# rti-IIDEING

AUG 28 

## 2015

RA-15-03488 JohnA. Hamilton Lead Administrator Regulatory Administration Commercial Airplanes

;f.. The Boeing Company P.O. Box 3707 MC 03-56 Seattle, WA98124-2207

U.S. Department ofTransportation Docket Operations, M-30 1200 NewJerseyAvenue, S.E. Room W12-140, West Bldg. Ground Floor Washington, DC 20590-0001 

### Subject:

Model: RA Project No Reference:

AD Related: Special Instructions:

This lettersubmits: Petition for Extension of747-8/-8F Limitation from Exemption No. 11070B in support ofCertification Plan 17123, Limitation Removal forOperation in Ice Crystal Icing (ICI) forthe 747-8/- 8F/GEnx-2B Airplane/Engine Combination. 747-8, 747-8F PS15-0493 a) Time Limited Grantof Exemption No. 11070B, Regulatory Docket No. FAA-2014-0299, issued June 10, 2015.

Yes- AD 2013-24-01 Avoidance of Ice Crystal Icing The BCA RegulatoryAdministration PA recommends the prime TPM forthe subject be Mr. Tom Thorson and the 140S Specialist be Ms. Sue Lucier.

(X) Request for Extension of Limitation from Exemption 11070B Boeing is requesting an Extension of Limitation end date currently publicized in Exemption No. 11070B at December 31, 2015. In the application forthe Reference a) Extension of Limitation, Boeing estimated that certification ofa fully compliant engine configuration bythe end of2015 was achievable. Discussions with both the FAA Engine Certification office and Aircraft Certification office involving the validating data and final limitation removal certification approaches, which began in the second quarterof2015, are taking longerto conclude than anticipated. There are multiple certification activities associated with ICI full limitation removal between the 787 and 747-8 programs, all requiring FAA involvement, such that final FAA approval ofthe AMOC to the existing ICI AD for GEnx-2B powered 747-8/-8F airplanes flows outto first quarterof2016. In support ofextending the Limitation end date of Exemption No. 11070B to September30, 2016, Boeing offers the rationale in the attached petition

# ~DEIND

RA-15-01262 Page 2

Ifthe enclosed Petition for Extension of Limitation from Exemption No. 11070B is granted, the extension would allow relieffor airplanes forwhich an application for an airworthiness certificate is made priorto September30, 2016forthe 747-8 and 747-8F models. Boeing Respectfully Requests this petition for an Extension of Limitation from Exemption No. 11070B be approved by December 1, 2015 to allow sufficient time for Boeing to complete the test, analysis and compilation ofsubstantiating documentation required to certify a configuration fully compliantwith the requirements of 14 CFR Part 25.939(a) by the extended date ofSeptember 30 2016. Note: 747-8/-8F ticketing and delivery after December 31, 2015 will be affected ifthis extension is notgranted. This letter is sentfor: (X) Review and FAA position on proposed amendmentto Exemption No. 11070B. Please contactthis office orthe following individuals ifyou have further questions: (X) ProjectAdministrator (PA): John Grover at (425) 239-9001. (X) BCA Regulatory Administration 747/767 Program Manager: Nicholas Smith at (425) 266-5484.
Sincerely,

for Digitallysigned by john.p.grover@boeing.com Date:2015.08.28 11:13:00 -07'00' Douglas M. Lane Director, RegulatoryAdministration (425) 237-1383, MC 03-56 FAX: (425) 294-9340
Enclosure: Petition for Extension of Limitation from Exemption No. 110708

cc: Name J. Sutherland (747-8/8F) R. Reed (747-8/8F) Enclosures Yes Yes Sharepoint Yes Yes Comments (FAA) 6Y-01 (FAA) 6Y-01Enclosureto RA-15-03488 Page 1of6



### Petition for Modificationtoand Extension ofLimitationfor Exemption No. 110708
The Boeing Company Douglas M. Lane, ODA Deputy Lead Administrator The Boeing Company PO Box 3707 Seattle, Washington, 98124


### Section ofthe Code of Federal Regulations (CFRs) thatare affected Regulation At Which Requires Amendment §25.939(a) 25-40 (a) Turbine engine operating characteristics must be investigated in flight to determine that no adverse !characteristics (such as stall, surge, orflameout) are present, to a hazardous degree, during normal and jemergency operation within the range ofoperating limitations ofthe airplane and ofthe engine.Enclosureto RA-15-03488 Page 2 of6


### The Original Extentof ReliefSoughtand Reason(s):
Reaulation Reauires: Relief is necessal'Lbecause: §25.939(a) 747-8/-8F airplanes The GEnx-28 engines installed on 747-8/-8F

### ~mendment powered by GEnx-28**~irplanes** have experienced engine flameout and**~5-40** engines incorporating**~ngine** mechanical damage in Ice Crystal Icing Electronic Engine (ICI) conditions in-service. The engine reaction Control (EEC) C068 in ICI conditions resulted in the issuance ofAD software (and later 12013-24-01, to addressthe unsafe condition. EEC software ODA Project Number PS14-0053, certified a versions), and revised AFM Certificate Limitation and Operating operating within the Procedure to accountforthe GEnx-28 engine associated GEnx-28 limitation associated with GEnx-28 Electronic Ice Crystal Icing (ICI) Engine Control (EEC) software version C068. engine limitation tfhe ICI functionality in C068 was developed envelope certified lthrough the use ofcomputational fluid dynamics underODA Project (CFD) modeling validated by engine testing at Number PS14-0053, lthe GE Winnipeg Test, Research and are required to Development Centre. The EEC software reduces comply with turbine he risk offlameouVrollback to a remote engine operating possibility, but is insufficientto fully mitigate the characteristics mechanical damage events, through the full requirements of jairplane operating envelope. §25.939(a). lfhe revised AFM Certificate Limitation and pperating Procedures were developed to prohibit airplane operation atengine power levels that could result in ice crystal accretion leading to mechanical damage. The AFM revision associated with RA Project PS14-0053 raises the current ICI operating floorfrom 30,000 eetto 35,500 feetwith use ofa flight crew procedure to maintain adequate engine power levels, implemented via minimum Mach number and grossweight operating limitations.
The FAA recently clarified that in-flight power setting restrictions undera crew procedure to avoid conditions thatwould result in unacceptable operating characteristics does not meetthe intent of§25.939(a).
With this petition, Boeing is requesting relieffor a limited period to allow sufficienttime to validate**~nd** certify an engine configuration that is fully**~ompliant**with §25.939(a).
lfhe requested extension to this time-limited !partial exemption will provide relieffromEnclosure to RA-15-03488 Page 3 of6 substantiating full compliance to 14 CFR §25.939(a) for new production Boeing 747-8F and 747-8 Models. This relief is required to allow sufficienttime to complete RA projects PS15- 0493 (CP 17123) and PS15-0380 (CP 17027).
The numerous certification projects associated with the final ICI Limitation revision for both the 787 and 747-8 airplanes have taken more time han initially estimated. In parallel, evaluation of he results ofthe extensive NASA Glenn testing has also taken more time than anticipated.
This requested time-limited 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.Enclosure to RA-15-03488 Page 4 of6

Description of Issue
The GEnx-2B engines installed on 747-8/-BF airplanes have been shown to be susceptible to flameout 

### Iengine damage during operation in ICI conditions. Test evidence from Winnipeg engine testing initially indicated ingestion ofice 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). However, subsequent simulated altitude testing at NASA Glenn, conducted across a range ofN1s encompassing the in-service encounters, has shown that ingestion of ice crystals results in accretion in the propulsor atthe rearward booster stator vane stages (stage 3 (S3) or outlet guide vanes (BOGV)), fan hub frame (FHF) outerflow path, and FHF strut leading edge. ICI logic included in GEnx-2B EEC software version C068 (and later EEC software versions) reduces the risk offlameout/rollback to a remote possibility within the envelope associated with the ICI engine limitation. ODA Project Number PS14-0545 certified EEC C068 software, which contains enhanced ice crystal icing (ICI) logic. ODA Project Number PS14-0914 certified EEC C075 software, which contained final enhancements to the T3 integrator logic and VBV proximity closure schedules.

The AFM revision associated with the interim limitation revision certification project (ODA Project Number PS14-0053) raised the current ICI operating floor from 30,000 feet to 35,500 feet with use ofa flight crew procedure to maintain adequate engine power levels, implemented via minimum Mach number and gross weight operating requirements. ICI logic in conjunction with the revised AFM limitation for avoidance of ICI conditions was substantiated as effective in identifying ICI conditions and addressing the ICI threat, when operating in ICI conditions. However, during the certification activity associated with ODA Project Number PS14-0053, the FAA 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), thus necessitating the need for revision A ofthisTLE.

The original Boeing request ofJanuary 2015 for revision ofTLE 11070 contained a requested exemption end date of December 31, 2015. The FAA, in their grantofTLE 11070A, dated February 2, 2015 (Regulator Docket No. FAA-2014-0299), approved an exemption end date applicable for 14 CFR 25.939(a) ofJune 30, 2015. The FAA rationale in selecting the June 30, 2015 date was "Extending the deadline forthe final design modifications wouldrequire more data anda thorough FAA reviewand wouldnotsupport the timeline ofBoeing's request for granting the amendedexemption". Knowing that certification ofa configuration fully compliant with 14 CFR §25.939(a) would not occur by June 30, 2015, Boeing provided, in RA letter RA15-00349, dated January 27, 2015, material requested bythe FAAto support an end date for the TLE of December 31, 2015. The FAA granted revised TLE 11070B on June 10, 2015. Processing of NASA Glenn data, validating the CFD model, defining fully compliant configurations and creating the associated certification projects, along with Boeing/GE/FAA engagements have continued well into 2015.
Relieffrom the original schedule is necessary because:

There are three projects associated with certification ofa fully compliant configuration for bothEnclosureto RA-15-03488 Page 5of6
the GEnx-1 Band GEnx-2B engines. RA Project PS14-0963 is the final limitation removal certification project forthe GEnx-1 B engine. RA Project PS15-0493 is the final limitation removal certification project forthe GEnx-2B engine. RA Project PS15-0380 is the GEnx-2B Booster Outlet Guide Vane (BOGV) modification certification project. Current project planning has RA Project PS15-0493 (GEnx-2B full limitation removal) receiving FAA approval February 1, 2016. This date indicates that an extension ofthe exemption end date in 11070B is necessary to cover planned production deliveries in early 2016. The quantity of ICI certification projects currently underway in conjunction with the consideration ofprevious ICI project flows, strongly influences a requested TLE end date for certification ofa fully compliant configuration to the requirements of 14 CFR §25.939(a) ofSeptember30, 2016.


### Statement of No Adverse Affecton Safety Due to Schedule Extension

A Message Courier message from Mr. John Groverto Mr's Thomas Thorson, Jim Voytilla and James Sutherland dated August 18, 2015 contained a summary ofrecent in-service ICI encounters that resulted in elevated engine vibrations. This information provides indication that the ICI logicthat is now 100% throughout the fleet is providing the expected benefitto the engines when operating in ICI conditions. The ICI logic, in conjunction with the currentAFM ICI certificate limitations and operating procedures (which bythemselves are acceptable from a workload and complexity standpoint), result in no compromise in the level ofsafety forthe airplane forthe requested time period ofthis Exemption.



### Statement of Public Interest
As the FAA determined in issuing Exemption No 11070, and reiterated in issuing Exemption No. 11070B- "The FAA has determined that thejustification forthe 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 this requested extension. 

### RequesttoWaive Publication and Comment Boeing requests that the public comment forthis revision to Time-Limited Exemption 11070B 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 11070B- Full compliance must be demonstratedpriorto removal ofallassociatedlimitations. Therefore, the FAA has determinedthatgoodcause exists fornotpublishing

### a summaryofthe petition, forpublic comment, in the Federal Registerbecause the requestedamendment to the exemption would notset

### a precedent, andanydelayin acting on thispetition wouldbe detrimental to The Boeing Companyandoperators andflightcrews of747-81-8Fairplanes.- is quite applicable to this requested revision ofend date. 

### Privileges ofthis Exemption Outsidethe United States

Per §11.81 (h), Boeing requests that the privileges ofthis Exemption be extended outside the United States. This extension ofprivileges 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 areEnclosure to RA-15-03488 Page 6 of6

intended forthe global market place with a launch customer based in a country utilizing the United States airworthiness standards.

Conclusion Boeing requests an additional nine (9) month extension to allow sufficienttime for Boeing and General Electric (GE) to complete review ofthe NASA Glenn data with the FAAs (ECO and ACO) and compile substantiating documentation required to certify a configuration fully compliantwith the requirements of 14 CFR Part §25.939(a). Additionally, resulting from Boeing/FAA discussions on the exemption text, Boeing requests the FAA clarify whether it was the FAA intent, with the sentence "Design changes and modifications to in-service Model 747-8 and 747-8F airplanes**involvin~** engine ice-protection systems and associated AFM limitations made after December 31 5

, 2015, must also fully comply with §25.939(a) at amendment25-40", to include revenue service airplanes in the exemption. Limiting in-service aircraft modifications afterthe TLE termination date could have the unintended effect of forcing major maintenance on all engines in the same maintenance period, a practice advised against in Boeing and industry publications.
The requested extension to the partial exemption termination date would result in an Exemption termination date of30 September2016 for airplanes that have not been issued an original airworthiness certificate priorto this date.

Summary to be Published in the Federal Register
PETITIONER: Boeing Commercial Airplanes
SECTION OF 14CFRAFFECTED: §25.939(a)
DESCRIPTION OF RELIEF SOUGHT: The Boeing Company has requested additional compliance time until 30 September2016 (an additional 9 months) for airplanes that have not been issued an original airworthiness certificate priorto this date, to define and certify a configuration fully compliantwith §25.939(a) for GEnx-2B powered 747-8/8F airplanes.