Airworthiness Directives; General Electric Company Engines

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2024-2417; Project Identifier AD-2024-00336-E; Amendment 39-23012; AD 2025-07-10]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; General Electric Company Engines</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The FAA is superseding Airworthiness Directive (AD) 2020-20-17 and AD 2021-15-05 for all General Electric Company (GE) Model GE90-110B1 and GE90-115B engines. AD 2020-20-17 prohibits dispatch of an airplane if certain status messages are displayed on the engine indicating and crew alerting system (EICAS) and if certain conditions are present; and as terminating action, requires revision of the existing FAA-approved minimum equipment list (MEL) by incorporating the dispatch restrictions into the MEL. AD 2021-15-05 requires initial and repetitive replacement of the full authority digital engine control (FADEC) integrated circuit (MN4) microprocessor. Since the FAA issued AD 2020-20-17 and AD 2021-15-05, the manufacturer has developed a software revision for the electronic engine control (EEC) FADEC that further mitigates the unsafe condition. This AD retains all the actions of AD 2020-20-17 and AD 2021-15-05, and also requires upgrading the EEC FADEC software to an EEC FADEC software version eligible for installation as a terminating action. The FAA is issuing this AD to address the unsafe condition on these products. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This AD is effective May 21, 2025. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of May 21, 2025. The Director of the Federal Register approved the incorporation by reference of certain other publications listed in this AD as of October 23, 2020 (85 FR 63443, October 8, 2020); and September 13, 2021 (86 FR 43409, August 9, 2021). </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> <E T="03">AD Docket:</E> You may examine the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2024-2417; 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 W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. <E T="03">Material Incorporated by Reference:</E> • For GE material identified in this AD, contact GE, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: <E T="03">aviation.fleetsupport@ge.com;</E> website: <E T="03">ge.com</E> . • You may view this material 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 (817) 222-5110. It is also available at <E T="03">regulations.gov</E> under Docket No. FAA-2024-2417. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Alexander Thickstun, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (202) 267-8292; email: <E T="03">alexander.m.thickstun@faa.gov</E> . </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Background</HD> The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2020-20-17, Amendment 39-21273 (85 FR 63443, October 8, 2020) (AD 2020-20-17) and AD 2021-15-05, Amendment 39-21652 (86 FR 43409, August 9, 2021) (AD 2021-15-05). AD 2020-20-17 and AD 2021-15-05 applied to all GE Model GE90-110B1 and GE90-115B engines. The NPRM published in the <E T="04">Federal Register</E> on November 1, 2024 (89 FR 87317). The NPRM was prompted by an in-service occurrence of loss of engine thrust control resulting in uncommanded high thrust. Degradation of the MN4 integrated circuit microprocessor solder balls in the FADEC can result in the engine not following throttle commands. In the NPRM, the FAA proposed to continue to prohibit dispatch of an airplane if certain status messages are displayed on the EICAS and if certain conditions are present; and as terminating action, require revision of the existing FAA-approved MEL by incorporating the dispatch restrictions into the MEL. The FAA also proposed to continue to require initial and repetitive replacement of the FADEC MN4 microprocessor. In the NPRM, the FAA also proposed to require upgrading the EEC FADEC software to an EEC FADEC software version eligible for installation as a terminating action for the actions retained from AD 2020-20-17 and AD 2021-15-05. <HD SOURCE="HD1">Discussion of Final Airworthiness Directive</HD> <HD SOURCE="HD1">Comments</HD> The FAA received comments from five commenters. The commenters were the Air Line Pilots Association, International (ALPA), The Boeing Company (Boeing), FedEx Express (FedEx), GE Aerospace (GE), and United Airlines (UAL). The following presents the comments received on the NPRM and the FAA's response to each comment. <HD SOURCE="HD1">Support for the NPRM</HD> ALPA expressed support for the proposed AD. FedEx concurred with the intent and scope of the proposed AD and stated that the FedEx fleet has already upgraded the EEC FADEC software version to A.0.8.6. UAL indicated that it had no objections to the proposed AD. <HD SOURCE="HD1">Request for Updated Definition</HD> GE requested that the FAA update the Material Incorporated by Reference under 1 CFR part 51 paragraph and revise the definition specified in paragraph (i)(1)(ii) of the NPRM to include a later revision of the acceptable service information. GE mentioned that the FAA has approved a global alternative method of compliance (AMOC) to the corresponding paragraph in AD 2021-15-05, which allowed the use of the later service information. GE pointed out that including the later service information would prevent similar requests for AMOCs to the NPRM. The FAA agrees with the request. The FAA has revised the Material Incorporated by Reference under 1 CFR part 51 paragraph and paragraph (i)(1)(ii) of this AD to include reference to GE GE90-100 Service Bulletin 73- 0118 R02, dated November 15, 2024 (GE GE90-100 Service Bulletin 73-0118 R02). Additionally, the FAA has added paragraph (n)(3) of this AD to allow AMOCs approved previously for AD 2021-15-05 as AMOCs for the corresponding provisions of this AD. <HD SOURCE="HD1">Request for Added Clarification of FADEC Software Version A.0.8.6</HD> GE requested that the FAA include a service bulletin reference (GE GE90-100 Service Bulletin 73-0122) in the required actions specified in paragraph (j) of the NPRM. GE pointed out that field configuration management is tracked with service bulletins that are used to release part numbers to the field, and that including reference to GE GE90-100 Service Bulletin 73-0122 provides clarification. The FAA agrees and has updated the new required actions specified in paragraphs (j) and (l) of this AD to refer to GE GE90-100 Service Bulletin 73-0122. <HD SOURCE="HD1">Request for Credit</HD> GE requested that the FAA include credit for previous versions of GE GE90-100 Service Bulletin 73-0122. GE pointed out that including credit would help avoid confusion about compliance with the required action. The FAA disagrees with the request. The FAA has updated the new required actions specified in paragraphs (j) and (l) of this AD to include reference to GE GE90-100 Service Bulletin 73-0122. Since the reference is clarifying and does not require any action in accordance with the service information reference, there is no need for any credit related to the action. The FAA did not change this AD as a result of this comment. <HD SOURCE="HD1">Request for Clarification of the Unsafe Condition</HD> Boeing requested that the FAA revise the unsafe condition specified in paragraph (e) of the NPRM. Boeing requested that the unsafe condition be reworded to focus on describing the unsafe condition or to include the new mitigations provided in the NPRM. Boeing also included proposed language to revise paragraph (e) of the NPRM. Boeing noted that paragraph (e) of the NPRM does not describe the potentially unsafe condition in detail and does not discuss the new mitigations that were added in the NPRM. The FAA agrees to clarify. However, the FAA has determined that the unsafe condition described in paragraph (e) of this AD correctly describes the unsafe condition and is consistent with the verbiage used in the previous (superseded) ADs. Instead, the FAA has determined to include an additional clarifying sentence in the Background of this AD, which states: “Degradation of the MN4 integrated circuit microprocessor solder balls in the FADEC can result in the engine not following throttle commands.” <HD SOURCE="HD1">Conclusion</HD> The FAA reviewed the relevant data, considered any comments received, and determined that air safety requires adopting the AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, and any other changes described previously, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator. <HD SOURCE="HD1">Material Incorporated by Reference Under 1 CFR Part 51</HD> The FAA reviewed GE GE90-100 Service Bulletin 73-0118 R02, which specifies procedures for replacing the FADEC MN4 microprocessor, which describes procedures for checking for an inbound FADEC EICAS “ENG EEC C1” status message and corresponding conditions. The FAA also reviewed GE GE90-1 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 23k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━