Enclosure to RA

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Petition for Extension of Limitation from Exemption No. 1 10 7 0A

The Boeing Company Douglas M. Lan e, Director, Regulatory Administration. The Boeing Company

PO Box 3707 Seattle, Washington, 98124

Section of the Code of Federal R e gulations (CFRs) that are affected

Regulation At

Amendment Which Requires

§25.939(a) 25

- 4 0 (a) Turbine engine operating characteristics must be investigated in flight to determine that no adverse

characteristics (such as stall, surge, or flameout) are present, to a hazardous degree, during normal and emergency operation within the range of operating limitations of the airplane and of the engine.Enclosure to RA

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The Original E xtent of R elief S ought and Reason(s):

Regulation Requires: Relief is necessary because: §25.939(a)

Amendment

25

- 40 747

- 8/

- 8F airplanes powered by GEnx

- 2B engines incorporating

Electronic Engine
Control (EEC) C068 software (and later
EEC software versions), and operating within the

associated GEnx

- 2B

Ice Crystal Icing (ICI) engine limitation envelope certified under ODA Project
Number PS14

- 0053, are required to comply with turbine engine operating

characteristics requirements of §25.939(a). The GEnx

- 2B engines installed on 747

- 8/

- 8F airplanes have experienced engine flameout and engine mechanical damage in Ice Crystal Icing (ICI) conditions in

- service. The engine reaction
in ICI conditions resulted in the issuance of AD

2013

- 24

- 01, to address the unsafe condition. ODA Proje ct Number PS14

- 0053, will certify a revised AFM Certificate Limitation and Operating

Procedure to account for the GEnx

- 2B engine
limitation associated with GEnx

- 2B Electronic Engine Control (EEC) software version C068. The ICI functionality in C068 was dev eloped through the use of computational fluid dynamics (CFD) modeling validated by engine testing at the GE Winnipeg Test, Research and Development Centre. The EEC software reduces

the risk of flameout/rollback to a remote possibility, but is insufficient to fully mitigate the mechanical damage events, through the full airplane operating envelope.

The revised AFM Certificate Limitation and Operating Procedure were developed to prohibit airplane operation at engine power levels that could result in ice crys tal accretion leading to mechanical damage. The AFM revision

associated with this interim solution raises the current ICI operating floor from 30,000 feet to 35,500 feet with use of a flight crew procedure to maintain adequate engine power levels, implemen ted via minimum Mach number and gross weight operating limitations.

The FAA recently clarified that in

- flight power setting restrictions under a crew procedure to

avoid conditions that would result in unacceptable operating characteristics does not

meet t he intent of §25.939(a).

With this petition for exemption, Boeing is requesting relief for a limited period to allow sufficient time to develop, validate, and certify an engine configuration that is fully compliant with §25.939(a).Enclosure to RA

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The requested time

- limited partial exemption will provide relief from the turbine engine operating characteristics requirements of §25.939(a) for

new production and in

- service Boeing Models

747

- 8F and 747

- 8 incorporating EEC C068 software (or later EEC software versions ), and

upon modification of the AFM to reflect the applicable GEnx

- 2B / C068 (and later EEC

software versions) engine ICI limitation. The relief sought is limited to 747

- 8/

- 8F airplanes prior to the incorporation of an engine configuration compliant to §25 .939(a). Certification of a compliant design will be accomplished by 31 December 2015, or the operation of the airplanes would revert to the existing AFM Certificate Limitation and Operating Procedure certified under ODA Project Numbers PS12

- 0298 and PS13

- 0956.

Certification of the Interim ICI Limitation has

been more complex than initially estimated. In parallel, Boeing and GE have been working the development of software supporting the final compliant configuration, which has also taken

more time than an ticipated. Evaluation and incorporation of the results of the extensive

NASA Glenn Testing are anticipated to take

several months.

Review of data with regulatory agencies and finalization of an agreed to cert approach will follow. Based on the previously mentioned items, the estimated completion date of a design compliant to §25.939(a) is December 31, 2015.

This requested time

- limited partial exemption will apply to future design changes requiring assessment of §25.939(a) while the AFM

Certificate Limitat ion and Operating Procedure

are necessary for safe operation in ICI

conditions.Enclosure to RA

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Description of Issue

The GEnx

- 2B engines installed on 747

- 8/

- 8F airplanes have been shown to be susceptible to flameout / engine damage during operation in ICI conditions. Ingestion of ice crystals results in accretion in the propulsor at the booster outlet guide vanes (BOGV), fan hub frame (FHF) outer flow path, and the HPC inlet guide vanes (IGV). ICI logic included in GEnx

- 2B EEC software version C068 (and later EEC software versions) reduces the risk of flameout/rollback to a remote possibility within the envelope associate d with the ICI engine limitation. EEC C068 software certified under ODA Project Number PS14

- 0545, detects the presence of ice crystal icing and activates the cycling of the variable bleed valve (VBV) doors. The AFM revision

associated with this interim sol ution (ODA Project Number PS14

- 0053) raises the current ICI operating floor from 30,000 feet to 35,500 feet with use of a flight crew procedure to maintain adequate engine power levels, implemented via minimum Mach number and gross weight operating limitat ions. This ICI logic in conjunction with the revised AFM limitation for avoidance of ICI conditions will be substantiated as effective in identifying ICI conditions and addressing the ICI threat, when operating in ICI conditions in

- service. The FAA recentl y clarified that in

- flight power setting restrictions under a crew procedure to avoid conditions that would result in unacceptable operating characteristics does not meet the intent of §25.939(a). Therefore, Boeing is requesting this time

- limited exemption in order to implement an engine configuration compliant to §25.939(a) prior to the expiration of this time

- limited exemption.

The above text was associated with the Boeing request of January 2015 for revision of TLE 11070. In that request, as is identified above in The Original Extent of Relief Sought and Reason(s):

, Boeing requested an exemption end date of December 31, 2015. The FAA, in their grant of TLE 11070A, dated February 2, 2015 (Regulator Docket No. FAA

- 2014

- 0299), approved an exemption end date applicable for 14 CFR 25.939(a) of June 30, 2015. The FAA rationale in selecting the June 30, 2015 date is “Extending the dea dline for the final design modifications would require more data and a thorough FAA review and would not support the timeline of Boeing's request for granting the amended exemption **”**

. The material following provides more detailed rationale, which is based on the program timeline associated with the recent interim limitation revision effort. The timeline of this recent effort clearly identifies a more appropriate end date for TLE 11070A as applies to 14 CFR 25.939(a) would be the December 31, 2015. Data collection at NASA Glenn has just very recently been concluded. Processing of this data and Boeing/GE ICI team engagements will continue well into 2015. Following this, t here will be significant Boeing/FAA engagement and FAA review time associated with the certification of a configuration no longer requiring an exemption to the requirements of 14 CFR 25.939(a). Finally, the impact of the end date associated with this TLE was clearly identified by the FAA in the issue of TLE 11070A

- Boeing must show full compliance to 14 CFR 25.939(a), at Amendment 25

- 40, for newly produced Model 747

- 8 and

747

- 8F airplanes in order to receive a certificate of airworthiness after June 30, 2015

.Enclosure to RA

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Relief from the original schedule is necessary because:

The current RA Project (PS14

- 0053) associated with revising the AFM Certificate Limitations and Operating Procedures has taken 11 months from the initial testing at Winnipeg to the release of 14 CFR Part 25 approved documents. The key activities in this timeframe were: 1) T he analysis of significant amounts of data from Winnipeg in conjunction with significant amounts of GEnx and Legacy data, 2) T he model prediction of the benefit of the ICI logic to our flameout engine reaction 3) T he discovery of root cause for our mechanical damage, both in location and accretion characteristic, and 4) T he translation of the revised engine limitation into acceptable Part 25 procedures.

Acknowledged during this interim AFM limitation project was the fact that substantiating an engine configuration that eliminated the need for an Ice Crystal Icing (ICI) operational limitation would involve simulated altitude testing. That testing began at the end of November 2014 and has been acquiring data into March , 2015. The effort associated with analyzing the significant volume of test data, further validating the CFD model, confirming a completely operable and compliant engine configuration, and preparing the necessary substantiating data

to achieve both 14 CFR Part 33 and Part 25 compliance is expected to require an equivalent

time that the interim AFM limitation exercise involved.

Boeing’s goal is to certify an engine configuration capable of full ICI limitation removal as quickly as possible

. R ecent experien ce of realistic progress for all the necessary pieces supporting certification strongly influences a requested TLE end date of Dec 31, 2015.

Statement of No Adverse Affect on Safety Due to Schedule Extension

As was stated in Boeing petition letter RA

- 15

- 00349, t he proposed AFM Certificate Limitation and Operating Procedure for operating near or in ICI conditions require the flight crew to maintain a minimum Mach, which maintains an adequate level of safety for the time period of this Exemption. The use of this AFM Certificate Limitation is consistent with other AFM Certificate Limitations such as Engine Anti Ice System, Weight Limitations and Center of Gravity Limits, and Ground Operations in Icing Conditions. Boeing has determined that this

AFM lim itation is acceptable from a workload and complexity standpoint, and is operationally feasible. Boeing contends that a 6 month increase in the time period of this exem ption will not compromise the level of safety for the airplane associated with the AFM C ertificate Limitation and Operating Procedure for operating near or in ICI conditions.

Statement of Public Interest

As the FAA determined in issuing Exemption No 11070 , and reiterated in issuing Exemption

No. 11070A

– “The FAA has determined that the j ustification for the issuance of Exemption No. 11070 remains valid with respect to this amendment and is in the public interest.”, Boeing asserts that the public interest rationale is still applicable to th is requested extension.Enclosure to RA

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Request to Waive Publication and Comment

Boeing requests that this revision to T ime

- L imited E xemption 11070A be waived as this is considered a minor addition to the existing exemption. Boeing contends the rationale stated by the FAA, associated with granting TLE 11070A

- Full compliance must be demonstrated prior to removal of all associated limitations. Therefore, the FAA has determined that good cause exists for not publishing a summary of the petition, for public comment, in the Federal Register because the requested am endment to the exemption would not set a precedent, and any delay in acting on this petition would be detrimental to The Boeing Company and operators and flight crews of747

- 8/

- 8F airplanes.

– is quite applicable to this requested

revision of end date.

Privileges of this Exemption Outside the United States

Per §11.81(h), Boeing requests that the privileges of this Exemption be extended outside the United States. This extension of privileges is necessary for operations based within foreign

countries having bilateral agreements with the United States accepting FAA 14 CFR Part 25 as their airworthiness standards for transport category aircraft. The 747

- 8F and 747

- 8 are intended for the global market place with a launch customer based in a country utili zing the
United States airworthiness standards.

Conclusion

Boeing requests an additional six ( 6 ) month extension to allow sufficient time for Boeing to complete the test, analysis and compilation of substantiating documentation required to certify

a configuration fully compliant with the requirements of 14 CFR Part 25.939(a). This would

result in an E xemption termination date of 31 December 2015 for airplanes that have not been

issued a n original airworthiness certificate prior to this date

.

Summa ry to be Published in the Federal Register

PETITIONER: Boeing Commercial Airplanes

SECTION OF 14 CFR AFFECTED: §25. 939 ( a )

DESCRIPTION OF RELIEF SOUGHT: The Boeing Company has requested additional compliance time until 3 1 December 2015 (an additional 6 months) for airplanes that have not been issued an original airworthiness certificat e prior to this date

, to define and certify a configuration fully compliant with §25. 939 ( a ) for GEnx

- 2B powered 747

- 8/8F airplanes.