Petition for Extension of Limi tation from Exemption No. 11081A

The Boeing Company Douglas M. Lane, Director, Regulatory Administration The Boeing Company

PO Box 3707 Seattle, Washington, 98124

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

Regulation At

Amendment Which Requires

§25.939(a) 25-40 (a) Turbine engine operating characteristics must be investigated in flight to determine that no adverse characteristics (such as sta ll, surge, or flameout) are present, to a hazardous degree, during normal and emergency operation within the range of operating

limitations of the ai rplane and of the engine.The Original Extent of Relief Sought and Reason(s):

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

Amendment

25-40 787-8/-9 airplanes powered by GEnx-1B engines incorporating Electronic Engine Control (EEC) B178 software (and later

EEC software versions), and operating within the

associated GEnx-1B 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-1B engines installed on 787-8/-9 airplanes have experienced engine flameout in Ice Crystal Icing (ICI) conditions in-service. The GEnx-2B engine, powering the 747-8/-8F airplane, has experienced mechanical damage in ICI conditions. This engine’s damage resulted in the issuance of AD 2013-24-01, which is applicable to both the GEnx-1B and GEnx-2B engine configurations, to address the unsafe condition. ODA Project Number PS14- 0053, certified a revised AFM Certificate Limitation and Operating Procedure to account for the GEnx-1B engine limitation associated with GEnx-1B Electronic Engine Control (EEC) software version B178. The ICI functionality in B178 was developed 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 remo te 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 crystal accretion leading to mechanical damage. The AFM

revision associated with this interim solution raises the current ICI operating floor from 30,000 feet to 37,500 feet with use of a flight crew procedure to maintain adequate engine power levels, implemented 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 the int ent 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 certifyan engine configuration that is fully compliant with §25.939(a).

The requested time-limit ed partial exemption will provide relief from the turbine engine operating characteristics requirements of §25.939(a) for new production and in-service Boeing Models 787-8 and 787-9 incorporating EEC B178 software (or later EEC software versions), and upon modifica tion of the AFM to reflect the applicable GEnx-1B / B178 (and later EEC software versions) engine ICI limitation. The relief sought is limited to 787-8/- 9 airplanes prior to the incorporation of an engine configuration compliant to §25.939(a).

Certification of a co mpliant 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 init ially 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 antici pated. Evaluation and incorporation of the re sults of the extensive NASA Glenn Testing are anticipated to take

several months.

Review of data with r egulatory 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-limit ed partial exemption will apply to future design changes requiring assessment of §25.939(a) while the AFM

Certificate Limitation and Operating Procedure are necessary for safe operation in ICI

conditions.Description of Issue

The GEnx-1B engines installed on 787-8/-9 ai rplanes have been shown to be susceptible to flameout during operation in ICI conditions. Ingestion of ice crystal s 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 in cluded in GEnx-1B EEC software version B178 (and later EEC software versions) reduces the ri sk of flameout/rollback to a remote possibility within the envelope associated with the ICI e ngine limitation. EEC B178 software, certified under ODA Project Number PS14-0621, detects the presence of ice crystal icing and activates the cycling of the variable bleed va lve (VBV) doors. The AFM revision associated with this interim solution (ODA Project Numb er PS14-0053) raises the current ICI operating floor from 30,000 feet to 37,500 feet with use of a flight crew procedure to maintain adequate engine power levels, implemented via minimu m Mach number and gross weight operating limitations. 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-servi ce. 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 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 Boei ng 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 11081A, dat ed January 30, 2015 (Regulator Do cket No. FAA-2014-0330), 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 deadline 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 ba sed on the program time line associated with the

recent interim limitation revision effort. The timeline of this re cent effort clearly identifies a more appropriate end date for TLE 11081A as appl ies to 14 CFR 25.939(a) would be the December 31, 2015. Data collection at NASA Gl enn has just very recent ly been concluded. Processing of this data and Boeing/GE ICI t eam engagements will continue well into 2015. Following this, there will be significant B oeing/FAA engagement and FAA review time

associated with the certif ication of a configuration no lon ger requiring an exemption to the requirements of 14 CFR 25.939(a). Finally, the impact of the end date a ssociated with this TLE was clearly identified by the FAA in the issue of TLE 11081A - Boeing must show full compliance to 14 CFR 25.939(a) , at Amendment 25-40, for newly produced Model 787-8 and 787-9 airplanes in order to receive a cert ificate of airworthiness after June 30, 2015

.

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 ta ken 11 months from the initia l testing at Winnipeg to therelease of 14 CFR Part 25 approv ed documents. The key activities in this timeframe were: 1) The analysis of significant amounts of data from Winnipeg in conjunction with significant amounts of GEnx and Legacy data,
2) The model prediction of the benefit of the ICI logic to our flameout engine reaction 3) The discovery of root c ause for our mechanical damage, bot h in location and accretion characteristic, and 4) The translation of the revised engine limi tation into acceptable Part 25 procedures.

Acknowledged during this interim AFM limitation project was the fa ct 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 va lidating the CFD model, confirming a completely operable and compliant engine confi guration, and preparing the nece ssary substantiating data to achieve both 14 CFR Part 33 and Part 25 compli ance is expected to require an equivalent

time that the interim AFM lim itation exercise involved.

Boeing’s goal is to certify an engine configurat ion capable of full ICI limitation removal as quickly as possible. Recent ex perience of realistic progress for all the necessary pieces supporting certification str ongly 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- 15-00350, the 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 adequa te 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 Ic e System, Weight Limita tions and Center of Gravity Limits, and Ground Operations in Icing C onditions. Boeing ha s determined that this AFM limitation 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 exemption will not compromise the level of safety for the airplane associated with the AFM Certificate Limitation and Operating Procedure for operating near or in ICI conditions.

Statement of Public Interest

As the FAA determined in issuing Exemption No 11081, and reiterated in issuing Exemption No. 11081A – “The FAA has determined that the ju stification for the issuance of Exemption No. 11081 remains valid with respect to this amendment and is in the public interest.”, Boeing asserts that the public interest rationale is still applicable to this requested extension.Request to Waive Publication and Comment

Boeing requests that this revision to Time-L imited Exemption 11081A be waived as this is considered a minor addition to the existing exemption. Boeing cont ends the rationale stated by the FAA, associated with granting TLE 11081A - 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 t he petition, for public comment, in the Federal Register because the requested amendment to the exemption would not set a precedent, and any delay in acting on this petition would be detrimental to T he Boeing Company and operators and flight crews of 787-8/-9 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 a ccepting FAA 14 CFR Part 25 as their airworthiness standards for transpor t category aircraft. The 787-8 and 787-9 are intended for the global market place with a launc h customer based in a country utilizing 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 s ubstantiating documentation required to certify a configuration fully compliant with the requi rements of 14 CFR Part 25.939(a). This would result in an Exemption termination date of 31 De cember 2015 for airplanes that have not been issued an original airworthiness ce rtificate prior to this date.

Summary 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 31 December 2015 (an additi onal 6 months) for airplanes that have not been issued an original airworthiness cert ificate prior to this date, to define and certify a configuration fully compliant with §25.939(a) fo r GEnx-1B powered 787-8/-9 airplanes.