Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-0206; Project Identifier MCAI-2024-00525-T; Amendment 39-23147; AD 2025-19-07]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) 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 adopting a new airworthiness directive (AD) for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. This AD was prompted by an investigation that showed a change in the feed-through connector O-ring material at a certain frame increased the electrical bonding resistance due to the current torque specification being inadequate. This AD requires electrical bonding tests between the feed-through connectors and the forward side of the bulkhead at a certain frame, and the installation of two electrical bonding plates, as applicable. 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 November 6, 2025. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of November 6, 2025. </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-2025-0206; 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, the mandatory continuing airworthiness information (MCAI), 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 Transport Canada material identified in this AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-663-3639; email <E T="03">TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca</E> . You may find this material on the Transport Canada website at <E T="03">tc.canada.ca/en/aviation.</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-2025-0206-T. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Steven Dzierzynski, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone 516-228-7300; email <E T="03">9-avs-nyaco-cos@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 by adding an AD that would apply to certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. The NPRM was published in the <E T="04">Federal Register</E> on February 19, 2025 (90 FR 9876). The NPRM was prompted by AD CF-2024-32, dated September 11, 2024 (Transport Canada AD CF-2024-32) (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states an Airbus Canada Limited Partnership investigation revealed a change in the feed-through connector O-ring material at frame (FR) 51 increased the electrical bonding resistance due to the current torque specification being inadequate, which may lead to electrical bonding levels which exceed allowable design limits, leaving the aircraft more susceptible to electromagnetic interference (EMI), high-intensity radiated fields (HIRF) and lightning strikes. In the NPRM, the FAA proposed to require electrical bonding tests to determine the resistance between the feed-through connectors and the forward side of the bulkhead at FR 51, and the installation of two electrical bonding plates if any connectors have more than the specified resistance, as specified in Transport Canada AD CF-2024-32. The FAA is issuing this AD to address the unsafe condition on these products. You may examine the MCAI in the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-0206. <HD SOURCE="HD1">Discussion of Final Airworthiness Directive</HD> <HD SOURCE="HD1">Comments</HD> The FAA received a comment from Air Line Pilots Association, International (ALPA) who supported the NPRM without change. The FAA received additional comments from two commenters, including Delta Air Lines (Delta) and one anonymous commenter. The following presents the comments received on the NPRM and the FAA's response to each comment. <HD SOURCE="HD1">Request for Adding an Exception</HD> Delta requested the FAA add an exception to the proposed AD to allow all electrical bonding tests to be completed in accordance with paragraph A. of Transport Canada AD CF-2024-32, followed, before further flight, by installation of electrical bonding plates in accordance with paragraph B. of Transport Canada AD CF-2024-32. Delta stated that, in the service information referenced in Transport Canada AD CF-2024-32, the electrical bonding test at one feed-through connector, followed immediately by the applicable corrective action, is repeated 21 more times for a total of 22 feed-through connectors. Delta stated the workflow in the proposed AD would be cumbersome, requiring multiple handoffs between skills and that multiple handoffs increase the possibility of turnover error through miscommunication. Delta stated Transport Canada AD CF-2024-32 allows the completion all tests, the identification of all discrepant connectors, and turnover of all required corrective actions to technicians for completion of that corrective action. Delta stated this reduces turnover error by only turning over test results one time and the end result of reviewing all connectors and the correction of any with unsatisfactory bonding resistance, as applicable, before further flight remains the same. The FAA agrees to clarify. The FAA notes that compliance times in ADs take precedence over any compliance time specified in referenced service information. The FAA notes that the time of “followed immediately by the applicable corrective action” is not specifically stated in the service information referenced in Transport Canada AD CF-2024-32 but is inferred. Regardless of if the service information contains a compliance time or not, operators must accomplish the required actions within the compliance time specified in Transport Canada AD CF-2024-32, except as specified in paragraphs (h)(1) and (2) of this AD. No exception is needed to this AD because, as noted by Delta, Transport Canada AD CF-2024-32 allows for all connectors to be inspected first and then the replacement of the discrepant connectors must be done before further flight as specified in paragraph B. of Transport Canada AD CF-2024-32. Since this AD mandates the compliance times in Transport Canada AD CF-2024-32, this AD also allows for all connectors to be inspected first. The FAA has not revised this AD in this regard. <HD SOURCE="HD1">Request for Revising Reporting Requirement</HD> Delta requested that the FAA add an exception to specify that where Airbus Canada Service Bulletin BD500-534011 states to record the electrical bonding test result in Appendix A of the service bulletin, the AD would permit the use of either Appendix A or an equivalent form developed by the operator and recording the same information. Delta commented that paragraph (i) of the proposed AD removes the reporting requirement, but it does not remove the requirement referenced in the service information referenced in Transport Canada AD CF-2024-32 to record the test results in Appendix A. Delta stated that they do not object to the requirement to record test results but prefer to use internally developed documentation. Delta stated that operators, as a matter of practice, frequently develop their own documentation to accomplish work instructions in a manner which complies with mandated work instruction documents including the recording of test results. Delta stated the mitigation of the unsafe condition is not affected by the use of alternative forms, provided the required information is reported. The FAA agrees to clarify. In excluding a reporting requirement, the FAA is also excluding the requirement to record test results and send them to Airbus Canada, as specified in the Airbus Canada Service Bulletin BD500-534011. Therefore, recording the test results is not required by this AD and no change to this AD is necessary. <HD SOURCE="HD1">Request for Additional Reporting Requirements</HD> An anonymous commenter stated the proposed AD should require operators to document and report the results of electrical bonding tests to the FAA. The commenter stated this data can support compliance verification and provide insight into broader trends in bonding degradation. The commenter noted that FAA Advisory Circular 43-210A, dated May 31, 2018, encourages structured data collection and reporting to support continued airworthiness actions. The FAA disagrees with this request. In general, the FAA only requires reporting if the results are needed to determinate the scope of the identified unsafe condition or to develop corrective actions. For this AD, reporting is not necessary as the installation of the bonding plates addresses ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 25k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━