installed in the zone ?

Y N

Continue with Task Summary &Consolidation Sheet

2. Are one of the following criteria met: Wiring close to both primary and back-up

hydraulic, mechanical or electrical flight controls Electric, electronic racks/flight compartment

Feeders

4. Can an effective Task be defined to

significantly reduce the likelihood of accumulation of combustible materials

AdditionalEnhancedEvaluation

Sheet 3 hasto be

compiled for each

additionalSpecific Area

NO YES

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Step 1: Accumulation of combustible material in zone

The assessment of expected combustible material in the zone is based on engineering judgement of service experience for zones/areas with similar environmental and installation conditions.

The "Accumulation of combustible material in zone" requires an evaluation of whether the zone mightcontain combustible material that could cause a fire to be sustained in the event of an ignition sourcearising in adjacent wiring.

Examples include the possible presence of fuel vapours, dust/lint accumulation, and contaminatedinsulation blankets.

With respect to commonly used liquids (e.g., oils, hydraulic fluids …) the analyst should refer to theproduct specification in order to assess the potential for combustibility. The product may be readilycombustible only in vapour/mist form and thus an assessment is required to determine if conditionsmight exist in the zone for the product to be in this state.

Vaporised synthetic oil and hydraulic fluids (e.g., Skydrol) should be considered combustible for thepurpose of the enhanced analysis. In non-vaporised state where these fluids are not consideredcombustible, they are a concern if they cause significant adherence of dust and lint.

Contamination by moisture (whether clean water or otherwise) need not be highlighted since,although it may increase the probability of arcing, it does not increase the combustibility of thematerial around a breach in the wiring insulation.

The analyst should assess what sources of combustible products may contaminate the zone followingany single failure considered likely from in-service experience. Unshrouded pipes having connectionswithin the zone are to be considered as potential contamination sources. Inherent ventilation in thezone should be taken into account when determining the potential for subsequent combustion.

For additional guidance on combustible material see the FAA AC25-27A (issue date 4th May 2010)

The following materials should not be considered as ignitable:

- Uncontaminated insulation blanket, however blankets soaked with hydraulic fluids will becomecombustible according to the flammability criteria of the hydraulic fluid. The only risk factor introduced by the blanket is the propagation of the hydraulic contamination by capillarity.

- Structural corrosion inhibitors, i.e. Temporary Protection System, although there is a flashpoint at ambient temperature.

- Moisture (though it may increase the probability of arcing)

- Wiring insulation

Materials that are combustible are described in the table provided on the “Enhanced Evaluation Sheet1” including applicable comments and details (e.g. location and assessment of effect on wiring relatedrisk)

Step 2: Are one of the following criteria met:

- Wiring close to both primary and back-up hydraulic, mechanical or electrical flight controls

- Electronic, electrical, racks /Flight compartment,

- Feeders

Even in the absence of combustible material, a localized wire arcing could impact continued safe flightand landing if hydraulic pipes or mechanical cables or wiring associated to flight controls are routed inclose proximity (i.e., within 2 inches/5 cm) to a wiring harness.In consideration of the redundancy in flight control systems, the question need to be answered ‘Yes’only if both the primary and back-up system might be affected by wire arcing. Note that in zones

where a fire might be sustained by combustible material the enhanced logic will automatically befollowed.

Avionics and instruments located in the flight compartment and equipment bays tend to attract dust. Inview of the heat generated by these components and the relatively tightly packed installations, the

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analyst should consider these zones as having potential for combustible material.Thus the enhanced logic should always be used for these zones.

Step 3: Describe combustible material

Describe combustible material in the table provided on the “Enhanced Evaluation Sheet 1” includingapplicable comments and details (e.g. location and assessment of effect on wiring related risk)

Step 4: Is there an effective task to significantly reduce the likelihood of accumulationof combustible materials

This question requires an evaluation of whether the accumulation on or adjacent to wiring can besignificantly reduced. Task effectiveness criteria should include consideration of the potential for damaging the wiring.

Dust and lint accumulation will constitute a hazard by enhancing fire ignition risk and consequentlypermitting fire propagation if the depth of accumulation is significant in the vicinity of electrical cablesor covering them.

Significant dust accumulation on wiring, confirmed by in-service a/c inspection and operator inputs inthe WG, may justify a cleaning task irrespective of accessibility. Any dust accumulation in closeproximity to wiring (e.g. on liners and insulation blankets) should be evaluated on a case by casebasis taking in consideration the wiring arcing potential, debris combustibility and environmentalconditions. Localised cleaning tasks may be appropriate irrespective of the degree of contaminationdue to the impact of the accumulation on the certified flammability properties of the material.

Though cleaning tasks are the most likely applicable tasks, the possibility to identify other tasks is noteliminated. A detailed inspection of a hydraulic pipe might be assessed as appropriate if high-pressure mist from pinhole corrosion could impinge a wire bundle and the inherent zone ventilation islow.

If the answer to Step 4 is 'YES', and a task is identified that can significantly reduce the likelihood of

accumulation of combustible materials, the task and an appropriate interval must be defined.

If the task identified is a cleaning task to remove dust/lint accumulation from wiring, the interval for thetask must be frequent enough to keep the wiring relatively clean based on the expected rate of accumulation of dust/lint on the wiring in the zone.

Note: The analysis is continued with definition of the applicable wiring inspection task(s) (Evaluationsheet 2. - Wiring inspection task determination) for all zones that contain wiring, regardless if acleaning is selected or not.

Step 5: Define task and Interval

This step will define an applicable task and an effective interval. It should be included as a dedicatedtask in the Systems & Power plant section (ATA 20).Though the cleaning tasks are the most likely applicable, the possibility to identify other tasks shouldnot be eliminated (Example: hydraulic corrosion inspection to avoid flammable mist emerging from apinhole). The task level may include:

- Servicing

- General Visual Inspection (GVI)

- Stand-alone GVI: The stand-Alone is a General Visual Inspection which is not performed aspart of a zonal inspection owing to the need to pay particular attention to specific items or features.

- Detailed Visual Inspection (DVI)- Restoration. It is not the intent that restoration tasks should be so aggressive as to damage

the wiring, but should be applied to a level that significantly reduces the likelihood of combustion.

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- Discard

Procedure for wiring inspection task determination (Evaluation sheets 2 and 3)While it is useful to know the Standard Zonal GVI interval while conducting this analysis, it is notassumed that the Zonal GVI interval selected during this analysis with respect to wiring will be thesame as the Standard Zonal inspection interval. During task consolidation after completion of theanalysis, the lowest Zonal GVI interval for the zone will take precedent.The minimum outcome of this analysis will always be a Zonal GVI of any zone where the presence of combustible materials is possible.

Step 6: Effective inspection level for all wiring in the Zone

The DENSITY, SIZE and POTENTIAL EFFECT OF FIRE IN ZONE assessment provide guidance if aZonal GVI alone is adequate for all wiring in the zone, or if the Zonal GVI must be augmented with aStand-alone GVI or a DVI of some portion of the wiring (Zonal GVI + Specific task).

There may be justification that within the same zone some wiring may be more vulnerable than othersand thus there needs to be a discussion on whether the same Inspection level is appropriate for allwiring in the zone.

Either of the following possibilities can be identified:- GVI of all wiring within the entire zone.

- A combination of a DVI for specific areas within the zone (e.g. wiring bundles routed in thefloor) and a GVI for other wiring in zone. In this case an applicable task combination should beselected. Note that in practice the GVI will apply to all the wiring in the zone since it isimpractical to suggest that the inspector does not look at wiring subjected to DVI.

Stand-aloneGVI or DVI for a specific area

in the zone

GVI for all wiring in thezone

GVI is adequate for allwiring in the zone

Wiring Routing

Wiring

WiringZONE XXX

ZONE YYY

Case 1:

Case 2:

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The following tables are used to select the appropriate task combination for the inspection of thewiring in the zone based on an assessment of zone size, density, and potential effects of fire in thezone:

The inspection task combination is determined on the base of the following criteria:

Density:

Density of installed equipment, including wiring, within the zone will be assessed relative to the size of the zone. The density of the zone is typically identified as low, medium or high.

This criterion refers to the number of components, their relative closeness to each other and their complexity (with several mechanical, hydraulic, electrical connections or exposed bell cranks, levers...)

Size of the area to be inspected:

Zone size will be assessed relative to the size of the aircraft, typically identified as small, medium or large.

Potential effect of fire on adjacent wiring and systems in the zone:

Potential effects of fire on adjacent wiring and systems requires the analyst to assess the potentialeffect of a localised fire on adjacent wiring and systems by considering the potential for loss of multiple functions to the extent that continued safe operation may not be possible:

- High: Zones with very important wiring/equipment installed

(e.g.: flight controls, engine control...).(i) in close proximity to G (Electrical Generation) & P (Power) routes.(ii) where segregation and redundancy cannot be considered sufficient to ensure continued

safe operation in the event of a localised fire in the zone.

- Moderate: Zones with important wiring/equipment installed.

(i) in close proximity to G & P routes.(ii) where segregation and redundancy cannot be considered sufficient to avoid significant

operational effect of a localised fire in the zone.

- Low: Other systems (Example: equipment related to cargo loading, passenger comfort, ...) or zones with no G & P routes

This criterion applies to the wiring and equipment that could be globally destroyed by the fire.Individual wiring assessment is not required because the relevant functional failure is coveredin standard system analysis.

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NOTA :

ATR A/C complying with SFAR88.

The required inspection level and interval may be influenced if “accumulation of combustible materialavoidance tasks” are identified in the previous Step 5. For example, if a cleaning task was selectedthat will minimise the accumulation of combustible materials in the zone, this may justify selection of a

lower inspection level and/or higher interval for the wiring inspection in the zone.If a Zonal GVI alone is adequate for all wiring in the zone, the analyst must select an interval (step 6).

If a Zonal GVI alone is not adequate for all wiring in the zone:

- a Zonal GVI must be identified and an interval selected (Step 7) for the other wiring in thezone (same as above).

- a complementary analysis (Enhanced Evaluation sheet 3) must be conducted for eachidentified Items/Areas where a Stand-alone GVI or a DVI inspection is justified (Step 7 andfollowing).

Whenever a GVI level is selected and some restriction applies to the required ‘touching distance’, it

must be highlighted.The working group may decide to deviate from the initial logic in cases where the logic drives to ``GVI+ SPECIFIC TASK’’.In such cases, the WG should validate the deviation from EZAP Analysis results only after inspectionof the applicable zone and review of appropriate data and when consensus has been reachedbetween working group members and regulatory authorities.

Step 7: Select interval for GVI of all wiring in the zone

The following rating tables including possibility of accidental damage and environment factors, assesslikelihood of damage to wiring in the zone to determine an appropriate interval for each inspection

task has to be identified:

INSPECTION INTERVAL

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The inspection interval is determined on the base of accidental damage and environment.

Accidental damage may be:

- Ground handling

- Cargo handling

- Maintenance :

Impacts arising during performance of maintenance - Servicing, repair, troubleshooting,modifications embodiment, TPS application, pressure washing, , ... -)

- Passenger traffic

- Weather effects (Hail, ingress of slush, mud, water, ...)

- Foreign objects

- Fluid spillage:Spillage from Oils, waste water, battery electrolyte, livestock waste, acid or alkaline products,salt water...)

Environmental criteria are factors resulting in changes in physical and chemical properties of

wiring insulation and consequently, the flexibility, the hardness, the tensile strength, thecompressive and torsion strength, the electrical insulation, etc.

They may be:

- Temperature (extremes, temperature cycles, )

- Vibrations

- Humidity, condensation

- Contamination (Organic or mineral aggressive agent, corrosive or abrasive dusts, alkaline or acid dusts, sulphide deposit may form on fuel tank components and wiring by which an arcingcould occur.)

- Chemical (Toilet fluids, de-icing…)

Due to in-service experience, the Zonal inspection interval can be altered from the basic guidanceinterval given in the rating chart. In this case the relevant section "Remarks" shall be completed inorder to substantiate such a deviation.

This rating table serves as a guideline. If another interval is selected by engineering judgement, justification for inspection interval falling outside of Zonal guidance interval must be provided onthe relevant box.

Step 8: Area/Wiring description

Area description/boundaries and identification of specific wiring installed in the area.

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Step 9: Select Inspection Level for Specific Area/Wiring in the zone

The following table is used to select the appropriate interval based on an assessment of zone size,density, and potential effects of fire in the zone (see Step 6 for the Rating System explanation):

INSPECTION LEVEL

DENSITY Size/Density:Low Moderate High

SIZESmall 1 2 2

Medium 2 2 3Large 3 3 3

SIZE/DENSITY FACTOR Remarks:1 2 3

Potentialeffect of fireon adjacentwiring andsystems in

the area

Low

Moderate Stand-

alone GVIStand-

alone GVI

High Stand-

alone GVI

Stand-alone GVI

Stand-alone GVI

DVI DVI

Note: The blank boxes indicate that the selection of a specific area within the zone is uselessbecause the GVI alone identified on the Evaluation sheet 2 is adequate for all wiring inthe zone.

Step 10: Select Interval for Specific Area/Wiring in the zone

The following table is used to select the appropriate level for the inspection of the specific wiring in thezone based on an assessment of environment factors and possible accidental damage (see Step 6for the Rating System explanation)

INSPECTION INTERVAL

Due to in-service experience, the zonal inspection interval can be altered from the basic guidanceinterval given in the rating chart. Any deviation from interval framework must be justified

Others

Humidity

Contamination

Chemical (toilet fluids,..)

Temperature

RATINGN/A=0,Low=1,

Moderate=2,High=3

Vibration

Others

Humidity

Contamination

Chemical (toilet fluids,..)

Temperature

N/A=0,Low=1,

Moderate=2,High=3

ENVIRONMENTAL

Vibration

Others

Passenger traffic

Maintenance

Weather effects

Foreign objects

Fluid spillage

Ground Handling

RATINN/A=0,Low=1,

Moderate=2,High=3

Cargo Handling

Others

Passenger traffic

Maintenance

Weather effects

Foreign objects

Fluid spillage

Ground Handling

RATINGN/A=0,Low=1,

Moderate=2,High=3

ACCIDENTALDAMAGE

Cargo Handling

ENVIRONMENTAL RATING

A – C3MO–2YE

A – C3MO–2YE

C–2C2YE–4YE

3

2C–4C4YE–8YE

4C8YE

1

C–4C2YE–8YE3

ACCIDENTALDAMAGE

RATING

21

C–4C2YE–8YE

2C–4C4YE–8YE

2

ENVIRONMENTAL RATING

3

20000FH8YE

1

5000-10000FH

2YE-4YE3

ACCIDENTALDAMAGE

RATING

21

10000-20000FH4YE –8YE

2

500-5000FH

3MO-2YE

5000-20000FH2YE-8YE

10000-20000FH4YE –8YE

5000-20000FH2YE-8YE

2YE-8YE5000-20000FH

500-5000FH

3MO-2YE

Select the Highest Rating

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Step 11: Is an additional Specific Area to be inspected

If the answer to Step 11 is "No", the analysis is continued with Task Summary and ConsolidationSheet. If the answer to Step 11 is "Yes" task must be defined for each specific area identified in thezone (an additional Evaluation Sheet 3 has to be compiled for each additional Specific Area).

Step 12: L/HIRF protection elements installed in the zone?

Directs to continue with MSG-3 L/HIRF Zonal analysis for all zones with L/HIRF protection elementsinstalled. For zones with no L/HIRF protection elements installed, the analysis is continued with tasktransfer and consolidation for that zone.

3-1-4-2-6 LIGHTNING / HIRF ANALYSIS PROCEDURE

The intent of the L/HIRF analysis procedure is to define L/HIRF protection maintenance tasks in order to reduce the possibility that a single failure cause (e.g. lightning strike), and the occurrence of acommon failure cause such as Environmental or Accidental Damage (ED or AD) across (functional)

redundant channels of L/HIRF protection, could impact aircraft airworthiness.

Each L/HIRF protection system item is evaluated in terms of its susceptibility to degradation fromenvironmental deterioration and/or accidental damage. The L/HIRF protection system maintenancetasks are developed in support of the aircraft type certification and MRB report development.

L/HIRF maintenance relies on adequate protection provided by both external and internal L/HIRFprotection components.

- L/HIRF protection features incorporated inside Line Replaceable Unit (LRU) will not beanalysed. This includes protection devices such as filter pin connectors, discrete filter capacitors and transient protection devices (transorbs) which may be installed within LRU. For LRUs whose failure could have an adverse effect on safety, the LRU manufacturer’maintenance philosophy ensures the continued effectiveness of L/HIRF protective features.

- All L/HIRF protections on the aircraft (any protection not within an LRU) whose failure wasidentified during L/HIRF certification as having an adverse effect on safety will be analysed.This includes items such as shielded wires, raceways, bonding leads, connectors, compositefairings with conductive mesh.

As per L/HIRF certification, three levels of equipment may be defined depending on their failure effecton aircraft safety.

Level A equipment perform critical functions whose failure would contribute to or cause a failurecondition which would prevent the continued safe flight and landing of the airplane. (catastrophicfailure condition for the aircraft)

Level B and C equipment perform essential functions whose failure would contribute to or cause afailure condition which would significantly impact the safety of the aircraft or the ability of the flightcrew to cope with adverse operating conditions. (hazardous or major failure condition for the aircraft)

ATR considers that hazardous/major and catastrophic conditions constitute an adverse effect onsafety.

All L/HIRF protection elements for level A, B and C equipment will be analysed.

Every Zones will be analysed in order to identify installed L/HIRF protection elements and to assessthe need for a dedicated L/HIRF maintenance task. Many protections against HIRF and Lightningindirect effects are naturally covered through the existing Zonal inspections. Where this Zonalmaintenance will not adequately identify degradation of the L/HIRF protection, additional scheduledmaintenance tasks may be generated.

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In cases where no dedicated L/HIRF tasks have been selected the following concepts must beensured :

1- All visible L/HIRF protections (wires, shields, connectors, bonding leads, raceways betweenconnectors or termination points) are covered by the Zonal Inspections.

2- L/HIRF protections within conduit are covered in the Zonal Inspections by confirming integrityof the protective covering.

3- Maintenance of the inherent conductivity of the aircraft structure is covered by the ZonalInspections. Corrosion concerns are addressed by the Structural Inspections.

4- Composite fairings with conductive mesh are covered by the Zonal Inspections.

Preparatory step (Description Sheet 4)

Before performing the L/HIRF Zonal Analysis, the following information is necessary:

1- Provide a list and a description of the L/HIRF protections installed in the zone. Protection withina given zone should include both electrical and non-electrical protection components.

2- Provide the protection component characteristics and applicable performance data (if available)for each protection component within the zone. Protection component characteristics areproperties that are relied upon to provide L/HIRF protection such as resistance to corrosion,effects of environment and robustness of design. Examples of applicable performance datainclude: development data, qualification test data, in service data etc.

3- Rate each item’s susceptibility to ED or AD as Yes or NO based on characteristics andengineering judgement.

4- Identify if further analysis is required based on AD/ED susceptibility. If the item is rated as notsusceptible to both AD and ED, further analysis is not required.

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For all identified L/HIRF protections or group of protections susceptible to ED or AD the followingL/HIRF Zonal Analysis procedure applies.

L/HIRF Zonal Analysis Flow Chart

L/HIRF Zo nal

A n a l y s i s

1. Effective INSPECTION LEVEL for all L/HIRF protections in the zone

GVI GVI + Specific Task

2. Using AD/ED rating tables,determine an appropriate GVI Task

and Interval

3. Description of specific Items in the zone for which an additional task is required

4. Select Inspection Level of specific element

5. Using AD/ED Rating Tables determine anappropriate inspection interval

6. Are additional protection items to be inspected?

NO YES

End of L/HIRF Zonal Analysis. Continue with Task

Summary & Consolidation Sheet

Continue with L/HIRF Zonal AnalysisEvaluation Sheet 2 (GVI must be

augmented with additional inspection of L/HIRF protection element)

2.1. Will the failurecondition due to expected

degradation incombination with an

L/HIRF event prevent thecontinued safe flight and

landing of the aircraft?

YES NO

GVI notcandidateto Zonal

GVIcandidateto Zonal

AdditionalL/HIRF

EvaluationSheet 2 has

to becompiled for

each

additionalprotectionelement

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Step 1: Inspection level determination

The DENSITY and L/HIRF PROTECTION DETERIORATION CRITERIA assessment provideguidance if a GVI is adequate to inspect some or all protection elements.

The following table is used to select the appropriate GVI type based on an assessment of zonedensity:

Density of equipment: Density of wiring, braided conduits, connectors, and equipment installed,etc. within the zone will be assessed relative to the size of the zone. The density of the zone istypically identified as low, moderate or high. This criterion refers to the number of component,their relative closeness to each other and their complexity.

L/HIRF protection AD/ED susceptibility criteria: Rate susceptibility of L/HIRF protection to AD andED in respect of technology robustness (e.g. resistance to corrosion, degradation mode,

inspectability, level of redundancy and degree of segregation).

- Low: L/HIRF protection elements susceptible to minor aging effects (in respect of technologyrobustness) or having anticipated deterioration clearly detectable by visual inspection.

- Moderate: L/HIRF protection elements susceptible to moderate aging effects (in respect of technology robustness) or having anticipated deterioration not clearly detectable by visualinspection.

- High: L/HIRF protection elements susceptible to significant aging effects (in respect of

technology robustness) and having anticipated deterioration that may not be immediatelyapparent.

If a Zonal GVI is adequate for all protection elements in the zone, the analyst must select aninterval (step 2).

If a Zonal GVI is not adequate for all protection elements in the zone:

A Zonal GVI must be identified and an interval selected (Step 3) for the other protectionelements in the zone (same as above).

A complementary analysis (L/HIRF Evaluation sheet 2) must be conducted for each identifiedItems/Areas where a Stand-alone GVI or a DVI is justified (Step 3 and following).

NOTA: - Whenever a GVI level is selected and some restriction applies to the required ‘touchingdistance’, it must be highlighted.

GVI +Specific

Task

GVI +Specific

Task

GVIModerate

GVI +

SpecificTask

GVI

High

Remarks:

GVIGVILowL/HIRFprotection

AD/EDsusceptibility

criteria

ModerateLow

GVI +

SpecificTask

GVI +

SpecificTask

High

DENSITY

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- The working group may decide to deviate from the initial logic in cases where the logic drivesto ``GVI + SPECIFIC TASK’’.In such cases, the WG should validate the deviation from L/HIRF Analysis results only after inspection of the applicable zone and review of appropriate data and when consensus hasbeen reached between working group members and regulatory authorities

Step 2: Determine GVI task interval:

The following rating table including possibility of accidental damage and environment factors, assesslikelihood of damage to equipment protection in the zone to determine an appropriate interval for eachinspection task identified.

Inspection interval

The inspection interval is determined on the base of the following criteria:

Accidental damage may be:

- Ground handling

- Cargo handling

- MaintenanceImpacts arising during performance of maintenance - Servicing, repair, troubleshooting,modifications embodiment, TPS application, pressure washing, , ... -)

- Passenger traffic

- Weather effects (Hail, ingress of slush, mud, water, ...)- Foreign objects

- Fluid spillageSpillage from Oils, waste water, battery electrolyte, livestock waste, acid or alkaline products,salt water...)

Environmental criteria may be:

- Temperature (extremes, temperature cycles, )

- Vibrations

- Humidity, condensation

- Contamination (Organic or mineral aggressive agent, corrosive or abrasive dusts, alkaline or acid dusts…)

- Chemical (Toilet fluids, de-icing…)

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Due to in-service experience, the Zonal inspection interval can be altered from the basic guidanceinterval given in the rating chart. In this case the relevant section "Remarks" shall be completed inorder to substantiate such a deviation.

This rating table serves as a guideline if another interval is selected by engineering judgement, justification for inspection interval falling outside of Zonal guidance interval must be provided on therelevant box.

Step 2.1: GVI candidate to Zonal ?

For every GVI task the following question must be answered:

Will the L/HIRF protection failure condition due to the expected degradation (accidental damageand/or environmental deterioration), including common mode in localized area, in combination with anL/HIRF event prevent the continued safe flight and landing of the aircraft?

If answer YES is selected, the GVI task can’t be reviewed as candidate for transfer to the StandardZonal Program. In this case the GVI task will be listed as separate task in the Systems & Powerplantsection of the MRBR under ATA Chapter 20 with no Failure Effect Category (FEC) quoted (same asGVI Stand-alone).

If answer NO is selected, the GVI task can be reviewed as candidate for transfer to the StandardZonal Program.

Step 3: Items description for which an additional task is required.

As some protection items have to be addressed specifically this step allows identifying them together with, if needed, the relevant access to be opened/removed.

Step 4: Inspection Level Determination.

The inspection level is determined by the working group based on their engineering judgement inconsideration of accessibility and type of degradation.:

The task level may be selected from:- Stand-alone GVI: a GVI that is not performed as part of a Zonal inspection

- DVI (Detailed Visual Inspection)

- FUT (Functional Test). One way to characterize the shielding effectiveness of the braidedconduits is to measure the loop resistance made by the element and its bonding to the aircraftstructure.The FUT should be selected if one of the following conditions are met:

+ if substantiated by the findings of the Certification Plan implementation (tests andinspections to be carried out on in service aircraft in order to quantify the possibleelectromagnetic protection degradation).

+ if In-service experience has identified that this technology is insufficiently robust andrequires a functional test in addition to visual inspections.

FUT

DVI

Remarks:Stand AloneGVI

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Step 5: Interval determination.

Same as Step 2.

Step 6: Are additional protection elements to be inspected?

If the answer to question 6 is "No", end Zonal Analysis and continue with Task Summary &

Consolidation Sheet. If the answer to question 6 is "Yes", task must be defined for each specificprotection element identified in the zone (an additional Evaluation Sheet 2 has to be filled up and soon).

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The Forms to be used for the Enhanced and L/HIRF Zonal Analysis Procedure are thefollowing:- COVER SHEET

- LIST OF EFFECTIVE PAGES

- LIST OF REVISIONS

- DESCRIPTION SHEET 1 (STRUCTURE)

- DESCRIPTION SHEET 2 (EQUIPMENT)

- DESCRIPTION SHEET 3 ( WIRING)

- ILLUSTRATION SHEET

- EVALUATION SHEET 1



- TASK SUMMARY & CONSOLIDATION SHEET

- MRB REPORT INTERFACE SHEET

- TASK DATA SHEET

COVER SHEET

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LIST OF EFFECTIVE PAGES

LIST OF REVISIONS

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DESCRIPTION SHEET 1 (STRUCTURE)

DESCRIPTION SHEET 2 (EQUIPMENT)

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DESCRIPTION SHEET 3 ( WIRING)

DESCRIPTION SHEET 4 (L/HIRF PROTECTION ELEMENTS)

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ILLUSTRATION SHEET

STANDARD ZONAL ANALYSIS - EVALUATION SHEET 1

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ENHANCED ZONAL ANALYSIS - EVALUATION SHEET 1


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L/HIRF EVALUATION SHEET 1

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L/HIRF EVALUATION SHEET 2

TASK SUMMARY & CONSOLIDATION SHEET

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TASK(S) TRANSFERRED TO ZONAL PROGRAM

MRB REPORT INTERFACE SHEET

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TASK DATA SHEET

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3-1-4-2-6 CONSOLIDATION OF REQUIREMENTS BETWEEN ENHANCED ZONAL ANALYSIS AND STANDARD

ZONAL ANALYSIS

Consolidation of System & Power plant/Structure Maintenance Requirements

Some GVIs related to System & Powerplant analysis can be transferred by the relevant WG for

incorporation into the Zonal program with the assumption that the general nature of the Zonalinspection is not a hindrance. Where GVIs require attention on specific item, transfer should not beproposed if the inspector could miss the failure or the discrepancy.

These GVIs will be considered as adequately covered by the Zonal program if:- the interval requirements are similar or less restrictive (interval equal or less frequent)

- the access requirements are similar or less restrictive (similar access or less access) than thecorresponding zonal task.

If the Zonal Working group decides that a specific GVI requirement is not covered by the Zonalinspection, these GVIs must be returned with explanations to the originating WG for further consideration.

The transferred tasks will be identified within the Zonal Inspection Program by the reference of therelevant MSI/SSI.

Consolidation of Enhanced Zonal Maintenance Requirements

GVIs Stand-alone and DVI Tasks will be listed as separate Tasks in the Systems & Powerplantsection of the MRBR under ATA Chapter 20 with no Failure Effect Category (FEC) quoted.The following rules shall be applied for consolidation between the Enhanced Zonal GVIs and theStandard Zonal requirements:

- If the Enhanced GVI is less restrictive than the Standard Zonal requirement, the StandardZonal requirement (interval, access) must be considered in order to cover the Enhanced GVI.

- If the Enhanced GVI is more restrictive than the Standard Zonal requirement, the mostappropriate solution has to be selected taking into account economic aspects, either byconsidering the more restrictive requirements (Interval, Access) as being effective for theEnhanced GVI and the Standard Zonal or by keeping the Enhanced GVI as stand-aloneinspection (no consolidation).

Stand-alone GVIs, DVIsand Cleaning

GVIs GVIs

System & Powerplantsection

Structuresection

Zonalsection

ENHANCEDZONAL ANALYSIS STANDARDZONAL ANALYSIS STRUCTURE ANALYSIS SYSTEM &POWERPLANT ANALYSIS

Task consolidation

GVIs not adequately covered by theZonal

GVIs consolidated in Zonal inspection

Procedure

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- The relevant GVI will be listed as separate Tasks in the Systems & Powerplant section.

- The Enhanced GVI will take precedence over the Standard requirement. Consequently, theStandard Zonal analysis shall be amended to reflect the more frequent interval and the

justification.When an Enhanced GVI cannot be consolidated with an existing Standard Zonal GVI it istransferred to ATA Chapter 20.This situation could lead to have a duplicated GVI applying to the same zone(s) both inchapter 20 and in the Zonal Inspection Program (ZIP). If this case occurs, this situation mustbe highlighted to ISC attention.

Consolidation of L/HIRF Maintenance Requirements

GVIs Stand-alone, DVIs and FUTs Tasks will be listed as separate Tasks in the Systems &Powerplant section of the MRBR under ATA Chapter 20 with no Failure Effect Category (FEC)quoted.The following rules shall be applied for consolidation between the L/HIRF GVIs and the StandardZonal requirements:

- If the L/HIRF GVI is less restrictive than the Standard Zonal requirement, the more restrictive

must be considered as effective.

- If the L/HIRF GVI is more restrictive than the Standard Zonal requirement, the latter will not beconsidered as effective. The relevant GVI will be listed as separate tasks in the Systems &Powerplant section of the MRBR under ATA Chapter 20 with no Failure Effect Category (FEC)quoted (same as GVI Stand-alone). An inspection is “more restrictive” if the interval and/or theaccess requirements are more restrictive (interval more frequent, additional access).

Task Data

The purpose of the Task Data sheet is to provide procedural information for EZAP taskaccomplishment and additional task planning data.

For every selected EZAP task listed, a Task Data sheet is to be established.

The level of detail for the task procedure should be such that:- The working group is able to get a clear idea of the steps necessary for task accomplishment

(including tool and GSE requirements).

- The Task Data Sheet could be used as a source document to develop any associatedtechnical maintenance documentation.

- The planning data established for the Task Data sheets are intended to facilitate an efficientassessment of the selected EZAP Task effectiveness during the Working Group review andshall not be used for other purposes without validation. The figures for “Elapsed Time” and“Man-hours” shall be the ones for the actual task and not include access or preparation time.

The description of the task procedure shall similarly be limited to the task itself.

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3-1-5 DESCRIPTION OF TRANSFER PROCEDURES

The working group chairpersons shall refrain to switch tasks from one system working group toanother or from the systems program to the structures program and vice-versa. Proper selection of MSIs and SSIs will minimize the need for this type of transfer.

In the rare occasions when it cannot be avoided, the normal transfer procedure outlined below shallbe used.Due to the interconnection of the MSG-3 activities, communication between the MWG is needed.Two types of transfers can be possible:

- external transfer : transfer between Systems or Structure and Zonal Analysis.- internal transfer : transfer between different MSIs (restricted to MSG-3 systems analyses)

3-1-5-1 EXTERNAL TRANSFER: TRANSFER TO ZONAL WORKING GROUP

The external transfer procedure allows the management and the coordination of the General VisualInspections (GVI) tasks selected by the Systems or Structure analyses and the Zonal analyses.

Tasks issued in order to compensate a failure cause that has a safety impact cannot be transferred tothe zonal program.That is why system tasks with safety routes (5 or 8) are not suitable for transfer.

A task accepted for transfer shall no longer appear in the program from which it originated.Transferred tasks in the MSG-3 analysis are traced and listed in the corresponding zonal analysis.

Any further change to a transferred task or the corresponding zonal task(s) shall be reviewed by theappropriate working groups. Transferability shall be re-evaluated, and the related MSG-3 analysis isrevised.

A list of all tasks transferred to the zonal program shall be appended to the MRB report.

3-1-5-2 INTERNAL TRANSFER: TRANSFER OF FAILURE CAUSES BETWEEN MSI

The internal transfer procedure allows the management and the coordination of the functional failuresand failures causes (FC) between different MSIs composing the System Maintenance Program.When a FC appears in one MSI but belongs to the functional analysis of another MSI, this FC istransferred to the corresponding MSI.

During the MSI development, Failure Causes related to other ATA and/or MSI leading to the loss of the functional failures should be identified.The concerned failure cause will be tag in the form 4 at FC level (identified as “Transferred to MSI XX-XX-XX”)The level 2 of analysis is not done. Remarks block is filled in to indicate that form 6 is missing due toFC transferred.

The MSI that receives the transfer will cover it by taking into account the origin of the transfer and thefunctional failure that leads to the transfer.

The traceability of all the systems internal transfers should be recorded by the manufacturer ensuringthe necessary level of information to justify that the transfer is correctly covered by the other MSI.

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3-1-6 APPROVAL PROCEDURE OF MRB REPORT PROPOSAL OR MAJOR REVISIONS.

Issuance of MRB report proposal

Within two weeks after the last ISC meeting, the aircraft manufacturer shall submit a MRB reportproposal to the MRB chairpersons, with a copy to the operators' ISC chairperson and to participating

foreign airworthiness authorities, as directed by the EASA chairperson.This proposal package shall also contain all the revised task evaluation sheets and transfer sheetsreflecting the latest corrections/decisions.

Any new or corrected MSG-3 analyses and/or justifying data which have not already been distributedwith the minutes of the working groups and ISC meetings shall be included in this final proposalpackage.

Since most issues should have been closed through previous communications between the MRB andthe manufacturer, this proposal should only require minor editing.

Following receipt of the MRB report proposal, the MRB chairpersons will:

- review its content with its respective advisors.

- confirm conformity with the other participating regulatory authorities' requirements.

- forward its comments or requests for additional changes to the manufacturer.

Depending on the nature and magnitude of the comments or requests, a final review meetingbetween the manufacturer and the MRB might be necessary.

The need for such a meeting should be known as early as possible and it should be scheduled nolater than six weeks after issuance of the proposal.

Final corrections to the MRB report proposal and resubmission to the MRB shall occur within twoweeks following the last review meeting.

Following receipt of the corrected final proposal, the MRB chairpersons shall circulate it, withappropriate comments and recommendations, through the various decision levels of their organizationand seek approval.

A formal letter of approval shall be sent by EASA and FAA MRB chairpersons within ninety days fromthe date of the original submission by the Manufacturer, unless corrections are required.

By formal letter, other foreign participating authorities should notify their acceptance of the MRBreport to the EASA MRB chairperson, with copy to the ISC.

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3-2 ADDITIONAL PROCEDURES FOR SOME SPECIFIC MRB ACTIVITIES

3-2-1 MRB REPORT REVISION

3-2-1-1 TEMPORARY REVISIONS

Minor temporary revision:

The minor temporary revision process should be used as little as possible for small scale correctionsof obvious errors, misprints, or to update sampling program tables following completion of a particular sampling phase.

Whenever the minor revision affects the contents of a task, the corrected evaluation sheet shall beenclosed with the proposal.

The temporary revision proposal shall clearly indicate that it is "minor".

The aircraft manufacturer shall submit the temporary revision proposal simultaneously to the ISC andMRB chairpersons.

Comments and corrections from the ISC and MRB chairpersons shall be made as promptly aspossible following receipt of the proposal.

The corrected proposal shall be immediately resubmitted to the ISC and MRB chairpersons by theaircraft manufacturer.

Approval by the MRB chairpersons should follow as soon as possible.

The effectiveness of this process depends on the availability and goodwill of all persons involved andthe use of the fastest means of communication (telephone, telefax, e-mail).

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Significant temporary revision:

Significant temporary revisions are primarily used to reflect changes to the various tasks as aresult of modifications or service experience.

A list of all modifications altering the maintenance requirements shall be provided by the aircraft

manufacturer. Any significant change to a task shall be documented on both pages of an evaluation sheet; thefirst page outlining the proposed change, the second page recording the decisions taken at thevarious levels (WG, ISC).

Since any change to the description, route and interval of a task must be reflected in the MSG-3analysis from which this task originated, the corrected or new MSG-3 analyses shall be attached tothe temporary revision proposal.

The impact of the proposed changes shall be assessed in all programs (systems, structures andzonal). Corrections to transfer sheets might be required.

Any other relevant information such as descriptive material, design office or field findings, reliabilitydata, etc... Shall also be included in the proposal.

From time to time, significant temporary revisions may also address policy changes which affectthe MRB report introductions, program rules, glossaries etc...In such cases, the appropriate reference documents shall be added to the proposal.

The temporary revision proposal shall be submitted by the aircraft manufacturer to the ISC andMRB chairpersons.

Simultaneously, this proposal will be widely distributed to the airlines for advice and comments. Airlines must forward their response to the ISC chairpersons and the aircraft manufacturer withinthree weeks.

The ISC chairpersons will submit the proposal, with airlines comments, to the appropriate workinggroup chairperson(s) for review.

The working group chairperson(s) shall complete this review within the following month.

Corrections or additional justifications may be requested from the aircraft manufacturer by the ISCchairperson(s) before acceptance of this proposal.

The final version of the proposal will be submitted by the manufacturer to the MRB for review.It shall be compiled into a single document containing all changes, corrections and additional

justifications produced at the preceding review/ decision levels.

Having reviewed the proposal with the appropriate advisors, the MRB may recommend further changes before approval of the proposal as a temporary revision to the MRB report.

Agreement to the proposal, with comments and recommendations, at the different decision levelswill be recorded on a temporary revision approval/acceptance sheet.

As this MRB report has been approved/ accepted by more than one regulatory authority, theproposed revision will be evaluated for concurrence by all approving/ accepting authorities as per letter of agreement, prior to approval by the MRB chairperson(s).

Subsequent to MRB approval, each temporary revision will be distributed to all MRB report holdersby the aircraft manufacturer. The number of temporary revision copies requested by the FAA willall be sent to the FAA MRB chairperson who will be responsible for his own distribution.

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3-2-1-2 MAJOR REVISION

A major revision is warranted when a given aircraft type has accumulated sufficient serviceexperience to justify an overall increase, for example, of low initial "A" and "C" checks intervals.

A major revision, with system task interval escalation as its main objective, may also be taken as anopportunity to create, revise or delete any task, following the incorporation of significant changes tothe aircraft.

In this case, a list of all modifications altering the maintenance requirements shall be provided by theaircraft manufacturer.

Historical escalation procedure (before IP 44):

For system tasks with safety routes (5 and 8), interval escalation must be justified by satisfactoryreports on individual task findings from the operators themselves.For failure finding tasks, proposed interval increase should remain consistent with CMRs limits whenapplicable.

For system tasks with economic routes (6,7 and 9), interval escalation may be based solely on fleetreliability data from the aircraft manufacturer.

The aircraft manufacturer will issue an evaluation sheet for each task.

Based on collected data (operators findings and fleet reliability), the aircraft manufacturer willdetermine the applicability, for each system task, of the proposed new "A" and "C" intervals.Tasks with intervals greater than "2A" or "2C" which cannot follow the proposed escalation must bedowngraded to the next lower multiple of "A" or "C":i.e. for an increase in "A" interval from 300 FH to 400 FH, a "3A" task may no longer be effective at1200 FH and need to be downgraded to 800 FH.

Information on Evolution process are detailed in §3-2-1-3 “Evolution process for C checks andmultiples”

Escalation procedure (with IP44): Compliance to IP44 Evolution/Optimization Guidelines will needto be demonstrated by ATR

The aircraft manufacturer will generate, revise or update the appropriate MSG-3 analyses.

The impact of the change shall be assessed in all programs (systems, structures and zonal).Corrections to transfer sheets might be required.

The revision process may be handled entirely by the ISC whenever its work scope consists of reviewing task findings, reliability data and minor editing changes to MSG-3 analyses.In this case, at least two ISC meetings will likely be required.

The revision process will require working group activity whenever a significant amount of technicaldata and new or thoroughly revised MSG-3 analyses are submitted for review.In this case, at least two ISC meetings will be required, one at the beginning and one at the end of the process.

The number and type of working groups will be determined at the first ISC meeting.Decisions taken at the various meetings will be recorded on each task evaluation sheet.

Following final review of decisions by the ISC, a MRB report major revision proposal will be submittedto the MRB chairpersons by the aircraft manufacturer.

Review and approval shall follow the general procedure outlined in section 3-1-6.

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3-2-1-3 EVOLUTION PROCESS FOR C CHECKS AND MULTIPLES (BEFORE IP44)

General

This section describes only the evolution of the maintenance program further to Operator feedback, It does not cover design modification review activities which is required by§3.2.1.2 “MAJOR REVISION“.

The term 'Evolution' is used to clarify that the exercise considers all means to improve theprogram and does not focus entirely on 'Escalation'.It is also equally important to assess the need for additional scheduled tasks.

The ISC shall be responsible for defining the objectives of the evolution exercise. The task of the WG is to review service experience in order to determine if justification is available tosupport evolution of the task intervals. Refer to Annexe §A3-6 “C CHECK EVOLUTIONWORKING GROUP” for details.

Methodology

The following procedure is valid for an ISC objective to review the intervals of a certainnumber of tasks associated with any of the ATR Aircraft Family programs included in the ATRMRB Reports. Where service experience is shown to be good and there is an absence of other constraints, interval escalation may be proposed.

For the purposes of the ATR Maintenance Program evolution to be launched in 2007, the ISCrequests that the MWGs determine whether justification is available to demonstrate that aninterval increase from:

1C Check interval from 4000 FH to 5000 FH2C Check interval from 8000 FH to 10 000 FH4C Check interval from 16 000 FH to 20 000 FH

In order to conduct a complete study, the evolution exercise shall be handled in four phases.Only when all phases are complete can the decision be made to propose task intervalescalation and program changes to the MRBR.

Phase 1 - Manufacturer's investigation

The manufacturer shall be responsible for an engineering review of all tasks under consideration for evolution.

This review shall assess whether the manufacturer has any reason not to agree to theevolution target. To make this statement the following is to be accomplished:

- a review of the basis for the original task and interval selection (eg MSG-3 analysis,WG minutes, ISC minutes, System Safety Assessments)

- a review of related Service Bulletin (SB), Inspection Service Bulletins (ISB), ServiceInformation Letters (SIL), Technical Follow-Up (TFU), etc

- discuss with design/product support specialists for their perception on the relatedtask interval evolution.

These assessments do not require a review of raw reliability data since this aspect is coveredby the Operator input in Phase 2.

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Phase 2 - Operators investigation

All operators shall be responsible for reviewing actual in-service experience and reporting thenecessary data to the manufacturer in an agreed format.

The aim is:

- to identify those tasks for which there is sufficient evidence to justify that proposedescalation will not have a significant impact on continued airworthiness, operationalreliability or cost of ownership.

- to identify those tasks where experience supports either the interval remaining asoriginally recommended or being reduced.

Phase 3 - Data Collection and management

The reported data will be collated by ATR in a dedicated database for each MSI. The phase 4of the evolution exercise will only be launched after ISC and MRB validation in view of the

reported in-service experience (quality and quantity).

Phase 4 - Working Group (WG) meetings and ISC meetings

The manufacturer will summarize the results from the data survey and prepare workingmaterial for the presentation to the WG. The WG will discuss the evolution on a task-by-taskbasis to determine the appropriate interval and any other changes to the program. Operatorsare also requested to provide in-service experience during the Working Group sessions. TheWG results will then be summarized and presented to the ISC for acceptance.Refer to Annexe §A3-6 “C CHECK EVOLUTION WORKING GROUP” for details.

Factors to be addressed

1. Geographical distribution.

This should be taken into account since the MRB Report shall be applicable for global use.Justification for escalation shall therefore include data to demonstrate that the new intervalcontinues to be applicable for entry into service in all regions. Ideally, if ISC constitutionpermits, data should be obtained from carriers operating in hot, cold, humid, dry, dusty,temperate and maritime conditions.

2. Age of aircraft.

The survey should include aircraft of different ages. A sample representative of aircraft age must be taken into account to validate interval evolution for a task.

3. Assessment of findings relative to type of maintenance task.

It should be understood that the assessment of findings regarding an interval increase alsodepends on the type of maintenance task. The meaning or consequence of a finding shouldbe considered on a case-by-case basis.

4.Quality of data retrieved.

In order to have good confidence in the data, it is requested that operators retrieve taskfindings / nil findings from consecutive checks on the same aircraft. Among other benefits,this minimises the chance that a 'finding' is omitted from the data supplied. Also, findings andexperience from unscheduled maintenance should be taken into account.

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5.Actual intervals

In order to assess the potential for interval evolution, it is important to consider the intervalwhich is used in-service by the operator. This “actual interval” may differ from the oneapproved by the operator’s local authority.

Presentation Material

For each MSI/zone under consideration, the Manufacturer will establish an evolution dossier,comprising at minimum the following parts:

- Cover page

- Maintenance Task Summary

- Extract of the MRBR Sheet

- Evolution Sheet

1. Cover page

This page specifies the MSI/zone considered with ATA reference, the aircraft applicability,people who performed the preparation and the presentation date.

2. Maintenance Task SummaryFor each task considered, the Maintenance Task Summary must show the task which isunder consideration highlighted.

3. Extract of the MRBR SheetFor each task considered, the extract of the MRBR must show the task highlighted.

4. Evolution SheetThe Evolution sheet will contain the following information:

- MSI/Zone and Task description:

This information will be issued from the current ATR MRBR revision:

- MRBR and MSG-3 status table:

This table is composed of 9 columns (for which the content is described below) and 3 rows,one dedicated to each ATR model.

For a dedicated column criterion, should the data be common to 2 ATR models, then bothcells should be merged into one unique cell, with the common information.

No cell shall be left empty. When there is no data applicable to one column (criteria not

applicable) or one row (e.g. not applicable to ATR72), then “N/A” shall be quoted in the cell.

The columns are defined as follows:

+ A/C Model+ MPD task reference+ MRBR task reference+ MRBR task description+ MSG-3 task reference(s) (from Maintenance Task Summary). All MSG-3 task

references have to be provided, with related validity if needed+ Current MSG-3 interval+ Current MRBR interval+ Failure Effect Category (FEC)+ MRBR Applicability

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5. In-service data Table:This table represents the in-service data available for the MRBR task(s) and is composed of:

- 8 columns- 1 row per MRBR task or group of MRBR tasks- Several sub-rows for specific data.

The columns and sub-rows consist of:- Number of reports: Total number of reported checks, Number of reported checks

on ATR42,- Number of reported checks on ATR72, Number of aircraft on which the task was

performed, Number of operators- Geographical distribution of a/c- Distribution adapted to intervals reported in flight hours.- Number of relevant findings: „NIL“ should be quoted in case of zero relevant finding

reported.- Relevant findings distribution according to reported intervals in flight hours- Finding rate: this is, in percentage, the number of findings versus the number of

reported checks.- Category: See evolution guidance matrix in page 133.- Relevant finding definition for MRBR systems task:

When assessing the potential for evolution of an MRBR task, a finding is consideredrelevant when it is linked to the Failure Cause(s) identified in the MSG-3 analysis for the selection of the MRBR task.

There are 3 cases of multiple MPD tasks linked to one MRBR task.They have to be handleddifferently:

1.First case

If the reason for multiple MPD tasks is linked to their applicability, then these MPD tasks willbe grouped in one In-service data table.

Ex1: MRBR task linked to 2 MPD tasks, one for pre mod and one for post modconfigurationEx2: MRBR task linked to 2 MPD tasks for 2 A/C types or models

The information reported in the in-service data table will be presented as follows:The number of reported checks, aircraft and relevant findings will be the addition of the reported checks, aircraft and relevant findings of each grouped MPD task (for which there is in-service data).However, each operator will be retained only once while counting the number of operators.

2.Second case

If the reason for multiple MPD tasks is linked to their affected areas, zones, parts,type of check, then, one In-service data table will be created for each MPD task (for whichthere is in-service data).Ex1: MRBR task linked to 2 MPD tasks in 2 different areas/zonesEx2: MRBR “operational check of X and Y” is linked to one MPD task “Op. Check of X”and one MPD task “Op. Check of Y”Ex3: MRBR “operational check and functional check of X” is linked to one MPD taskfor “Op. Check of X” and one MPD task for “Funct. Check of X”

3.Third case

If the reason for multiple MPD tasks is a combination of 1st and 2nd case, oneIn-service data table will be created for each existing area, zone, part or type of check. The tasks with multiple applicability involved in each area, zone, part or type of checkwill be grouped together.

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- Details of findings:For each relevant finding (one finding per row), the following information should bequoted

- Related MRBR task reference

- Relevant Finding description

- Corrective action :“Relevant Finding description” and “Corrective action” will be copied from the in-servicedatabase.

- Relevant SIL, SB and ISB:This field should read the TFU, SIL, ISB documents that bring additional information(i.e. reliability, in-service experience, ATR recommendation) on the task or task relatedfunction, functional failure or failure cause.Only the TFU, SIL, SB and ISB references will be provided on the Evolution sheet.The TFU, SIL, SB and ISB mentioned will be listed and associated to the task or the

equipment concerned by task analysed for evolution.

- Additional information:This field could be used to provide any additional information.

- Task Interval proposition:This table is composed of:

- 3 rows (1 per ATR model)- 2 columns for MSG-3 and MRBR next revision- 2 sub-columns for “Revised” statement and “Interval”

In each column it should be stated whether the interval is proposed for revision in the MRBRand MSG-3 analysis (Yes or No) and the associated interval.The interval proposal is based on evolution guidance matrix in the first instance, and thenwhen applicable, by subsequent analysis of relevant in service findings and specialist input.

A category C or D determination may finally be evolved by the WG or the ISC so long as no“safety” findings are related to this item.(refer to WG results).

- Other Materials:During WG meeting the following documents will be made available:

- AMM procedure for the task under consideration- Full MSG-3 analysis dossier of the MSI under consideration

- Complete MRB Reports and MPDs- Complete in-service database

- WG results:Systems Evolution Result Summary will be presented to the Industry Steering Committee withthe addition of PREVIOUS INTERVAL column and a JUSTIFICATION column.The changes agreed during the WG meetings and approved by the ISC will then beintroduced in the MSI/zone analysis.

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EVOLUTION FORM SHEETS FOR EVOLUTION PROCESSFOR C CHECK AND MULTIPLES

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EVOLUTION GUIDANCE MATRIX

V.min V.min+1 - 10 11 - 20 21 - 50 > 50

NIL D B A A A

< 25 % D B B B A

25 - 50 % D B B B B

> 50 % D B C C C

ATR42 - ATR72 EVOLUTION GUIDANCE

C, 2C, 4C Interval ChecksNumber of tasks performed

% of significant/relevant findings

V.min= 1 for 4C Interval tasks

V.min= 3 for C to 2C Interval tasks

ESCALATIONA

EVOLUTION TO BE DEFINED WITH TECHNICAL DATA

(MTBF, SIL, ISB…)B

C

STATISTICALLY IRRELEVENT

REDUCTION

D

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3-2-2 DEVELOPMENT OF DERIVATIVE AIRCRAFT PROGRAMS

A derivative aircraft can be defined as an aircraft covered by an existing type certificate whoseperformances are significantly different from other models of the same type.

If design changes required achieving the new performance objectives are minor and result in

revision or creation of few tasks, the derivative aircraft maintenance requirements may beincorporated in the existing MRB report for the type.

If design changes are major and/or result in revision or creation of a significant number of tasks,the derivative aircraft maintenance requirements shall be compiled in a separate MRB report.

Definition of the derivative aircraft program development work scope shall begin with identification,by the aircraft manufacturer, of all functional commonalties between the derivative aircraft andexisting model(s).refer to flowchart on next page.

Functional commonalties exist whenever identical components perform identical functions insimilar operating conditions (pressure, temperature, humidity, vibrations, duty cycle, etc..).

The aircraft manufacturer shall provide a list of all modifications specific to the derivative aircraft.Regardless of the magnitude of the change, an evaluation sheet shall be issued for each tasksubmitted for review.

The aircraft manufacturer shall reassess all new or modified functional characteristics from anMSG-3 standpoint.

The impact of the changes shall be assessed in all programs (systems, structures and zonal).Correction to transfer sheets might be required.

As for major revisions, derivative aircraft maintenance programs shall be developed through aseries of ISC and WG meetings.

The final approval process shall be in accordance with section 3-1-6.

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N o t e : T w o “ p a r e n t ” A / C

s h o w n

( “ A ” a n d “ B ” )

A / C

“ A ” p r o g r a m

r e v i s i o n

o l d e r t h a n A / C “ B ”

r e v i s i o n

D

E R I V A T I V E

A I R C R A

F T

( F R O M

O N E O R

S E V E

R A L

A / C

O F S A M E F A M I L

Y )

T A

S K

S E L E C T I O N

L O

G I C

Y

N e w

/ r e v i s e d A / C

“ A ” t a s k s i n c e l a s t

M R B

N e w

/ r e v i s e d

M S G

- 3 a n a l y s i s

I s s u e d e r i v a t i v e

A / C

e v a l . s h e e t

M R B r e v i e w

N e w

/ r e v i s e d

A / C

“ A ” t a s k f o r

d e r i v a t i v e A / C

I s s u e d e r i v a t i v e

A / C

e v a l . s h e e t

E x i s t i n g A / C

“ A ”

t a s k f o r


N

Y

D e r i v a t i v e A / C

f u n c t i o n a l f e a t u r e

S a m e a s

A / C

“ A ”

S a m e a s

A / C

“ B ”

N e w

/ r e v i s e d

A / C

“ A ”

e v a l . s h e e t

M R B r e v i e w

N e w

/ r e v i s e d

A / C

“ A ” t a s k

N

Y

S a m e a s

A / C

“ B ”

I s s u

e d e r i v a t i v e

A / C

e v a l . s h e e t

E x i s t i n g A / C

“ B ”

t a s k f o r


N

N

Y

D e r i v a t i v e A

/ C

m a i n t e n a n c e p r o g r a m

S p e c i f i c d e r i v a t i v e

A / C

f e a t u r e

N e w

/ r e v i s e d

M S G

- 3 a n a

l y s i s

I s s u e d e r i v a

t i v e

A / C

e v a l . s h e e t

M R B r e v i e

w

S p e c i f i c d e r i v

a t i v e

A / C

t a s k

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A-1 SPECIFIC SCOPE

A1-1 COMPLETE REDESIGN OF THE SYSTEMS/POWERPLANT PROGRAMME (ALL MODELS)

Objectives:

Eliminate ineffective tasks from the systems and powerplant program or transfer tozonal program

Eliminate or increase intervals for tasks with current intervals shorter than a week

Increase “A” check interval to 500 flight hours and “C” check to 4000 hours

Review systems/powerplant tasks transferred to zonal

Modularize restoration tasks for landing gears and propellers

Ways of achieving objectives:

Redo completely all systems/powerplant MSG-3 analyses as opposed to modifyingexisting analyses in order not to be hindered by logic errors commonly found in theoriginal analyses; all 3 ATR models will be combined in the same analyses.

Use of in service data: as in any MSG-3 analysis, the upcoming reanalysis of the ATRa/c will consider in service data as guidance material and not as a unique decisionfactor when dealing with task and interval selection; other aspects should be taken intoaccount (criticality of the failure mode being looked at, experience of similar a/c,engineering judgement of working group members, …)

Realization:

All systems/powerplant MSG-3 analyses have been completely redone.

The interval of “A” check and the interval of “C” check have been respectively increased to 500FH and 4000 FH.

These evolutions were introduced in NOV 00 MRBR revisions for all models.

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A1-2 CORROSION PREVENTION AND CONTROL PROGRAMME (ALL MODELS)

Objectives:

Define CPCP requirements and incorporate them into the zonal and structure MRBReport sections

Reduce disparity between tasks in flight hours and tasks in years in zonal programme


In service data collection for structure and zonal inspections related to corrosion inorder to justify calendar interval adjustment.

Synthesize ATR experience with respect to corrosion damage rectification and repair through our structural engineering specialists

Realization:

The CPCP results were introduced in OCT 04 MRBR revisions for all models.

Regular updates are performed through Structural Task Group meetings

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A1-3 ENHANCED ZONAL ANALYSIS PROGRAM (EZAP)

Objectives:

Define EZAP requirements and incorporate analysis results into the MRB report.


Review of existing zonal program to determine where specific tasks dedicated to EZAPrequirements are applicable.

Realization:

The EZAP results were introduced in NOV08 MRBR revisions for all models.Regular updates are made through zonal MSG-3 analyses when needed.

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A1-4 EVOLUTION PROCESS FOR C CHECK AND MULTIPLES

Objectives :

Increase:1C check interval from 4000FH to 5000FH2C check interval from 8000FH to 10 000FH4C check interval from 16 000FH to 20 000FH


In-service experience data collection and analysis according to general methodologypresented in § 3-2-1-3.

Realization:

The evolution results were introduced in NOV08 MRBR revisions for all models.

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A1-5 TBO LANDING GEAR EVOLUTION

Objectives:

The evolution concerns ATR42-400/-500 and ATR72 programs. ATR42-200/-300/-320 will beconsidered later on, if necessary.

Increase TBO landing gear to 20000 cycles Increase calendar TBO landing gear to:

10 years for ATR42-400/-500 9 years for ATR72


For each landing gear model, results from 3 landing gear ship sets will be analyzedfor calendar study and 3 landing gear ship sets for cycling study.

Selection of samples is determined on the basis of environmental criteria and

operators are selected according to climatic distribution: Temperate Tropical Arctic.

The TBO landing gear evolution methodology is based on a first assessment performed inaccordance with Messier-Dowty work sheet 5030/06, followed by an ATR Non-TechnicalObjection, if positive results, to postpone the overhaul. Then, the sampling methodology for the overhaul is based on Messier-Dowty documents referenced:

for Nose Landing Gear 5024/06 ATR42-500 (calendar and cycles)5029/06 ATR72 (cycles)5031/06 ATR72 (calendar)

for Main Landing Gear 5026/06 ATR42-500 (calendar and cycles)5032/06 ATR72 (cycles)5033/06 ATR72 (calendar)

Follow-up:

ATR42-400/-500 evolution will not be achieved for calendar objective but study is still on-goingfor cycle evolution.

ATR42-200/-300/-320 will not be part of the study.

Realization:

TBO evolution (cycles) was introduced in NOV13 MRBR revision on main and noselanding gear for ATR72.

TBO evolution (calendar) was introduced in NOV 14 MRBR revision on main and noselanding gear for ATR72.

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A1-6 AVIONICS SUITE MODIFICATION

Objectives:

Analyze the impact of the modification 5948 “N AVIGATION – INSTALL NEW AVIONICS

SUITE” on the MSG-3 analyses and introduce the results into the MRB Report.

The New Avionics Suite (NAS) is only applicable to ATR42-500 and ATR72-212A.

The major design objective of the new avionics suite is to provide the crew with themost realistic picture of the in-flight situation and with the most comprehensiveaircraft systems displays.


Systems:

A complete review of MSG-3 analyses must be performed.

If the MSG-3 analysis concerns existing functionalities, percentage of analysis modificationhas been determined:

- With a low impact, existing dossier is updated.

- With a large impact, existing dossier remains unchanged with applicability“PRE MOD 5948”, and a new one is created specifically for “POST MOD5948”

If the MSG-3 analysis concerns new functionalities, a dossier is created with applicability“POST MOD 5948”

Zonal:

When impact is detected, zonal dossier is updated.

The L/HIRF regulation will be applied only on zonal dossiers impacted by new avionics suiteimplementation

Structure:

If impact is detected, structure dossier would be updated.

Realization:

NAS impact was introduced in NOV11 MRBR revisions for ATR42-500 and ATR72-212A.

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A-2 SCHEDULE OF ACTIVITIES

A2-1 MAINTENANCE REVIEW BOARDS AND INDUSTRY STEERING COMMITTEES

ISC KICK OFF MEETING (TOULOUSE, OCT 27-28 1998)

IS C

Members

N. CONG THANHK. DAYN. EDGER. EVANGELISTAS. HAMALAINEN

A. HAMONC. JOLIVETT. KANTINANV. KUKLAE. LEHTONEN

O. MADSENP. PAQUETTEJ. PAYNEM. RAVANELLIS. REEDM. SHERIDANH. TALFUMIERN. THANH HAIG. VENDITTOS. VISOUNARATHW. WHITTLE

VIETNAM AIRLINESCITYFLYER EXPRESSGILL AIRWAYS

ALITALIA EXPRESSFINNAIRBRIT AIR

ATR DS/TSBANGKOK AIRWAYSCSAFINNAIR

CIMBER AIRPRATT & WHITNEY CANADA

ATR DS/W ALITALIA EXPRESSCONTINENTAL EXPRESSHAMILTON STANDARD

ATR DS/TS/MVIETNAM AIRLINES

ATR DS/TS/M ATR DS/TS/M AIR NEW ZEALAND

MRB m e m b e r s M. DOUGANF. LEBLONDT. NEWCOMBEF. SCOGNAMIGLIOJ. TUMAF. VASSEUR

CIVIL AVIATION AUTHORITYDGAC – SFACTFEDERAL AVIATION ADMINISTRATIONREGISTRO AERONAUTICO ITALIANOCZECH CIVIL AVIATION AUTHORITYGSAC PARIS

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ISC FOR PPH APPROVAL (TOULOUSE, MAY 24-26 2005)

C hai rpers ons O. MADSENN. GUALINA

CIMBER AIR ATR

ISC Members D. ANDERSONO. BAYERM. CAJANIS. DE MARTINOO. ELANID. HARTSONH. JENSENP. KALTTONENK. LYKINSM. MAERAND

A. MINUTOM. MOORE

J. OJALAJ.C. PRADA QUINTEROG. VANNUCCHIH. WHITTENW. WHITTLE

FIRST AIRCSA

ATR ATR ARKIA ISRAELI AIRLINESEMPIRE AIRLINESCIMBER AIRFINNAIR

AMERICAN EAGLE/EXECUTIVE AIRLINES AERO AIRLINES AS ALENIA ATR NORTH AMERICA

AERO AIRLINES AS AEROCARIBBEAN ATRFEDEX

AIR NEW ZEALANDMRB

m e m b e r s

M. DUSSURGETD. GORDONH. HERESONF. JOUVARD

A. RUGGIERO

DGAC/GSACUNITED KINGDOM CIVIL AVIATION AUTHORITYDGAC/EASADGAC/EASAENTE NAZIONALE per l’AVIAZIONE CIVILE(ENAC)

ISC FOR PPH APPROVAL (TOULOUSE, OCT 25-27 2005)

C hai rpers ons O. MADSENN. GUALINA

CIMBER AIR ATR

ISC Members D. ANDERSONO. BAYERM. CAJANID. DUGGANO. ELANI

A. FALGA

D. HARTSONP. KALTTONEN A. MINUTOM. MOORED. NORLUNDF. O’HAGANJ. OJALAN. PALMERG. VANNUCCHIW. WHITTLE

FIRST AIRCSA

ATRFEDEX EUROPE

ARKIA ISRAELI AIRLINES AIRBUS

EMPIRE AIRLINESFINNAIR ALENIA ATR NORTH AMERICA AMERICAN EAGLE/EXECUTIVE AIRLINES AIRCONTRACTORS AERO AIRLINES ASFEDEX

ATR AIR NEW ZEALAND

MRB

Members

M. DUSSURGETH. HERESON

F. JOUVARD A. RUGGIERO

DGAC/GSACDGAC/EASA

EASAENTE NAZIONALE per l’AVIAZIONE CIVILE(ENAC)

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ISC FOR PPH APPROVAL (TOULOUSE, MAR 6-7 2007)

C hai rpers ons H. JENSENN. GUALINA

CIMBER AIR ATR

ISC Members J. C. PRADA QUINTEROG. BJELICA

A. RISHD. DUGGANP. H. CHRISTENSENP. KALTTONENV. PÄÄKKÖNENO. BAYERS. BONJEANN. VANQUINL. KÜHND. ANDERSONJ. J. MARTINEZW. O’BRIEN

O. ELANIN. DEGROUTTEM. CAJANI

AEROCARIBBEANCROATIA AIRLINES

EMPIRE AIRLINESFEDEXDATFINNAIRUTAIRCSA

AIR CARAÏBES AIR TAHITICONTACT AIRFIRST AIR

AIR NOSTRUM AIR CONTRACTORS

ARKIA ATR ATR

MRB

Members

F. JOUVARDG. LAYTON

A. RUGGIERO

EASAFAAENTE NAZIONALE per l’AVIAZIONE CIVILE(ENAC)

ISC FOR PPH APPROVAL (TOULOUSE, JAN 31-FEB 1 2011)

C hai rpers ons H. JENSEN

N. GUALINA

CIMBER AIR

ATRISC Members M. CUCALO CARBALLO

O. DA SILVAN. DEGROUTTER. HARDEMANH. JENSENL. LATVENASR. D. MADSENJ.C. PRADA QUINTEROL. VERDECIA SANCHEZM. VINCIGUERRASPECIALISTS MSG-3G. ARCANGELI

GAM TECHNICS AZUL ATR ATR ASSETCIMBER STERLINGDOT LTDAT

AEROCARIBBEAN AEROCARIBBEANTHALES

SONOVISION GROUPEKISMRB

Members

A. RUGGIEROM. A. SULLIVAN

ENACFAA

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ISC FOR PPH APPROVAL (TOULOUSE, 1 DEC 2011)

C hai rpers ons D. DUGGANN. GUALINA

FEDEX EUROPE ATR

ISC Members L. CARBONELLIO. DA SILVA JUNIORN. DEGROUTTE

A. HARARIR. HARDEMANN. GUALINAP. KODISAL. LATVENAS

A. LAXM. MACHINJ. MELNICKM. MILLERJ.C. PRADA QUINTEROO. ROMIEUG. ROY

N. SCALIL. VERDECIA SANCHEZM. VINCIGUERRAK.J. WANGS. YAO

ALENIA AZUL ATR

ISRAIR ATR ASSET ATR AIR BOTSWANADOT LTFEDEX USGAM TECHNICS

ATR WASHINGTON AMERICAN EAGLE AEROCARIBBEAN AIR LINAIRFIRST AIR

ALENIA AEROCARIBBEANTHALESUNI-AIRUNI-AIR

MRB

Members

F. JOUVARDK. E. MILLER

A. RUGGIERO

EASAFAAENAC

ISC FOR PPH APPROVAL (TOULOUSE, 22 NOV 2013)

C hai rpers ons D. DUGGANN. FIGUE-DEGROUTTE

FEDEX EUROPE ATR

ISC Members P. ARJAMAAR. HARDEMANN. GUALINAV. IVANOVL. LATVENASO. LAUNOISP. LEE BENG CHUANM. L. MOTSETEC. RUCKHABER

W. STRICKLANDY.H. SUE. WILBOT

FLYBE FINLAND OY ATR ASSET ATRUTAIR AVIATIONDOT LTHOP! AIRLINAIRMAS WINGS

AIR BOTSWANALUFTHANSA TECHNIK

FEDEX EXPRESSEVA AIRWAYS ATR

MRB

Members

J. NEVEUXK. E. MILLER

A. RUGGIERO

EASAFAAENAC

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ISC FOR PPH APPROVAL (TOULOUSE, 10 JUN 2015)

C hai rpers ons L. LAIMONASN. FIGUE

DOT LT ATR

ISC Members P. ARJAMAAG. DAVIDSONN. GUALINA

R. HARDEMANO. LAUNOISD. LINC. RUCKHABER

J. DAVIDM. LARROQUEJ. SALVIE. WILBOT

FLYBE FINLANDFIRST AIR

ATR

ATR ASSETHOP AIRLINAREVA AIRLUFTHANSA TECHNIK

ATR ATR ATR ATR

MRB

Members

J. NEVEUX EASA

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A2-2 WORKING GROUPS

HYDROMECHANICAL WORKING GROUP (OCT 1998)

C hai rman

C o-c hai rman

S.REEDG. VENDITTO

CONTINENTAL EXPRESS ATR DS/TS/M

WG Members N. EDGES. HAMALAINEN

A. LABOUEH.P REIFV. KUKLAW. WHITTLES. BROCHUE. FOCHF. BRESSANR.EVANGELISTA

GILL AIRWAYSFINNAIRBRIT AIREUROWINGSCSA

AIR NEW ZEALANDINTERCANADIEN

AEROSPATIALE AIR DOLOMITI ALITALIA EXPRESS

M R B A d v i s o r s F. LEBLONDM. NEWCOMBEF. SCOGNAMIGLIO

DGAC - SFACTFEDERAL AVIATION ADMINISTRATIONREGISTRO AERONAUTICO ITALIANO

AVIONICS/ELECTRIC WORKING GROUP (OCT 1998)

C hai rman

C o-c hai rman

S.REEDH. TALFUMIER

CONTINENTAL EXPRESS ATR DS/TS/M

WG Members A. LABOUEH.P REIFD. CLERCS. BROCHUF. BRESSANM. RAVANELLIN. EDGE

BAGGES. VISOUNARATH

BRIT AIREUROWINGS

AEROSPATIALEINTERCANADIEN

AIR DOLOMITI ALITALIA EXPRESSGILL AIRWAYSFINNAIR

ATR DS/TS/MM R B A d v i s o r s T. NEWCOMBE

M. DOUGANM. DUSSURGET

FEDERAL AVIATION ADMINISTRATIONCIVIL AVIATION AUTHORITYGSAC TOULOUSE

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FUEL/POWERPLANT WORKING GROUP (OCT 1998)

C hai rman

C o-c hai rman

A. LABOUEP. PAQUETTE

BRIT AIRPRATT & WHITNEY CANADA

WG Members S. REED

S. BROCHUF. BRESSANT. KANTINAN

GIULIANIC. FAERGEMANN

T.B.DB. VALLEAUM. SHERIDANG. VENDITTO

CONTINENTAL EXPRESS

INTERCANADIEN AIR DOLOMITIBANGKOK AIRWAYS

ALITALIA EXPESSCIMBER AIRFINNAIR

AEROSPATIALEHAMILTON STANDARD

ATR DS/TS/MM R B A d v i s o r s T. NEWCOMBE

M. PAINCHAUDR. DUBUS

FEDERAL AVIATION ADMINISTRATIONTRANSPORT CANADAGSAC TOULOUSE

1ST POWERPLANT WORKING GROUP (TOULOUSE, FEBRUARY 23-25 1999)

W G

Members

F. BRESSANC. DE FALCO

A. ERIGOC FAERGEMANN

A. GIULIANID. JACOBC. JOLIVETE. LEHTONEN

E. PANELLAC. PERIEH. TALFUMIERB. VALLEAUG. VENDITTO

AIR DOLOMITI ALENIAGUARDIA DI FINANZACIMBER AIR

ALITALIA EXPRESSPRATT & WHITNEY CANADA

ATR DS/TSFINNAIR

GUARDIA DI FINANZA ATR DS/TS ATR DS/TS/M AEROSPATIALE ATR DS/TS/M

MRB

A d v i s o r s

M. DUSSURGETH. DYCKT. NEWCOMBE

GSAC TOULOUSETRANSPORT CANADAFEDERAL AVIATION ADMINISTRATION

EZAP EVOLUTION WORKING GROUP (JUN 2007)

C hai rman L. O’BRIEN AIR CONTRACTORS

WG Members P.E. CHRISTENSENT. DOMISES. GENDELMANN. GUALINAH. M. JENSENP. KALTTONENR. KEARSLEY

M. MACHINJ. SVOBODA

DATSONOVISION-ITEP

ARKIA ISRAELY AIRLINES ATRCIMBERFINNAIRFIRST AIR

AEROCARIBBEANCSAM R B A d v i s o r s A. RUGGIERO

G. LAYTONENACFAA

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EZAP EVOLUTION WORKING GROUP (OCT 2007)

C hai rman D. DUGGAN FEDEX

WG Members D. ANDERSONP.E. CHRISTENSENE. CLARKE

V. DAUDIERM. GANTERN. GUALINAP. KALTTONENR. KEARSLEYM. MACHINJ. SVOBODA

FIRST AIRDAT

AERARANN

SONOVISION-ITEPSONOVISION-ITEP

ATRFINNAIRFIRST AIR

AEROCARIBBEANCSA

M R B A d v i s o r s A. RUGGIEROH. W. THARPS

ENACFAA

C CHECK EVOLUTION WORKING GROUP (NOV 2007)

C hai rman D. SIMS AIR NEW ZEALAND

WG Members D. ANDERSONP. ARJAMAAP.E. CHRISTENSENE. CLARKED. DUGGANN. GUALINA

A. HARARIP. KALTTONENV. KUKLAM. MACHIN

J.C. PRADA QUINTERON. THIBAUDM.D. TOANN.A. VU

FIRST AIRFINNISH COMMUTER AIRLINESDAT

AERARANNFEDEX

ATRISRAIRFINNAIRCSA

AEROCARIBBEAN

AEROCARIBBEANSONOVISION-ITEPVIETNAM AIRLINESVIETNAM AIRLINES

MRB

A d v i s o r s

A. RUGGIEROH. W. THARPS

ENACFAA

C CHECK EVOLUTION WORKING GROUP (NOV 2008)

C hai rman D. ANDERSON FIRST AIR

WG Members P. ARJAMAA

P.E. CHRISTENSENL. CELMIJ.J. CRUZN. DEGROUTTED. FLANIGINS. GARCIAN. GUALINA A. HARARIL. LATVENASM. MACHINM. MOOREJ.C. PRADA QUINTEROC. RODRIGUES

N. THIBAUDK. VASUDEVL. VERDECIA SANCHEZ

FINNISH AIRCRFAT MAINTENANCE

DAT ATR AMR EXECUTIVE ATR ATR AMR EXECUTIVE ATRISRAIRDOT LTGAM TECHNICS ATR AEROCARIBBEAN (comments only)KINGFISHER

SONOVISION-ITEPKINGFISHER AEROCARIBBEAN

MRB

A d v i s o r s

A. RUGGIEROH. W. THARPS

ENACFAA

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ZONAL WORKING GROUP (DEC 2009)

C hai rman D. DUGGAN FEDEX

WG Members P. ARJAMAAT. BAMBRICK

J. BURDENN. DEGROUTTEO. ELANIS. GARCIAN. GUALINAV. IVANOVL. LATVENAS

A. LAXP. LYNCHM. MACHINR. MADSEN

A. MINUTO

J.C. PRADA QUINTEROG. ROYD. SIMSL. VERDECIA SANCHEZSPECIALISTS MSG-3

FINNISH AIRCRAFT MAINTENANCE AIR CONTRACTORS

AMR EXECUTIVE ATR ARKIA AMR EXECUTIVE ATRUTAIRDOT LTFEDEX EXPRESSFIRST AIRGAM TECHNICSDAT

ALENIA

AEROCARIBBEANFIRST AIR AIR NEW ZEALAND AEROCARIBBEANSONOVISION GROUP

M R B A d v i s o r A. RUGGIERO ENAC

NEW AVIONICS SUITE WORKING GROUP (JAN 2011)

C hai rman O. DA SILVA AZUL

WG Members M. CUCALO CARBALLO

N. DEGROUTTEN. GUALINAR. HARDEMANH. JENSENL. LATVENASR. D. MADSENJ.C. PRADA QUINTEROL. VERDECIA SANCHEZM. VINCIGUERRASPECIALISTS MSG-3G. ARCANGELI

GAM TECHNICS

ATR ATR ATR ASSETCIMBER STERLINGDOT LTDAT

AEROCARIBBEAN AEROCARIBBEANTHALESSONOVISION GROUPEKIS

MRB

A d v i s o r s

A. RUGGIERO

M. A. SULLIVAN

ENAC

FAA

NEW AVIONICS SUITE WORKING GROUP (APR 2011)

C hai rman O. DA SILVA AZUL

WG Members T. CAERN. GUALINAR. HARDEMANL. LATVENASM. MACHINM. VINCIGUERRA

SPECIALISTS MSG-3G. ARCANGELI

AIR TAHITI ATR ATR ASSETDOT LTGAM TECHNICSTHALES

SONOVISION GROUPEKISM R B A d v i s o r A. RUGGIERO ENAC

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APPENDIX B: SAMPLE ANALYSIS

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APPENDIX C: ACRONYMS/MSG-3 GLOSSARY

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C-1 ACRONYMS

AAS Anti-Ice Advisory System

AC Advisory Circular AD Accidental Damage ADC Air Data Computer AEG Aircraft Evaluation Group AHRU Attitude and Heading Reference Unit ATA Air Transport Association ATC Air Traffic Control ATPCS Automatic Take-off Power Control SystemBO BoroscopeCA Calendar CAC Crew Alerting Computer CLA Condition Lever AngleCMMv Component Maintenance Manual Vendor CMR Certification Maintenance RequirementCPCP Corrosion Prevention and Control ProgramCS Certification SpecificationCVR Cockpit Voice Recorder DFDR Digital Flight Data Recorder DGAC Direction Générale de l'Aviation CivileDME Distance Measuring EquipmentDET/DVI Detailed Visual InspectionDY DailyEASA European Aviation Safety Agency

EC Eddy CurrentECTM Engine Condition Trend MonitoringED Environmental DamageEEC Electronic Engine ControlEWIS Enhanced Wiring Inspection SystemEZAP Enhanced Zonal Analysis ProgramFAA Federal Aviation AdministrationFAR Federal Aviation RegulationFD Fatigue DamageFH Flight Hour FI Flight IdleF Flight cycle

FWD ForwardGPWS Ground Proximity Warning SystemGSAC Groupement pour la Sécurité de l’Aviation CivileGVI General Visual InspectionHSD Hamilton StandardHSI Hot Section InspectionIMA Integrated Modular AvionicsISC Industry Steering CommitteeITT Inter Turbine TemperatureJAA Joint Aviation AuthoritiesJAR Joint Airworthiness RequirementsL/HIRF Lightning & High Intensity Radiation Fields

LC Line CheckLDG A complete Landing sequenceLP Liquid PenetrantMB Messier Bugatti

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MEL Minimum Equipment ListMFC Multi-Function Computer MLG Main Landing Gear MMEL Master Minimum Equipment ListMP Magnetic ParticleMPD Maintenance Planning DocumentMPP Maintenance Program Proposal

MRB Maintenance Review BoardMSG-3 Maintenance Steering Group - 3rd task forceMSI Maintenance Significant Item`NDI Non Destructive InspectionNDT Non Destructive TestNLG Nose Landing Gear Np Propeller speedNR National RequirementNTM Non destructive Testing Manual

N OD Other Damage or DeteriorationPEC Propeller Electronic ControlPIU Propeller Interface Unit

PLA Power Lever AnglePPD Policy and Procedure DocumentPPH Policy and Procedures HandbookPVM Propeller Valve ModulePWC Pratt & Whitney CanadaSB Service BulletinSDI Special Detailed InspectionSIL/SL Service (Information) Letter SSI Structural Significant ItemSTBY Stand-byTAS True Air Speed

TC Tire ChangeTCA Transport Canada AviationTCAS Traffic Control Avoidance SystemTBO Time Between OverhaulTI Threshold InspectionTII Threshold Inspection IntervalTT Tap TestUT Ultrasonic TestVR Vendor RequirementVFE Velocity Flap ExtendedWA Walkaround inspectionWG Working Group

WOW Weight On WheelWY WeeklyXR X-rayYE Year

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C-2 MSG-3 GLOSSARY

ACCIDENTAL DAMAGE (AD)

Physical deterioration of an item caused by contact or impact with an object or influence,which is not a part of the aircraft, or by human error during manufacturing, operation of the

aircraft, or maintenance practices.AGE EXPLORATION

A systematic evaluation of an item based on analysis of collected information from in-serviceexperience. It verifies the item’s resistance to a deterioration process with respect toincreasing age.

AIRWORTHINESS LIMITATIONS

A section of the Instructions for Continued Airworthiness that contains each mandatoryreplacement time, structural inspection interval and related structural inspection task. Thissection may also be used to define a threshold for the fatigue-related inspections and the

need to control corrosion to Level 1 or better. The information contained in the AirworthinessLimitations section may be changed to reflect service and/or test experience or new analysismethods.

COMPONENT

A unit with one or several specific functions.

CORROSION LEVEL 1

(1) Corrosion occurring between successive inspection tasks that is local and can bereworked or blended out within the allowable limitor

(2) Corrosion damage that is local and exceeds the allowable limit, but can be attributed toan event not typical of operator’s usage of other aircraft in the same fleet (e.g. mercury spill)or (3) Operator experience has demonstrated only light corrosion between each successivecorrosion inspection task; and the latest corrosion inspection task results in rework or blendout that exceeds the allowable limit.

CORROSION LEVEL 2

Corrosion occurring between any two successive corrosion inspections task that requires asingle rework or blend out which exceed allowable limitor

Corrosion occurring between successive inspections that is widespread and requires a singleblend-out approaching allowable rework limits, i.e. it is not light corrosion as provided in level1, definition (3).

A finding of level 2 corrosion requires repair, reinforcement, or complete or partialreplacement of the applicable structure.

CORROSION LEVEL 3

Corrosion occuring during the first or subsequent accomplishments of a corrosion inspectiontask that the operator determines to be an urgent airworthiness concern.

CORROSION PREVENTION AND CONTROL PROGRAM (CPCP)

A program of maintenance tasks implemented at a threshold designed to control an aircraftstructure to Corrosion Level 1 or better.

DAMAGE TOLERANT

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A qualification standard for aircraft structure. An item is judged to be damage tolerant if itcan sustain damage and the remaining structure can withstand reasonable loads withoutstructural failure or excessive structural deformation until the damage is detected.

DELAMINATION/DISBOND

Structural separation or cracking that occurs at or in the bond plane of a structural element,within a structural assembly, caused by in service accidental damage, environmental effectsand/or cyclic loading.

DIRECT ADVERSE EFFECT ON OPERATING SAFETY

Direct:To be direct, the functional failure or resulting secondary damage must achieve itseffect by itself, not in combination with other functional failures (no redundancy existsand it is primary dispatch item).

Adverse Effect on Safety:Safety shall be considered as adversely affected if the consequences of the failurecondition would prevent the continued safe flight and landing of the aircraft and/or

might cause serious or fatal injury to human occupants.Operating:

This is defined as the time interval during which passengers and crew are on board for the purpose of flight.

DISCARD

The removal from service of an item at a specified life limit.

ECONOMIC EFFECTS

Failure effects which do not prevent aircraft operation, but are economically undesirable

due to added labor and material cost for aircraft or shop repair.

ENVIRONMENTAL DETERIORATION (ED)

Physical deterioration of an item’s strength or resistance to failure as a result of chemicalinteraction with its climate or environment.

FAILURE

The inability of an item to perform within previously specified limits.

FAILURE CAUSE

Why the functional failure occurs.FAILURE EFFECT

What is the result of a functional failure?

FATIGUE DAMAGE (FD)

The initiation of a crack or cracks due to cyclic loading and subsequent propagation.

FATIGUE RELATED SAMPLING INSPECTION PROGRAM

Inspections on specific aircraft selected from those which have the highest operatingage/usage in order to identify the first evidence of deterioration in their condition caused byfatigue damage.

FUNCTION

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The normal characteristic actions of an item.

FUNCTIONAL CHECK

A quantitative check to determine if one or more functions of an item performs withinspecified limits.

FUNCTIONAL FAILURE

Failure of an item to perform its intended function within specified limits.

GENERAL VISUAL INSPECTION

See INSPECTION – GENERAL VISUAL (GVI)

HIDDEN FUNCTION

1. A function which is normally active and whose cessation will not be evident to theoperating crew during performance of normal duties.

2. A function which is normally inactive and whose readiness to perform, prior to it being

needed, will not be evident to the operating crew during performance of normal duties.

INHERENT LEVEL OF RELIABILITY AND SAFETY

That level which is built into the unit and, therefore, inherent in its design. This is the highestlevel of reliability and safety that can be expected from a unit, system, or aircraft if it receiveseffective maintenance to achieve higher levels of reliability generally requires modificationsor redesign.

INSPECTION

An examination of the item against a specific standard.

INSPECTION – DETAILED VISUAL (DVI) An intensive visual examination of a specific structural area, system, installation or assemblyto detect damage, failure or irregularity. Available lighting is normally supplemented with adirect source of good lighting at an intensity deemed appropriate by the inspector. Inspectionaids such as mirrors, magnifying lenses, etc. may be used. Surface cleaning and elaborateaccess procedures may be required.

INSPECTION - GENERAL VISUAL (GVI)

A visual examination of an interior or exterior area, installation or assembly to detectobvious damage, failure or irregularity. This level of inspection is made from within touchingdistance unless otherwise specified. A mirror may be necessary to enhance visual access toall exposed surfaces in the inspection area. This level of inspection is made under normallyavailable lighting conditions such as daylight, hangar lighting, flashlight or drop-light and mayrequire removal or opening of access panels or doors. Stands, ladders or platforms may berequired to gain proximity to the area being checked.

INSPECTION - SPECIAL DETAILED (SDI)

An intensive examination of a specific item, installation, or assembly to detect damage,failure or irregularity. The examination is likely to make extensive use of specialized

Inspection Techniques and/or equipment. Intricate cleaning and substantial access or disassembly procedure may be required.

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INSPECTION - ZONAL A collective term comprising selected general visual inspections and visual checks that isapplied to each zone, defined by access and area, to check system and powerplant

installations and structure for security and general conditions.

INITIAL INTERVAL

See THRESHOLD

INTERVAL

The specific value of a usage parameter (flight cycles, flight hours, etc.), at which a taskshould be conducted.

ITEM

Any level of hardware assembly (i.e. system, sub-system, module, accessory, component,unit, part, etc.).

LUBRICATION & SERVICING

Any act of lubricating or servicing for the purpose of maintaining inherent design capabilities.

MAINTENANCE SIGNIFICANT ITEMS (MSI)

Items, identified by the manufacturer, whose failure:

a) Could affect safety (on ground or in flight), and/or b) Is undetectable during operations, and/or c) Could have significant operational impact, and/or d) Could have significant economic impact.

MULTIPLE ELEMENT FATIGUE DAMAGE

The simultaneous cracking of multiple load path discrete elements working at similar stress levels.

MULTIPLE SITE FATIGUE DAMAGE

The presence of a number of adjacent, small cracks that might coalesce to form a singlelong crack.

NETWORK

The network is a collection of computers and devices interconnected by communicationschannels that facilitate communications among users and allows users to share resources

NON-METALLICS

Any structural material made from fibrous or laminated components bonded together by amedium. Materials such as graphite epoxy, boron epoxy, fiberglass, kevlar epoxy, acrylicsand the like are non-metallics. Non-metallics include adhesives used to join other metallic or non-metallic structural materials.

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OPERATING CREW NORMAL DUTIES

Operating Crew:Qualified flight compartment and cabin attendant personnel who are on duty.

Normal Duties:Those duties associated with the routine operation of the aircraft, on a daily

basis, to include the following:a. Procedures and checks performed during aircraft operation in accordance with the AircraftFlight Manualb. Recognition of abnormalities or failures by the operating crew through the use of normalphysical senses (e.g., odor, noise, vibration, temperature, visual observation of damage or failure, changes in physical input force requirements, etc.).

OPERATIONAL CHECK

An operational check is a task to determine that an item is fulfilling its intended purpose.Does not require quantitative tolerances. This is a failure finding task.

OPERATIONAL EFFECTSFailure effects which interfere with the completion of the aircraft mission. These failurescause delays, cancellations, ground or flight interruptions, high drag coefficients, altituderestrictions, etc.

OTHER STRUCTURE

Structure which is judged not to be a Structural Significant Item. "Other Structure" is definedboth externally and internally within zonal boundaries.

REPEAT INTERVAL

The interval (after the threshold/initial interval) between successive accomplishments of aspecific maintenance task.

RESIDUAL STRENGTH

The strength of a damaged structure.

RESTORATION

That work necessary to return the item to a specific standard. Restoration may vary fromcleaning or replacement of single parts up to a complete overhaul.

SAFE LIFE STRUCTURE

Structure which is not practical to design or qualify as damage tolerant. Its reliability isprotected by discard limits, which remove items from service before fatigue cracking isexpected.

SCHEDULED MAINTENANCE CHECK

Any of the maintenance opportunities which are prepackaged and are accomplished on aregular basis.

SPECIAL DETAILED INSPECTION

See INSPECTION – SPECIAL DETAILED (SDI)

STRUCTURAL SIGNIFICANT ITEM - (SSI)

Any detail, element or assembly, which contributes significantly to carrying flight, ground,pressure or control loads and whose failure could affect the structural integrity necessary for the safety of the aircraft.

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STRUCTURAL ASSEMBLY

One or more structural elements which together provide a basic structural function.

STRUCTURAL DETAIL

The lowest functional level in an aircraft structure. A discrete region or area of a structural

element, or a boundary intersection of two or more elements.

STRUCTURAL ELEMENT

Two or more structural details, which together form an identified manufacturer’s assemblypart.

STRUCTURAL FUNCTION

The mode of action of aircraft structure. It includes acceptance and transfer of specifiedloads in items (details /elements /assemblies) and provides consistently adequate aircraftresponse and flight characteristics.

TASKS – MAINTENANCE

An action or set of actions required to achieve a desired outcome which restores an item toor maintains an item in serviceable condition including inspection and determination of condition.

THRESHOLD

Interval between the start of service-life and the first task accomplishment.

TYPICAL FRAMES

“Typical frames” designation used in the Structure Program covers all the formed frames

whose design is similar, excluding main and intermediate frames as well as frames adjacentto door openings.

These typical frames are listed here below:

- Section 13: FR 13, FR 17 to 22

- Section 15: FR 23, 24, FR 28

- Section 16: FR 29 to 35, FR 40,41

- Section 18: FR 42,43

VISUAL CHECK

A visual check is an observation to determine that an item is fulfilling its intended purpose.

Does not require quantitative tolerances. This is a failure finding task.

WALKAROUND INSPECTION

A general visual inspection conducted from ground level to detect obvious discrepancies.

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APPENDIX D: LIST OF OTHER STRUCTURE

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Figure 2

Complete view of other structure

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ATA 52 - DOORS

Pax/Crew plug door (ST2 only) – Shoot bolt (Fig. 2) Emergency exit door – Shoot bolt fittings (Fig 3) Avionic compartment access door (Fig. 4) NLG wheel well access door (Fig. 5) Main landing gear doors (except attach fittings) (Fig. 6) Nose landing gear FWD/AFT door (Fig.7)

Figure 3

Pax/crew plug door shoot bolts

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Figure 4

Emergency exit door shoot bolts fitting

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Figure 5

Avionics compartment access door

Figure 6

NLG wheel well access door

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Figure 7

MLG doors

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Figure 8

NLG doors Fwd and Aft

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ATA 53 – FUSELAGE

Floor panels (Fig. 8) Ice shields (Fig. 9) Aerodynamic fairings – Radome (Fig. 10)

Wing ot fuselage fairings panels and structure (Fig. 11) Main landing gear fairings panels and structures (Fig. 12, Fig. 13) Tail cone (Fig.15)

Figure 9

Floor panels

Figure 10

Fuselage center section – Ice shields LH and RH

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Figure 11

Radome

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Figure 12

Wing to fuselage fairings panel and structure

Figure 13

Wing to fuselage fairing frames and intercostals

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Figure 14

MLG fairings

Figure 15

MLG fairing frames

Figure 16

Tail cone

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ATA 54 - NACELLES/PYLONS

COWLS and FAIRINGS

Nacelle front section - Upper cowl; LH/RH side cowl; Beam;FWD air inlet cowl; Rear air inlet cowl; Leading edge (Fig. 16)

Nacelle center section – Lateral panel; Firewall; Upper cowl (Fig. 17)

Nacelle rear section – Fairing structure (Fig. 18)

Figure 17

Nacelle front section cowl

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Figure 18

Nacelle center section panel

Figure 19

Nacelle rear section fairing structure

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ATA 55 - STABILIZERS

Horizontal stabilizer trail ing edge (Fig. 19) Elevator leading edge (Fig. 20) Vertical Stabilizer leading edge (Fig. 21) Dorsal fin (Fig. 22) Rudder leading edge (Fig. 23) Horizontal to vertical stabilizer fairings (Fig. 24)

Figure 20

Horizontal stabilizer trailing edge structure

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Figure 21

Elevator leading edge

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Figure 22

Vertical stabilizer leading edge

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Figure 23

Dorsal fin structure

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Figure 24

Rudder leading edge

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Figure 25

Horizontal to vertical stabilizer fairings

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ATA 56 – WINDOWS

Flight compartment- Cockpit windshields (Fig. 25)

Figure 25

Cockpit windshields

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ATA 57 – WINGS

Wing tip structure (Fig. 26) Inboard & outboard flap – Deflector structure – Cam guide (Fig. 27) Upper and lower Trailing edge (Fig. 28) Aerodynamic flap and aileron fairings (Fig.29)

Figure 26

Wing tip structure

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Figure 27

Deflector cam guide structure

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Figure 28

Trailing edge structure

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Figure 29Aerodynamic flap and aileron fairings

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APPENDIX E: CORROSION SENSITIVITY RATINGS DOCUMENT

NOTE AIRBUS: ESWOG_D04006697

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APPENDIX F: POLICY AND PROCEDURE DOCUMENT (PPD)

NOTE-DO-TS-2923-05-EN

Documents

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