U.S. Department 

of Transportation 

Federal Aviation 

Administration 

JUN 1 0 2015 

Exemption No. 11081 B 

Transport Airplane Directorate 

1601 Lind Avenue, S.W. 

Renton, Washington 98057-3356 

Regulatory Docket No. F AA-20 14-0330 

Mr. Tim Dowling 

Regulatory Administration 787 Program Manager 

The Boeing Company 

P.O. Box 3707 MC 03-56 

Seattle, W A 98124-2207 

Dear Mr. Dowling: 

This letter is to inform you that we have again amended exemption no. 11081. It explains 

the basis for our decision and describes its effect. 

The Basis for Our Decision 

By letter no. RA-15-0 1286, dated March 26, 2015, you petitioned the Federal Aviation 

Administration (FAA), on behalf of The Boeing Company, to permit extended time-limited 

relief from the regulations to allow time for Boeing to upgrade ice-crystal icing (ICI) 

indicator software, per Title 14, Code of Federal Regulations (14 CFR) 25.939(a), on Boeing 

Model 787-8 and -9 airplanes equipped with GEnx-1 B engines. 

Exemption no. 11081 was issued in support of Certification Plan 16286 and provides 

temporary relief from the requirements of§ 25.1305(c)(5). Exemption no. 11081 was 

modified by exemption no. 11081A, which granted relief from§ 25.939(a). The extension 

now requested would allow relief for the Model 787-8 and -9 airplanes for which an 

application for an airworthiness certificate was made prior to December 31, 2015, for a 

limited time, to allow sufficient time for Boeing to develop, validate, and certify an engine 

configuration that is fully compliant with§ 25.939(a). 

Your petition states, in pertinent part, that: 

Boeing's goal is to certify an engine configuration capable offull ICI limitation 

removal as quickly as possible. Recent experience of realistic progress for all the 

necessary pieces supporting certification strongly influences a requested [timelimited grant of extended exemption] end date ofDec 31 , 2015. 

Certification ofthe Interim ICI Limitation has been more complex than initially 

estimated. In parallel, Boeing and [General Electric] have been working the 

development of software supporting the final compliant configuration, which has 
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also taken more time than anticipated. 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 [type 

certification] 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 [Airplane Flight Manual] Certificate 

Limitation and Operating Procedure are necessary for safe operation in ICI 

conditions. 

Other than requesting an extended time-limit deadline, the FAA finds that your petition 

includes no request for substantive change in the conditions, and reasons relative to public 

interest and safety, that were the basis for granting the original time-limited exemption. We 

now tind that extending the expiration for this time-limited exemption to December 31, 

2015, is in the public interest. In the previous amendment to the exemption, we granted your 

request for certain relief from§ 25 .939(a). We did not extend the expiration, as requested, to 

December 31, 2015, due to Boeing's request for expedited review and immediate FAA 

decision on granting relief from§ 25.939(a). 

We have subsequently reviewed the data Boeing provided and have determined that the 

requested 6 additional months will allow Boeing to complete testing, compile and analyze 

extensive test data, and complete a thorough showing of compliance. Additionally, other 

measures, including operating limitations, will continue to ensure that operators, during the 

duration of this extension, avoid the environments that are likely to cause engine icing. 

Therefore, we find that this extension is in the public interest. 

Federal Register Publication 

The FAA has determined that good cause exists for not publishing a summary of the petition 

in the Federal Register for public comment because the requested amendment to the 

exemption would not set a precedent, and any delay in acting on this petition would be 

detrimental to Boeing airplane deliverables. 

Our Decision 

The FAA has determined that the justification for the issuance of exemption no. 11081 

remains valid with respect to this amendment and is in the public interest, for the reasons 

Boeing stated in their petition and as discussed above. 

The Effect of Our Decision 

Our decision extends a time-limited exemption from § 25.939(a), at Amendment 25-40, for 

Model 787-8 and -9 airplanes that have incorporated engine-ice-protection system 

modifications and associated AFM limitations. This grant of amended exemption provides a 

revised expiration date to exemption no. 11081 . 

The Grant of Amended Exemption 

In consideration of the foregoing, I find that a time-limited grant of exemption is in the 

public interest regarding § 25.939(a) at Amendment 25-40. Therefore, pursuant to the 

authority contained in 49 U.S.C. 40113 and 44 701 , delegated to me by the Administrator, I 

grant The Boeing Company an exemption until December 31 , 2015, from the requirements 
of§ 25.939(a), as amended by Amendment 25-40. Specifically, this amendment approves 

substituting laboratory and ground tests for the requirement to investigate engine operating 

characteristics in flight and permitting use of airplane speed as a means to set minimum 

engine power needed to maintain engine operability in ice crystal icing environments. This 

amendment to the exemption is applicable to new production and in-service Boeing Model 

787-8 and -9 airplanes incorporating modified EEC software with engine-ice-protection 

system changes and associated AFM limitations. 

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Boeing must show full compliance to§ 25.939(a), at Amendment 25-40, for newly produced 

Model 787-8 and -9 airplanes in order to receive a certificate of airworthiness after 

December 31,2015. Design changes and modifications to in-service Model 787-8 and -9 

airplanes involving engine-ice-protection systems and associated AFM limitations made 

after December 31 , 2015, must also fully comply with§ 25.939(a) at Amendment 25-40. 

All conditions and limitations of exemption no. 11081 remain the same. This letter must be 

attached to, and is a part of, exemption no. 11081. 

Sincerely, ~ 

fJ#;[ 

Jeffrey E. Duven 

Manager, Transport Airplane Directorate 

Aircraft Certification Service