Rule

Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes

A Rule by the Federal Aviation Administration on 03/27/2026

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• Public Inspection Published Document: 2026-05984 (91 FR 14755) Document Headings ###### Department of Transportation

Federal Aviation Administration

1. 14 CFR Part 39
2. [Docket No. FAA-2025-2559; Project Identifier MCAI-2025-00053-T; Amendment 39-23295; AD 2026-06-06]
3. RIN 2120-AA64 ( printed page 14755) # AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. This AD was prompted by the discovery on the production line that the electrical system harnesses in lavatory A had reduced bend radii, were not properly secured, and did not meet the requirement for clearance from an oxygen supply line. This AD requires an inspection of the sleeve and electrical harness for chafing damage and incorrect installation, and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.

DATES:

This AD is effective May 1, 2026.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of May 1, 2026.

ADDRESSES:

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2025-2559; 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.

Material Incorporated by Reference:

• 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.
• 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 regulations.gov under Docket No. FAA-2025-2559.

FOR FURTHER INFORMATION CONTACT:

Yves Petiote, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 202-975-4867; email: yves.petiote@faa.gov.

SUPPLEMENTARY INFORMATION:

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 September 29, 2025 (90 FR 46533). The NPRM was prompted by AD CF-2025-45, dated August 29, 2025 (Transport Canada AD CF-2025-45) (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states it was discovered on the production line that electrical system harnesses in lavatory A had reduced bend radii, were not properly secured and did not meet the requirement for clearance from an oxygen supply line. Inadequately secured and installed wire harnesses could create a chafing condition leading to a source of ignition, and when combined with an oxygen leak as well as loss of ventilation, may lead to an uncontrolled fire.

In the NPRM, the FAA proposed to require an inspection of the sleeve and electrical harness for chafing damage and incorrect installation, and applicable on-condition actions, as specified in Transport Canada AD CF-2025-45. 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-2025-2559.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from the Air Line Pilots Association, International (ALPA) who supported the NPRM without change.

The FAA received additional comments from the Citizens Rulemaking Alliance. The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Justify Forgoing Notice and Comment or Issue an NPRM

The Citizens Rulemaking Alliance requested that the FAA either provide its justification for finding good cause to bypass notice and comment procedures, convert this action to an NPRM, or stay the effective date until 30 days after close of a comment period of at least 45 days. The commenter asserted the FAA has not adequately justified use of the good cause exemption to bypass notice and comment and the 30-day delayed effective date.

The FAA notes the comment was submitted in response to an NPRM for which the FAA provided a 45-day comment period. This final rule is effective 35 days after its publication in the Federal Register. Therefore, no change to this AD is necessary.

Request To Make Incorporation by Reference (IBR) Materials Reasonably Available

The Citizens Rulemaking Alliance stated that the FAA's current practices for IBR frequently fail to meet the legal and regulatory standards for reasonable availability. The commenter called on the FAA to guarantee that all IBR materials are easily and freely accessible to the public and affected parties for both commenting and compliance purposes. The commenter also requested that this access be documented in the rulemaking record.

The FAA's practices comply with 5 U.S.C. 552(a) of the Administrative ( printed page 14756) Procedure Act and 1 CFR part 51. The FAA makes IBR materials available in the AD docket when the final rule is published in the Federal Register, following formal approval of the IBR by the Office of the Federal Register. Materials may only be posted before the final rule's publication if they are already publicly available or if there is written consent from the owner of the IBR material. All relevant materials incorporated by reference will be accessible in the AD docket on Regulations.gov, which the public can access without registration or fees.

The FAA also provides summaries and access details in the preamble and regulatory text, makes materials available for inspection at FAA and National Archives and Records Administration (NARA) offices, offers publisher contact information, and obtains formal IBR approval from the Office of the Federal Register. These efforts are intended to ensure that all IBR materials meet the “reasonably available” standard required by 1 CFR part 51. The FAA did not change this AD as a result of this comment.

Request To Comply With the Paperwork Reduction Act (PRA)

The Citizens Rulemaking Alliance requested that the FAA revise the AD to comply with the PRA if reporting is required or remove any reporting provisions until PRA requirements are satisfied. If reporting is not required, the commenter requested the FAA clarify that in the AD.

The FAA notes this AD does not require reporting. If an AD were to require reporting, the preamble of the AD would include a paragraph titled “Paperwork Reduction Act” that would provide the applicable OMB control number, required PRA statements, and the estimated time to collect the required information (burden). Any costs associated with the reporting requirement would be included in the Costs of Compliance section in the preamble of the AD. Therefore, the FAA did not change this AD as a result of this comment.

Request To Consider Impact on Small Entities

The commenter requested that the FAA either provide the reasoned basis for its certification under the Regulatory Flexibility Act (RFA) that the AD will not have a significant economic impact on a substantial number of small entities, or prepare an initial regulatory flexibility analysis if certification cannot be supported.

The FAA disagrees with preparing an initial regulatory flexibility analysis. The RFA of 1980 (5 U.S.C. 601-612), as amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (Pub. L. 104-121) and the Small Business Jobs Act of 2010 (Pub. L. 111-240), requires Federal agencies to consider the effects of the regulatory action on small business and other small entities and to minimize any significant economic impact. The term “small entities” comprises small businesses and not-for-profit organizations that are independently owned and operated and are not dominant in their fields, and governmental jurisdictions with populations of less than 50,000.

The FAA identified two air carriers and two corporate trustees that will be affected by this AD. Based on the Small Business Administration size standard for air carriers and corporate trustees, all four entities are large businesses:

| NAICS 2 Code | Description | Size standard |
| --- | --- | --- |
| 481111 | Scheduled Passenger Air Transportation | 1,500 employees. |
| 523991 | Trust, Fiduciary, and Custody Activities | $47.0 million. |
| 1 Source: U.S. Small Business Administration, Table of Small Business Size Standards, https://www.sba.gov/​sites/​default/​files/​2023-06/​Table%20of%20Size%20Standards_​Effective%20March%2017%2C%202023%20%282%29.pdf. | | |
| 2 North American Industrial Classification System. | | |
If an agency determines that a rulemaking will not result in a significant economic impact on a substantial number of small entities, the head of the agency may certify that under section 605(b) of the RFA. Therefore, as provided in section 605(b) and based on the foregoing, the head of FAA certifies that this AD will not result in a significant economic impact on a substantial number of small entities. The FAA did not change this AD as a result of this comment.

Request To Provide Additional Cost Information

The Citizens Rulemaking Alliance requested that the FAA add to the AD docket the methodology and assumptions supporting the estimated cost of the proposed AD and reopen the comment period for public input on the additional cost information. The commenter stated that the FAA should also provide the per airplane labor and parts cost, any assumed downtime or out-of-service impacts, and the aggregate costs for the U.S. fleet.

The FAA recognizes that, in doing the actions required by an AD, operators might incur indirect or incidental costs in addition to the direct costs. The cost analysis in an AD typically describes only the direct costs of the specific actions required by an AD, which does not include indirect or incidental costs such as downtime, loss of revenue, planning, or time necessitated by other administrative actions since those costs might vary significantly among operators. The number of work hours necessary to do the required actions of an AD is provided by the manufacturer. This number represents the time necessary to perform only the actions actually required by an AD. The cost of parts or special tools, if necessary, to complete the actions required by an AD is also provided by the manufacturer. Further, when the FAA is informed that the manufacturer may cover some or all of the estimated costs of an AD under warranty, the FAA indicates that in the AD.

In the Cost of Compliance section of the proposed AD, the FAA disclosed the estimated number of work hours, the number of airplanes affected on the U.S. registry, estimated parts cost, and the aggregate costs for the U.S. fleet. Since the FAA has assessed and disclosed the total known costs of the AD requirements in the Costs of Compliance section of the proposed AD, and the commenter did not provide additional cost data for the FAA to consider in its cost analysis, it is not necessary to reopen the comment period or provide additional information in the AD docket. The FAA did not change this AD as a result of this comment.

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 ( printed page 14757) 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-2025-45, which specifies procedures for an inspection of the sleeve and electrical harness for chafing damage and incorrect installation, and applicable on-condition actions. On-condition actions include repair of damage and installation of tie-down straps on the electrical harness.

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 83 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

| Labor cost | Parts cost | Cost per product | Cost on U.S. operators |
| --- | --- | --- | --- |
| 3 work-hour × $85 per hour = $85 | $0 | $255 | $21,165 |
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:

| Labor cost | Parts cost | Cost per product |
| --- | --- | --- |
| 3 work-hours × $85 per hour = $255 | $4,935 | $5,190 |
| * The FAA has received no definitive data on which to base the cost estimates for the on-condition repairs specified in this AD. | | |

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:

2026-06-06 Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.): Amendment 39-23295; Docket No. FAA-2025-2559; Project Identifier MCAI-2025-00053-T.

(a) Effective Date

This airworthiness directive (AD) is effective May 1, 2026.

(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-2025-45, dated August 29, 2025 (Transport Canada AD CF-2025-45).

(d) Subject

Air Transport Association (ATA) of America Code 92, Electrical system installation.

(e) Unsafe Condition

This AD was prompted by the discovery on the production line that electrical system harnesses in lavatory A had reduced bend radii, were not properly secured and did not meet the requirement for clearance from an oxygen supply line. The FAA is issuing this AD to address inadequately secured and installed wire harnesses, which if not addressed, could result in a chafing condition leading to a source of ignition, and when combined with an oxygen leak as well ( printed page 14758) as loss of ventilation, may lead to an uncontrolled fire.

(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-2025-45.

(h) Exceptions to Transport Canada AD CF-2025-45

(1) Where Transport Canada AD CF-2025-45 refers to its effective date, this AD requires using the effective date of this AD.

(2) Where Transport Canada AD CF-2025-45 refers to January 30, 2025 (the effective date of Transport Canada AD CF-2025-04, dated January 16, 2025), this AD requires using the effective date of this AD.

(i) 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 (j) 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 (i)(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.

(j) Additional Information

For more information about this AD, contact Yves Petiote, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 202-975-4867; email: yves.petiote@faa.gov.

(k) 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-2025-45, dated August 29, 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. 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 March 20, 2026.

Peter A. White,

Deputy Director, Integrated Certificate Management Division, Aircraft Certification Service.

[FR Doc. 2026-05984 Filed 3-26-26; 8:45 am]

BILLING CODE 4910-13-P

Published Document: 2026-05984 (91 FR 14755)