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Federal Register / Vol. 86, No. 150 / Monday, August 9, 2021 / Rules and Regulations Worth, TX 76177; telephone 817 2225786;
email david.wilson@faa.gov.
2 The subject of this AD is addressed in Transport Canada Emergency AD CF2021
23, dated July 5, 2021.
Issued on July 30, 2021.
Ross Landes, Deputy Director for Regulatory Operations, Compliance & Airworthiness Division, Aircraft Certification Service.
FR Doc. 202117024 Filed 8521; 4:15 pm BILLING CODE 491013P

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration 14 CFR Part 39
Docket No. FAA20210347; Project Identifier AD202001610E; Amendment 3921652; AD 20211505
RIN 2120AA64

Airworthiness Directives; General Electric Company Turbofan Engines Federal Aviation Administration FAA, DOT.
ACTION: Final rule.
AGENCY:

The FAA is adopting a new airworthiness directive AD for all General Electric Company GE GE90
110B1 and GE90115B model turbofan engines. This AD was prompted by an in-service occurrence of loss of engine thrust control resulting in uncommanded high thrust. This AD
requires initial and repetitive replacement of the full authority digital engine control FADEC integrated circuit MN4 microprocessor. The FAA
is issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective September 13, 2021.
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD
as of September 13, 2021.
ADDRESSES: For service information identified in this final rule, contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone:
513 5523272; email:
aviation.fleetsupport@ae.ge.com;
website: www.ge.com. You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 1200 District Avenue, Burlington, MA 01803. For information on the availability of this material at the FAA, call 781 238
7759. It is also available at https
www.regulations.gov by searching for and locating Docket No. FAA2021
0347.

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SUMMARY:

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Examining the AD Docket You may examine the AD docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210347; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M
30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
Stephen Elwin, Aviation Safety Engineer, ECO Branch, FAA, 1200
District Avenue, Burlington, MA 01803;
phone: 781 2387236; fax: 781 238
7199; email: Stephen.L.Elwin@faa.gov.
SUPPLEMENTARY INFORMATION:
Background The FAA issued a notice of proposed rulemaking NPRM to amend 14 CFR
part 39 by adding an AD that would apply to all GE GE90110B1 and GE90
115B model turbofan engines. The NPRM published in the Federal Register on May 7, 2021 86 FR 24554.
The NPRM was prompted by an inservice occurrence of loss of engine thrust control resulting in uncommanded high thrust. The FAA
received a report from the manufacturer of an in-service loss of engine thrust control that occurred on October 27, 2019, resulting in uncommanded high thrust. Analysis by the manufacturer found accumulated thermal cycles of the MN4 integrated circuit in the FADEC, through normal operation, causes the solder ball joints to wear out and eventually fail over time. The FAA
published AD 20202017 85 FR
63443, dated October 8, 2020 to prohibit dispatch of an airplane if certain status messages are displayed on the engine indicating and crew alerting system and if certain conditions are present per the manufacturers service information. As a terminating action, AD 20202017 also requires revision of the existing FAA-approved minimum equipment list MEL by incorporating into the MEL the dispatch restrictions listed in AD 20202017. Since the effective date of AD 20202017, the manufacturer published GE GE90100
Service Bulletin SB 730118 R00, dated November 6, 2020, and Revision 01, dated April 27, 2021, to replace the FADEC MN4 microprocessor and solder.
In the NPRM, the FAA proposed to require initial and repetitive replacement of the FADEC MN4
microprocessor using an approved
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overhaul procedure. The FAA is issuing this AD to address the unsafe condition on these products.
Discussion of Final Airworthiness Directive Comments The FAA received comments from five commenters. Commenters included Air Line Pilots Association, International ALPA, Boeing Commercial Airplanes Boeing, Cathay Pacific Airways Limited Cathay, FedEx Express FedEx, and United Airlines, Inc. The following presents the comments received on the NPRM and the FAAs response to each comment.
Request To Revise Installation Prohibition Cathay requested the FAA revise paragraph h, Installation Prohibition, of the NPRM that specifies no more than three replacements of the FADEC MN4
microprocessor may be performed on the same main channel board. Cathay suggested that the FAA revise proposed paragraph h to prohibit installation onto any engine of any FADEC that is not compliant with GE GE90100 SB
730118. Cathay stated that the MN4
processor replacements are managed by the original equipment manufacturers OEM internal maintenance procedures and operators do not have visibility into the number of replacements that have been performed.
The FAA partially agrees. As stated by Cathay, the MN4 processor replacements are managed by the OEMs internal maintenance procedures and, therefore, are not necessary in this AD.
The FAA has removed paragraph h, Installation Prohibition, from this AD.
The subsequent paragraphs of this AD
have been redesignated accordingly.
Request To Add Terminating Action FedEx requested the upcoming FADEC software revision A085 be included in this AD as a terminating action. FedEx commented that this AD
may no longer be necessary due to the development and pending release of GEs new and improved FADEC
software upgrade A085.
The FAA disagrees. The new FADEC
software revision A085 has not been approved by the FAA. Therefore, this software is not eligible for installation and cannot be referenced in this AD.
The FAA considers this AD to be an interim action. If terminating action is identified later, the FAA might consider additional rulemaking. The FAA did not change this AD.

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