OLM FBW 2006 – Toulouse – 26-28 September 2006 · 2012. 6. 27. · l l ri g h t s r e s e r v e d. C o nf i d e n t i al a n d p r o p r i e t a r y d o c u m e n t. Takeoff with

Takeoff with upper wing frost

Presented by

Hélène DouxSingle Aisle Flight ManualGroup Mgr

OLM FBW 2006 – Toulouse – 26-28 September 2006

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Takeoff with upper wing frost 2 OLM FBW 2006

1

5 Conclusion

4 Progress report

3 Airbus proposal

2 Upper wing frost phenomenon

Airbus recommendations

Contents

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Airbus recommendations1

5 Conclusion

4 Progress report

3 Airbus proposal



Contents

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Removal of frozen contamination from all surfaces priorRemoval of frozen contamination from all surfaces priorto takeoffto takeoff Particular care on critical surfaces (aerodynamic surfaces)

Two exceptions are allowed:1. A thin layer of frost on the upper surface of the fuselageupper surface of the fuselage is

allowed, such that the markings can be seen through the frost

2. A thin layer (3mm) of frost on the lower surface of the winglower surface of the wing inthe region of the fuel tanks is allowed

Current recommendationsCurrent recommendations

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FCOM 3.04.91 (Supplementary techniques / Adverse Weather)

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2

Current recommendationsCurrent recommendationsCurrent recommendationsCurrent recommendations

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NTSB recommendation following several ground icing relatedaccidents

Required by the FAAFAAOperational Authorities : FAA-Ops 121.629

Airworthiness Authorities : FAA AC 20-117 issued in 1983

Current recommendationsCurrent recommendationsCurrent recommendationsCurrent recommendations

Before the ‘clean wing concept’ (1983), Airbus allowed takeoffwith upper wing frost (in FCOM)

““clean wing conceptclean wing concept”” enforced since years 1980

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A310 - old FCOM Procedure, removed after AC 20-117

Previous recommendationsPrevious recommendations

ICE ACCRETION ON UPPER WING SURFACELIMITED AT OUTER TANKS SURFACE

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Upper wing frost phenomenonUpper wing frost phenomenon

1

5 Conclusion

4 Progress report

3 Airbus proposal

2

Contents


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Upper wing frost phenomenon

Some parts of the wing are more vulnerable to frost thanothers…

Fuel tanks:Fuel tanks: If fuel has become cold soaked during a long flightand is in contact with the skin, frost may form after landing, evenif the OAT is above freezing.

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Some parts of the wing are more vulnerable to frost thanothers…

Heavy parts of structureHeavy parts of structure. Similar to the fuel tank, heavy piecesof structure can become cold soaked and promote frostformation after landing.

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Long flights at high altitude and cold temperature

Moisture during descent or at arrival

Thermal conductivity of structure material

Fuel tank quantity at landing

Short turnarounds


Factors promoting upper wing frost

(apart outside icing conditions):

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What is the effect of the frost?


The effect of the frost may be significant or insignificant,depending on its location, size and thickness

This is unknown at present on Airbus A/C, since design andcertification assumes a clean wing

Dependent on individual aircraft design (up to 30 % wing liftreduction already measured on non Airbus aircraft)

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This has several consequences:Dispatch delays

Possible need to procure de-icing equipment at airports that donot usually experience cold weather

Environmental impact due to use of de-icing fluids

Additional costs to the operators

Possibility that pilots may make their own judgement about theseverity of a ‘small’ patch of frost and not de-ice– …But pilot actually has no means of quantifying the effect.

Under current recommendations, this frost,whatever the thickness or extent, has to beremoved with a full and symmetric defull and symmetric de--icingicing.

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After long flights, consider performing manual outer tank fueltransfers to inner tanks immediately after landing (refer tocold weather operations, impact on fuel system).

Note: refer to FCOM 3.04.91 (Supplementary techniques /Adverse Weather)

(only possible on A330/A340)

Way to mitigate the effect of cold soak:

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1

5 Conclusion

4 Progress report

3 Airbus proposal


Airbus proposal

Contents


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Airbus proposal

Objectives : allow takeoff with frost when it is withinObjectives : allow takeoff with frost when it is withinacceptable limitsacceptable limits

Requires a comprehensive evaluation of the effects

What is / is not acceptable for safe operations ?

2. Determine aerodynamic effects of the frost,effect on takeoff performance?

3. Propose modifications of the aircraft manuals :Limitations?Procedures? Performance?

4. Get certification of upper wing frost takeoff (AFM)

1. Which aircraft areas are concerned?

Operators feedback requestedOperators feedback requested

–– Precise reports of events (OAT, turnaround duration, remainingPrecise reports of events (OAT, turnaround duration, remainingfuel in inner and outer tanksfuel in inner and outer tanks……))

–– Photos of wing areas covered by frostPhotos of wing areas covered by frost

Questionnaire sentQuestionnaire sent

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Airbus proposal








Operators feedback requested– Precise reports of events (OAT, turnaround duration, remaining

fuel in inner and outer tanks…)– Photos of wing areas covered by frost

Questionnaire sent

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Airbus proposal

Proposedquestionnaireto reportupper frostoccurrence

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Airbus proposal

Proposedquestionnaireto reportupper frostoccurrence

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Airbus proposal









Questionnaire sent


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Airbus proposal









Questionnaire sent


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Airbus proposal










Questionnaire sent

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Airbus proposal

Frost (not ice) would then be allowedon upper wing under conditions e.g.:

Frost allowed within a certain region ofthe wing

Frost limited to a certain thickness

Performance penalties may beconsidered (e.g. speed increase, MTOWreduction…)

Frost only allowed in non-icing outsideair conditions (non environmentalicing/frosting)

…

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1

5 Conclusion

4 Progress report

3 Airbus proposal


Progress report

Contents


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Progress report

Project launched within airbus:

Certification and operational authorities contacted:

JAR OPS refers to AFM procedures

Principle agreement to go to certification obtained from EASA

Several operational authorities have recently authorized (cold soak)upper wing frost operations on other A/C as per AFM.

FAA has certified takeoff with upper wing frost but FAR 121-629 (ops)still forbids such kind of operations.

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Progress report

Wind tunnel tests analysed on A340 and A310

Flight tests performed on A300-600 (being analysed)

Next steps…

Determination of level of demonstration to be provided

Finalization of current studies to determine effect of wingfrost

Establishment of certification plan and of associatedplanning

Project launched within airbus:

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1

5 Conclusion

4 Progress report

3 Airbus proposal


Conclusion

Contents


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Airbus objective : authorize takeoff with upper wing frost

Studies have been launched

Airline feed back and experience is necessary for preciselytargeting actual operational impact for studies and certification

In the meantime clean wing concept remains applicable,refer to FCOM recommendations.

Conclusion

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Airbus objective : authorize takeoff with upper wing frost

Studies have been launched

Airline feed back and experience is necessary for preciselytargeting actual operational impact for studies and certification

In the meantime clean wing concept remains applicable,refer to FCOM recommendations.

Conclusion

Documents

OLM FBW 2006 – Toulouse – 26-28 September 2006 · 2012. 6. 27. · l l ri g h t s r e s e r v e d. C o nf i d e n t i al a n d p r o p r i e t a r y d o c u m e n t. Takeoff with