Airworthiness Directives; The Boeing Company Airplanes

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2024-2144; Project Identifier AD-2024-00424-T; Amendment 39-23174; AD 2025-21-02]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; The Boeing Company Airplanes</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) 2022-15-06, which applied to all The Boeing Company Model 777-200, -200LR, -300, -300ER, and 777F series airplanes. AD 2022-15-06 required disconnecting certain connectors and capping and stowing the wires that had been attached to the affected transorb modules. Since the FAA issued AD 2022-15-06, the agency has determined additional connectors are affected. Also, a replacement has been developed to address the unsafe condition, which would terminate the existing actions. This AD continues to require the actions specified in AD 2022-15-06 and requires those actions for additional connectors. This AD also requires determining if affected transorb modules are installed, replacing or testing affected transorb modules, and applicable on-condition actions. This AD also prohibits the installation of affected parts. 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 January 2, 2026. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of January 2, 2026. </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-2024-2144; 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 Boeing material identified in this AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone 562-797-1717; website <E T="03">myboeingfleet.com</E> . • You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available at <E T="03">regulations.gov</E> under Docket No. FAA-2024-2144. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Raja Vengadasalam, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-3859; email: <E T="03">raja.vengadasalam@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 2022-15-06, Amendment 39-22126 (87 FR 47334, August 3, 2022) (AD 2022-15-06). AD 2022-15-06 applied to all The Boeing Company Model 777-200, -200LR, -300, -300ER, and 777F series airplanes. The NPRM was published in the <E T="04">Federal Register</E> on September 26, 2024 (89 FR 78827). The NPRM was prompted by the determination that connectors that were not identified in AD 2022-15-06 are affected and by the development of a replacement action to address the unsafe condition, which would terminate the existing actions. In the NPRM, the FAA proposed to continue to require the actions specified in AD 2022-15-06 and require those actions for additional connectors. The NPRM also proposed to require determining if affected transorb modules are installed, replacing or testing affected transorb modules, and applicable on-condition actions. The NPRM also proposed to prohibit the installation of affected parts. The NPRM was prompted by high electrical resistance within the gust suppression sensor (GSS) transorb modules due to corrosion on the transorb threads and insufficient engagement of the anti-rotation teeth. The FAA is issuing this AD to address high electrical resistance in both transorb modules, which can result in two actuator control electronics (ACEs) being exposed to damaging lightning transient voltages in excess of the qualification levels, potentially inducing erroneous or oscillatory outputs to flight control surfaces. The unsafe condition, if not addressed, could result in loss of control of the airplane. <HD SOURCE="HD1">Discussion of Final Airworthiness Directive</HD> <HD SOURCE="HD1">Comments</HD> The FAA received comments from Air Line Pilots Association, International (ALPA), and Cathay Pacific, who supported the NPRM without change. The FAA received additional comments from five commenters, including American Airlines, Boeing, FedEx Express, and United Airlines (United). The following presents the comments received on the NPRM and the FAA's response to each comment. <HD SOURCE="HD1">Request To Revise the Applicability</HD> Boeing requested that paragraph (c) of the proposed AD be revised to limit the applicability to the airplanes affected by Boeing Alert Requirements Bulletin 777-27A0125 RB, dated February 3, 2023. Boeing stated that if the AD applies to all The Boeing Company Model 777-200, -200LR, -300, -300ER, and 777F series airplanes (including the airplanes after line number 1726-the airplanes that will have this change already incorporated in production), then the airplanes delivered after the effective date of this AD would need to document that these AD actions were incorporated in production in an AD Letter (ADL), stating that the airplane is not affected by the AD. The FAA disagrees with Boeing's request that paragraph (c) of this AD be revised because the transorbs are rotable and these parts could later be installed on airplanes that were initially delivered with acceptable parts, thereby subjecting those airplanes to the unsafe condition. All airplanes are subject to the parts installation prohibition specified in paragraph (k) of this AD, which does not allow affected parts to be installed as of the effective date of the AD. The FAA notes that airplanes produced after the effective date of this AD do not need to document that the actions in Boeing Alert Requirements Bulletin 777-27A0125 RB, dated February 3, 2023, were done because paragraphs (i)(1) and (2) of this AD only apply to airplanes produced on or before the effective date of this AD. Additionally, the FAA has revised paragraphs (g) and (h) of this AD to limit those requirements to airplanes produced on or before the effective date of this AD since airplanes produced after the effective date of this AD will not be delivered with the affected transorb modules or connectors. <HD SOURCE="HD1">Request To Allow Optional Action to the Replacement of Required Actions</HD> FedEx Express requested that the FAA revise paragraph (i)(2) of the proposed AD to allow continued flight with the GSS connectors stowed per paragraphs (g) and (h) of the proposed AD, as an optional action. The commenter stated that the reactivation in paragraph (i)(2) of the proposed AD does not appear to lend any effort towards airworthiness of the aircraft outside of passenger comfort. Additionally, the commenter noted that such a system is not a requirement of 14 CFR part 25 and therefore expenditure of valuable time and resources on a system not appreciably utilized by a cargo carrier would seem pointless. The FAA acknowledges the commenter's request. The purpose of this AD is to restore the affected fleet to an acceptable level of safety. The FAA is issuing this AD to address high electrical resistance in both transorb modules, which can result in two actuator control electronics (ACEs) being exposed to damaging lightning transient voltages in excess of the qualification levels, potentially inducing erroneous or oscillatory outputs to flight control surfaces and could result in loss of control of the airplane. Allowing the connectors to be disconnected long-term may not address the unsafe condition in the affected fleet, as an operator may inadvertently reconnect the affected connectors in the future. Therefore, the replacement of affected connectors must be done to address the unsafe condition. However, any person may request approval of an alternative method of compliance (AMOC) under the provisions of paragraph (l)(2) of this AD. This AD has not been changed regarding this request. <HD SOURCE="HD1">Request for Removing/Revising Paragraphs (g) and (h) of the Proposed AD and References to Connector D02099P</HD> Boeing requested that the FAA remove paragraph (h) of the proposed AD, update paragraph (g) of the proposed AD by referring to bundle/connector W6313/D02098P, and remove references to connector D02099P from “Actions Since AD-2022-15-06 Was Issued” in the NPRM. Boeing suggested some revised wording for paragraph (g) of the proposed AD to account for additional wire to bundles/connector part numbers that are present on some airplanes. Boeing stated paragraph (h) of the proposed AD could be misleading to operators as it does not highlight that the difference in the bundle and connector callouts are line number dependent. In addition, Boeing stated the connectors called out in paragraph (h) of the proposed AD are incorrect and reference two disconnect points on the same wire bundle. Boeing recommended that connector D02099P not be referenced as a disconnect point in the NPRM. United requested that the FAA revise paragraph (h) of the proposed AD ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 28k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━