Background 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 Federal Register on May 21, 2025 (90 FR 21700). The NPRM was prompted by AD CF-2025-07, dated January 27, 2025 (Transport Canada AD CF-2025-07) (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states a production quality escape was discovered, where the interface pin of the secondary load path in the upper gimbal of the HSTA was incorrectly installed. This condition, if not corrected, could compromise the secondary load path in the upper gimbal of the HSTA and cause a mechanical disconnect of the horizontal stabilizer leading to a loss of control of the airplane. In the NPRM, the FAA proposed to require a detailed visual inspection of the interface pin of the HSTA to determine if the interface pin is incorrectly installed, and applicable on-condition actions, as specified in Transport Canada AD CF-2025-07. The FAA is issuing this AD to address the unsafe condition on these products. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2025-0911. Discussion of Final Airworthiness Directive Comments The FAA received a comment from Air Line Pilots Association, International (ALPA) who supported the NPRM without change. Conclusion 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. Material Incorporated by Reference Under 1 CFR Part 51 The FAA reviewed Transport Canada AD CF-2025-07, which specifies procedures for a detailed visual inspection of the interface pin of the secondary load path in the upper gimbal of the HSTA to determine if the interface pin is incorrectly installed, and applicable on-condition actions including modification of an incorrectly installed interface pin. 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 ADDRESSES section. Costs of Compliance The FAA estimates that this AD affects 90 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: Estimated Costs for Required Actions Labor cost Parts cost Cost per product Cost on U.S. operators 1 work-hour × $85 per hour = $85 $0 $85 $7,650 The FAA estimates the following costs to do any necessary on-condition action that would be required based on the results of any required actions. The FAA has no way of determining the number of aircraft that might need this on-condition action: Estimated Costs of On-Condition Actions Labor cost Parts cost Cost per product 5 work-hours × $85 per hour = $425 $49,370 $49,795 The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators. Authority for This Rulemaking 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. Regulatory Findings This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. For the reasons discussed above, I certify that this AD: (1) Is not a "significant regulatory action" under Executive Order 12866, (2) Will not affect intrastate aviation in Alaska, and (3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. The Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: PART 39-AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 [Amended] 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2025-17-01 Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.): Amendment 39-23111; Docket No. FAA-2025-0911; Project Identifier MCAI-2025-00119-T. (a) Effective Date This airworthiness directive (AD) is effective September 29, 2025. (b) Affected ADs None. (c) Applicability This AD applies to Airbus Canada Limited Partnership (Type Certificate previously held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Model BD-500-1A10 and BD-500-1A11 airplanes, certificated in any category, as identified in Transport Canada AD CF-2025-07, dated January 27, 2025 (Transport Canada AD CF-2025-07). (d) Subject Air Transport Association (ATA) of America Code 27, Flight controls. (e) Unsafe Condition This AD was prompted by reports that the interface pin of the secondary load path in the upper gimbal of the horizontal stabilizer trim actuator (HSTA) was incorrectly installed. The FAA is issuing this AD to ensure the interface pin of the HSTA is installed correctly. The unsafe condition, if not addressed, could result in a mechanical disconnect of the horizontal stabilizer leading to a loss of control of the airplane. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Requirements Except as specified in paragraph (h) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, Transport Canada AD CF-2025-07. (h) Exception to Transport Canada AD CF-2025-07 (1) Where Transport Canada AD CF-2025-07 refers to its effective date, this AD requires using the effective date of this AD. (2) Where Transport Canada AD CF-2025-07 refers to hours air time, this AD requires using flight hours. (i) Special Flight Permit Special flight permits, as described in 14 CFR 21.197 and 21.199, are not allowed. (j) Additional AD Provisions The following provisions also apply to this AD: (1) Alternative Methods of Compliance (AMOCs): The Manager, AIR-520, Continued Operational Safety Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or responsible Flight Standards Office, as appropriate. If sending information directly to the manager of the Continued Operational Safety Branch, send it to the attention of the person identified in paragraph (k) of this AD and email to: AMOC@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the responsible Flight Standards Office. (2) Contacting the Manufacturer: For any requirement in this AD to obtain instructions from a manufacturer, the instructions must be accomplished using a method approved by the Manager, AIR-520, Continued Operational Safety Branch, FAA; or Transport Canada; or Airbus Canada Limited Partnership's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature. (k) Additional Information For more information about this AD, contact Camille Seay, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 817-222-5149; email: camille.l.seay@faa.gov. (l) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this material as applicable to do the actions required by this AD, unless this AD specifies otherwise. (i) Transport Canada AD CF-2025-07, dated January 27, 2025. (ii) [Reserved] (3) 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 TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca; website at tc.canada.ca/en/aviation. (4) 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. (5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email fr.inspection@nara.gov. Issued on August 19, 2025. Lona C. Saccomando, Acting Deputy Director, Integrated Certificate Management Division, Aircraft Certification Service.