was prompted by reports of fuel leakage near rib 6 during production pressure testing. An investigation found oversized holes in a certain outboard shear-tie. This proposed AD would require an inspection of the fasteners and fastener holes at rib 6 for discrepancies and applicable on-condition actions. The FAA is proposing this AD to address the unsafe condition on these products.

Dates

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The FAA must receive comments on this proposed AD by October 26, 2026.

Addresses

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You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods: Federal eRulemaking Portal: Go to regulations.gov. Follow the instructions for submitting comments. Fax: 202-493-2251. Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2026-8797; 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 NPRM, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above. Material Incorporated by Reference: For Transport Canada material identified in this proposed AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-663-3639; email [email protected]. You may find this material on the Transport Canada website at tc.canada.ca/en/aviation. It is also available at regulations.gov under Docket No. FAA-2026-8797. 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.

For further information contact

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Isabel Saltzman, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: [email protected].

Supplementary information

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Comments Invited

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The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under the ADDRESSES section. Include "Docket No. FAA-2026-8797; Project Identifier MCAI-2025-01338-T" at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend this proposal because of those comments. Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.

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Confidential Business Information

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CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as "PROPIN." The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Isabel Saltzman, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: [email protected]. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

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Background

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Transport Canada, which is the aviation authority for Canada, has issued Transport Canada AD CF-2025-39, dated August 7, 2025 (Transport Canada AD CF-2025-39) (also referred to as the MCAI), to correct an unsafe condition for certain Bombardier, Inc., Model BD-700-2A12 airplanes. The MCAI states that reports of fuel leakage near rib 6 were found during production pressure testing. An investigation found five oversized holes upon the removal of the doubler on rib 6 close to stringer 8L. The oversized holes were found in the outboard shear-tie between stringers 8L and 9L, attaching rib 6 to the lower skin of the wing. A fatigue analysis of oversized holes in the inboard and outboard shear-ties between stringers 8L and 9L attaching rib 6 to the skin of the wing indicated the potential for crack formation. This condition, if not addressed, could lead to failure of shear-ties, resulting in the loss of redundant structure and the consequent loss of structural integrity of the airplane. The FAA is proposing 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-2026-8797.

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Material Incorporated by Reference Under 1 CFR Part 51

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Transport Canada AD CF-2025-39 specifies procedures for conducting an inspection of the fasteners at rib 6 for discrepancies (any gaps under the nuts or evidence of nut loosening), and of the fastener holes for discrepancies (oversizing, elongation, ovalization, and cracking), and applicable on-condition actions. On-condition actions include repair and reinstalling fasteners. 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.

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FAA's Determination

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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 is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop in other products of the same type design.

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Proposed AD Requirements in This NPRM

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This proposed AD would require accomplishing the actions specified in Transport Canada AD CF-2025-39 described previously, except for any differences identified as exceptions in the regulatory text of this proposed AD.

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Explanation of Compliance Time That Specifies a Calendar Date

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Transport Canada AD CF-2025-39 includes a compliance time that specifies a calendar date. In determining this compliance time, a fatigue analysis was done based on usage from the fleet leader of the affected aircraft. To ensure that the unsafe condition was addressed based on the original calculated compliance time, the compliance time was adjusted, and the usage was set from the issuance date of Bombardier Service Bulletin 700-57-7525, dated October 26, 2022, i.e., within 1,400 flight cycles from October 26, 2022. The FAA is adopting this same compliance time.

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Explanation of Required Compliance Information

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In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some civil aviation authority (CAA) ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, the FAA proposes to incorporate Transport Canada AD CF-2025-39 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with Transport Canada AD CF-2025-39 in its entirety through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Material required by Transport Canada AD CF-2025-39 for compliance will be available at regulations.gov under Docket No. FAA-2026-8797 after the FAA final rule is published.

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Costs of Compliance

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The FAA estimates that this AD, if adopted as proposed, would affect 13 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:

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Estimated Costs for Required Actions

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Cost per Cost on U.S. Labor cost Parts cost product operators