Background The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701 & 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. The NPRM was published in the Federal Register on August 21, 2025 (90 FR 40780). The NPRM was prompted by AD CF-2024-41, dated December 5, 2024 (Transport Canada AD CF-2024-41) (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states that new or more restrictive airworthiness limitations have been developed. In the NPRM, the FAA proposed to require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations, as specified in Transport Canada AD CF-2024-41. The FAA is issuing this AD to address reduced structural integrity and reduced controllability of the airplane. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2025-2261. 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-2024-41, which specifies new or more restrictive airworthiness limitations for airplane structures and safe life limits. 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 600 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: The FAA has determined that revising the existing maintenance or inspection program takes an average of 90 work-hours per operator, although the agency recognizes that this number may vary from operator to operator. Since operators incorporate maintenance or inspection program changes for their affected fleet(s), the FAA has determined that a per-operator estimate is more accurate than a per-airplane estimate. Therefore, the agency estimates the average total cost per operator to be $7,650 (90 work-hours × $85 per work-hour). 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: 2025-25-03 MHI RJ Aviation ULC (Type Certificate Previously Held by Bombardier, Inc.): Amendment 39-23211; Docket No. FAA-2025-2261; Project Identifier MCAI-2024-00717-T. (a) Effective Date This airworthiness directive (AD) is effective January 16, 2026. (b) Affected ADs This AD affects the ADs specified in paragraphs (b)(1) through (4) of this AD. (1) AD 2023-06-06, Amendment 39-22392 (88 FR 17682, March 24, 2023); corrected April 12, 2023 (88 FR 21900) (AD 2023-06-06). (2) AD 2023-09-02, Amendment 39-22425 (88 FR 32625, May 22, 2023) (AD 2023-09-02). (3) AD 2023-24-03, Amendment 39-22619 (88 FR 87331, December 18, 2023) (AD 2023-24-03). (4) AD 2025-11-11, Amendment 39-23057 (90 FR 24315, June 10, 2025) (AD 2025-11-11). (c) Applicability This AD applies to all MHI RJ Aviation ULC (Type Certificate previously held by Bombardier, Inc.) airplanes, certificated in any category, identified in paragraphs (c)(1) through (5) of this AD. (1) Model CL-600-2C10 (Regional Jet Series 700, 701, & 702) airplanes. (2) Model CL-600-2C11 (Regional Jet Series 550) airplanes. (3) Model CL-600-2D15 (Regional Jet Series 705) airplanes. (4) Model CL-600-2D24 (Regional Jet Series 900) airplanes. (5) Model CL-600-2E25 (Regional Jet Series 1000) airplanes. (d) Subject Air Transport Association (ATA) of America Code 05, Time Limits/Maintenance Checks. (e) Unsafe Condition This AD was prompted by a determination that new or more restrictive airworthiness limitations are necessary. The FAA is issuing this AD to address reduced structural integrity and reduced controllability of the airplane. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Maintenance or Inspection Program Revision 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-2024-41, dated December 5, 2024 (Transport Canada AD CF-2024-41). (h) Exception to Transport Canada AD CF-2024-41 (1) Where Transport Canada AD CF-2024-41 refers to its effective date, this AD requires using the effective date of this AD. (2) Where Transport Canada AD CF-2024-41 specifies to "complete the new or more restrictive limitations contained in the MHIRJ MRM CSP B-053 Part 2, revision 27, dated 15 September 2023, as applicable to the aeroplane model and configuration within the thresholds and repeat intervals or discard time identified within the tasks", this AD requires replacing that text with "revise the existing maintenance or inspection program, as applicable, by incorporating the information specified in MHIRJ MRM CSP B-053 Part 2, Revision 27, dated September 15, 2023, except when incorporating Appendix A2, only incorporate the AMM tasks, including the interval limitation, specified in the limitations table in Appendix A2". (3) The initial compliance time for doing the tasks specified in the "Corrective Actions" section of Transport Canada AD CF-2024-41 is at the applicable time specified in paragraph (h)(3)(i) or (ii) of this AD. (i) For tasks that have "thresholds" and "discard times" specified: The initial compliance time is at the applicable "thresholds" and "discard times" as specified in the material referenced in Transport Canada AD CF-2024-41, or within 30 days after the effective date of this AD, whichever occurs later. (ii) For tasks that only have "intervals" specified: The initial compliance time is before the applicable interval limitation specified in the material referenced in Transport Canada AD CF-2024-41 since the date of issuance of the original airworthiness certificate or the original export certificate of airworthiness, or within 30 days after the effective date of this AD, whichever occurs later. (i) Provisions for Alternative Actions, Intervals, and Critical Design Configuration Control Limitations (CDCCLs) After the existing maintenance or inspection program has been revised as required by paragraph (g) of this AD, no alternative actions ( e.g., inspections), intervals, and CDCCLs are allowed unless they are approved as specified in the provisions of the "Corrective Actions" section of Transport Canada AD CF-2024-41. (j) Terminating Action for Certain Tasks Required by Other ADs Accomplishing the actions required by this AD terminates the corresponding requirements of paragraph (h) of AD 2023-09-02 and paragraph (h) of AD 2023-24-03 for the AMM tasks identified in the material referenced in Transport Canada AD CF-2024-41 only. (k) Terminating Action for AD 2023-06-06 and AD 2025-11-11 Accomplishing the actions required by this AD terminates all requirements of AD 2023-06-06 and AD 2025-11-11. (l) Additional AD Provisions The following provisions also apply to this AD: (1) Alternative Methods of Compliance (AMOCs): The Manager, International Validation Branch, 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 International Validation Branch, send it to the attention of the person identified in paragraph (m) 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, International Validation Branch, FAA; or Transport Canada; or MHI RJ Aviation ULC's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature. (m) Additional Information For more information about this AD, contact Fatin Saumik, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: 9-avs-nyaco-cos@faa.gov. (n) 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-2024-41, dated December 5, 2024. (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. You may find this material on the Transport Canada 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 December 5, 2025. Steven W. Thompson, Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.