WPG 331-250 Revised

Honeywell International Inc. P.O. Box 52181 Phoenix, AZ 85072-2181 U.S.A. CAGE: 99193 Telephone: (800) 601-3099 (U.S.A.) Telephone: (602) 365-3099 (International) Web site: http://portal.honeywell.com/wps/portal/aero

21 Nov 2007 SIL-APU-133Revision 0, 21 Nov 2007 Page 1 of 3

© Honeywell International Inc. Do not copy without express permission of Honeywell.

SERVICE INFORMATION LETTER APPLICABLE:

MAINTENANCE

& ENGINEERING

FLIGHT

OPERATIONS

FOR ALL AIRFRAME MANUFACTURERS USING GENERAL AVIATION, GENERAL PRODUCTS AND/OR AUXILIARY POWER UNITS, OWNER/OPERATORS, DISTRIBUTORS, SALES AND SERVICE ORGANIZATIONS, AND FIELD SERVICE REPRESENTATIVES.

AIRBORNE AUXILIARY POWER – GAS TURBINE ENGINE – Workscope Planning Guide (WPG 331-250[F]/[H])

Honeywell – Confidential THIS DOCUMENT AND ALL INFORMATION AND EXPRESSION CONTAINED HEREIN ARE THE PROPERTY OF HONEYWELL INTERNATIONAL INC., ARE PROVIDED IN CONFIDENCE, AND MAY BE USED BY PERSONS REQUIRED BY FEDERAL AVIATION REGULATION PART 21.50 TO COMPLY WITH ANY OF THE TERMS OF THESE INSTRUCTIONS. EXCEPT AS SET FORTH ABOVE, NO PERSON MAY, IN WHOLE OR IN PART, USE, DUPLICATE OR DISCLOSE THIS INFORMATION FOR ANY PURPOSE WITHOUT THE PRIOR WRITTEN PERMISSION OF HONEYWELL INTERNATIONAL INC.

Honeywell Materials License Agreement The documents and information contained herein (“the Materials”) are the proprietary data of Honeywell International Inc. and Honeywell Intellectual Properties Inc (collectively “Honeywell”). These Materials are provided for the exclusive use of Honeywell Service Centers; Honeywell-authorized repair facilities; operators of Honeywell aerospace products subject to an applicable product support agreement, their wholly owned-subsidiaries or a formally designated third party service provider; and direct recipients of Materials from Honeywell’s Aerospace Technical Publication Distribution. The terms and conditions of this License Agreement govern your use of these Materials, except to the extent that any terms and conditions of another applicable agreement with Honeywell regarding the operation, maintenance, or repair of Honeywell aerospace products conflict with the terms and conditions of this License Agreement, in which case the terms and conditions of the other agreement will govern. However, this License Agreement will govern in the event of a conflict between its terms and conditions and those of a purchase order or acknowledgement.

1. License Grant - If you are a party to an applicable product support agreement, a Honeywell Service Center agreement, or an authorized repair facility agreement, Honeywell hereby grants you a limited, non-exclusive license to use these Materials to operate, maintain, or repair Honeywell aerospace products only in accordance with that agreement.

If you are a direct recipient of these Materials from Honeywell’s Aerospace Technical Publication Distribution and are not a party to an agreement related to the operation, maintenance or repair of Honeywell aerospace products, Honeywell hereby grants you a limited, non-exclusive license to use these Materials to maintain or repair the subject Honeywell aerospace products only at the facility to which these Materials have been shipped ("the Licensed Facility"). Transfer of the Materials to another facility owned by you is permitted only if the original Licensed Facility retains no copies of the Materials and you provide prior written notice to Honeywell.

SERVICE INFORMATION LETTER

21 Nov 2007 SIL-APU-133Revision 0, 21 Nov 2007 Page 2


2. Rights In Materials - Honeywell retains all rights in these Materials and in any copies thereof that are not expressly granted to you, including all rights in patents, copyrights, trademarks, and trade secrets. No license to use any Honeywell trademarks or patents is granted under this License Agreement.

3. Confidentiality - You acknowledge that these Materials contain information that is confidential and proprietary to Honeywell. You agree to take all reasonable efforts to maintain the confidentiality of these Materials.

4. Assignment And Transfer - This License Agreement may be assigned to a formally designated service designee or transferred to a subsequent owner or operator of an aircraft containing the subject Honeywell aerospace products. However, the recipient of any such assignment or transfer must assume all of your obligations under this License Agreement. No assignment or transfer shall relieve any party of any obligation that such party then has hereunder.

5. Copies of Materials - Unless you have the express written permission of Honeywell, you may not make or permit making of copies of the Materials. Notwithstanding the foregoing, you may make copies of only portions of the Material for your internal use. You agree to return the Materials and any copies thereof to Honeywell upon the request of Honeywell.

6. Term - This License Agreement is effective until terminated as set forth herein. This License Agreement will terminate immediately, without notice from Honeywell, if you fail to comply with any provision of this License Agreement or will terminate simultaneously with the termination or expiration of your applicable product support agreement, authorized repair facility agreement, or your formal designation as a third party service provider. Upon termination of this License Agreement, you will return these Materials to Honeywell without retaining any copies and will have one of your authorized officers certify that all Materials have been returned with no copies retained.

7. Remedies - Honeywell reserves the right to pursue all available remedies and damages resulting from a breach of this License Agreement.

8. Limitation of Liability - Honeywell does not make any representation regarding the use or sufficiency of the Materials. THERE ARE NO OTHER WARRANTIES, WHETHER WRITTEN OR ORAL, EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, (i) WARRANTIES ARISING FROM COURSE OF PERFORMANCE, DEALING, USAGE, OR TRADE, WHICH ARE HEREBY EXPRESSLY DISCLAIMED, OR (ii) WARRANTIES AGAINST INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OF THIRD PARTIES, EVEN IF HONEYWELL HAS BEEN ADVISED OF ANY SUCH INFRINGEMENT. IN NO EVENT WILL HONEYWELL BE LIABLE FOR ANY INCIDENTAL DAMAGES, CONSEQUENTIAL DAMAGES, SPECIAL DAMAGES, INDIRECT DAMAGES, LOSS OF PROFITS, LOSS OF REVENUES, OR LOSS OF USE, EVEN IF INFORMED OF THE POSSIBILITY OF SUCH DAMAGES. TO THE EXTENT PERMITTED BY APPLICABLE LAW, THESE LIMITATIONS AND EXCLUSIONS WILL APPLY REGARDLESS OF WHETHER LIABILITY ARISES FROM BREACH OF CONTRACT, WARRANTY, TORT (INCLUDING BUT NOT LIMITED TO NEGLIGENCE), BY OPERATION OF LAW, OR OTHERWISE.

9. Controlling Law - This License shall be governed and construed in accordance with the laws of the State of New York without regard to the conflicts of laws provisions thereof. This license sets forth the entire agreement between you and Honeywell and may only be modified by a writing duly executed by the duly authorized representatives of the parties.

Copyright - Notice Copyright 2007 Honeywell International Inc. All rights reserved.

Honeywell is a registered trademark of Honeywell International Inc. All other marks are owned by their respective companies.

SERVICE INFORMATION LETTER

21 Nov 2007 SIL-APU-133Revision 0, 21 Nov 2007 Page 3


Transmittal Information

This sheet transmits Revision Number 0 of Service Information Letter SIL-APU-133

Revision History

This is the initial release of Service Information Letter SIL-APU-133 as summarized in Table 1.

Table 1. Service Information Letter Revisions

Revision Date of Release

Initial Release 21 Nov 2007

1. General Information:

A. Subject:

Workscope Planning Guide (WPG 331-250[F]/[H])

B. Applicability:

Part Number (PN) 381336-1, 381388-1

Applicable to specific repair facilities maintaining the 331-250[F]/[H] Auxiliary Power Unit

C. References:

(1) WPG 331-250[F]/[H]

2. Background:

The attached WPG provides guidelines to assist specific APU repair facilities in returning APU’s to service in the most efficient and cost-effective manner.

3. Summary:

The shop workscope determines the level of disassembly and whether exposed parts are checked to continue-time or zero-time check criteria per the applicable Inspection Repair Manual (IRM).

4. Actions:

A. Post and distribute this Service Information Letter (SIL), with references, for review of applicable personnel.

B. If there are any questions regarding this SIL, please contact:

Jay M. Brooks Honeywell International, Inc. 111 S. 34th Street Phoenix, AZ 85034 Telephone: 602-231-7004 [email protected]

mailto:[email protected]

Honeywell Workscope Planning Guide for the 331-250 [F]/[H] APU

WPG 331-250 [F]/[H] R0

Distributed by SIL No. APU-133 Revision 0 Dated Nov 21/2007

REPORT NO.: SIL APU-133 / WPG 331-250 [F]/[H]

ECCN 9E991 - The technical data in this document is under the jurisdiction of the Export Administration Regulations (EAR). "Diversion contrary to U.S. law is prohibited" By accepting this Workscope Planning Guide (WPG), the receiver agrees to the following terms and conditions. If the user does not agree to these terms, these documents should not be accepted and returned to Honeywell. The WPG is intended for use as a general guideline based upon Honeywell experience using genuine Honeywell parts and Honeywell-recommended maintenance procedures. Individual user experience may vary. There is no representation or warranty, implied or express, with respect to the information contained in this document(s) or the use thereof. Nor does Honeywell assume any responsibility or liability of any kind or make any warranty with respect to any part, module, LRU, APU or engine that may be repaired, manufactured, sold or used as a result of this WPG, except for any Warranty that would otherwise be applicable from Honeywell. This document and all information and expression contained herein are the proprietary property of Honeywell International Inc., are provided in confidence. Except as set forth above, no person may, in whole or in part, use, duplicate or disclose this information for any purpose without the prior written permission of Honeywell International Inc. WARRANTY/LIABILITY ADVISORY WARNING: HONEYWELL ASSUMES NO RESPONSIBILITY OR LIABILITY OF ANY KIND FOR ANY HONEYWELL EQUIPMENT WHICH IS NOT MAINTAINED AND/OR REPAIRED IN ACCORDANCE WITH HONEYWELL’S PUBLISHED INSTRUCTIONS OR OPERATED IN ABNORMAL ENVIRONMENTS. NEITHER DOES HONEYWELL ASSUME RESPONSIBILITY OR LIABILITY OF ANY KIND FOR SPECIAL TOOLS AND TEST EQUIPMENT FABRICATED BY COMPANIES OTHER THAN HONEYWELL. INCORRECTLY REPAIRED COMPONENTS CAN AFFECT AIRWORTHINESS OR DECREASE THE LIFE OF THE COMPONENTS. INCORRECTLY FABRICATED SPECIAL TOOLING OR TEST EQUIPMENT CAN RESULT IN DAMAGE TO PRODUCT COMPONENTS OR GIVE UNSATISFACTORY RESULTS. Copyright (c) 2002 Honeywell International Inc Record of Revisions:

Revision By Approved Date Pages and/or Paragraphs Affected New SV J. Julian 08-26-02 All (Initial Issue)

A SV J. Julian 02-24-03 Added: Table 4, Appendix I and IV. Revised: Revised Appendix II, general revision to all sections renumbered subsequently

B CEL J. Julian 11-15-04 General Revision C CEL J. Julian 08-15-05 Revised: paragraph 4.1, Table 3, 4.3.1(c), 4.9,

Appendix I, and V through IX R0 JB/DM J. Brooks 11-21-07 Complete Revision

TABLE OF CONTENTS

Page1. INTRODUCTION 1 2. UNIT DESCRIPTION 1 3. SHOP MAINTENANCE PHILOSOPHY 3

3.1 General 3.2 Levels of Repair

4. APU WORKSCOPE DEVELOPMENT 5

4.1 Customer Documentation 4.2 APU Operational and Repair History 4.3 As-received Checklist (Table 1) 4.4 SOAP and Oil Filter Back-flush Analysis 4.5 As-received Test 4.6 Life Limited Parts (LLP) 4.7 Build (Modification) Standard (Table 2)

5. LRU WORKSCOPE DEVELOPMENT 24

5.1 Regulatory Information 5.2 Levels of Repair 5.3 LRU Workscopes

6. GEARBOX WORKSCOPE 31 7. LOAD COMPRESSOR WORKSCOPE 34 8. POWER SECTION WORKSCOPE 36 9. FAILURE MODE SPECIFIC WORKSCOPES 40 10. SPECIAL APU WORKSCOPES 42 11. SHOP WATCH LIST 44

WPG 331-250 [F]/[H] APU i

Copying, use or disclosure of information on this page is subject to proprietary restrictions.

LIST OF FIGURES

Page Figure 1. APU Cutaway View 2 Figure 2. 331-250 APU Cross Section 2

LIST OF TABLES

Page Table 1. As-received Checklist 5 Table 2. APU Service Bulletin List 7 Table 3. LRU Workscopes 26 Table 4. Special LRU Workscopes 29 Table 5. Failure Mode Specific Workscopes 40 Table 6. Special APU Workscopes 42 Table 7. Shop Watch List 44

LIST OF APPENDIX

I. SMARTSCOPING OVERVIEW II. OIL SYSTEM OVERVIEW AND METAL IN OIL APU/LRU WORKSCOPES

WPG 331-250 [F]/[H] APU ii


WORKSCOPE PLANNING GUIDE

331-250[F]/[H] AUXILIARY POWER UNIT

1. INTRODUCTION

This document provides shop workscope information for the Honeywell 331-250, Auxiliary Power Unit (APU) PN 381336 (331-250 [F]) and PN 381388 (331-250 [H]). It supplements the Honeywell Inspection Repair Manual (IRM) 49-23-49 and Component Maintenance Manual (CMM) 49-22-63.

The various workscopes and suggestions provided in this document may be adjusted by repair facility engineering based on the APU/LRU time since repair, as-received condition, operational history/environment, and customer requirements etc.

2. UNIT DESCRIPTION

The 331-250 APU (Figures 2 and 3) has three basic sections:

•

•

•

Gearbox assembly

Load Compressor

Power Section

WPG 331-250 [F]/[H] APU 1


Figure 1. 331-250[F]/[H] APU (331-200 cutaway used for illustration purposes)

Figure 2. 331-250 APU Cross Section

WPG 331-250 [F]/[H] APU 2


3. SHOP MAINTENANCE PHILOSOPHY

3.1 General

Honeywell APU’s are designed and qualified as on-condition units. With periodic checks and shop visits the APU can continue operation utilizing the full service life of most components, provided design knowledge and shop experience are used to avoid premature in-service issues and failures. The Honeywell shop maintenance philosophy for APU’s described in more detail in Appendix I uses knowledge of the design intent/capability coupled with repair facility and operator experience to develop the most effective Workscope for units returned to the shop. Continue-time of units, modules, or parts is emphasized to avoid unnecessary exposure, repair, or replacement. There are several key considerations in developing the Workscope:

• Aircraft and operator maintenance specifications and requirements (Instructions for Continued Airworthiness or ICA)

• Operator expectations for an acceptable time between shop visit

• Variations in operating environment and on-wing maintenance practices

• Reliance on realistic and effective inspection/check criteria continuously updated using shop experience

The IRM provides two sets of check criteria, Continue-time and Zero-time, to support the WPG philosophy. The Continue-time criteria equates to an “Inspected” or “Repaired” notation on the Regulatory Airworthiness Form (8130). Zero-time criteria equates to “Overhauled” notation on the form. The decisions from the workscope development contained in this document determine which set of check criteria to use. A Light or Medium Repair level as defined below utilizes Continue-time Check criteria. A Heavy Repair as defined below utilizes Zero-time Check criteria.

The CMM supports the WPG Continue-time philosophy by providing:

• Limited test table to allow partial testing for Continue-time units

• Continue-time (Repaired) and Zero-time (Overhaul) operating limits and test release limits where feasible

WPG 331-250 [F]/[H] APU 3


3.2 Levels of Repair

There are three levels of repair for the 331-250 APU:

Light Repair

• External work only (calibration, adjustment, electrical, plumbing, LRU repair/replacement, etc.) and/or partial gearbox repair.

• Exposed parts checked to IRM Continue-time and General Check criteria.

Medium Repair

• Complete gearbox disassembly and/or partial or complete disassembly of the load compressor and/or power section with reuse or limited repair/replacement of parts.

• Exposed parts checked to IRM Continue-time and General Check criteria.

• Limited use of IRM Zero-time Check criteria, as requested by repair facility engineering, where additional checks are needed on specific parts based on part condition, failure mode or operating environment.

Heavy Repair

• At a minimum, complete disassembly of the power section and load compressor.

• Power section and load compressor parts checked to IRM Zero-time Check criteria.

• Other exposed parts checked to IRM Continue-time and General Check criteria.

• Limited use of IRM Zero-time Check criteria, as requested by repair facility engineering, where additional checks are needed on specific parts based on part condition, failure mode or operating environment.

WPG 331-250 [F]/[H] APU 4


4. APU WORKSCOPE DEVELOPMENT

The following information (if available) assists in developing an effective APU workscope:

4.1 Customer Documentation

• Reason for removal

• On-wing complaints and maintenance actions prior to removal (last 90 days preferred)

• Customer Maintenance Specification or Statement of Work requirements

• Life Limit cards for all Life Limited Parts (LLP)

4.2 APU Last Shop Visit History

• Reason for removal at last shop visit

• APU hours since last shop visit

• APU hours since last Heavy Repair (Overhaul)

• Work accomplished at last shop visit

• Final (Release) test cell performance at last shop visit

4.3 As-received Checklist The following checklist is used to assess the general condition of the APU.

Table 1. As-received Checklist

• Condition and description of the APU shipping container • Overall APU condition recording any handling damage and missing components • Inventory customer furnished and aircraft interface parts (QEC) • Inventory the components and accessories recording part number and serial number • Electrical harness and connector damage • Damage to mounts, ducts, thermal blankets, brackets, clamps, plumbing and components • Damage or debris in the inlet and tailpipe areas • Freedom of APU rotation • Freedom of IGV movement • External fuel and oil leaks • Condition of fuel and oil filters and filter bowl contents • Chip detector, magnetic plug, and monopole for damage and presence of metal • Condition of residual oil and presence of contamination and debris

WPG 331-250 [F]/[H] APU 5


4.4 Spectrographic Oil Analysis Program (SOAP) and Oil Filter Back-flush Analysis

In general SOAP and oil filter back-flush analysis is not recommended, however if an analysis is conducted the following guidelines are provided. If metal is observed refer to Appendix II for further diagnostics.

• For a typical APU returning with average service time and no physical metal indications, total filter back-flush contamination weight less than 40 mg is considered normal.

• For a newly-overhauled (Heavy Repair) APU or after a 25-hour penalty run, with no physical metal indications, total filter back-flush contamination weight up to 15 mg is considered normal.

• If total filter back-flush contamination weight is greater than 40 mg, with no physical metal indications, a 25-hour penalty run after oil/filter change is suggested.

• For SOAP results of quantities of less than 2 ppm for any metal are considered normal.

• For SOAP results in excess of 2 ppm, a 25-hour penalty run and recheck after oil/filter change is suggested along with a filter back-flush analysis. If the back-flush requirements are met, with no physical metal indications, no further action is needed regardless of the SOAP results.

4.5 As-received Test

• Prior to an as-received test ensure operation of the APU will not cause further damage to the unit or pose a safety concern for test personnel.

• Use performance tests to verify the customer reason for removal and to reveal other problems requiring corrective action.

• Use data from high-time APU/LRU’s to determine service life of detail parts and the relationship between part condition and acceptable APU operation.

• Minimize as-received testing after experience is gained on reasons for removal, and failure modes.

4.6 Life Limited Parts (LLP)

Refer to CMM 49-22-63 for information about Life Limited Parts.

• Consider the impact of life limited parts on the APU workscope.

• The customer is responsible for providing records indicating the total hours/cycles.

• If the remaining life on a part is less than 2500 hours/cycles, the customer should be contacted to determine if replacement is desired.

WPG 331-250 [F]/[H] APU 6


4.7 Build (Modification) Standard

A list of service bulletins and suggested incorporation rates is provided in Table 2. Consider customer requirements prior to SB incorporation and the impact of SB incorporation on the APU workscope.

The suggested compliance codes in Table 2 may be adjusted by repair facility engineering based on the APU/LRU time since repair, as-received condition, operational history/environment, and customer requirements etc.

Table 2. APU Service Bulletin List

Compliance Codes Service Bulletin 250[F] 250[H]

Title or Brief Description

A64847 49-02 NSV NSV

IGV Actuator (Moog Bulletin) – Rework IGVA A64847-4 to A64847-5 (Hon PN remains 3886167-3) by replacing the torque motor cap to provide additional clearance between the IGV actuator and APU assembly. (Mod 17-470D)

A64847 49-03 ANR ANR IGV Actuator (Moog Bulletin) – Replace Parker Actuator PN 3886060-2/-4 with Moog

3886167-3. (See SB 49-5971)

A64847 49-04 ANR ANR IGV Actuator (Moog Bulletin) – Rework IGVA A64847-5 to A64847-006 (Hon PN

remains 3886167-3) by replacing the electrical connector.

10-617075 49-1 NSV NSV

Ignition Exciter (Unison Bulletin) – Rework 3888058-1 (Unison 10-617075-4) to 3888058-3 (Unison 10-617075-5) by replacing the power supply and relocating internal components. (See replacement SB 49-5551)

10-617075 49-5 NSV NSV Ignition Exciter (Unison Bulletin) – Test 3888058-1/-3/-5 (Unison 10-617075-4/-5/-6) for

EMI and identify with Revision "T".

10-617075 49-04 ANR ANR

Ignition Exciter (Unison Bulletin) – Inspect 3888058-1/-3/-5 (Unison 10-617075-4/-5/-6) circuit board for loose eyelet creating possible loose connection and identify with SB on data plate.

10-617075 49-11 ANR ANR

Ignition Exciter (Unison Bulletin) – Rework 3888058-3 (Unison 10-617075-5) to 3888058-5 (Unison 10-617075-6) to improve case sealing. (See replacement SB’s 49-5770 and 49-5916)

10-617075 49-13 ANR ANR

Ignition Exciter (Unison Bulletin) –Rework 3888058-1/-3/-5 (Unison 10-617075-4/-5/-6) by replacing the transistor (no longer available) and updating the component board and identify with Revision “C”.

49-2125 NSV NA Starter Motor - Rework starter motor 519858-2-1 to 519858-3 by replacing the stator assembly 47229-6 with 47229-7 for improved reliability. (See Replacement SB 49-5391)

49-2126 NSV NA Starter Motor - Rework starter motor 519858-3 to 519858-4 by replacing the spring 48337 with 517449-1 and brush assembly 516048-1 with 2043924-1 for improved reliability. (See Replacement SB 49-5391)

49-2137 NSV NSV Starter Motor – Rework starter motor 519858-4 to 519858-5 with replaced end bell, bolts for ground strap attachment and relocated brush wear indicator. (See Replacement SB 49-5638)

49-2165 SCI SCI Starter Motor - (Superseded See SB 49-2369) Rework starter motor 519858-5 to 519858-5 Series 2 by replacing the drive end bearing 533399-1 with sealed bearing 2011632-1 to prevent internal contamination.

49-2171 SCI SCI Starter Motor - (Superseded See SB 49-2369) Rework starter motor 519858-5 Series 2 to 519858-6 by incorporating an improved brush base assembly, field coil and brush wear indicator. (See Replacement SB 49-5730)

WPG 331-250 [F]/[H] APU 7




49-2234 SCI SCI Starter Motor - Invalid - Superseded by 49-2369.

49-2369 NSV NSV Starter Motor - Rework starter motor 519858-5/-6/-7 to 519858-8 incorporating an improved brush lead shunt to prevent separation, an improved brush base, field coil and a brush wear indicator and lens cover to prevent damage for improved reliability. (See Replacement SB 49-7500)

49-5360 SCI NA Power Section - Rework or replace combustion chamber 3830051-1 to 3830051-3 adding cooling around igniter boss to prevent hot spots.

49-5362 NPE NA Power Section - Replace turbine bearing seal "T" bolts 865397-2 with 3844071-1 to prevent thermal growth of bolt and possible oil leakage.

49-5363 NPE NA Load Compressor - Rework/replace IGV cover assembly 3810123-4 with 3810123-5 with larger shaft relief pockets to prevent interference between cover and sector gears.

49-5366 ANS NA Power Section - Replace turbine bearing oil return tube 3880169-1 with 3880169-2 for improved durability and rework heat shield 3880170-1 to 3880170-3 to accept new tube.

49-5367 NPE NA Power Section - Add expander spring 3844087-2 under first stage turbine stator seal ring to prevent unseating during installation.

49-5368 NPE NA Power Section - Install scuff washers between inlet housing and sound insert to prevent corrosion and fretting.

49-5370 NSV NA Power Section - Rework secondary fuel manifold 3882492-1 to 3882492-2 by replacing fuel nozzles 3830057-2 with 3830057-6 with larger thread size than the primary nozzles to prevent improper assembly.

49-5376 NSV NA Gearbox Assembly - Rework gearbox housing 3862219-4/-7 to 3862219-8/-9 to increase pinion bearing clearance.

49-5386 NSV NA Fuel Control Assembly - Rework fuel control assembly 3882500-6/-7 to 3882500-8 by replacing the fuel solenoid to prevent possible internal leakage causing high EGT during APU start (Recommend upgrade to 3882500-17 per 49-7156).

49-5387 NSV NA Fuel Control Assembly - Replace fuel control assembly 3882500-6/-7 with 3882500-8 with a new fuel solenoid to prevent possible internal leakage causing high EGT during APU start (Recommend upgrade to 3882500-17 per 49-7157).

49-5391 NSV NA Starter Motor - Replace engine starter motor 519858-1/-3 with 519858-4 with different brush material and retention to improve brush life. (See Rework SB’s 49-2125 and 49-2126).

49-5405 SCI MC Flow Sensor - (Superseded see SB 49-5894) Replace differential pressure transducer 3876085-1 with 3876085-2 to prevent damage from pressure spikes with a 40% higher pressure limit.

49-5407 NSV NA Flow Sensor - Replace total pressure sensor 3876086-1 with 3876086-2 adding a DFCV (Check Valve) to prevent damage to the system from pressure spikes.

49-5408 NPE NA Power Section - Rework/replace turbine seal assembly 3844065-1 with 3844065-2 to add drain holes for increased scavenging and reduced coking.

49-5409 NSV NA Lube Pump Assembly - Rework lube pump 3880190-3 by replacing lube pump gears 3880005-17/-18 with 3880005-28/-29 to increase clearance to prevent possible pump seizure.

49-5410 NPE NA Power Section - Rework/replace turbine seal rotor 3840011-1 with 3840011-3 to increase axial clearance with the carbon seal to prevent possible oil leakage.

WPG 331-250 [F]/[H] APU 8




49-5413 NPE MC Power Section - Rework power section 3801003-1/-5 to 3801003-3/-7 by replacing the inlet housing 3810175-2 with 3810259-1/-3 due to possible cracking at weld locations.

49-5415 NPE NA Load Compressor - One time check of LC inlet housing assembly 3810176-3/-4 for proper manufacture (drain holes).

49-5420 SCI NA Power Section - Cancelled - On-time check of tie shaft 3822077-1 (Superseded by 49-5428).

49-5421 NSV MC Surge Control Valve - Replace surge control valve 979806-4/-5/-6/-7 with 979806-8 with improved nozzle linkage hardware. (Recommend upgrade to 979806-12 per SB 49-7047)

49-5422 NSV NA Gearbox Assembly - Replace gearbox housing plug 3862280-1 with 3862380-1 and add lockwire feature to prevent leakage.

49-5423 NPE MC Power Section - Rework/replace second-stage turbine stator assembly 3844011-2 with 3844011-5 to increase clearance between stator and first-stage turbine blade retainers.

49-5424 NSV NA APU General - Install oil warning placard to prevent over servicing.

49-5425 NSV NA Gearbox Assembly - Stake oil jets (5) in gearbox assembly 3862180-1/-3 to prevent loosening.

49-5426 SCI MC Gearbox Assembly - Rework/replace oil level sight gage housing 3862245-1 to 3862245-2 on gearbox assembly to correct oil level (Related SB's are recommended for improved and corrected oil level indications).

49-5428 NSV MC Power Section - Rework/Replace tie shaft 3822077-1 to 3822077-2 with oversize turbine scavenge coupling 3822078-1 to prevent slippage.

49-5430 ANS NA Power Section - Rework power section 3801003-1/-5 to 3901003-7 or 3801003-2/-6 to 3801003-8 by replacing the compressor shroud 3826135-1/-3 with 3826138-3 for reduced weight and tighter impeller tip clearance.

49-5434 NSV MC Lube Pump Assembly - Replace turbine bearing oil return check valve 771-503-9008 with 771-503-9023 to prevent possibility of backwards installation.

49-5435 NSV NA APU General - Rework wiring harness 3888123-1 to 3888123-2 to add insulation at the thermocouple leads and replace brackets at the leads to prevent a possible short.

49-5437 NPE MC Power Section - Replace inlet bell 3810147-1/-2 or 3810211-2 with 3810211-3 having a fiberglass doubler to prevent sheet metal fracture.

49-5439 ANS MC APU General - Replace thermocouple 3876027-3 (Round head) with 3876027-4 (Rectangular head) for improved reliability.

49-5440 SCI MC Flow Sensor – Replace static flow sensor 3876087-1 (Gasket sealing) with 3876096-1 (O-ring sealing) to prevent leakage.

49-5450 NSV MC APU General – Replace surge air duct 3884293-1 or 3884196-1 with two-piece rubber ducts 3884391-1 and 3884292-2 using kit 3609913-1.

49-5451 NSV MC Lube Pump Assembly – Add de-oil temperature switch 3876023-3 using kit 3876101-2 to de-oil system to prevent possible no start during cold soak conditions with current use of APU oil temperature bulb.

49-5452 SCI NA Gearbox Assembly – One time inspection of oil pump gearshaft 3860165-1 for installation and security of plug. (Refer to SPB GTE0514).

WPG 331-250 [F]/[H] APU 9




49-5454 NSV NA Load Compressor – Replace IGV bellcrank trunion bushing 3826165-1 (Aluminum) with 3826165-2 (CRES 416) and shims to prevent premature wear.

49-5455 NPE NA Load Compressor – Replace LC impeller 3822074-1/-2 with 3822074-3 having thicker backface material to prevent fracture

49-5464 NSV MC Gearbox Assembly – Replace the clutch oil jet, starter gear and gearshaft to improve reliability, service bulletin 49-5470 must also be incorporated (Related SB’s are recommended for improved starter clutch reliability).

49-5470 NSV NA Gearbox Assembly – Rework gearbox assembly 3862180-1 to 3862180-6 and gearbox housing 3862219-7/-9 to 3862219-8 to simplify/standardize plumbing hardware installation and replace de-oil solenoid and adapter

49-5485 NSV NA Fuel Flow Divider – Rework fuel flow divider 3882550-1 to 3882550-2 replacing the solenoid valve 3876046-1 with 3876046-4 to provide a positive locking feature on the connector.

49-5486 NSV MC Fuel Flow Divider – Replace fuel flow divider 3882550-1 with 3882550-2 having a new solenoid valve 3876046-4 with a positive locking feature on the connector.

49-5487 SCI MC APU General – Rework or replace IGV actuator 3886070-1 with 3886070-2 with self locking connector to prevent loosening.

49-5491 NPE NA Power Section – Rework inlet housing 3810259-1 to 3810259-3 to prevent interference with compressor housing.

49-5492 ANS MC APU General – Replace fan exhaust duct 3862231-2 (Metal) with 3862431-1 (Composite) to prevent fracture.

49-5493 SCI NA Gearbox Assembly - One time inspection of generator spur gearshaft 3860180-2 for plug installation and security (Recommend SB 49-5704 incorporating gear 3860180-5 (Rework) or 3860180-6 (Replace)).

49-5494 SCI SCI APU General – Rework fan isolation valve 397728-4 to 397728-6 by replacing the butterfly plate to prevent corrosion.

49-5495 NSV MC APU General – Replace tube 3884268-1 with 3884405-1 to provide cooling to surge control valve.

49-5497 ANR NA Oil Pump Assembly – (Superseded see SB 49-5683) Rework oil pump 3880190-3 by reworking the housing 3880131-6 to 3880131-7 correcting a possible line bore problem and shaft binding.

49-5499 NPE NA Load Compressor - Rework IGV assembly 3810231-1/-6 to 3810231-9/-10 by replacing the IGV De-whistler pins 566-017-9028 (Steel) with S9008M346 (Aluminum) to prevent corrosion.

49-5500 NPE NA Gearbox Pressurization - One time inspection gearbox shutoff valve 3289514-1 (Series 1 only) for installation and security of plug.

49-5512 SCI SCI Flow Sensor (Cancelled see SB 49-5861) - Replace variable volume chamber 3289618-1 with 3289804-1.

49-5517 ANS MC Power Section - Rework/replace first stage stator 3844040-1 to 3844040-3 by replacing the machine forged baffle and support with investment castings to reduce cost and weight.

49-5518 NPE MC Load Compressor - Rework the load compressor to prevent fretting and rotation of the sound insert by replacing insert 3810149-1 with 3810210-4 or rework insert 3810210-2 to 3810210-4 and rework LC inlet housing 3810176-3/-4 to 3810176-7/-8 and add scuff washers.

49-5519 ANS MC Starter Motor - Replace igniter plug 369949-3 with 305766-1 to prevent erosion and corrosion.

WPG 331-250 [F]/[H] APU 10




49-5522 SCI NA Cooling Fan - Replace fan assembly 3862160-3 with 3862160-4 incorporating a new fan seal to prevent oil leakage (Recommend rework of gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272).

49-5523 SCI NA Cooling Fan - Rework fan assembly 3862160-3 to 3862160-4 to incorporate new fan seal to prevent oil leakage (Recommend rework of gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272).

49-5526 SCI MC APU General - Replace fan isolation valve 397728-4 with 397728-6 with new butterfly plate to prevent corrosion.

49-5531 NSV MC Lube Pump Assembly - Replace oil level sensor 3876082-3 (Non GE) with 3876082-4 (GE) and re-identify GE 3876082-3 as 3876082-4 due to interference with aircraft installation.

49-5532 NSV NA Gearbox Assembly - Rework gearbox assembly 3862180-6 to 3862180-7 and gearbox housing 3862219-8 to 3862219-10 by replacing the oil filler housing oil level sight glass with a prismatic design for improved visual clarity.

49-5534 SCI NA Surge Control Valve – (Superseded See SB 49-6504) Rework 979806-8 surge valve to series 2 to incorporate improved stop screw and washer.

49-5535 SCI NA Gearbox Pressurization – (Superseded see SB 49-7380) Rework gearbox shutoff valve 3289514-1 to series 1 by welding guide pin to prevent loosening of the plug and leakage.

49-5543 SCI SCI LOP Switch – (Superseded see SB 49-7478) Replace low oil pressure switch 3876024-2 with 3876024-3 for improved reliability.

49-5546 SCI MC Cooling Fan - Replace fan assembly 3862160-3/-4 with 3862160-5 with an added fan discharge housing and improved security of the containment ring (Recommend rework of and gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272).

49-5547 SCI NA Cooling Fan - Rework fan assembly 3862160-3/-4 to 3862160-5 adding a fan discharge housing and improving the security of the containment ring (Recommend rework of gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272).

49-5548 NSV MC APU General - Rework starter resistor assembly 307668-1/-2 to 307668-3 with terminal stud to prevent damage during installation.

49-5549 NPE MC Fuel Manifold - Rework/replace fuel nozzle shrouds 3830054-3/-4/-7 to 3830054-9 to increase nozzle slot dimensions to prevent interference during installation.

49-5551 NSV MC Ignition Exciter - Replace ignition exciter 3888058-1 (10-617075-4 Unison) with 3888058-3 (10-617075-5 Unison) with an improved power supply. (See Unison SB 49-1).

49-5552 NSV MC APU General - Replace igniter plug lead 3888076-1 with 3888076-2 incorporating an improved socket at higher temperatures.

49-5560 SCI NA Load Compressor - One time inspection of IGV linkage for proper adjustment

49-5565 NSV MC Gearbox Assembly - Rework gearbox assembly 3862180-7/-9 to 3862180-8/-10 to incorporate an air-oil separator 3610862-1, rework the compound idler gear 3860182-1 to 3860182-2 and the gearbox pressure regulator adapter 3862284-1/-5 to 3862284-6 to prevent oil venting.

49-5566 SCI SCI Oil Pump Assembly – (Superseded see SB 49-5682 and 49-5781) Replace oil pump assembly 3880190-3 with 3880190-5 with new pump gears and shear shaft to prevent the APU from starting following an oil pump failure.

49-5567 SCI NA Oil Pump Assembly – (Superseded see SB 49-5683 and 49-5782) Rework oil pump assembly 3880190-3 to 3880190-5 with new pump gears and shear shaft to prevent the APU from starting following an oil pump failure.

WPG 331-250 [F]/[H] APU 11




49-5569 NSV NSV Fuel Control Assembly - Replace fuel control 3882500-10/-11, Series 1 & 2 with 3882500-10, Series 3 and replace 3882500-12/-13, Series 1 with 3882500-12, Series 2 with new torque motor and fuel transfer adapter for improved altitude start reliability (Recommend upgrade to 3882500-17 per 49-7157).

49-5570 NSV NSV Fuel Control Assembly - Rework fuel control 3882500-10/-11, Series 1 & 2 to 3882500-10, Series 3 and rework 3882500-12/-13, Series 1 to 3882500-12, Series 2 with new torque motor and fuel transfer adapter for improved altitude start reliability (Recommend upgrade to 3882500-17 per 49-7156).

49-5572 NSV MC APU General - Rework wiring harness 3888123-3 to 3888123-4 and remove de-oil kit harness 3888155-1 to simplify the wiring and prevent switching of the generator delta P and de-oil connectors.

49-5574 SCI SCI Generator Scavenge Pump – (Superseded see SB 49-5661) Replace generator scavenge pump assembly 3880200-4 with 3880200-5 incorporating wrought metal gears for improved durability.

49-5575 SCI NA Generator Scavenge Pump – (Superseded see SB 49-5662) Rework generator scavenge pump assembly 3880200-4 to 3880200-5 wrought metal gears for improved durability.

49-5579 ANR MC Gearbox Pressurization - Replace gearbox regulating valve 3289504-1 with 3289504-2 to aid in oil pump priming during cold soak starts with a lower actuation pressure. (See SB 49-5606)

49-5582 SCI SCI Fuel Control Assembly – (Cancelled See SB 49-5640) Rework fuel control 3882500-6/-7/-8/-9 (Recommend upgrade to 3882500-17 per 49-7156).

49-5591 ANR NA Gearbox Pressurization - Rework gearbox regulating valve 3289504-1 to 3289504-2 to aid in oil pump priming during cold soak starts with a lower actuation pressure. (See SB 49-5606)

49-5598 NPE MC Load Compressor - Rework the load compressor 3804002-3 to 3804002-7 by reworking/ replacing the IGV bellcrank trunion block 3826383-1/-2 or 58494 with 3826383-3, replace bellcrank 3826150-2 with 3826150-3 and replace the bellcrank bearing 3826165-2 or 3826381-2 with a non-metallic "Vespel" bushing 3826381-3 for improved durability.

49-5599 NPE MC Load Compressor - Replace forward load compressor seal 3606514-1 with 3611175-1 incorporating an internal "Omni -C-" seal to prevent oil leakage.

49-5605 NSV NSV APU General - Rework compressor inlet screens 3810198-1/-2 to 3810198-3/-4 incorporating a gusset to prevent fracture at the T-bolt strap.

49-5606 NSV NA Gearbox Pressurization - Rework gearbox regulator valve 3289504-1 to 3289504-1 Change 2 (Production Series 3) or 3289504-2 to 3289504-2 Change 1 (Production series 2) with reworked poppet 3170879-1 to 3170879-2 with an added sleeve to reduce operational noise (Buzzing).

49-5610 NSV MC Gearbox Assembly - Replace oil inlet tube (Pick-up) 3862188-1 with 3862550-1 in the gearbox and oil transfer tube 3862158-1 with 3862552-1(With screen) to reduce oil flow restrictions during cold soak conditions.

49-5611 SCI NA Surge Control Valve – (Superseded see SB 49-6504) Rework surge control valve 979806-8 to series 2 with improved actuator linkage.

49-5617 NPE NPE Load Compressor – Rework IGV assembly 3810231-9/-10 to 3810231-11/-12 by adding kapton (Scuff) washer above spring washer and replacing De-whistler baffle 3610898-1 (Aluminum) with 3810230-1 (Carbon).

49-5623 ANR ANR Power Section – Rework heat shield 3844020-2/-3 to 3613195-1/-2/-3 or replace 3844020-2/-3 with 3844199-1 (New Part) having increased material thickness and gussets to prevent cracking.

49-5625 NPE MC Fuel Manifold – Replace primary fuel manifold 3882491-1 with 3882491-2 with replaced nozzle assembly to prevent interference between nozzle body and shroud.

WPG 331-250 [F]/[H] APU 12




49-5626 NPE NPE Fuel Manifold – Rework primary fuel manifold 3882491-1 to 3882491-2 by reworking nozzle assembly 3830057-1 to 3830057-7 and body 3830053-3 to 3830053-5 to prevent interference with nozzle shroud.

49-5638 NSV NSV Starter Motor – Replace starter motor 519858-4 with 519858-5 incorporating replaced end bell, bolts for ground strap attachment and relocated brush wear indicator. (See Rework SB 49-2137).

49-5639 NSV NSV Fuel Control Assembly – Replace fuel control assembly 3882500-8/-9 with 3882500-11 incorporating an improved gearshaft, shaft seal, high pressure relief valve and adapter to prevent leakage and improve reliability (Recommend upgrade to 3882500-17 per 49-7157).

49-5640 NSV NSV Fuel Control Assembly – Rework fuel control assembly 3882500-8/-9 to 3882500-11 incorporating an improved gearshaft, shaft seal, high pressure relief valve and adapter to prevent leakage and improve reliability (Recommend upgrade to 3882500-17 per 49-7156).

49-5643 SCI SCI Gearbox Assembly – Replace fan idler gear 3860169-1/-2 with 3860169-4 incorporating increased thickness and shaft flats to aid in bearing removal (Recommend SB 49-7268 incorporating gear 3860169-5).

49-5644 SCI SCI Surge Control Valve – (Superseded see SB 49-6504) Rework surge valve 979806-8 to 979806-9 incorporating a visual position indicator.

49-5645 NSV NSV De-oil Solenoid – Replace de-oil solenoid valve 3876047-4 with 3876166-1 incorporating a larger flow area for improved high altitude and cold soak starts.

49-5650 NSV NSV Gearbox Assembly – Replace starter sprag clutch 892571-6 with 3611304-1, inner shaft 3860167-2 with 3868023-1, and bearings with new replacements to improve clutch assembly durability.

49-5655 ANR MC APU General – Rework APU assembly 381336-1 (331-250F) to 381388-1 (331-250H) by incorporation of multiple service bulletins.

49-5661 ANR ANR Generator Scavenge Pump – Replace generator scavenge pump assembly 3880200-5 with 3880200-6 incorporating heat treated gears for increased durability.

49-5662 ANR ANR Generator Scavenge Pump – Rework generator scavenge pump assembly 3880200-5 to 3880200-6 incorporating heat treated gears for increased durability.

49-5672 NSV NSV Fuel Control Assembly – Rework fuel control 3882500-11 to 3882500-13 and 3882500-10 to 3882500-12 to incorporate internal fuel deflector to prevent housing erosion (Recommend upgrade to 3882500-17 per 49-7156).

49-5674 NPE NPE Power Section – Rework/replace combustion chamber 3830051-3 with 3830051-4 incorporating additional cooling holes and a cooling tab around the igniter boss.

49-5682 ANR MC Oil Pump Assembly – Replace oil pump assembly 3880190-3/-5 with 3880190-8 incorporating increased gear axial clearance to prevent binding. (Recommend upgrade per SB 49-5781 to 3880190-10).

49-5683 NSV NSV Oil Pump Assembly – Rework oil pump assembly 3880190-3/-5 to 3880190-8 incorporating increased gear axial clearance to prevent binding. (Recommend upgrade per SB 49-5782 to 3880190-10).

49-5685 NA NSV Gearbox Assembly – One time inspection of gearbox oil passage plug installation and security at the cooling fan oil jet location.

49-5688 NSV NSV Fuel Control Assembly – Replace fuel control 3882500-11 with 3882500-13 and 3882500-10 with 3882500-12 incorporating an internal fuel deflector to prevent housing erosion (Recommend upgrade to 3882500-17 per 49-7157).

49-5692 NSV NSV APU General – Replace/rework generator filter assembly 3880210-2 to 3880210-4 to eliminate the generator Delta P switch and add a plug, and rework the wiring harness 3888103-4/-5 to 3888208-1 to replace the Delta P switch connector with a jumper.

WPG 331-250 [F]/[H] APU 13




49-5696 SCI SCI Surge Control Valve – (Superseded see SB 49-6506) Replace surge valve 979806-8 to 979806-9 incorporating a visual position indicator.

49-5704 NPE NPE Gearbox Assembly – Rework generator gearshaft 3860180-2 to 3860180-5 or replace with 3860180-6 to improve ease of bearing removal.

49-5706 SCI SCI LOP Switch – (Superseded see SB 49-7478) Replace low oil pressure switch 3876024-2/-3 with 3876024-4 to prevent oil leakage.

49-5707 SCI SCI Surge Control Valve – (Superseded see SB 49-6504) Rework surge valve 979806-9 to 979806-10 to increase filter capacity and improve feedback spring retention for improved reliability.

49-5713 NPE NPE Load Compressor – Rework the load compressor 3804002-7 to 3804002-10 by reworking the IGV assembly 3810231-11 to 3810231-16 to prevent IGV corrosion with an anodized IGV housing and cover and replacement ring gear, ring gear bearing and vane bushings.

49-5714 ANR ANR

Gearbox Assembly – Rework gearbox assembly 3862180-18 to 3862180-19, 3862180-15 to 3862180-13, or 3862180-16 to 3862180-20 and the gearbox housing 3862219-12/-13 to 3862699-1, 3862219-14 to 3862699-2 or 3862219-10 to 3862219-17 by incorporating an LRU starter clutch, bearing and gear assembly (Related SB’s are recommended for improved starter clutch reliability).

49-A5715 SCI SCI Cooling Fan – Replace fan assembly 3862160-5 with 3862160-9/-10 to improve containment with improved through bolts (Recommend rework of plumbing per SB 49-5867 and gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272)

49-5716 SCI SCI Cooling Fan – Rework fan 3862160-5 to 3862160-9/-10 to improve containment with replacement through-bolts (Recommend rework of gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272).

49-5717 SCI SCI Surge Control Valve – (Superseded see SB 49-6504) Rework surge valve 979806-8 to 979806-8 series 4 to increase filter capacity and improve feedback spring retention.

49-5718 SCI SCI Surge Control Valve – (Superseded see SB 49-6506) Replace surge valve 979806-9 with 979806-10 with increased filter capacity and improve feedback spring retention for improved reliability.

49-5720 SCI SCI Cooling Fan – Rework fan assembly 3862160-5, Series 2 to 3862160-5, Series 3 or 3862160-10, Series 2 to 3862160-9, Series 1 by replacing fan rotor having shot peen and frequency screening to prevent blade separations (Recommend rework gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272) .

49-5723 SCI SCI Power Section – One time inspection of the second and third stage turbine stators for proper assembly and third stage turbine wheel for evidence of damage or rub.

49-5728 SCI SCI

Cooling Fan – Rework fan assembly 3862160-5/-10 by replacing containment ring 3862234-1 with 3611603-3 (Production) or 3862327-1 (Rework with DC abradable) or 3862327-2 (Rework with abradable strip) to prevent loosening of abradable shroud (Recommend rework of plumbing per SB 49-5867 and gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272) .

49-5729 SCI SCI Cooling Fan – Rework fan assembly 3862160-5 by replacing fan rotor 969249-1 with frequency screened rotor 969249-4 (Recommend rework of plumbing per SB 49-5867 and gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272) .

49-5730 SCI SCI Starter Motor – (Superseded See SB 49-7500) Replace starter motor 519858-5 with 519858-6 incorporating an improved brush base, brush wear indicator and field coil insulator for improved reliability.

WPG 331-250 [F]/[H] APU 14




49-5734 NSV NSV

Gearbox Assembly – Rework gearbox assembly 3862180-10 to 3862180-15, 3862180-9 to 3862180-18 or 3862180-14 to 3862180-16 by replacing the generator scavenge tube 3862186-1 with 3613699-1 to increase lubrication to the starter clutch assembly during rolldown for improved reliability (Related SB’s are recommended for improved starter clutch reliability).

49-5770 NSV NSV Ignition Exciter – Replace ignition exciter 3888058-3 (10-617075-5 Unison) with 3888058-5 (10-617075-6 Unison) to prevent hermetic seal failure and improve reliability. (See Unison rework SB 49-11)

49-5780 NSV NSV APU General – Rework oil cooler mounting on the upper inlet plenum to prevent cracking and facilitate oil cooler removal on-wing

49-5781 ANR ANR Oil Pump Assembly – Replace oil pump assembly 3880190-8 with 3880190-10 incorporating a stronger shear shaft and pump gears for increased durability.

49-5782 NSV NSV Oil Pump Assembly – Rework oil pump assembly 3880190-8 to 3880190-10 to incorporate a stronger shear shaft and pump gears for increased durability.

49-5811 NPE NPE APU General – Rework heat shields 3844020-3 to 3844020-6, 3844021-4/-5 to 3844021-9/-10, 3613194-1/-2/-3/-4 to 3613194-5/-6/-7/-8, 3844199-1 to 3844199-2, 3844268-1/-2 to 3844268-3/-4 or 3613195-1/-2/-3 to 3613195-4/-5/-6 replacing the welded thermocouple boss nut plates with a riveted nut plate to improve maintainability.

49-5814 NSV NSV APU General – Remove turbine scavenge oil return check valve 771-503-9008, 771-503-9023 or 3880366-1 and replace with adapter MS21900J4 to prevent coking and possible blockage in the oil return.

49-5817 NSV NSV APU General – Relocate low oil pressure switch to APU inlet plenum to reduce vibration and improve reliability.

49-5827 NPE NPE Power Section – Rework/replace tie shaft assembly 3822077-2 to 3822077-4 or replace tie shaft assembly 3822077-5 with 3822077-4 to prevent turbine scavenge drive insert slippage and possible oil leakage.

49-5835 NSV NSV Gearbox Assembly – Replace oil filler cap assembly 3862247-1 with oil cap and adapter 572-533-9601 to improve maintainability.

49-5839 NPE NPE Power Section – Replace combustion transition liner 3844001-1 with 3844001-3 incorporating a thermal barrier coating (TBC) to improve durability.

49-5842 NPE NPE Power Section – Rework/replace the combustion chamber 3830051-4 to 3830051-5 incorporating a thermal barrier coating (TBC) to improve durability.

49-5844 SCI SCI Power Section – (Superseded by SB 49-5965) Rework first-stage turbine wheel assembly 3840002-2 to 3840002-3 by replacing the turbine blades 3840004-1 with 3840004-2.

49-5845 ANR ANR

Power Section – Rework/replace first-stage stator assembly 3844040-3 to 3844040-5 by replacing the nozzle 3844038-1 (IN738) with 3844038-4 (Improved material MAR-M-247), or stator assembly 3844040-8 to 3844038-5 by replacing the nozzle 3614744-1 (Bi-Cast) with 3844038-4 and baffle 3844080-2 with 3844080-1 to improve resistance to hot gas corrosion, erosion and reduce cost.

49-5846 ANR ANR Power Section – Rework second-stage stator 3844011-5 to 3844011-9 by replacing nozzle 3844012-1 (IN738) with 3844012-3 (Improved material MAR-M-247) and stator seal 3844036-1 with 3844036-2 to improve resistance to hot gas corrosion and erosion.

49-5849 SCI SCI LOP Switch – (Superseded see SB 49-7478) Replace low oil pressure switch 3876024-4 with 3876024-5 incorporating a shunt disc design for improved reliability.

49-5854 NSV NSV Gearbox Assembly – Replace starter clutch inner shaft bearing 892575-1 with 3614423-1 due to unavailability of the older bearing and improved durability (Related SB’s are recommended for improved starter clutch reliability).

WPG 331-250 [F]/[H] APU 15




49-5861 ANS ANS Flow Sensor – Replace variable volume chamber 3289618-1 (Crimped) with 3290594-1 incorporating a bolted flange design to allow cleaning and repair and reduce cost of ownership.

49-5863 SCI SCI APU General – (Superseded by SB 49-7177) Replace igniter adapter gasket 3888052-1 and 3612628-2/-4 with MS35769-11 to prevent leakage.

49-5866 NSV NSV APU General – Relocate separate surge control components to flow sensing module 3614400-2 to improve maintainability with new total pressure probe, plumbing and mounting pallet and rework wiring harness 3888103-5 to 3888103-6 or harness 3888208-1 to 3888208-2

49-5867 SCI SCI

Cooling Fan – Replace cooling fan assembly 3862160-5/-9/-10 with 3614416-1 incorporating a shrouded fan rotor and new carbon seal and rework plumbing to incorporate buffer air supply to fan seal for improved reliability (Recommend rework of plumbing per this service bulletin and rework of the gearbox assembly per 49-7268 for installation of new cooling fan 3616959-6 per SB 49-7272)

49-5883 NPE NPE

Power Section – Rework/replace second stage turbine stator seal 3844036-1 with 3844036-2 or 3609721-1/-3 to 3615081-1/-2 third stage seal 3844043-1 to 3844043-2 and interstage labyrinth seal 3844002-1 with 3844002-2 or 3844050-1 with 3844050-2 or 3609721-4/-5 to 3615081-1 incorporating honeycomb seals in place of felt metal for improved turbine section reliability.

49-5884 NPE NPE Power Section – Rework/replace third-stage turbine curvic V-seal 868892-2 to 3842130-7 incorporating more cooling holes to increase cooling to the third stage turbine wheel to decrease thermal distress.

49-5888 NSV NSV

Fuel Control Assembly – Replace fuel control assembly 3882500-12, with 3882500-14 incorporating a replaced torque motor 3882506-3 with 3882506-5/-6 or FCU 3882500-13 with 3882500-15 incorporating a replaced torque motor 3882480-1/-2 with 3882480-1/-2 or 3882480-3 to prevent bobbin cracking and APU overtemperature or overspeed shutdowns (Recommend upgrade to 3882500-17 per 49-7157).

49-5890 SCI SCI Load Compressor – Replace outer insulator shield 3826118-5 or 3826118-6 and inner insulator shield 3826119-5 or 3826119-6 with a one-piece insulator 3826680-1 for improved durability (Refer to SB 49-7056).

49-5891 NSV NSV APU General – Replace ignition lead 3888076-1/-2 with 3888076-3 incorporating a silicon insulated wire to prevent separation and a subsequent APU “No Flame”.

49-5894 NSV NSV Flow Sensor – Replace differential pressure transducer 3876085-2 with 3876085-3 for improved resistance to contamination and reliability.

49-5895 NSV NSV

Fuel Control Assembly – Rework fuel control assembly 3882500-12, Series 2 to 3882500-14 replacing torque motor 3882506-3 with 3882506-5/-6 or rework fuel control assembly 3882500-13 to 3882500-15 replacing torque motor 3882480-1/-2 with 3882480-1/-2 or 3882480-3 to prevent bobbin cracking and APU overtemperature or overspeed shutdowns (Recommend upgrade to 3882500-17 per 49-7156).

49-5900 SCI SCI IGV Actuator – Replace IGV actuator 3886070-2 with 3886070-4 incorporating a replacement actuator shaft end to prevent interference with the bellcrank assembly. (Refer to SB 49-5971)

49-5907 NPE NPE Power Section – Rework primary fuel manifold 3882491-2 to 3842491-3 and secondary fuel manifold 3882492-2/-3 to 3882492-5/-6 by replacing nozzle retainer 3830055-1 with 3613619-1 to prevent possible air leakage and retainer cracking.

49-5908 NPE NPE Fuel Manifold – Replace primary fuel manifold 3882491-2 with 3842491-3 and secondary fuel manifold 3882492-2/-3 with 3882492-5/-6 incorporating a replacement nozzle retainer 3830055-1 with 3613619-1 to prevent possible air leakage and retainer cracking.

49-5916 NSV NSV Ignition Exciter – Replace ignition exciter 3888058-4 (Simmonds) with 3888058-5 (Unison Revision T or greater) or 3888058-6 (Unison) to prevent internal arching and malfunction.

WPG 331-250 [F]/[H] APU 16




49-5929 ANR ANR Power Section and Load Compressor – Replace the aft load compressor and fwd power section ball bearings 3822071-1 with 3613827-1 to prevent separator fracture and improve reliability.

49-5960 NSV NSV Fuel Flow Divider – Rework flow divider and drain valve assembly 3882550-2 to 3882550-3 by replacing inlet filter 870886-2 with 3882892-2 to prevent leakage from contamination at the drain valve resulting in poor fuel atomization, degraded APU performance and possible no-start.

49-5961 NSV NSV Fuel Flow Divider – Replace flow divider and drain valve assembly 3882550-2 with 3882550-3 incorporating a replaced inlet filter 870886-2 with 3882892-2 to prevent leakage from contamination at the drain valve resulting in poor fuel atomization, degraded APU performance and possible no-start.

49-5962 NSV NSV Gearbox Assembly – Rework gearbox assembly 3862180-7 to 3862180-9 to add a generator magnetic plug and relocate the de-oil temperature switch to improve maintainability

49-5965 NPE NPE Power Section – Rework/replace the first-stage turbine wheel assembly 3840002-2/-3 to 3840002-5 by replacing the turbine blades 3840004-1/-2 with 3840004-5 increasing the fir tree clearance to prevent blade shift from thermal ratcheting.

49-5968 ANR ANR Power Section – Rework heat shield 3844199-1/-2, 3613195-1/-2/-3/-4/-5/-6 or 3844020-1/-2/-3/-4/-5/-6 by replacing the heat shield seal 3844056-1/-2 with 3614949-1 to prevent air leakage.

49-5971 ANR ANR IGV Actuator – Replace IGV actuator 3886070-2/-4 (Parker) with 3886167-3 (A64847-5 Moog) for improved reliability. (See SB A64847-49-03).

49-5977 SCI SCI Surge Control Valve – (Superseded see SB 49-6504) Rework surge control valve 979806-8/10 to incorporate a different feedback assembly improving calibration capability and reducing wear.

49-5994 ANS ANS Turbine Scavenge Pump – Replace turbine scavenge pump assembly 3880160-2 with 3880160-3 incorporating a new shaft and pilot bushing to reduce wear, a harder material pump gear to prevent chipping, an added inlet screen to prevent FOD and larger pump elements for increased pump capacity.

49-6503 SCI SCI Power Section – Replace turbine case 3844004-3/-6 or 3844124-1 with 3844124-2 incorporating a reversed heat shield seal flange to reduce seal deterioration and prevent air leakage.

49-6504 NSV NSV Surge Control Valve – Rework surge control valve 979806-8/-9/-10 to 979806-11 by incorporating multiple improvements for increased reliability. (See replacement SB 49-6506 and recommended upgrade per SB 49-7047)

49-6506 NSV NSV Surge Control Valve – Replace surge control valve PN 979806-10 with PN 979806-11 incorporating multiple improvements for increased reliability. (See rework SB 49-6504 and recommended upgrade per 49-7526)

49-6530 NSV NSV Load Compressor – Replace IGV bellcrank assembly 3826150-3 with 3826527-2 or rework bellcrank 3826527-1 to 3826527-2 replacing the needle bearing 369144 with a non metallic bushing 3827098-1 to prevent corrosion and binding.

49-6536 NPE NPE Power Section – Rework third-stage turbine wheels 3840010-1/-2/-3 and 3840020-2/-3 by reworking the rivet hole area to reduce stresses preventing cracks and possible blade separations or replace with turbine wheel 3840022-3/-4.

49-6566 NSV NSV APU General – Rework identification strap on wiring harness 3888103-1/-2/-3/-4/-5 or 3888208-1 at the P2 and P3 connectors to prevent possible cross connections and APU operational difficulties

49-6570 NSV NSV APU General – Rework flow sensing module 3614400-2 to 3614400-6 by reworking/replacing the static pressure manifold 3614410-1 with 3615884-1 to correct installation interference at the aircraft mount strut.

WPG 331-250 [F]/[H] APU 17




49-6614 NSV NSV APU General – Relocate separate surge control components to flow sensing module 3614400-4 to improve maintainability with new total pressure probe, plumbing and mounting pallet and rework wiring harness 3888103-5 to 3888103-6 or harness 3888208-1 to 3888208-2.

49-6617 SCI SCI Turbine Scavenge Pump - Invalid - Rework turbine scavenge pump assembly 3880160-2 to 3880160-4 incorporating a shaft pilot bushing to reduce wear, a harder material pump gear to prevent chipping, an added inlet screen to prevent FOD and larger pump elements to increase pump capacity.

49-6622 SCI SCI Power Section – Invalid – Rework/replace first-stage stator assembly 3844040-3/-5 with 3844040-8 (Bi-cast).

49-6628 SCI SCI Surge Control Valve – (Superseded see SB 49-6504) Rework surge control valve 979806-10 by replacing the cover and diaphragm assembly to prevent leakage.

49-6660 ANR ANR APU General – Rework load control valve 979786-2 by replacing the retainer and air diaphragm 3163370-2 with a stretch fit diaphragm 3169821-1 to improve reliability

49-6674 SCI SCI Fuel Control Assembly – (Superseded See SB 49-7156) Rework fuel control assembly 3882500-14 to 3882500-16 to incorporate a shaft seal with a pressed on seal rotor and low drag bushings in the pump assembly to prevent fuel leakage and possible APU no-start during cold soak conditions.

49-6679 SCI SCI Flow Sensor (Superseded see SB 49-7568) – Replace differential pressure transducer 3876085-3 with 3876085-4 incorporating reverse pressure protection, increased temperature resistance and isolation of internal electronics to prevent calibration shift and premature deterioration.

49-6696 NPE NPE Power Section – Rework second-stage stator 3844011-9 by replacing rivets NAS1399C4-5 with M7885-5-4-05 and rework third-stage stator 3844018-1 by replacing rivets NAS1398C4-5 with M7885-4-4-04 for improved rivet retention.

49-6697 SCI SCI Power Section – Invalid – Superseded See SB 49-5827.

49-6746 ANS ANS APU General – Replace total pressure transducer 3876084-1 with 3876084-2 incorporating increased temperature resistance and solid state components to prevent calibration shift and premature deterioration.

49-6747 ANS ANS Flow Sensor – Replace inlet pressure transducer 3876035-4 with 3876035-5 incorporating increased temperature resistance and solid state components to prevent calibration shift and premature deterioration.

49-6766 NPE NPE APU General – Remove mid-frame oil scavenge screen to minimize possible secondary damage following internal failure.

49-6778 SCI SCI Fuel Control Assembly – (Superseded See SB 49-7157) Replace fuel control assembly 3882500-14 with 3882500-16 incorporating a shaft seal with a pressed on seal rotor and low drag bushings in the pump assembly to prevent fuel leakage and possible APU no-start during cold soak conditions.

49-6845 SCI SCI

Cooling Fan – Rework cooling fan assembly 3614416-1 to 3614416-2 by reworking the containment ring 3614588-1 to 3614588-8 or 3614588-2 to 3614588-9 to increase the clearance between the rotor shroud and containment ring to prevent contact resulting in fan rotor damage or possible failure (Recommend rework of gearbox assembly per 49-7268 and cooling fan to 3676959-6 per SB 49-7281).

49-6918 NSV NSV Starter Motor – Replace ignition unit 3888058-1/-3/-5 (Pre revision T) with 3888058-5 (Revision T or greater) to prevent possible EMI causing electronic interference with the IGV actuator and position resulting in APU no start.

49-6921 ANR ANR Flow Sensor - Rework flow sensing module 3614400-1/-2/-4/-6 to 3614400-7 by replacement of the adjustable static pressure probe 3614404-4 and sensor assembly 3614408-1 with calibrated probe assembly 3876243-1 to prevent improper adjustment and calibration and resistance to FOD.

WPG 331-250 [F]/[H] APU 18




49-6938 SCI SCI

Cooling Fan – Replace cooling fan assembly 3614416-1 with 3614416-2 replacing the containment ring 3614588-1 with 3614588-8 or 3614588-2 to 3614588-9 to increase the clearance between the rotor shroud and containment ring to prevent contact resulting in fan rotor damage or possible failure (Recommend rework of gearbox assembly per 49-7268 and cooling fan to 3676959-6 per SB 49-7281).

49-6941 SCI SCI

Turbine Scavenge Pump – (Cancelled no further rework permitted, see SB 49-5994 for pump replacement) Rework turbine scavenge pump assembly 3880160-2 to 3880160-5 incorporating a new shaft and pilot bushing to reduce wear, a harder material pump gear to prevent chipping, an added inlet screen to prevent FOD and a reworked housing with larger pump elements for increased pump capacity.

49-6948 NPE NPE Load Compressor – Rework/replace IGV assemblies 3810231-16/-17/-18/-19 to 3810231-20/-21/-22/-23 and rework IGV housings 3810224-7/-8/-9/-10 to 3810224-11/-12/-13/-14 and IGV cover 3810123-6 to 3810123-8 by replacement of the vane stem and main gear bushings utilizing Karon V liners for improved durability.

49-6953 ANS ANS APU General – Replace compressor inlet screen 3810198-3/-4/-5 with two 3615139-1 screens for easier installation and improved security.

49-6972 ANR ANR Power Section – Rework power section assembly 3801003-7 by reworking the heat shield 3844199-2 to 3844199-3 and installing a separate surge air deflector 3616209-1

49-6980 ANR ANR Surge Control Valve - Rework surge control valve 979806-8/-9/-10/-11 by replacing washers under the actuator cover screws to prevent scuffing and loss of anodize. (See recommended upgrade per SB 49-7047)

49-6985 NSV NSV

Surge Control Valve - Rework surge control valve 979806-11 to 979806-11 Change 2 (Series 3 for production new) by reworking/replacing rod assembly 3172199-3 to 3172199-4 and inspect air diaphragm 117500-28 for a properly installed elastomer seal gland to correct a stack tolerance and prevent possible quick dump leakage. (See recommended upgrade per SB 49-7047)

49-6994 NSV NSV

APU General - Rework fan isolation valve 397728-6 to 397728-8 by replacing the cover 885094-3 with 3181293-1 to prevent cracking and leakage, replacing the spring 885090-1 with 3181184-1 to increase operation margin for SB's 49-7192/7193 and reworking the diaphragm assembly 882568-2 to 882568-3 by replacing diaphragm 882572-1 with 3181183-1 (Stretch Fit) to improve durability.

49-6995 SCI SCI APU General - Rework fan isolation valve 397728-6 by reworking the diaphragm assembly 882568-2 to 882568-3 by replacing the diaphragm 882572-1 with 3181183-1 (Stretch Fit) to prevent leakage and improve durability.

49-7009 SCI SCI APU General - Rework fan isolation valve 397728-6-1 by replacing cover assembly 885094-3 with 3181293-1 to prevent cracking and leakage.

49-7035 ANR ANR Load Control Valve – Rework load control valve 979786-2 by incorporating diaphragm assembly 3182175-1 for product standardization and improved reliability.

49-7036 ANR ANR Load Control Valve – Rework load control valve 979786-2 by incorporating linkage assembly 3182244-2 for product standardization and improved reliability.

49-7041 NSV NSV

Surge Control Valve – Rework surge control valve 979806-11 to 979806-12 incorporating a reduced regulator setting to prevent overstressing of the spring and regulator droop, replacement of the servo, feedback spring and control orifice to reduce airflow, temperature and contamination and, a replacement torque motor to allow valve closure between 80mA and 90mA tripling the ambient closing margin.

49-7047 NSV NSV Surge Control Valve - Rework surge control valves 979806-11 and 979806-12 replacing the lever assembly Part No. 3173837-2 with 3173837-3 and the adapter assembly Part No. 3169768-1 with 3169768-4 to improve wear resistance and life. Replace diaphragm assembly Part No. 117500-28 with 117500-29 for surge control valve Part No. 979806-12.

49-7049 ANR ANR Load Control Valve – Rework load control valve 979786-2 to 979786-4 by replacing ball bearing 3169407-1 with 117088 with improved durability.

WPG 331-250 [F]/[H] APU 19




49-7056 ANS ANS Load Compressor - Replace load compressor insulator shield 3826680-1 with 3826680-2 with a new material for improved durability.

49-7061 SCI SCI Starter Motor – (Superseded See SB 49-7500) Replace starter motor 519858-5/-6 with 519858-7 incorporating a non-metallic split brush for improved reliability, torsion brush springs, new cam operated brush wear indicator, an added o-ring packing behind the face seal to prevent oil leakage, and improvements to the stator coil and negative terminal post.

49-7065 ANR ANR Flow Sensor - Replace flow sensing module 3614400-1/-2/-4/-6 with 3614400-7 incorporating a replacement of the adjustable static pressure probe 3614404-4 and sensor assembly 3614408-1 with calibrated probe assembly 3876243-1 to prevent improper adjustment and calibration and resistance to FOD.

49-7082 NSV NSV Power Section - Install external heat shield tadpole seal 651-5503-9002 and retainers 3616847-1 and 3616847-2 to prevent air leakage at the heat shield seal.

49-7119 NSV NSV APU General - Replace ignition unit insulator 3826170-1 with extended insulator 3826170-2 to prevent surge exhaust air leakage from the heat shield from impinging on the ignition exciter.

49-7147 SCI SCI Gearbox Pressurization - Invalid - Replace gearbox shutoff valve 3289514-1 with 3616848-1 eliminating elastomer components to prevent degradation and valve malfunction (See SB 49-7380, A7264).

49-7156 NSV NSV

Fuel Control Assembly - Rework fuel control assembly 3882500-14/-16 to 3882500-17 incorporating a new bellows carbon seal to prevent fuel leakage, a 40 micron filter to prevent contamination and a "racetrack" pump bushing to prevent binding and possible APU no start during cold operation. (See Replacement SB 49-7157)

49-7157 NSV NSV Fuel Control Assembly - Replace fuel control assembly 3882500-14/-16 with 3882500-17 incorporating a new bellows carbon seal to prevent fuel leakage, a 40 micron filter to prevent contamination and a "racetrack" pump bushing to prevent binding and possible APU no start during cold operation. (See Rework SB 49-7156)

49-7177 NSV NSV Power Section - Replace igniter adapter gasket MS35769-11 with 362-509-9003 to prevent leakage of combustion hot gas.

49-7181 NSV NSV APU General - Replace fan isolation valve 397728-6 with 397728-8 incorporating a replacement cover to prevent cracking and leakage, a new spring to increase operation margin for SB's 49-7192/7193 and a new diaphragm (Stretch Fit) to improve durability.

49-7193 NSV NSV APU General - Rework plumbing and electrical assemblies to relocate the fan isolation valve muscle pressure supply from the surge control valve regulator to a direct PCD1 source to reduce internal temperatures and contamination at the SCV for improved reliability.

49-A7264 CAM CAM Lube Pump Assembly - Replace gearbox shutoff valve 3616848-1 with 3616848-2 due to possible blockage of the valve flow area resulting in high oil consumption at altitude.

49-7268 NSV NSV Gearbox Assembly - Rework gearbox assembly 3862180-13 to 3862180-21, 3862180-15 to 3862180-22 and 3862180-17/-18/-19/-20 (change numbers) by replacing the fan idler gear 3860169-4 with 3860169-5 to prevent fracture, and replacing plug 3862380-1 with 3617041-1 to allow installation of cooling fan 3616959-6 post SB 49-7272.

49-7272 NSV NSV

Cooling Fan - Replace cooling fan 3614416-1/-2 with 3616959-6 incorporating a new fan rotor to prevent blade separations, stretched tie shaft to improve internal rigidity, hydraulic bearing mount for improved durability, and an external mount strut for added support (Rework of gearbox assembly per SB 49-7268 is required prior to or in conjunction with this bulletin).

49-7274 NSV NSV Flow Sensor - One-time inspection and test of total pressure transducer (P-Total) 3876084-2, differential pressure transducer (Delta-P) 3876085-4 and inlet pressure transducer (P2) 3876035-5 for proper function and calibration.

WPG 331-250 [F]/[H] APU 20




49-7281 NSV NSV

Cooling Fan - Rework cooling fan 3614416-1/-2 to 3616959-6 incorporating a new fan rotor to prevent blade separations, stretched tie shaft to improve internal rigidity, hydraulic bearing mount for improved durability, and an external mount strut for added support (Rework of gearbox assembly per SB 49-7268 is required prior to or in conjunction with this bulletin).

49-7337 NSV NSV Fuel Control Assembly - One time inspection of the fuel control 3882500-14/-16/-17 at the housing delta P valve port for improper machining.

49-7341 ANS ANS Power Section - Replace heat shield insulation blanket segments to allow a better fit following incorporation of service bulletin 49-7082.

49-7345 SCI SCI Cooling Fan - Rework cooling fan 3614416-1/-2 by replacing the axial through bolts with a stronger material to prevent fracture in the event of a cooling fan failure (Recommend rework of gearbox assembly per 49-7268 and cooling fan to 3676959-6 per SB 49-7281).

49-7349 NPE NPE Power Section - One-time inspection of specific serialized second-stage turbine stators 3844012-3 and assemblies 3844011-9 for a manufacturing defect which could cause increased stress on the second stage turbine blades.

49-7380 ANR ANR Gearbox Pressurization - Replace gearbox shutoff valve 3289514-1 with 3616848-2 eliminating elastomer components to prevent degradation and valve malfunction.

49-7401 SCI SCI Load Compressor - Invalid - Replace load compressor backshroud packing with retainers, bolts and washers to prevent oil leakage (See SB 49-7479).

49-7417 OPR OPR Power Section - Replace turbine seal T-bolt gaskets 865106-3 with 3617447-1 and turbine scavenge pump oil return gasket 3880922-1 with 3617446-1 to prevent oil leakage

49-7426 ANS ANS Power Section - Replace third-stage turbine wheel assembly 3840010-3, 3840020-3 and 3840022-3 with 3840022-4 for increased service life and ease of manufacture and repair.

49-7478 SCI SCI LOP Switch (Superseded by 49-7593) - Replace Low Oil Pressure (LOP) switch 3876024-2/-3/-4/-5 with 3876024-6 with improved manufacturing techniques and testing for improved reliability.

49-7479 NPE NPE Load Compressor - Replace load compressor backshroud packing with retainer (Threadseal) 583-523-9003 or 583-522-9404 with 583-512-9204 (Stato Seal) and bolt MS9557-09 or MS9557-10 with 3617762-1 to prevent deterioration and oil leakage.

49-7500 ANR ANR Start Motor - Replace start motor 519858-5/-6/-7 with 519858-8 incorporating an improved brush lead shunt to prevent separation and a brush wear indicator lens cover to prevent damage for improved reliability. (See Rework SB 49-2369)

49-7526 NSV NSV

Surge Control Valve - Replace surge control valve 979806-11 with 979806-12 incorporating a reduced regulator setting to prevent overstressing of the spring and regulator droop, replacement of the servo, feedback spring and control orifice to reduce airflow, temperature and contamination and, a replacement torque motor to allow valve closure between 80mA and 90mA tripling the ambient closing margin.

49-7568 ANS ANS Flow Sensor - Replace differential pressure transducer (Delta-P) 3876085-4 with 3876085-5 to prevent negative calibration shift, limit affects from a sticking DFCV and reduce internal contamination for improved reliability.

49-7573 OPR OPR Flow Sensor - Rework flow sensing module 3614400-7 to 3614400-8 by replacing the Delta-P transducer 3875085-4 with 3876085-5 to prevent negative calibration shift, limit affects from a sticking DFCV and reduce internal contamination for improved reliability.

49-7607 ANR ANR APU General - Replace load control valve 979786-2 with 979786-4 incorporating a replacement ball bearing 3169407-1 with 117088 with improved durability.

49-7619 ANR ANR APU General - Rework/replace wiring harness 388103-6 to 3888466-1 or 3888488-1 to incorporate a time totalizing meter and start counter using kit 3888492-1 to enable hours and cycles tracking.

WPG 331-250 [F]/[H] APU 21




49-7782 ANR ANR Power Section - Rework/replace turbine bearing support assembly.

49-7933 OPR OPR APU General - Bulletin outlining Honeywell approved oils for use in APU’s.

GTE0514 ANR ANR Gearbox Assembly – Replace Oil Pump Spur Gear, PN 3860165-1 with PN 3860165-2 and Spur Gear Shaft, PN 3860180-2 with PN 3860180-6.

GTE0573 NPE NPE Load Compressor - Replace rod end bearing 137-542-9500 with 137-542-9501 with improved corrosion resistance (Refer to SB 49-5577).

GTE0574 NPE NPE Power Section - Replace asbestos gaskets 3888052-2 with 3612628-2 or S8157BS400-031 (igniter) and 3888052-1 with MS35769-11 (plenum drain). See SB 49-5691 and 49-5863.

GTE0575 NPE NPE Power Section - Replace asbestos gasket 3880171-2 with 3880922-1 (turbine scavenge oil return). Superseded by 49-7417.

GTE0676 ANR ANR Load Compressor - Replace insert MS51830CA201L with 423-603-9011 to standardize the inserts.

GTE0678 ANR ANR APU General - Replace EGT thermocouple terminal 724-505-9008 with 724-505-9013 and terminal 724-505-9010 with 724-505-9014. Use clamp M8504952-1-24N as an alternate clamp for MS3417-24N.

GTE0719 ANS ANS Power Section - Replace 3810138-2 first stage compressor shroud with 3810138-1.

GTE0733 ANS ANS Power Section - Replace turbine bearing seal and pump gaskets 865091-2, 865095-3, 865106-2 and 865792-1 with 865091-4, 865095-5, 865106-3 and 865792-3 to replace with non-asbestos turbine bearing seal and pump gaskets.

GTE0773 ANS ANS Load Compressor – Replace IGV Bellcrank set Part No. 3826150-3 with an alternate bellcrank assembly Part No. 3826527-1.

GTE0777 ANS ANS Power Section - Replace gasket Part No. 3101768-1 with 3830351-1 to incorporate the alternate gaskets on primary and secondary fuel nozzles.

GTE0778 ANS ANS Power Section - Replace bolt Part No. NAS1003-20 with NAS1003-15 and AN960-10 washer with AN960C10L for first stage compressor diffuser assembly.

GTE0781 ANS ANS Turbine Scavenge Pump - Replace oil pump spur gear Part No. 3880162-1 with 3881106-1 to provide commonality with new configuration turbine scavenge pump.

GTE0782 ANS ANS Turbine Scavenge Pump - Replace rotor set Part No. 692233 with 3881149-2 to provide commonality with new configuration turbine scavenge pump.

GTE1051 ANR ANR Load Compressor - Replace pin Part No. S9008BM278 with MS16562-209 to ease installation of pin during assembly of the load compressor impeller coupling and knife edge seal assembly.

GTE1106 NA ANS Gearbox Assembly - Replace gearbox housing stud Part No. 682-558-2106 with 682-558-2108.

GTE1107 ANS ANS APU General - Replace identification plate Part No. S9803-3 with S20000-1.

GTE1117 NPE NPE Power Section - Replace gasket Part No. S8157BS400-031 with 3883327-1.

GTE1239 ANR ANR Power Section - Replace Bolt Part No. MS9565-08 with MS9705-08, Bolt Part No. MS9565-11 with MS9705-11 and Bolt Part No. MS9705-12 with MS9565-12 to standardize the bolt material used on the fuel manifolds.

WPG 331-250 [F]/[H] APU 22




GTE1284 ANS ANS Fuel Flow Divider - Replace fuel solenoid valve Part No. 3876049-4 with 3876049-5.

GTE1293 ANR ANR Cooling Fan - Replace ball bearing Part No. 3613704-2 with 3613704-3 on cooling fan 3616959-6 for improved reliability.

GTE1294 ANR ANR Cooling Fan - Replace fan rotor Part No. 3616977-2 with 3616977-3 on cooling fan 3615959-6 to provide fan rotor without damping coating to improve reparability.

GTE1308 ANS ANS APU General – Replace Delta P Sensor with interchangeable multiple part numbers.

Compliance Codes

ANR At Next Repair (incorporate next time part requires repair) NPE Next Part Exposure (incorporate next time part is removed from APU and exposed)

ANS At Next Scrap/Replacement (attrition to incorporate when part is not reparable or no longer available)

NSV Next Shop Visit (incorporate next time part/unit is returned to the repair facility)

CAM Mandatory or Campaign (remove to incorporate or incorporate on-wing at next opportunity)

MC Model Conversion (Upgrade modification from one model to another)

FE Evaluation Only (incorporate as requested by the operator and as indicated in FE service bulletin)

SCI Superseded, Cancelled or Invalidated

NA Not applicable OPR Operator Request Only (Not part of standard workscope)

WPG 331-250 [F]/[H] APU 23


5. LRU WORKSCOPE DEVELOPMENT

5.1 Regulatory Information

Workscoping/disposition terms differ from those required for Regulatory Airworthiness Forms (such as the FAA 8130, Block 12 Status/Work). These forms use the following words: ”New”, “Overhauled”, ”Prototype”, ”Inspected”, “Repaired”, “Rebuilt”, “Modified” (“Altered”), or “Export”.

For Regulatory Airworthiness Form purposes, “Heavy Repairs” should be entered as “Overhauled”; “Medium and Light Repairs” should be entered as “Repaired” in Block 12.

5.2 Levels of Repair (LRU)

Similar to the APU levels of repair, components (LRU’s) have three levels of repair:

“Light Repair”- IRM continue-time inspection criteria applies. No part exposure or replacement (only calibration, testing, adjustments, etc). Qualifies for a Regulatory Airworthiness Form (8130 or equivalent) noted as “Repaired”. (See IRM definition of “Continue-time”).

“Medium Repair” – IRM continue-time inspection criteria applies. Partial disassembly and/or parts replacement (external component replacement, sub-module disassembly, etc) or complete disassembly with reuse (continue-time) of major parts. Qualifies for a Regulatory Airworthiness Form (8130 or equivalent) noted as “Repaired”. (See IRM definition of “Continue-time”).

"Heavy Repair" - LRU Component Maintenance Manual (CMM) criteria applies. Complete disassembly, inspection and test of all major parts. The terms “overhauled”, “heavy repair” and “zero-time” are synonymous. Qualifies for a Regulatory Airworthiness Form (8130 or equivalent) noted as “Overhauled”. (See IRM definition of “Zero-time”).

WPG 331-250 [F]/[H] APU 24


5.3 LRU Workscopes

The following information (if available) assists in developing an effective LRU workscope:

• On-wing squawks or APU test cell maintenance actions

• APU/LRU hours (or calendar time equivalent) since last shop visit

• APU/LRU hours (or calendar time equivalent) since last Heavy Repair

• Work accomplished/test results from last shop visit and last Heavy Repair

• Incoming induction checks/test to verify reasons for removal

• Experience and knowledge of typical issues with the LRU

In some cases, even if a LRU CMM exists, continue-time check and limited test criteria for Light and Medium repairs is provided in the APU level IRM.

If continue-time check criteria are not provided in the APU level IRM, the LRU can still qualify for a Light or Medium repair when partial or limited disassembly and check is accomplished. The LRU must meet the CMM test requirements if a limited test is not provided in the APU level IRM.

Refer to the applicable LRU CMM for information including disassembly, cleaning, detailed inspection, assembly and complete test instructions.

Table 3 provides suggested LRU workscopes based on APU/LRU operating hours since repair and module depth of repair. Table 4 provides Special LRU Workscopes based on unique operating environments and conditions.

WPG 331-250 [F]/[H] APU 25


Table 3. LRU Workscopes

The suggested workscopes provided in this table may be adjusted by repair facility engineering based on the APU/LRU time since repair, as-received condition, operational history/environment, and customer requirements etc.

LRU Part Numbers Latest SB Suggested Workscope

Wiring Harness 3888103-1 thru -6 3888208-1/-2 3888466-1 3888488-1

49-7619 Visual ESV – Code 0 if OK Code 3 - If removed from APU

Ignition Exciter 3888058-3/-4/-5/-6 49-5916 Visual ESV

Code 3 > 5000 LRU Hrs or TSLAPUSV

Igniter Plug 369949-3 305766-1 49-5519 Visual ESV

Igniter Lead 3888076-2/-3 49-5891 Visual ESV

Starter Motor 519858-5/-6/-7/-8 49-7500 Code 5 ESV - Visual/Clean Brush Dust Code 3 - If Brush Indicator is less than 50%

Speed Sensor 3876026-2/-3 625938-3 GTE0403 Visual at Exposure – Code 0 if OK

EGT Thermocouple 3876027-3/-4 49-5439 Visual at Exposure – Code 0 if OK

Inlet Press P2 Sensor 3876035-4/-5 49-6747 Visual at Exposure – Code 0 if OK Code 3 > 5000 LRU Hrs or TSLAPUSV

LC Inlet Temp LCIT Sensor 3876072-1/-2 None Visual at Exposure – Code 0 if OK

Pneu Flow Sensor Assy (Pallet) 3614400-2/-4/-6/-7/-8 None Visual ESV - See Individual Components

Pneu Variable Volume Chamber 3289618-1 3290594-1 49-5861 Code 3 > 5000 LRU Hrs or TSLAPUSV

Pneu Total Press PT Sensor 3876084-1/-2 49-6746 Visual at Exposure – Code 0 if OK

Pneu Delta Press DP Sensor 3876085-1 thru -5 49-7568 Visual ESV Code 3 > 5000 LRU Hrs or TSLAPUSV

Pneu Total Press PT Probe 3876086-2 49-5407 Visual and Code 5 ESV

Pneu PT/PS Probe (Fixed) 3876243-1 49-6921 Visual and Code 5 ESV

Pneu PT/PS Probe (PS Adj.) 3614408-1 None Visual and Code 5 ESV

Pneu Static Flow Sensor (Ring) 3876096-1 49-5440 Visual and Code 5 ESV

WPG 331-250 [F]/[H] APU 26



Oil Press Switch LOP 3876024-4/-5/-6 49-7478 Visual @ Exposure – Code 0 if OK

Oil Temp Switch HOT MS28034-3 None Visual @ Exposure – Code 0 if OK

Gen Filter Delta P Switch 3876048-1/-2 Deleted Per SB 49-5692 Visual @ Exposure – Code 0 if OK

Gen Oil Filter Plug 3888026-1 49-5692 Visual @ Exposure – Code 0 if OK

De-Oil Temp. Switch 3876023-2 49-5451 Code 3 ESV

De-Oil Solenoid 3876047-2/-4 3876166-1 49-5645 Code 3 ESV

GBX Press Reg Valve 3289504-1/-2 49-5579 Code 3 > 5000 LRU Hrs or TSLAPUSV

GBX Press Shutoff Valve 3289514-1 3616848-1/-2 49-7380 Code 3 > 5000 LRU Hrs or TSLAPUSV

GBX Press Shuttle Valve 420-44A6BBB (771-527-9002) None Visual ESV – Shake test for movement

Code 6 > 5000 LRU Hrs or TSLAPUSV

Oil Pump Assy 3880190-5/-8/-10 49-5781 Code 3 > 10,000 LRU Hrs or TSLAPUSV

Cooling Fan Assy 3614416-1/-2 3616959-6 49-7272 Visual ESV

Code 4 > 5000 Hrs TSLAPUSV (PN 3614416)

Cooling Fan Isolation Valve 397728-4/-6/-8 None Visual ESV - Check for Diaphragm Leakage

Oil Cooler/Reg Assy 160126-2 None Code 5 > 5000 TSLAPUSV (Cooler) Code 3 > 5000 TSLAPUSV (Valve)

Oil Cooler Supply Check Valve 3880232-1 3880486-1 GTE0286 Visual at Exposure – Code 0 if OK

Oil Cooler Return Check Valve 3880233-1 3880487-1 GTE0286 Visual at Exposure – Code 0 if OK

Turbine Scavenge Pump 3880160-2/-3/-4/-5 49-5994 Code 4 > 5000 Hrs TSLAPUSV

Generator Scavenge Pump 3880200-5/-6 49-5661 Visual ESV – Rotation and bushing positionCode 4 > 10,000 LRU Hrs or TSLAPUSV

Fuel Control 3882500-14/-17 49-7157 Code 3 > 10,000 LRU Hrs or TSLAPUSV

Fuel Flow Divider 3882550-1/-2/-3 49-5961 Code 3 > 10,000 LRU Hrs or TSLAPUSV

Fuel Manifold (Primary) 3882491-1/-2/-3 49-5908 Code 3 > 5000 Hrs TSLAPUSV

WPG 331-250 [F]/[H] APU 27



Fuel Manifold (Secondary) 3882492-1/-2/-3/-5/-6 49-5908 Code 3 > 5000 Hrs TSLAPUSV

IGV Actuator 3886070-2/-4 3886167-3 49-5971 Code 3 > 10,000 LRU Hrs or TSLAPUSV

Surge Control Valve 979806-10/-11/-12 49-7526 Code 5 ESV – Replace Filter Code 3 > 5000 LRU Hrs or TSLAPUSV

Turbine Plenum Drain Valve 968214-6 None Visual at Exposure – Code 0 if OK

Starter Clutch Assembly 3612844-1 49-5714 Code 4 > 5000 Hrs TSLAPUSV

Load Control valve 979786-2/-4 49-7607 Code 3 > 5000 LRU Hrs or TSLAPUSV

Disposition Codes: 0 - Reuse & Test on APU 1 - Modify/Upgrade 2 - FT for Findings 3 - FT and Repair as Necessary 4 - Disassemble, Inspect and Repair 5 - Clean and Flush 6 - Replace Abbreviations: ESV - Each Shop Visit TSLAPUSV - Time (Hours) Since Last APU Shop Visit NOTE: The visual checks listed in the Suggested Workcsope are basic examinations for obvious damage, contamination and wear. If the component can be accessed for examination while installed on the APU, removal is not required.

WPG 331-250 [F]/[H] APU 28


Table 4. Special LRU Workscopes


Special Condition

Suggested Workscope

High Sulfur/Salt Environments (Corrosive)

LRU’s exposed to these environments may require special attention in addition to what is listed in Table 3.

In some cases LRU’s only require disassembly and cleaning to remove contaminants prior to return to service.

High Sand Environments (Erosive)

LRU’s exposed to these environments may require special attention in addition to what is listed in Table 3.

In some cases LRU’s only require disassembly and cleaning to remove contaminants prior to return to service.

Wiring Harness Special Test APU’s have been removed for cold soak start problems where standard troubleshooting procedures were unsuccessful. Electrical testing of the de-oil system revealed a problem with the diodes in the wiring harness which prevented proper de-oiling during APU start.

The function of the de-oil system is not verified during APU test so the following check of the wiring harness is suggested at each shop visit.

NOTE: The diodes are “Zener” diodes so the ohmmeter indication in the forward biased condition will be about 34.5 K ohms. Another method is to use the DIODE function available on some digital meters.

• Disconnect the starter terminal, de-oil temp switch (P25) and de-oil solenoid (P23) connectors.

• Verify POSITIVE continuity from the starter terminal to (P25) pin 1. • Verify NO continuity from (P25) pin 1 to the starter terminal. • Verify POSITIVE continuity from the main APU connector (P2) pin e to

(P23) pin 1 and (P25) pin 2. • Verify NO continuity from (P23) pin 1 and the main APU connector (P2)

pin e.

If repair is necessary, the diodes are located within the sleeving at the (P25) connector.

NOTE: Wiring Harness may have gray or white sleeves. Both assemblies are considered acceptable for service.

WPG 331-250 [F]/[H] APU 29


Special Condition

Suggested Workscope

Speed Sensor Special Test The speed sensor (monopole) has both continue-time and zero-time check criteria in the APU level IRM.

If a speed sensor (monopole) has a problematic history, the following additional test is suggested:

• Perform IRM Zero-time procedures at -40°F (-40°C) and 350°F (177°C) • Perform IRM Zero-time procedure while inducing vibration • Comply with remaining IRM Zero-time requirements

Fuel Flow Divider Test The functional test procedure for the fuel flow divider (3882550) is provided in CMM 49-31-63. However, to perform a complete functional test of the assembly, the fuel solenoid (3876046) should be tested per CMM 49-31-15.

WPG 331-250 [F]/[H] APU 30


6. GEARBOX WORKSCOPE

Refer to Appendix II for metal-in-oil guidelines and CMM 49-22-63 for disassembly and assembly procedures.

6.1 Gearbox External Visual Examination at Each Shop Visit

• Examine the magnetic plugs and residual oil for metal contamination. If significant contamination is found the gearbox should be removed for further examination.

• The Generator (or generator cover) should be removed at each shop visit. Examine the generator cavity for damage and contamination. If damage or significant contamination is found the generator should be sent for cleaning and repair, and the gearbox removed for further examination.

• Examine the generator scavenge pump (installed) for bushing migration. If either busing is shifted from the pump housing remove the pump and route for repair per CMM 49-27-15.

• Look for oil leakage from the generator, lube pump, de-oil adapter, starter motor, cooling fan, magnetic/drain plugs, oil sensors, oil cap/scupper, and sight glass, etc. Oil leakage at these locations can be repaired without removal of the gearbox.

• Look for oil leakage at the main gearbox to load compressor flange. If leakage is suspected, an operational check in a test cell is suggested to verify the source.

• Using the 5/16 inch drive on the forward end of the starter motor, or appropriate spline drive with the starter removed, check the clutch for proper “lock-up” in the counter clockwise (CCW) direction. In the clockwise direction (CW) the clutch should glide smoothly without rough or binding operation. Some friction may be felt when examining the clutch with the starter removed. If damage or wear is suspected (Pre-SB 49-5714) the gearbox should be removed to examine the clutch components for damage and wear. If Post-SB 49-5714, the clutch assembly can be removed for examination without removal of the gearbox assembly.

• The cooling fan should be removed at each shop visit. Examine the fan drive gear and idler gear in the gearbox for damage and wear. The “grind lines” from original manufacture may be visible across the tooth face and should not be obscured by a gray or dulled contact area or step. A polished appearance is a normal condition. A wear step, chipped or broken teeth, evidence of side loading, or a wavy polished appearance are not normal conditions. Axial movement of the idler gear in the gearbox is a normal condition.

WPG 331-250 [F]/[H] APU 31


6.2 Gearbox 5000 Hour Examination (Removal of the gearbox is not required)

If the gearbox has accumulated 5000 operating hours or greater, since last repair, the following additional examinations are suggested.

• Remove the starter clutch and adapter assembly (Post-SB 49-5714). Replace the inner shaft bearings and visually examine the remaining components for damage.

6.3 Gearbox Removed

If the gearbox is removed, the following additional examinations are suggested:

• Examine the starter clutch oil jet for contact with the generator oil-scavenge return tube. Contact between the jet and tube is not a normal condition. The tube can be adjusted to create a running clearance. If fretting is observed the oil jet can be removed for further examination.

• Examine for metal contamination. If significant metal contamination is found, complete disassembly of the gearbox is suggested.

• Examine exposed gear teeth for damage, wear and evidence of uneven loading. Wear resulting in a wear step (detected by passing a scribe of the tooth surface) is not a normal condition.

• Note damage to gears, bearings, tubes, retainers, seals, mating surfaces, threaded inserts, studs, etc. If damage is found, the gearbox should be disassembled to the extent necessary to repair the damage.

6.4 Partial Gearbox Disassembly

If the gearbox is removed and partially disassembled, the following additional examinations are suggested:

• Examine the bearing retainer (Spider) and exposed gearbox housing bearing liners for damage. Scratches, discoloration, and light scoring are normal conditions. Wear resulting in a wear step between the bearing race contact and non contact areas is not a normal condition.

• Examine exposed gear teeth for damage, wear and evidence of uneven loading. Wear resulting in a wear step (detected by passing a scribe of the tooth surface) is not a normal condition.

• Examine the combination idler gear (two piece gear) for cracks in the gear web and looseness of the “huck” bolts.

• Examine the accessory bores and mount surfaces for damage. Scratches, discoloration and light scoring are normal conditions provided leakage is not observed.

WPG 331-250 [F]/[H] APU 32


6.5 Gearbox Detail Part Check

Refer to IRM 49-23-49 for gearbox assembly Continue-time check criteria. The following guidelines are provided for detail parts exposed:

• The use of IRM Continue-time Check criteria for all detail parts should be maximized.

• The use of IRM Zero-time Check criteria for detail parts should be limited to:

(1) Requirements in customer maintenance specifications and other agreements.

(2) Instances of significant secondary damage to ensure part integrity.

(3) Instances where a gearbox “Overhaul” or “Heavy Repair” is requested.

WPG 331-250 [F]/[H] APU 33


7. LOAD COMPRESSOR WORKSCOPE

Refer to CMM 49-22-63 for removal, disassembly and assembly procedures.

The repair facility Engineer should be consulted to determine if an observed condition requires corrective action.

7.1 Load Compressor External Visual Examination

• Nicks, scratches, dents, fretting, pitting and other cosmetic discrepancies are normal conditions.

• Examine the load compressor outlet duct for damage, the presence of oil and the condition of the threaded inserts. Oil in the outlet duct is not a normal condition and may be an indication of carbon seal deterioration or oil ingestion.

• Note any damaged or loose plumbing, brackets, clamps, sensors, and ducts.

• Remove the IGV actuator and observe the movement of the inlet guide vanes. The IGV’s should move smoothly through full travel. Stiff movement is a normal condition. Binding or rough movement are not normal conditions and can indicate damage or corrosion. Excessively loose movement is not a normal condition and may indicate bushing or vane stem wear. The inlet screens can be removed to examine individual vane movement if wear is suspected.

7.2 Load Compressor Borescope Examination

• Examine the inlet guide vanes for damage. Erosion, scratches and discoloration and nicks without significantly displaced material are normal conditions but may be an indication of downstream damage. There should be two de-whistler baffles present. Broken, cracked, or bent vanes or de-whistler baffles are not normal conditions.

• Examine the load compressor impeller blade leading edges and contours for damage. Rough edges, erosion, and a few blade nicks (3-4 per blade) without significantly displaced material are normal conditions. Broken, cracked, or bent blades are not normal conditions.

• Examine the load compressor shroud for damage. Scratches, nicks and scoring are normal conditions. Heavy contact between the impeller and shroud or separation of shroud material is not normal and may be an indication of bearing deterioration, improper shimming of the impeller or severe surge.

• Examine the load compressor diffuser, where accessible, for damage. Erosion, nicks, scratches and discoloration are normal conditions. Broken, cracked, or bent vanes are not normal conditions.

WPG 331-250 [F]/[H] APU 34


7.3 Load Compressor Removed

If the LC is removed, the following additional actions are suggested:

• Note freedom of LC rotation.

• Examine the forward and aft bearing cavities for damage and debris.

• Examine the bearings (installed) for damage.

• Further examine the IGV’s for freedom of movement through full travel. Binding or rough movement are not normal conditions and can indicate damage or corrosion. Excessively loose movement is not a normal condition and may indicate bushing or vane stem wear.

7.4 Partial Load Compressor Disassembly

The load compressor can be partially disassembled to correct a specific discrepancy.

• The LC Impeller, shaft and knife edge seal does not require disassembly for continue-time check.

• The IGV’s can remain assembled on the LC inlet housing if repair is not required.

• Replacement of exposed carbon seals, seal rotors, gaskets, and packings is suggested.

• Replacement of the LC aft bearing (if exposed) is suggested if the bearing has accumulated more than 5000 hours.

7.5 Load Compressor Detail Part Check

The following guidelines are provided for detail parts exposed during repair:

• The use of IRM Continue-time Check criteria for all detail parts should be maximized.


(1) Requirements in customer maintenance specifications.


(3) Instances where a load compressor “Overhaul” or “Heavy Repair” is requested.

WPG 331-250 [F]/[H] APU 35


8. POWER SECTION WORKSCOPE

Refer to CMM 49-22-63 for disassembly and assembly procedures.

The repair facility engineering should be consulted to determine if an observed condition requires corrective action.

8.1 Power Section External Visual Examination

• Examine the thermal blankets for damage. Tears and punctures can be repaired without removal of the blanket using silicone RTV. Loss of the lockwire buttons is not a normal condition.

• Examine the heat shield for damage and cracks. Scratches, dents, fretting and other cosmetic discrepancies are normal conditions. Cracks and material separation are not normal conditions.

• Examine the heat shield “belly band” for security and damage.

• Look for leakage around the fuel atomizers and oil transfer tubes.

• Note damaged or loose plumbing, brackets, clamps, ducts and mounts.

8.2 Power Section Tailpipe Visual Examination

• Note power section freedom of rotation.

• Examine the exhaust housing for damage and cracks.

• Examine the third stage turbine blades for damage. Scratches, discoloration, pitting and nicks without significantly displace material are normal conditions. Erosion at the blade tips is normal provided the erosion is similar on all blades. Broken, cracked, or bent blades are not normal conditions.

• Examine the exhaust cap and turbine support for damage and cracks.

• Examine the oil transfer tubes and gearbox vent for leakage.

• Look for oil under the center cap and turbine wheel.

WPG 331-250 [F]/[H] APU 36


8.3 Engine Compressor Borescope Examination

• Examine the compressor inlet bellmouth for damage. Nicks scratches, dents and pitting are normal conditions. Tears, punctures, cracks and material separation are not normal conditions and can be an indication of downstream damage.

• Examine the engine compressor impeller blade leading edges and contours for damage. Rough edges, erosion, and a few blade nicks (3-4 per blade) without significantly displaced material are normal conditions. Broken, cracked, or bent blades are not normal conditions.

• Examine the engine compressor shroud for damage. Scratches, nicks and scoring are normal conditions. Heavy contact between the impeller and shroud or separations of shroud material are not normal conditions and can be an indication of bearing deterioration, improper shimming of the impeller or severe surging of the APU.

• Through an atomizer port, compressor deswirl and second stage compressor diffuser, examine the second stage impeller for damage. Contact between the impeller and shroud with some metal spray is a normal condition. Contact resulting in a heavy build-up of metal spray, bent impeller trailing edges or binding APU rotation is not a normal condition.

WPG 331-250 [F]/[H] APU 37


8.4 Turbine Section Borescope Examination

If an observed condition is suspect, a test cell performance evaluation is suggested to determine if there is an affect on APU performance.

• Examine the combustion chamber through an atomizer port for damage. Cracks, erosion carbon build-up, and loss of TBC are normal conditions. Burn through is not a normal condition.

• Examine the combustion chamber transition ring for cracks and separation. A continuous crack around the transition ring circumference can cause material separation and degraded APU performance.

• Examine the first stage turbine nozzle through an atomizer port for damage. Nicks, erosion, cracks and pitting are normal conditions. Trailing edge material loss, due to erosion, up to approximately 25% of the vane length is a normal condition. Broken or missing vanes are not normal conditions.

• Examine the first stage turbine blades through an atomizer port and first stage nozzle for damage. Scratches, discoloration, pitting and nicks without significantly displace material are normal conditions. Erosion at the blade tips is normal provided the erosion is similar on all blades. Broken, cracked, bent or displaced (shifted) blades are not normal conditions.

• Examine the third stage turbine nozzle through the tailpipe and third stage turbine blades for damage. Eroded, cracked and pitted vanes are normal conditions. Broken or bent vanes are not normal conditions.

WPG 331-250 [F]/[H] APU 38


8.5 Power Section 5000 Hour Examination

If the APU has 5000 hours or greater since last shop visit the following additional examinations are suggested.

• Remove the turbine scavenge pump for disassembly, cleaning and visual examination.

• Refer to CMM 49-22-63 for detailed procedures and applicable CAUTIONS. While properly securing the rotating group, examine the pump drive splined insert in the tie shaft for security. Utilize an appropriate splined adapter and torque wrench, apply 200 to 250 in/lb (11,2 to 14,0 m/kg) maximum torque in the counter clockwise (CCW) direction. No slippage should be observed.

8.6 Partial Power Section Disassembly

The power section can be partially disassembled to correct a specific discrepancy. The following guidelines are provided for partial power section disassembly:

• The orientation of removed rotating group parts should be marked for proper reassembly.

• Replacement of exposed carbon seals, gaskets, and packings is suggested.

• Replacement of the Bi-cast turbine stator (if exposed) with the mono-cast design is suggested.

• Replacement of the PS forward bearing (if exposed) is suggested if the bearing has accumulated more than 5000 hours.

• If the entire rotating group is not exposed, and replacement of a rotating part is required, the following step is suggested:

(1) The replacement part should be orientated with the curvic marks in a “High to Low” position.

8.7 Power Section Detail Part Check

The following guidelines are provided for detail parts exposed during repair:

• The use of IRM Continue-time Check criteria for all detail parts is suggested.


(1) Requirements in customer maintenance specifications.


(3) Instances where an APU or PS “Overhaul” or “Heavy Repair” is requested.

WPG 331-250 [F]/[H] APU 39


9. FAILURE MODE SPECIFIC WORKSCOPES

The following information is supplemental to the module workscopes (Sections 6 through 8) providing workscope instructions for specific failure modes.


Table 5. Failure Mode Specific Workscopes

Failure Mode

Suggested Workscope

Cooling Fan or Gearbox Bearing/Gear Damage.

Common Symptoms

• High oil temperature. • Low oil pressure. • Metal contamination in the

gearbox sump, magnetic plug and/or oil pump filter bowl.

1) Refer to Appendix II for guidelines associated with metal contamination. 2) Remove and flush all external oil system plumbing and components. 3) Remove and completely disassemble the gearbox. 4) Examine bearings for contamination, do not reuse contaminated bearings. 5) Do not reuse the fan idler or starter clutch inner shaft bearings. 6) Flush the gearbox housing and check per IRM Continue-time criteria. 7) Remove and replace the forward LC roller bearing, seal and seal rotor. 8) Remove, disassemble and flush the turbine scavenge pump. 9) Examine the turbine bearing cavity for contamination. 10) Borescope the mid-frame thrust bearings for contamination and damage.

Turbine Section Deterioration.

Common Symptoms

• High EGT • Low bleed pressure • Turbine damage • No start (Slow Start) • Borescope observations

1) Separate the Gearbox and Load Compressor from the Power Section.

The gearbox and load compressor can remain as assembled unit. 2) Removal of the turbine module without complete disassembly of the

power section is possible. However, when severe turbine section deterioration is observed, complete disassembly of the Power Section is suggested.

3) If the deterioration is considered premature, based on the hours of operation and the operating environment, functional (bench) test of the fuel system components is suggested.

4) Replacement of exposed seals, gaskets, packings, carbon seals and “piston” ring seals is suggested.

5) Replacement of the turbine module hardware (nuts & bolts) is suggested. 6) The use of Continue-time check criteria for all exposed parts is

suggested. However, additional inspections and scrutiny may be applied to turbine module components based on the APU operating environment as advised by the repair facility engineer.

WPG 331-250 [F]/[H] APU 40


Failure Mode

Suggested Workscope

Load Compressor Carbon Seal Leakage.

Common Symptoms

• Oil loss through the gearbox vent in the tailpipe

• Smell in cabin • Oil in bleed duct • Oil leakage out seal drains

An incoming APU test is suggested to confirm the oil loss and isolate the discrepant carbon seal.

Problems with the gearbox pressurization and buffer system components can present similar symptoms as well as deteriorated LC Backshroud Stato Seals or loose LC Backshroud bolts.

1) Remove and bench test the gearbox pressurization and buffer system components.

2) Remove the gearbox assembly. 3) Verify breakaway torque on the LC Backshroud bolts. Forward Seal Only

a) Remove the LC Backshroud, seal carrier, seal rotor and bearing. b) Replace the seal and seal rotor.

Aft Seal a) Disassemble the LC leaving the IGV’s assembled on the LC inlet

housing and the LC impeller and knife edge seal on the shaft. b) Replacement of both the forward and aft seals and seal rotors is

suggested. 4) Replace all exposed packings and seals. 5) Check exposed parts to IRM Continue-time criteria.

Forward Power Section or Aft Load Compressor Thrust Bearing Damage.

Common Symptoms

• Restricted APU rotation • Turbine damage • No start • Burned residual oil • Metal contamination on the

gearbox sump, oil pump filter bowl, monopole tips, and gearbox and/or mid frame magnetic plugs.

1) Refer to Appendix II for guidelines associated with metal contamination. 2) Completely disassemble gearbox, load compressor and power section. 3) Remove and flush all external oil system plumbing and components. 4) Flush the gearbox housing and check per IRM Continue-time criteria. 5) Examine gearbox bearings for contamination, do not reuse contaminated

bearings. 6) Replace the rotating group main shaft bearings. 7) Replace exposed seals, seal rotors and packings. Aft LC Bearing Damage

a) Check the LC support structure (housings), bearing carriers and rotating group parts to IRM Zero-time criteria.

Forward PS Bearing Damage a) Check the PS support structure (housings), bearing carriers and

rotating group parts to IRM Zero-time criteria. 8) Check the remaining exposed parts to IRM Continue-time criteria.

WPG 331-250 [F]/[H] APU 41


10. SPECIAL APU WORKSCOPES

The following information is supplemental to the module workscopes (Sections 6 thru 8) providing specific workscope instructions for unique operating conditions.


Table 6. Special APU Workscopes

Special Condition

Suggested Workscope

High Sulfur Environments (Corrosive)

A significant impact on APU service life has been observed on APU’s operated in environments high in sulfur and other emissions. The turbine section components, primarily the turbine nozzles and blades, exhibit a rapid deterioration compared to APU’s returned from other environments.

A more detailed inspection of hot section components from APU’s operated in this environment may be needed. The following guidelines should be considered:

• Inspect turbine blades and nozzle vanes to the Zero-time check section. • Utilize Borescope findings to help identify deterioration.

High Sand Environments (Erosive)

Environments high in sand can increase the rate of erosion on compressor and turbine blade airfoils. Buildup of sand within the APU can block turbine section cooling passages, combustion chamber effusion holes and carbon seal buffer air passages.

A more detailed inspection of compressor impellers and turbine blades from APU’s operated in this environment may be needed. The following guidelines should be considered:

• Inspect compressor impellers and turbine blades to the Zero-time check section if significant erosion is observed.

WPG 331-250 [F]/[H] APU 42


Special Condition

Suggested Workscope

In-Flight Oil Consumption Look for evidence of oil leakage at the gearbox and scroll split line. Leakage can occur at altitude and not during ground operation. The use of a black light can help identify the presence of oil.

Look for turbine seal and bearing cover gasket leakage. Deterioration of the lube module turbine scavenge element or blockage of the return screen can cause leakage at the turbine seal.

Look for evidence of oil at the gearbox vent indicated the APU may be experiencing high gearbox pressure or leakage of the air oil separator seal. An evaluation in the test cell can determine if the APU is experiencing high gearbox pressure.

Look for evidence of oil in the bleed duct and seal drain indicating load compressor carbon seal leakage or loss of seal buffer pressure. The use of a black light can help identify the presence of oil. Partial disassembly to access the seal and load compressor area may be needed.

Smell in Cabin Examine the inlet area for ingestion of oil and other materials.

The use of a black light or white cloth can help identify the presence of oil and is more dependable than a Millipore check in the test cell.

Look for evidence of oil in the bleed duct and seal drain indicating load compressor carbon seal leakage or loss of seal buffer pressure. Partial disassembly may be required to access the load compressor area to check for leakage.

APU Lease Return The following are minimum guidelines for a lease return APU, unless specified differently in the customer agreement. Additional work may be required as dictated by shop findings:

1. Comply with WPG Sections 3 through 6. 2. Perform complete power section and load compressor disassembly. 3. Check all exposed detail parts to EM Continue-time Check criteria. 4. Indicate work accomplished as “Medium Repair”.

WPG 331-250 [F]/[H] APU 43


11. Shop Watch List

The following table provides a list of emerging failure modes reported by APU repair facilities. Once a failure mode has been addressed by a specific product improvement, or is not recurring, it will be removed from the list.

Table 7. Watch List and Program Status

Shop Topic

Program Status

Cooling Fan The latest cooling fan PN 3616959-6 has shown a significant improvement in reliability. It is strongly suggested that the following Spare Parts Bulletins be incorporated at the next opportunity to provide maximum benefit:

GTE1293 (Replacement of the fan ball bearing with PN 3613704-3)

GTE1294 (Removal of the fan rotor damping coating)

As a result of some returns of failed cooling fans, an investigation is being conducted based on findings associated with a similar problem found on the 331-350 cooling fan.

WPG 331-250 [F]/[H] APU 44


I-i

Workscope Planning Guide Appendix IWorkscope Planning Guide Appendix I

SmartScopingSmartScoping OverviewOverview

A Shop Maintenance PhilosophyA Shop Maintenance Philosophy

B06-096

HONEYWELL CONFIDENTIAL: This copyrighted work and all information are the property of Honeywell International Inc., contain trade secrets and may not,in whole or in part, be used, duplicated, or disclosed for any purpose without prior written permission of Honeywell International Inc. All Rights Reserved.

I - 1HONEYWELL CONFIDENTIAL

Use or disclosure of information contained on this page is subject to the restrictions on the cover.

August 7, 2007

SmartScoping is a general shop maintenance philosophy for end unit repair facilities with heavy emphasis where the major decisions on unit disassembly and detail part disposition (reuse, repair, replace) are made

What Is “SmartScoping”?

Effective Use of SmartScoping Reduces Costs & TAT Without Compromising Reliability

The most effective decisions are those made with: • good knowledge and understanding the aircraft system and end unit design intent• consideration of aircraft, end-unit and component history• focus on the reason for return and work accomplished at last shop visit• knowledge of the typical design/service life of critical parts in the unit

and potential to build, test and on-wing service life and cost• knowledge of detail part design and manual check intent• avoidance of unnecessary work that has no perceivable benefit to the end-user• properly trained personnel and awareness with stakeholders… combined with

proper attention on all aspects of shop operations



August 7, 2007

Old Philosophy NewPhilosophy

• No/little incoming testing to confirm reason forremoval, determine end unit health, build service lifeexperience

• More Heavy Repairs (“Overhauled”)• High test reject rate due to lack of continue-time limits or

unnecessary performance testing• Over-inspection: excessive NDT, dimensional

checks• No Continue-time Limits/over application of zero-time limits • No manual allowance for normal wear, cosmetic defects• Strives to make everything “good as new”• Unnecessary repair of all part features to “Repair Limits”/no

limited repair• Minimal reliance on SPM, no authority to use SPM• Vague/conflicting General Check provisions in IRM/EM• Interpretation that end unit “overhaul” requires 100% parts

inspected to zero-time limits

• As-received testing/accumulated experienceto limit depth of disassembly and establish basis for detailpart check and unit/part service life

• More Light/Medium Repairs (“Repaired”)• Lower test reject rate, no/limited performance testing for

Light/Medium Repairs, expanded test releaselimits for continue-time of end unit

• More reliance on visual checks and Engineering designknowledge/Shop experience

• Provides continue-time limits for end units/detail parts • More allowance for normal wear, cosmetic defects• Strives to utilize remaining service life • Limited repair: only features out of continue-time limits,

allow repair to continue-time limits for standard repairs• More standard (fast) repairs, SPM authorized by IRM• New General Check provisions for continue-time/zero-

time flexibility• Interpretation that end unit “overhaul” requires only core

parts inspected to zero-time limits

What’s Different?...



August 7, 2007

SmartScoping Focus…

End UnitWorkscope

End UnitTest

Detail Part Decisions

DEPTH OF REPAIR FOCUSLimit detail parts exposure

OPERATIONAL FOCUSAvoid test rejectsExpand release criteria

DETAIL PART FOCUSReuse partsLimited Repair to maintain

SmartScoping Is Avoiding Unnecessary Work!



August 7, 2007

• Minimizing disassembly and exposure of detail parts• Minimizing repair/replacement of exposed detail parts• Providing workscopes/manuals that assure acceptable future service life of

each reused part/unit rather than trying to make unit/part “good as new”• Providing zero-time and continue-time check/release criteria, with clear visual

descriptions in manual of what’s allowed/not allowed • Continually refining manual check criteria and test cell release limits based on

design intent/capability AND shop experience to minimize rejects/repairs/replacements

• Standardizing terms/definitions for check & depth of disassembly• Clearly understanding how Continue-time and Zero-time decisions are made • Working with customers upfront to build in SmartScoping in new/re-negotiated

maintenance agreements to avoid unrealistic/unjustified customer requirements• Separation of workscope and detail part inspection criteria• Customizing workscopes for abnormally harsh environments

SmartScoping Is Based On:

Fewer Parts Exposed/More Parts Reused Means Fewer End Units Awaiting new Detail Parts- and Reduced Overall Turn Time and Work!



August 7, 2007

•Standard as-received checklist•MinimizeDepth ofDisassembly•Focus on Reason for Return•Light/Medium/Heavydetermination that establishes C/T vs Z/T check criteria

•Partial disassembly•Avoid part damage duringdisassembly& cleaning

•Follow WS direction of C/T vs Z/T:–Continue-timeCriteria for Light/Medium–Zero-time Criteria for Heavy Repair•Maximize reuseof parts•Minimize dimensional& FPI•Challenge/expand/feedback inspectioncriteria• Implement scrap reviews

•On-Wing History•Last Shop Visit•Cost Reqmts•As-recv.d Test*

• Drive the right levelof repair, focusingon critical features

• Insure repaired parts do not causebuild issues.

•Accept cosmeticdamage

• Rebuild with same parts

•Feedback buildissues

•Develop continuetime release limitsbased on as-receivedtest findings

•Provide limited testcapability

•Feedback issues related to WPG

•Feedback unnecessary test rqmts•Front-endDispos toAvoid TCRs

* Only required to establish deterioration rate, verify reason for return if not obvious, or learn module/part service life

Gate 0 Gate 1 Gate 2 Gate 3

SmartScoping Through Typical Shop Flow

Detail PartInspection

Detail Part Repair

Disassembly& Wash Assembly Final

TestAs-received

TestWorkscope

Development



August 7, 2007

OUTPUT(WORKSCOPE)

OUTPUT(WORKSCOPE)

INPUTINPUT

CustomerWorkscope

Requirements/Mod Status

Continue-time or Zero-timeDecision/Flowdown

to Analytical

Correlation of Definitionswith Customer/RAF(8130) Tag

Life-Limited Parts

As-received Findings

Removal Reason* Confirmed?

Preventative Action

Typical Workscope…

Re-disposition (after DisassemblyFindings/Test Reject)

Last Shop Visit History

Honeywell WorkscopeGuidelines

(Standard/Special/Customized)

As-received Test Results/Experience

Necessary Depth of Repair Is an Output of the End Unit Disposition

On-wing History

* See Definitions

Shop Findings Report

Cause For Removal Confirmed

Depth of Repair (Module & End Unit):Light/Medium/Heavy



August 7, 2007

(8130 “Overhaul”) (8130 “Repair”)

End Unit Disposition….

• Major modules/sections disassembled completely• Core Parts checked to Zero-time Limits• Other parts checked to Continue-time Limits• Tested to Heavy Repair (“overhaul”) limits• End unit 8130 Tag Block 12 noted “Overhauled”• TSO reset to zero hours (except for time-controlled or

life-limited)• Special/Customized Workscopes as required

• Major modules/sections disassembled as needed • Exposed parts checked to Continue-time limits• Tested to Light/Medium Repair (Continue-time) limits• End unit 8130 Tag Block 12 noted “Repaired”• TSO continued, TSR reset to zero hours• Special/Customized Workscopes as required

Heavy Repair Light/Medium Repair

End Unit Disposition Determines Whether Continue-time or Zero-time Criteria Is Used



August 7, 2007

• “Overhauled” vs “Repaired”• “End Unit”, “Major/Minor Repair”, “Repair” vs “Rework”• “Zero-time” vs “Continue-time”• “Inspection vs Check”• “Repair Limit” vs “Repairable Limit” vs “Serviceable Limit”• “Depth of Repair” vs “Depth of Disassembly”• “New/Newly Overhauled” vs “Used”• “Proprietary Repair”• “Light Repair” vs “Medium Repair” vs “Heavy Repair”• “Hard” time vs “Soft” time• “On-condition” vs “Run to Failure”• “Normal Light”• “Primary” vs “Secondary” Damage• “Imminent Failure”, “Visual Check”, “Core”, “Cosmetic”• “Light”, “Medium”, “Heavy” Repair • “Reason For Removal”• “Functional Test” vs “Bench Test”• “Unnecessary”• “Non-chargeable” vs “Chargeable”APU Shop Visits

Standard Definitions for…..

Refer to Applicable Inspection/Repair Manual (IRM) or Engine Manual (EM) for These Standard Definitions



August 7, 2007

Component Maintenance

Manual

Component Maintenance

Manual

Illustrated Parts

Catalog

Illustrated Parts

Catalog

Inspection Repair Manual

Inspection Repair Manual

ServiceBulletinsService

BulletinsWorkscope

Planning Guide

Workscope Planning

Guide

Service InformationLetter (SIL)

APU Manuals

• Approved Parts List/Configuration

• Part Zero-time Criteria• Part Continue-time criteria

• Design/ConfigurationChanges

• Shop philosophy • Depth of repair focus• Standard definitions• Partial disassembly allowance• Special/Customized workscopes• Engineering approved• SB incorporation guidelines• LRU Checklists/WPGs

APU WPG vs. Manuals

WPGs Released as Service Information Letters WPGs Released as Service Information Letters



August 7, 2007

• SmartScoping definitions are in compliance with Code of Federal Regulations 14, Part 43 and have been reviewed by the FAA for correct interpretations

• References to 8130 forms can be generalized to refer to Regulatory Airworthiness Form (RAF)as a general name for serviceability forms like the 8130 form used for FAA-controlled products

• SmartScoping recommends noting highest level manual used on 8130 form (CMM or EM), as IRM,SPM, IPC, WPG are all authorized by links from the CMM/EM

• All Part 145 Repair Stations conduct work in accordance with customer instructions (ONLY).Customer approval of the top level manual (CMM/EM) implies approval of all referenced/linkedmanuals

• Standard RAF (8130) wording is suggested as follows:

- Block 12: Enter “Overhauled” for Heavy Repairs and “Repaired” for Light and Medium Repairs

- Block 13 REMARKS: “Product disassembled to the extent necessary to perform cleaning,inspection, repair, and testing IAW customer- authorized documents (list top level manual)”. If thecustomer depth of repairs are different than Honeywell, note the equivalency in this section.

Regulatory Clarifications

Operators Are Responsible For Their “Instructions For Continued Airworthiness” (ICA), Which Are the Only Documents Part 145 Repair Stations Can Use



August 7, 2007

No Early Retirement For Parts Under SmartScoping!

APPENDIX II

WPG 331-250[F]/[H] APU

OIL SYSTEM OVERVIEW AND METAL-IN-OIL APU/LRU WORKSCOPES

WPG 331-250[F]/[H] APU II-i


TABLE OF CONTENTS Page

1. METAL-IN-OIL APU/LRU WORKSCOPES 1.1 General II-1 1.2 Initial Investigation II-1 1.3 Oil Cooled Generator Failures II-2 1.4 Oil Cooler Contamination II-3 1.5 Bearing Contamination II-3 1.6 Descriptions of Engine Metals in Oil-wetted Areas II-41.7 Types and Categories of Metal Debris in Oil II-5 1.8 Typical Failure Modes Generating Metal II-51.9 Metal Particle Passage Sizes II-5

LIST OF FIGURES Figure II-1. Simplified Lubrication System Schematic II-6 Figure II-2. Maximum Particle Passage Sizes (Microns) II-7 Figure II-3. APU Cross Section II-7 Figure II-4. Examples of Magnetic Plug Metal Contamination II-15

LIST OF TABLES Table II-1. Determining Metal Source and Extent of Disassembly II-6 Table II-2. External Components Exposed to Oil Contamination II-8 Table II-3. Materials in Oil-Wetted Areas II-8 Table II-4. Lubrication System Operating Data II-9 Table II-5. Typical Failure Modes/Symptoms/Indications/Extent of Contamination II-10 Table II-6. Maximum Particle Passage Sizes (MPP) by Component II-13

WPG 331-250[F]/[H] APU II-ii


1. METAL-IN-OIL APU/LRU WORKSCOPES

1.1 General

This Appendix provides information for thoroughly diagnosing and accounting for contamination of the lubrication system and oil-wetted components. The focus is primarily on metal generated by typical failure modes, with additional information provided as reference materials for determining the extent of the contamination.

The objective is to use detectable indications of metal in the oil system to assure proper system and component cleanout without unnecessary disassembly or repair of the APU, modules, or LRUs.

1.2 Initial Investigation

The following information (if available) assists in developing an effective APU workscope for APU’s returned with contamination of the oil system:

• Review on-wing history/actions taken prior to removal relative to metal findings, rerun periods, and filter/debris samples taken prior to APU removal/return. The time of operation with a failed condition will greatly influence the extent of contamination and damage.

• It is not uncommon to find some light flakes or ‘filings’ on filters/magnetic plugs on new or recently repaired APUs. This could indicate minor wear, insufficient cleaning from a previous failure, contamination during servicing, or debris from detail part repair or manufacture and should diminish within the first several hours of operation.

• Check for obvious symptoms of metal-generation such as rough or restricted rotating group rotation or oil pump shaft shears (see Table II-5, Typical Failure Modes, Symptoms, Indications, Extent of Contamination).

• If the checks above reveal no indications or source of failure, base decisions on the primary devices for indicating lube system contamination:

a. Magnetic plug (see Figure II-4)

b. Oil filter/filter bowl observations

c. Oil filter impending bypass (pop-up) indicator

d. Evidence of oil filter bypass/operating time with bypass

e. Metal on speed sensors/monopoles

f. Borescope findings

WPG 331-250[F]/[H] APU

• Having isolated the distressed areas, the knowledge of the lubrication system and shop experience is used to isolate to the problem. Some disassembly may be required.

II-1 Copying, use or disclosure of information on this page is subject to proprietary restrictions.

• SOAP or filter backflush analysis may be used to identify debris in the oil or support the above visual observations. Table II-3 can assist in identifying parts from material observations.

• Considering maximum particle passage sizes are helpful in determining extent of damage/disassembly required. Table II-6 lists the design particle passages in the various lubrication system components. Figure II-2 indicates the different levels of filtration/passage sizes on the oil system schematic.

• An as-received test cell run, following removal of minor contamination, can be used to determine if the APU is “making metal” or exhibiting high vibration, fluctuating or low oil pressure, or oil loss related to internal damage. If no further contamination is found and all operating parameters are met, the APU should be considered for continued operation.

1.3 Oil-cooled Generator Failures

• Check and clean gearbox sump magnetic plug/chip detector.

• If no cross-contamination, replace generator scavenge filter and clean generator scavenge screens.

• Run APU for 15 minutes with generator load. If no further metal generated, consider for continued operation.

WPG 331-250[F]/[H] APU II-2


1.4 Oil Cooler Metal Contamination

Oil coolers can be flushed to remove contamination and should not require recore or repair for metal contamination only. The primary concern about cooler cleaning is not related to oil cooling, but leaving residual particles inside that could contamination the system.

NOTE

The largest piece of debris that can enter and oil cooler is the largest size piece that can pass through the oil pump (see Figure II-2 and Table II-6). The wavy fin cooler has 0.023 inch (590 microns) passages on the oil side (accounting for flow separators inside). This means pieces of metal less than 0.023 inch (590 microns) will pass through the cooler without obstructing it, and any larger pieces won't pass. The thermostatic/pressure valve has a minimum particle passage (MPP) of 0.100 inch (2560 microns) so it will most likely not trap particles. The cooler is downstream of the pump that has 0.200 inch (5130 microns) MPP, so any metal from the bearings will get back to the sump, picked up through a 800 micron screen, pass through the pump and on into the cooler (the 25 micron oil filter is downstream of the cooler). Typically only larger pieces of debris get into the cooler core oil passages and generally are easy to flush. They will be at the cooler inlet and should be flushed from the cooler exit side in order to not drive the contamination further into the core.

1.5 Bearing Contamination

• Bearings are designed to accept particle sizes up to 0.001 inch (25 micron) which is why most oil filters are 25 micron or less. As long as the filters have not bypassed (except for cold oil bypass), there is little concern for bearing distress from oil system contamination.

• If the filter(s) have bypassed from being plugged with metal, there is concern that bearings may have been damaged by the debris.

• Ball bearings are more susceptible to damage from contamination than roller bearings.

• Jetted (by jets or passages) bearings are more prone to damage than splash-lubricated bearings.

• The material of the contaminants are important: hard metal (in excess of Rockwell C 42) greater than 0.001 inch (25 micron) will interrupt the bearing oil film and/or damage bearing metal surfaces, resulting in subsequent fatigue or oil starvation failure. Softer metals/debris will not necessarily damage the bearing if greater than 0.001 inch (25 micron).

• Smaller particle debris such as from gear/spline/liner wear is not harmful to the bearing and can be flushed from the system.

WPG 331-250[F]/[H] APU

II-3 Copying, use or disclosure of information on this page is subject to proprietary restrictions.

1.6 Descriptions of Engine Metals in Oil-Wetted Areas

• Ferrous metals are easily distinguished from such non-ferrous metals as aluminum, magnesium, titanium, bronze, CRES, Inconel, etc by their magnetism. Bearing and gear ring, rolling elements, and separators are ferrous. Refer to Table II-3 for common steels in oil-wetted areas.

• Aluminum, magnesium, and titanium are not normally in contact with moving parts and would indicate an unusual contact between parts, or washout of machining chips.

• Bronze material usually comes from gearbox bearing cages, pump bushings, or journal bearings (found alone in fine particles, bronze typically indicates normal wear rather than failure).

• Silver is used as plating in main rotor bearing separators and some gears (found alone, this not a serious metal finding).

• Magnesium from gearbox housings can cause the oil to turn purple.

• Carbon in crystalline form is typically from carbon seal wear. Amorphous carbon is usually coke or degraded nonmetallic material.

• Copper typically comes from electrical devices such as generators and starter motors.

• See Table II-3 “Materials in Oil-Wetted Areas” for a summary of materials that might be observed in the oil system.

NOTE

If oxidation corrosion is identified on an oil-wetted surface of any lubrication system component, all remaining bearings/gears/seals should be checked for oxidation corrosion.

WPG 331-250[F]/[H] APU II-4


1.7 Types/Categories of Metal Debris in Oil

• Very fine particles “filings” in filters and filter bowls generally indicate normal wear. If excessive wear is suspected, SOAP can be used.

• Spiral, curled, and/or rippled chips or significant filings may be from machined parts that were insufficiently cleaned before, or shaved during installation or assembly.

• Flat metal pieces can be from sheet metal parts such as shims, locking devices, retainers, wave springs, etc.

• Round pieces can be lockwire, anti-rotation pins, keys, bearing screens, bearing cage rivets, coil springs, etc.

• Flakes of silver are typically from main rotor bearing separators, and are not considered significant as a sole finding.

• Chunks, slivers, platelets, and flakes of magnetic metal are typical of bearings or gear sources. Platelets usually indicate compressor mainshaft duplex bearing distress.

1.8 Typical Failure Modes Generating Metal To help develop Table II-1, Table II-5, Typical Failure modes/Symptoms/Indications/ Extent of Contamination lists in greater detail indications and extent of contamination of various types of failures. This list is limited to actual known failure modes rather than all potential failure modes, and will be updated as experience dictates.

1.9 Metal Particle Passage Sizes The particle passage sizes in Table II-6 were used to develop Table II-5. These are design parameters specified for the lubrication components listed. By considering the size of a metal particle found in the oil, the extent of travel of that particle can be determined. Shape and material are equally as important as size. For example, oil pumps will generally “chew” aluminum, bronze, copper, silver, and other soft materials and pass without damaging the pump elements. Bearings will also pass softer materials without damage. On the hand, some particle shapes can become wedged in pump passages and bearings and cause damage or seizure.

WPG 331-250[F]/[H] APU II-5


Table II-1. Determining Metal Source and Extent of Disassembly

Figure II-1. Simplified Lubrication System Schematic

WPG 331-250[F]/[H] APU II-6


Figure II-2. Maximum Particle Passage Sizes (Microns)

Figure II-3. APU Cross Section

WPG 331-250[F]/[H] APU II-7


Table II-2. External Components Exposed to Oil Contamination

Part/Area Description Workscope Notes

Internal/External Oil Lines, Fittings, and Valves

Clean and flush thoroughly in both directions to clear all contaminants.

Lube Pump/Scavenge Pump Disassemble, clean, and reassemble per CMM.

Oil Cooler (Plate Fin) Check and flush oil passages in accordance with Paragraph 1.4.

Thermostatic Bypass Valve Clean and flush in accordance with Paragraph 1.4.

Low Oil Temperature Sensor Clean and visually check. LOP Switch Clean and visually check. Low Oil Quantity Sensor Clean and visually check. Generator (Oil-Cooled) Clean and flush per Paragraph 1.3. Fan Assembly Clean and visually check drive gear. Disassemble if contaminated. High Oil Temperature Switch Clean and visually check. Speed Sensor/Monopole Clean and visually check. Pressure Regulator/Relief Valve Clean and visually check. Note: Items downstream of the lube filter bypass valve may not need to be removed for inspection, if the bypass can be confirmed to not have activated. The extent of inspection should be based on the quantity, location of metal found, observed failure modes causing metal-in-oil, and repair facility judgment.

Table II-3. Materials in Oil-Wetted Areas

Material Type Typical Application

Aluminum AMS4027 (6061-T6), AMS4088 (2024-T3), AMS 4284 (356-T4)

Gearbox housings, oil pump housings/plates, filter bowls, compressor static structure

Copper Alloy (Bronze, Bronze/Brass, Copper)

AMS4610/4616 Oil pump bushings

Magnesium AMS4439/4418 Gearboxes Nickel AMS2405/2424 (Metco 450) Repair coatings Stainless Steel AMS7225/7228 (300/304 CRES) Screens, bearing separator rivets, carbon

seal springs Nickel AMS2405/2424 (Metco 450) (40%Cr, 60% Ni) Electroless-nickel plate on splines,

bearing races Steel AMS6414/6415 (4340) Main rotor and gearbox bearing rolling

elements Steel AMS6260 (9310) Gears, gearshafts Steel AISI 52100/AMS6491 (AISI M50) Bearing rings, races Stainless Steel 440C Bearing rings and races Silver Main rotor bearing separator (silver-

plated)

WPG 331-250[F]/[H] APU II-8


WPG 331-250[F]/[H] APU II-9

Regulated Oil Pressure 60 to 70 psig (414 to 483 kPa) Pressure Relief Crack Pressure 225 to 255 psig (1551 to 1758 kPa) Lube Filter Pop-Up (Delta P) 15 to 25 psid (103 to 172 kPa) with oil

temperature >90 to 140°F (32 to 60°C) Generator Scavenge Filter Pop-Up (Delta P) 15 to 25 psid (103 to 172 kPa) Generator Scavenge Filter Bypass 15 to 25 psid (103 to 172 kPa) High Oil Temperature (HOT) ASD 310°F (154°C) Low Oil Pressure (LOP) ASD (normally closed)

31 to 40 psig (214 to 276 kPa)

De-Oil Valve (normally closed) Opens on start with oil temperature <20°F (-7°C), closes during starting at 31 to 55% speed.

Oil Cooler Thermal Bypass Opens <140°F (60°C), closes >170°F (77°C), pressure bypass at 50 psid (345 kPa)

*Under normal operating conditions, a molecule of oil will completely pass the lubrication system in 7 to 10 seconds.

Table II-4. Lubrication System Operating Data*


Table II-5. Typical Failure Modes/Symptoms/Indications/Extent of Contamination

Failure Mode

Typical Symptoms

Typical Indications of Extent of Contamination

Typical Extent of Contamination*

Notes

Power Section (P/S) Aft (Roller) Bearing (Turbine)

• Rough rotation/rub • Oil out exhaust • High oil

consumption (HOC)/LOP ASD

• Magnetic chip detector moderate accumulation

• Lube module (fine particles)

• Lube pump/filter • Turbine scavenge

pump • Gearbox • Oil cooler

Front L/C (Roller) Bearing • Rough rotation/rub • Metal found

• Magnetic chip detector moderate to heavy accumulation

• Gearbox sump metal accumulation

• Lube filter/pump minor debris

• Lube pump/filter • Gearbox • Oil cooler

Bearing exposed to gearbox sump.

Generator (Aft Bearing) • No electrical • Generator scavenge filter (moderate to heavy metal)

• Generator scavenge MCD (if installed)

• Metal in generator pad cavity and in some cases, gearbox sump

• Gearbox sump (can damage generator scavenge pump)

• Lube pump/filter • Oil cooler

If generator scavenge filter bypasses or the generator cavity overflows, can contaminate gearbox and starter clutch [see Paragraph 1.3]

L/C Aft (Ball) Bearing • Low oil/LOP ASD • Rough rotation/rub • Oil in bleed duct • Lube pump binding • Metal found

• Lube filter pop-up extended

• Magnetic chip detector (heavy accumulation)

• Gearbox sump (chunks, chips)

• Monopole (heavy metal chip accumulation)

• Lube pump/filter • Gearbox • Oil cooler • Midframe cavity

Typically no generator or turbine contamination

P/S Forward (Ball) Bearing • Low oil/LOP ASD • Rough rotation/rub • Oil in bleed duct • Lube pump binding • Metal found

• Lube filter pop-up extended

• Magnetic chip detector (heavy accumulation)

• Gearbox sump (chunks, chips)

• Monopole (heavy metal chip accumulation)

• Lube pump/filter • Midframe cavity • Oil cooler • Gearbox

Typically no generator or turbine contamination

* Typically measured from gearbox sump to some downstream component, unless stopped before returning to gearbox sump

WPG 331-250[F]/[H] APU II-10


Table II-5. Typical Failure Modes/Symptoms/Indications/Extent of Contamination (Cont)

Failure Mode

Typical Symptoms



Notes

L/C Forward Carbon Seal • Odor in cabin • Oil leak (overboard

drain) • HOC/LOP ASD

• Gearbox MCD (chips) • Lube filter/bowl

(chips/particles)

• Lube module

Starter Clutch (ATS or Electric) • No start • Fails clutch check

• Gearbox MCD (chunks, chips

• Lube filter

• Gearbox Typically no L/C or P/S contamination.

Cooling Fan Gear or Bearings • No start • Metal found • Lube filter ΔP

popped • LOP faults • HOT faults

• Magnetic plug – heavy accumulation

• Gearbox sump – particles, pieces of gear chunks

• Lube filter (particles)


Generator Drive Bearing (Gearbox)

• Metal found





Cooling Fan Idler Gear • Lube filter ΔP popped

• LOP faults • Missing/damaged

teeth (inspected through fan pad)





Oil Pump Gear (Gearbox) (Worn/Missing Teeth)

• Abnormal noise • Metal found






WPG 331-250[F]/[H] APU II-11


Table II-5. Typical Failure Modes/Symptoms/Indications/Extent of Contamination (Cont)

Failure Mode

Typical Symptoms



Notes

Starter Clutch Forward Bearing • Metal found • No start





Air-Oil Separator Bearing/Gear • Metal found • High oil

consumption






WPG 331-250[F]/[H] APU II-12


Table II-6. Maximum Particle Passage Sizes (MPP) by Component

Component

Maximum Particle Size

(2)(3)

Downstream Oil

Jet/Passage Size (6)

Downstream Bearing Passage Without

Damage (1)

Conclusion Magnetic Plug/Chip Detector

5130 microns 0.200 inch



Sump magnetic plug will show mainshaft bearing debris.

Gearbox Sump/Oil Tank Pickup Screen




If lube filter not bypassed, mainshaft bearings OK. If filter bypassed, check mainshaft bearings and jets.

Oil Pump – Pressure Element

5130 micron 0.200 inch



If lube filter not bypassed, mainshaft bearings OK. If filter bypassed, check mainshaft bearings and jets.

Oil Pressure Regulator and Relief Valve




OPR/RV unlikely to restrict with metal.

Oil Cooler – Plate 590 microns 0.23 inch



Pump can pass large enough particles not to pass through cooler but pass through bypass valve. Flush cooler and valve.

Oil Cooler Bypass Valve 3850 microns 0.150 inch



Pump can pass large enough particles to not pass through cooler but pass through bypass valve. Flush cooler and valve.

Lube Pump Filter 25 microns 0.001 inch



If filter is not bypassed, bearings OK. If filter bypassed, check downstream bearings.

Generator Pad Cavity Port 6400 microns 0.250 inch



Large metal that can pass to generator will pass through generator pad cavity back to sump. Small metal may flow through generator. Check/flush generator.

Generator Aft Bearing End 1540 microns 0.060 inch



Small metal passing through generator should be evident on generator scavenge magnetic plug. Check/flush generator.

Generator In-Line Orifice 800 microns 0.031 inch



If generator scavenge is not bypassed, downstream components OK.

Generator Scavenge Filter Bypass




Metal on generator and magnetic plug and sump magnetic plug indicates generator scavenge filter bypassed. If generator scavenge filter is not bypassed (Metal on generator magnetic plug but not on sump magnetic plug), downstream components OK.

Generator Scavenge Filter 0.001 inch 770 microns 0.030 inch


Metal on generator magnetic plug and sump magnetic plug indicates generator scavenge filter bypassed. If generator scavenge filter is not bypassed (metal on generator magnetic plug but no on sump magnetic plug), downstream components OK. If filter is not bypassed, bearings OK. If filter bypassed, check downstream bearings.

Generator scavenge Pump 5130 microns 0.200 inch



Pump OK if turbine magnetic plug clean.

WPG 331-250[F]/[H] APU II-13


WPG 331-250[F]/[H] APU II-14


Table II-6. Maximum Particle Passage Sizes (MPP) by Component (Cont)

Component

Maximum Particle Size

(1)(2)(3)

Downstream Oil Jet/Passage Size

(2)(3)(6)

Downstream Bearing Passage Without Damage (1)(2)(3)

Conclusions Oil Pump – Midframe Scavenge Element




Pump OK if mid-frame magnetic plug clean.

Oil Pump – Turbine Scavenge Element




Pump OK if turbine magnetic plug clean.

1. See paragraph 1.5. 2. Micron conversion to inches: 1000 times inches divided by 0.039. 3. Inches conversion to microns: 0.039 times microns divided by 1000. 4. Oil cooler maximum oil passage nominally 0.023 inch (590 microns) for staggered (offset) plate fin core designs (20 fins/inch) with flow separators.

Cooler cores are specified for minimum upstream filtering of 0.0039 (100 microns). 5. Oil cooler thermostatic/pressure bypass valve maximum passage (0.100 inch or 2540 microns) based on full-open poppet. 6. Sizes shown are for jets. Oil annular passages and inner/outer race lube passages are 0.060 to 0.100 inch or 1540 to 2540 microns.

Figure II-4. Examples of Magnetic Plug Metal Contamination

WPG 331-250[F]/[H] APU II-15
