SUPPLEMENTARY INFORMATION:

Comments Invited

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-2026-8794; Project Identifier MCAI-2025-01464-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.

Confidential Business Information

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 Anthony Decaro, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 562-627-5374; email: anthony.d.decaro@faa.gov. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.

Background

The FAA issued AD 2021-17-07, Amendment 39-21690 (86 FR 44600, August 13, 2021) (AD 2021-17-07), for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. AD 2021-17-07 was prompted by an MCAI originated by Transport Canada, which is the aviation authority for Canada. Transport Canada issued AD CF-2021-09, dated March 11, 2021 (Transport Canada AD CF-2021-09), to correct an unsafe condition.

AD 2021-17-07 requires an inspection for damage of the right and left MF flexible fuel hose assemblies (including the flexible hose and shroud assemblies) and replacing damaged parts. The FAA issued AD 2021-17-07 ( printed page 56378) to address the potential of improper installation of the flexible hose assembly of the fuel MF during production that may result in a twist to the MF flexible fuel hose, which can restrict the flow of fuel for the MF and cause fuel imbalance and possible damage, including abrasion, to the shroud assembly. This condition, if not addressed, could result in abrasion of the fuel line and a possible fuel leak; as a result, the electrical harness connectors in the wing area could be a potential ignition source and pose a risk of fire.

Actions Since AD 2021-17-07 Was Issued

Since the FAA issued 2021-17-07, Transport Canada superseded Transport Canada AD CF-2021-09 and issued Transport Canada AD CF-2025-47, dated September 11, 2025 (Transport Canada AD CF-2025-47) (also referred to as the MCAI), to correct an unsafe condition for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. The MCAI states that since Transport Canada AD CF-2021-09 was issued, a new installation procedure was implemented by Airbus Canada Limited Partnership in production, and it was discovered that Transport Canada AD CF-2021-09 was not correctly implemented on four additional Model BD-500-1A11 airplanes.

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-2026-8794.

Explanation of Retained Requirements

Although this proposed AD does not explicitly restate the requirements of AD 2021-17-07, this proposed AD would retain all of the requirements of AD 2021-17-07. Those requirements are referenced in Transport Canada AD CF-2025-47, which, in turn, is referenced in paragraph (g) of this proposed AD.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Transport Canada AD CF-2025-47, which specifies procedures for a general visual inspection for damage (including permanent deformities) of the left and right MF fuel line assemblies (including the flexible-hose assembly and shroud assembly), and replacement of affected MF fuel line assemblies (including cleaning of the ends of the flexible-hose assembly, injecting grease at both ends of the flexible-hose assembly, and torquing the aft end of the flexible-hose assembly).

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.

FAA's Determination

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.

Proposed AD Requirements in This NPRM

This proposed AD would require accomplishing the actions specified in Transport Canada AD CF-2025-47 described previously, except for any differences identified as exceptions in the regulatory text of this proposed AD.

Explanation of Required Compliance Information

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 retain the incorporation by reference (IBR) of Transport Canada AD CF-2025-47 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with Transport Canada AD CF-2025-47 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-2025-47 for compliance will be available at regulations.gov under Docket No. FAA-2026-8794 after the FAA final rule is published.

Costs of Compliance

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:

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 these on-condition actions:

According to the manufacturer, some or all of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. The FAA does not control warranty coverage for affected ( printed page 56379) individuals. As a result, the FAA has included all known costs in the cost estimate.

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

The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 this proposed regulation:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

2. The FAA amends § 39.13 by:

a. Removing Airworthiness Directive (AD) 2021-17-07, Amendment 39-21690 ( 86 FR 44600, August 13, 2021); and

b. Adding the following new AD:

Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes: Docket No. FAA-2026-8794; Project Identifier MCAI-2025-01464-T.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by October 19, 2026.

(b) Affected ADs

This AD replaces AD 2021-17-07, Amendment 39-21690 (86 FR 44600, August 13, 2021).

(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-2025-47, dated September 11, 2025 (Transport Canada AD CF-2025-47).

(d) Subject

Air Transport Association (ATA) of America Code 28, Fuel.

(e) Unsafe Condition

This AD was prompted by the potential of improper installation of the flexible hose assembly of the fuel motive flow (MF) during production that may result in a twist to the MF flexible fuel hose, which can restrict the flow of fuel for the MF and cause fuel imbalance and possible damage, including abrasion, to the shroud assembly. This AD was also prompted by a determination that additional airplanes are subject to the unsafe condition. The FAA is issuing this AD to address this condition. The unsafe condition, if not addressed, could result in abrasion of the fuel line and a possible fuel leak; as a result, the electrical harness connectors in the wing area could be a potential ignition source and pose a risk of fire.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Requirements

Except as specified in paragraphs (h) and (i) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, Transport Canada AD CF-2025-47.

(h) Exceptions to Transport Canada AD CF-2025-47

(1) Where Transport Canada AD CF-2025-47 refers to its effective date, this AD requires using the effective date of this AD.

(2) Where Transport Canada AD CF-2025-47 refers to March 25, 2021 (the effective date of Transport Canada AD CF-2021-09), this AD requires using August 30, 2021 (the effective date of AD 2021-17-07).

(3) Where Transport Canada AD CF-2025-47 specifies to “if necessary, replace the left and right motive flow fuel line assemblies”, for this AD, replace that text with “if any damage (including any permanent deformity) is found on any motive flow flexible fuel line assembly, replace the damaged assembly before further flight”.

(i) No Return of Parts Requirement

Although the material referenced in Transport Canada AD CF-2025-47 specifies to send removed parts to the manufacturer, this AD does not include that requirement.

(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.

(3) Required for Compliance (RC): Except as required by paragraph (j)(2) of this AD, if any material contains procedures or tests that are identified as RC, those procedures and tests must be done to comply with this AD; any procedures or tests that are not identified as RC are recommended. Those procedures and tests that are not identified as RC may be deviated from using accepted methods in accordance with the operator's maintenance or inspection program without obtaining approval of an AMOC, provided the procedures and tests identified as RC can be done and the airplane can be put back in an airworthy condition. Any substitutions or changes to procedures or tests identified as RC require approval of an AMOC.

(k) Additional Information

For more information about this AD, contact Anthony Decaro, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 562-627-5374; email: anthony.d.decaro@faa.gov.

(l) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference of ( printed page 56380) 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-2025-47, dated September 11, 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. 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 98198. 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.

91 FR 56377