.rti--IIDEING 

1/27/15 

RA-15-00349 

C) 

John A. Hamilton The Boeing Company 

Lead Administrator P.O. Box 3707 MC 03-56 

Regulatory AdministratiO}f ;'!} ;:nA/I=hifi'eP\l!e. WA 98124-2207 

Commercial Airplanes .. ;.~.·u:~i)J.t;!;:.~'J!. '-!1 

,-. .-~;;·;~·l·~~~i{~~~UYt:r., 

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 to Amend Partial Time Limited Exemption No. 

11070 to include 14 CFR 25.939(a) at Amendment 25~40 in 

support of Certification Plan 15053, Operation in Ice 

Crystal Icing for GEnx engines on 747-8/-8F Airplanes 

747-8, 747-8F 

PS14-0053 

a) Boeing letter RA-14-0221 0, Petition for a Time Limited 

Exemption from 14 CFR 25.1305(c)(5) at Amendment 25-

120 in support of Certification Plan 15053, Operation in Ice 

Crystal Icing for GEnx engines on 7 4 7 -8/-8F airplanes, 

dated May 2, 2014. 

b) Time Limited Grant of Exemption No. 11070, Regulatory 

Docket No. FAA-2014-0299 

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

The BCA Regulatory Administration PA recommemds the 

prime TPM for the subject be Mr. Tom Thorson. 

(X) Amendment to Exemption 

The Boeing Company respectfully submits this petition for a partial time limited 

exemption from the requirements of 14 CFR 25.939(a} at Amendment 25-40 to 

be amended to the existing Reference (b) Exemption No. 11070, in support of 

Certification Plan 15053, Operation in Ice Crystal Icing for GEnx engines on 747-

8/-8F airplanes. Enclosed with this letter is the Exemption No. 11070 amendment 

petition. 

Your timely cooperation in these matters is greatly appreciated. 
~BEING 

RA-15-00349 

Page2 

Boeing Respectfully Requests this petition for a time limited exemption be 

approved by January 28, 2015 for the following reason: 

If requested relief is not granted, continued adherence to the current AFM 

limitation with the ICI accommodations provided in EEC C068 software (and later 

EEC software versions) will result in unnecessary flight crew workload and 

burdensome operational planning that can result in otherwise avoidable 

cancelled and diverted flights. 

Additionally, Boeing has received reports from the airlines that adherence with 

the cu~rent AFM limitation is onerous on the airlines and flight crews. The AFM 

limitation requires new and unique flight operations planning, carrying of 

additional fuel, increased workload for flight crews and in numerous instances 

has resulted in extensive diversions resulting in disruptions to the airline 

operations. Granting of this amended exemption will diminish the likelihood of 

future events of this nature. 

The public interest will be advanced by the grant of exemption as it is in the best 

economic interest of the United States. Modification of the AFM to reflect the 

new GEnx-2B I C068 (and later EEC software versions) engine ICIIimitation for 

avoidance of ICI conditions makes the 747-8/-8F airplanes more operationally 

economical and provides a competitive advantage for future airplane sales; As 

many 747-8/-8F customers are foreign, further delays in the modification of the 

AFM limitation is not in the interest of the public due to the potential negative 

impact to export sales, the balance-of-trade, the gross domestic product, and the 

economic health of the United States. 

This letter is sent for:· 

(X) Review and FAA position on proposed amendment to Exemption No. 11070. 
rtL-.HDEINC 

RA-15-00349 

Page 3 

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

questions: 

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

BCA Regulatory Administration 747/767 Program Manager: Jeremy Taylor 

for 

Digitally signed by 

Jeremy J Taylor, 

1802561 

Date: 2015.01.26 

20:07:26 -08'00' 

Douglas M. Lane 

Director, Regulatory Administration 

(425) 237-1383, MC 03-56 

FAX: (425) 294-9340 

Enclosure: Petition to Amend an Existing Time Limited Exemption No. 11070 to 

include 14 CFR 25.939(a) atAmendment 25-40 for 747-8 and 747-8F Airplane 

Minor Models, ODA Project Number PS14-0053 

cc: 

Name 

R. Reed (747-

J. Sutherland 

Share 

Yes 

Yes 

Comments 

(FAA) 6Y-01 

(FAA) 6Y-01 
Enclosure to RA-15-00349 

Page 1 of 5 

Petition to Amend Exemption 11070 to Include §25.939(a) Amendment 25-40 for 747-8 

and 747-SF Airplane Minor Models, ODA Project Number PS14-0053 

I A. Name and Address of the Petitioner 

Doug Lane, Director Regulatory Administration 

The Boeing Company, 

PO Box 3707, 

Seattle, Washington, 98124 

I B. Section of the Code of Federal Regulations (CFRs) that are affected 

As provided for in §11_61(b), Boeing hereby petitions for a partial time-limited 

exemption to the following CFR: 

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 

emergency operation within the range of operating 

limitations of the airplane and of the engine. 

I C. The extent of relief being sought 

Requlation Requires: Relief is necessary because: 

§25.939(a) 747-8/-8F The GEnx-28 engines installed on 747-8/-8F 

Amendment airplanes airplanes have experienced engine flameout and 

25-40 powered by engine mechanical damage in Ice Crystal Icing 

GEnx-2B (ICI) conditions in-service. The engine reaction in 

engines ICI conditions resulted in the issuance of AD 

incorporating 2013-24-01, to address the unsafe condition. 

Electronic ODA Project Number PS14-0053, will certify a 

Engine Control revised AFM Certificate Limitation and Operating 

(EEC) C068 Procedure to account for the GEnx-2B engine 

software (and limitation associated with GEnx-2B Electronic 

later EEC Engine Control (EEC) software version C068. 

software The ICI functionality in C068 was developed 

versions), and through the use of computational fluid dynamics 

operating (CFD) modeling validated by engine testing at the 

within the GE Winnipeg Test, Research and Development 

associated Centre. The EEC software reduces the risk of 

GEnx-28 Ice flameout/rollback to a remote possibility, but is 

Crystal Icing insufficient to fully mitigate the mechanical 

(ICI) engine damage events, through the full airplane operating 

limitation envelope. 
Enclosure to RA-15-00349 

Page 2 of 5 

envelope 

certified under 

ODA Project 

Number PS14-

0053, are 

required to 

comply with 

turbine engine 

operating 

characteristics 

requirements 

of §25.939(a). 

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 

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 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). 

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 I C068 (and later EEC software 

versions) engine ICIIimitation. 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 anticipated. Evaluation and 

incorporation of the results of the extensive NASA 
Enclosure to RA-15-00349 

Page 3 of 5 

I D. Description of the Issue 

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 Limitation and Operating Procedure are 

necessary for safe operation in ICI conditions. 

The GEnx-2B engines installed on 7 4 7 -8/-BF airplanes have been shown to be susceptible to 

flameout I 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-28 EEC 

software version C068 (and later EEC software versions) reduces the risk of flameouUrollback 

to a remote possibility within the envelope associated 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 solution (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 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-service. 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. 

I E. Statement of No Adverse Effect on Safety 

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 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 limitation is acceptable from a workload and complexity 

standpoint, and is operationally feasible. The revised AFM Certificate Limitation and 

associated Operating Procedure will be extensively communicated to the operators and their 
Enclosure to RA-15-00349 

Page4 of 5 

flight crews via Flight Crew Operations Manual, Fleet Team Digest, Multi-Operator Message 

and other operator forums. 

Investigation of the in-service ICI events in conjunction with CFD modeling and engine ice 

crystal ingestion testing has identified that ice crystals accrete in the propulsor at the booster 

outlet guide vanes (BOGV), fan hub frame (FHF) outer flow path, and the HPC inlet guide 

vanes (IGV). Analysis, validated by engine testing, substantiates that the ICI detection (delta 

T3) and mitigation logic (cycling VBV doors) in EEC software C068, reduces the risk of 

flameout/rollback to a remote possibility when operating in ice crystal icing. While the threat of 

engine mechanical damage is not fully abated by the EEC C068 software, the application of 

the AFM Certificate Limitation and Operating Procedure between 30,000 feet and 35,500 feet 

does prevent mechanical damage events. 

I F. Statement of Public Interest 

If the requested relief is not granted, continued adherence to the current AFM limitation with 

the ICI accommodations provided in EEC C068 software (and later EEC software versions) will 

result in unnecessary flight crew workload and burdensome operational planning that can 

result in otherwise avoidable cancelled and diverted flights. 

Additionally, Boeing has received reports from the airlines that adherence with the AFM 

limitation is onerous on the airlines and flight crews. The AFM limitation requires new and 

unique flight operations planning, carrying of additional fuel, increased workload for flight crews 

and in numerous instances has resulted in extensive diversions resulting in disruptions to the 

airline operations. Granting of this amended exemption will diminish the likelihood of future 

events of this nature. 

The public interest will be advanced by the grant of exemption as it is in the best economic 

interest of the United States. Modification of the AFM to reflect the new GEnx-28 I C068 (and 

later EEC software versions) engine ICIIimitation for avoidance of ICI conditions makes the 

' 747-8/-8F airplanes more operationally economical and provides a competitive advantage for 

future airplane sales. As many 747-8/-8F customers are foreign, further delays in the 

modification of the AFM limitation is not in the interest of the public due to the potential 

negative impact to export sales, the balance-of-trade, the gross domestic product, and the 

economic health of the United States. 

I G. Request for Waiver of Publication 

The petitioner requests that the public comment period for this petition for amended exemption 

11070 be waived, as this is considered a minor addition to the existing exemption. A delay in 

processing of the exemption could delay the modification of the AFM to reflect the new GEnx28 I C068 (and later EEC software versions) engine ICIIimitation for avoidance of ICI 

conditions. The scheduled closure of ODA Project Number PS14-0053 is January 2015. 

Granting of the exemption is critical to the operators as the seasonal conditions associated 

with weather fronts containing ICI is approaching. Currently, the limitations require diversion 

from standard jetways when encountering ICI conditions; the granting of this exemption will 

result in less diversions and more standard airline operations. The revised operational 
Enclosure to RA-15-00349 

Page 5 of 5 

envelope will expand the options to flight crews when confronted with weather fronts 

associated with ICI conditions. 

I H. 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. 

It Conclusion 

The requested partial time-limited exemption will allow 7 4 7 -8/-8F airplanes relief from the 

turbine engine operating characteristics requirement of §25.939(a) for the ICI VBV system. 

Boeing petitions for amended exemption from §25.939(a) at amendment 25-40 for the GEnx2B ICI VBV ice protection system based on the proposed AFM Certificate Limitation and 

Operating Procedure, in conjunction with adequate operator and flight crew communication. 

The Boeing petition for exemption applies specifically to the turbine engine operating 

characteristics requirement of §25.939(a), for new production and in-service Boeing Models 

747-8F and 747-8, to allow modification of the AFM to reflect the new GEnx-2B I C068 (and 

later EEC software versions) engine ICIIimitation for avoidance of ICI conditions. The relief 

sought .is limited until 31 December 2015, at which time production 747-8F and 747-8 airplanes 

will incorporate a compliant design, 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. 

I