rti-IIDEING 

AUG 2 8 2015 

RA-15-03488 

John A. Hamilton 

Lead Administrator 

Regulatory Administration 

Commercial Airplanes 

;f.. 

The Boeing Company 

P.O. Box 3707 MC 03-56 

Seattle, WA 98124-2207 

U.S. Department of Transportation 

Docket Operations, M-30 

1200 New Jersey Avenue, S.E. 

Room W12-140, West Bldg. Ground Floor 

Washington, DC 20590-0001 

Subject: 

Model: 

RA Project No 

Reference: 

AD Related: 

Special 

Instructions: 

This letter submits: 

Petition for Extension of 747-8/-8F Limitation from Exemption 

No. 11 070B in support of Certification Plan 17123, Limitation 

Removal for Operation in Ice Crystal Icing (ICI) for the 747-8/-

8F/GEnx-2B Airplane/Engine Combination. 

747-8, 747-8F 

PS15-0493 

a) Time Limited Grant of Exemption No. 11 070B, Regulatory 

Docket No. FAA-2014-0299, issued June 10, 2015. 

Yes- AD 2013-24-01 Avoidance of Ice Crystal Icing 

The BCA Regulatory Administration PA recommends the prime 

TPM for the subject be Mr. Tom Thorson and the 140S 

Specialist be Ms. Sue Lucier. 

(X) Request for Extension of Limitation from Exemption 11 070B 

Boeing is requesting an Extension of Limitation end date currently publicized in 

Exemption No. 11 070B at December 31, 2015. In the application for the 

Reference a) Extension of Limitation, Boeing estimated that certification of a fully 

compliant engine configuration by the end of 2015 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 quarter of 2015, are taking longer to 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 of the AMOC to the existing ICI AD for 

GEnx-2B powered 747-8/-8F airplanes flows out to first quarter of 2016. 

In support of extending the Limitation end date of Exemption No. 11 070B to 

September 30, 2016, Boeing offers the rationale in the attached petition 
~DEIND 

RA-15-0 1262 

Page 2 

If the enclosed Petition for Extension of Limitation from Exemption No. 11 070B is 

granted, the extension would allow relief for airplanes for which an application for 

an airworthiness certificate is made prior to September 30, 2016 for the 7 47-8 

and 747-8F models. 

Boeing Respectfully Requests this petition for an Extension of Limitation from 

Exemption No. 11 070B be approved by December 1, 2015 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) by the extended date of September 30 

2016. 

Note: 747-8/-8F ticketing and delivery after December 31, 2015 will be affected 

if this extension is not granted. 

This letter is sent for: 

(X) Review and FAA position on proposed amendment to Exemption No. 

11070B. 

Please contact this office or the following individuals if you have further 

questions: 

(X) Project Administrator (PA): John Grover at (425) 239-9001. 

(X) BCA Regulatory Administration 747/767 Program Manager: Nicholas Smith 

at (425) 266-5484. 

Sincerely, 

for 

Digitally signed by 

john.p.grover@boeing.com 

Date: 2015.08.28 11:13:00 

-07'00' 

Douglas M. Lane 

Director, Regulatory Administration 

(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-01 
Enclosure to RA-15-03488 

Page 1 of6 

Petition for Modification to and Extension of Limitation for Exemption No. 110708 

The Boeing Company 

Douglas M. Lane, ODA Deputy Lead Administrator 

The Boeing Company 

PO Box 3707 

Seattle, Washington, 98124 

Section of the Code of Federal Regulations (CFRs) that are 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, or flameout) are 

present, to a hazardous degree, during normal and 

jemergency operation within the range of operating 

limitations of the airplane and of the engine. 
Enclosure to RA-15-03488 

Page 2 of6 

The Original Extent of Relief Sought and Reason(s): 

Reaulation Reauires: Relief is necessal'L because: 

§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 of AD 

software (and later 12013-24-01, to address the unsafe condition. 

EEC software ODA Project Number PS14-0053, certified a 

versions), and revised AFM Certificate Limitation and Operating 

operating within the Procedure to account for the 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 of computational fluid dynamics 

under ODA 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 of flameouVrollback to a remote 

engine operating possibility, but is insufficient to 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 at engine 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 floor from 30,000 

eet 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 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 intent of §25.939(a). 

With this petition, Boeing is requesting relief for a 

limited period to allow sufficient time 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 relief from 
Enclosure 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 

sufficient time 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 7 4 7-8 airplanes have taken more time 

han initially estimated. In parallel, evaluation of 

he results of the 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 I engine damage during operation in ICI conditions. Test evidence from Winnipeg 

engine testing initially indicated 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). However, subsequent simulated altitude testing at NASA Glenn, 

conducted across a range of N1 s encompassing the in-service encounters, has shown that 

ingestion of ice crystals results in accretion in the propulsor at the rearward booster stator 

vane stages (stage 3 (S3) or outlet guide vanes (BOGV)), fan hub frame (FHF) outer flow 

path, and FHF strut leading edge. 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 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 of a 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 of thisTLE. 

The original Boeing request of January 2015 for revision of TLE 11070 contained a requested 

exemption end date of December 31, 2015. The FAA, in their grant of TLE 11 070A, 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 was "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". Knowing that certification of a 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 by the FAA to support an end date for 

the TLE of December 31, 2015. The FAA granted revised TLE 11 070B 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. 

Relief from the original schedule is necessary because: 

There are three projects associated with certification of a fully compliant configuration for both 
Enclosure to RA-15-03488 

Page 5 of6 

the GEnx-1 Band GEnx-2B engines. RA Project PS14-0963 is the final limitation removal 

certification project for the GEnx-1 B engine. RA Project PS15-0493 is the final limitation 

removal certification project for the 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 of the exemption end date in 11 070B is 

necessary to cover planned production deliveries in early 2016. The quantity of ICI 

certification projects currently underway in conjunction with the consideration of previous ICI 

project flows, strongly influences a requested TLE end date for certification of a fully compliant 

configuration to the requirements of 14 CFR §25.939(a) of September 30, 2016. 

Statement of No Adverse Affect on Safety Due to Schedule Extension 

A Message Courier message from Mr. John Grover to Mr's Thomas Thorson, Jim Voytilla and 

James Sutherland dated August 18, 2015 contained a summary of recent in-service ICI 

encounters that resulted in elevated engine vibrations. This information provides indication 

that the ICI logic that is now 100% throughout the fleet is providing the expected benefit to the 

engines when operating in ICI conditions. The ICI logic, in conjunction with the current AFM 

ICI certificate limitations and operating procedures (which by themselves are acceptable from 

a workload and complexity standpoint), result in no compromise in the level of safety for the 

airplane for the requested time period of this Exemption. 

Statement of Public Interest 

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

No. 11 070B- "The FAA has determined that the justification 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 this requested extension. 

Request to Waive Publication and Comment 

Boeing requests that the public comment for this revision to Time-Limited Exemption 11 070B 

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 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 amendment 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 of747-81-8F 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 
Enclosure to RA-15-03488 

Page 6 of6 

intended for the 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 sufficient time for Boeing and 

General Electric (GE) to complete review of the NASA Glenn data with the FAAs (ECO and 

ACO) and compile substantiating documentation required to certify a configuration fully 

compliant with 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 

amendment 25-40", to include revenue service airplanes in the exemption. Limiting in-service 

aircraft modifications after the 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 of 30 September 2016 for airplanes that have not been issued an 

original airworthiness certificate 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 30 September 2016 (an additional 9 months) for airplanes that 

have not been issued an original airworthiness certificate prior to this date, to define and 

certify a configuration fully compliant with §25.939(a) for GEnx-2B powered 747-8/8F 

airplanes.