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-2025-0344; Project Identifier MCAI-2024-00638-T; Amendment 39-23141; AD 2025-19-01]</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 superseding Airworthiness Directive (AD) 2022-25-51, which applied to all Airbus Canada Limited Partnership Model BD-500-1A10 and Model BD-500-1A11 airplanes. AD 2022-25-51 required revising the Limitations section of the existing airplane flight manual (AFM) to include a new warning and a new limitation. Since the FAA issued AD 2022-25-51, updated primary flight control computer (PFCC) software has been developed to address the unsafe condition. This AD continues to require the actions in AD 2022-25-51, requires installing the updated PFCC software, which terminates the AFM revision, and removes airplanes from the applicability. 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 October 23, 2025. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of October 23, 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-2025-0344; 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-2025-0344. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Rochelle Montgomery, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 405-798-2043; email <E T="03">rochelle.montgomery@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 2022-25-51, Amendment 39-22282 (87 FR 75911, December 12, 2022) (AD 2022-25-51). AD 2022-25-51 applied to all Airbus Canada Limited Partnership Model BD-500-1A10 and Model BD-500-1A11 airplanes. AD 2022-25-51 required revising the Limitations section of the existing AFM by revising the title of the existing autopilot AFM limitation, including a new warning prior to the existing autopilot engagement limitations, and a new limitation prohibiting selecting or reselecting autothrottle during takeoff after thrust levers are advanced to the takeoff setting after the existing autopilot engagement limitations. The FAA issued AD 2022-25-51 to address inadvertent engagement of the autopilot below 400 feet above ground level (AGL) when the flightcrew attempts to engage autothrottle. The unsafe condition, if not addressed, could result in premature rotation due to inadvertent autopilot engagement, possibly leading to tail-strike, inability to climb, and loss of control of the airplane. The NPRM was published in the <E T="04">Federal Register</E> on March 18, 2025 (90 FR 12498). The NPRM was prompted by AD CF-2024-36, dated October 22, 2024, issued by Transport Canada, which is the aviation authority for Canada (Transport Canada AD CF-2024-36) (also referred to as the MCAI). The MCAI states that there have been multiple in-service reports associated with PFCC software deficiencies leading to nuisance messages on the engine-indicating and crew-alerting system (EICAS) such as rudder fail, aileron fail, and spoiler fail, and flight control fault due to erroneous transmissions from the remote electronic unit (REU). Investigations also indicated design deficiencies in the PFCC software such as an incorrectly implemented built-in test, which is unable to detect a failed REU internal hold-up capacitor, or non-implemented self-tests and monitoring mechanisms to prevent erroneous computations to be transmitted to consumers. Other in-service events indicated a lack of software robustness, which may not prevent an un-annunciated deployment of ground spoilers or an inadvertent autopilot engagement during the take-off roll. These deficiencies and lack of PFCC software robustness, if not corrected, could lead to increased flightcrew workload as well as a large reduction of safety margins. Additionally, during specific flight phases or in combination with other failures, these conditions could lead to loss of control of the airplane. The updated software installation required by this AD addresses the unsafe condition identified in AD 2022-25-51 and terminates the AFM revision required by AD 2022-25-51. In the NPRM, the FAA proposed to continue to require the actions in AD 2022-25-51, require installing the updated PFCC software, which terminates the AFM revision, and remove airplanes from the applicability, as specified in Transport Canada AD CF-2024-36. 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-2025-0344. <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) who supported the NPRM without change. The FAA received an additional comment from an individual commenter that did not make a request related to the NPRM. <HD SOURCE="HD1">Conclusion</HD> These products have been approved by the civil aviation authority of another country and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, that authority has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, 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> Transport Canada AD CF-2024-36 specifies procedures for revising the Limitations section of the existing AFM to include a new warning, installation of updated PFCC software part number 810-0337-009 on the three PFCCs, which terminates the AFM revision, and applicable concurrent software updates. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the <E T="02">ADDRESSES</E> section. <HD SOURCE="HD1">Costs of Compliance</HD> The FAA estimates that this AD affects 133 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: <GPOTABLE COLS="5" OPTS="L2,nj,i1" CDEF="s50,r50,xs64,xs64,xs68"> <TTITLE>Estimated Costs for Required Actions</TTITLE> <CHED H="1">Action</CHED> <CHED H="1">Labor cost</CHED> <CHED H="1">Parts cost</CHED> Cost on U.S. operators </CHED> <ROW> <ENT I="01">Retained actions from AD 2022-25-51</ENT> <ENT>1 work-hour × $85 per hour = $85</ENT> <ENT>$0</ENT> <ENT>$85</ENT> <ENT>$11,305.</ENT> </ROW> <ROW> <ENT I="01">New actions</ENT> <ENT>Up to 5 work-hours × $85 per hour = $425</ENT> <ENT>Up to $10,000</ENT> <ENT>Up to $10,425</ENT> <ENT>Up to $1,386,525.</ENT> </ROW> </GPOTABLE> <HD SOURCE="HD1">Authority for This Rulemaking</HD> Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority. The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. <HD SOURCE="HD1">Regulatory Findings</HD> This AD will not have federalism implications under Executive Order 13132. This AD will not have a substa ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 19k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━