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 February 13, 2025 (90 FR 9526). The NPRM was prompted by Transport Canada AD CF-2024-21, dated June 6, 2024 (Transport Canada AD CF-2024-21), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states that ECS ducts, located on forward and aft cargo compartment ceiling panels, having part numbers D761189-105, D761189-501, and D762232-509, have been manufactured using material APF1180-7781, which replaced discontinued legacy material Solvay L591PG-7781. The material change to APF1180-7781 was done without changing the ECS duct part number. Subsequent certification testing of the ECS ducts made using material APF1180-7781 failed flammability test requirements. These noncompliant ECS ducts may have been installed on certain affected airplanes during production. Noncompliant ECS ducts could result in the inability to contain a fire within the cargo compartment, which could result in an uncontrolled fire.

In the NPRM, the FAA proposed to require inspecting the affected ECS ducts and, as applicable, installing a fire-resistant sleeve assembly over any non-compliant ECS duct, and to prohibit the installation of ECS ducts as replacement parts under certain conditions, as specified in Transport Canada AD CF-2024-21.

The FAA issued a supplemental notice of proposed rulemaking (SNPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. The SNPRM was published in the Federal Register on September 25, 2025 (90 FR 46098). The SNPRM was prompted by Transport Canada AD CF-2025-10, dated February 27, 2025 (Transport Canada AD CF-2025-10) (also referred to as the MCAI), which superseded Transport Canada AD CF-2024-21. Transport Canada AD CF-2025-10 states that since Transport Canada AD CF-2024-21 was issued, Airbus Canada revised the instructions in their service information to include a requirement to re-identify the ceiling panel liners to ensure configuration control. In the SNPRM, the FAA proposed to require inspecting affected ECS ducts, installing a fire-resistant sleeve assembly over any non-compliant ECS duct as applicable, and re-identifying the ceiling panel liners in affected cargo compartments, and to prohibit the installation of ECS ducts as replacement parts under certain conditions, as specified in Transport ( printed page 31346) Canada AD CF-2025-10. 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-2025-0199.

Discussion of Final Airworthiness Directive

Comments

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

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

Request To Except or Delay Compliance for Re-Identification of Unaffected Parts

JetBlue requested that the FAA add an exception to paragraph (h) of the proposed AD to specify, where Airbus Canada Limited Partnership (ACLP) Service Bulletin BD500-501003, Issue 001, dated December 21, 2023 (Issue 001 of the ACLP Service Bulletin); or ACLP Service Bulletin BD500-501003, Issue 002, dated November 15, 2024 (Issue 002 of the ACLP Service Bulletin); is used to accomplish Part I of Transport Canada AD CF-2025-10 before the effective date the AD, only the “affected and repaired” ceiling panel liners in the cargo compartments must be re-identified using ACLP Service Bulletin BD500-501003, Issue 003, dated December 18, 2024 (Issue 003 of the ACLP Service Bulletin), or later revisions. JetBlue added, if the FAA determines unaffected ducts or liners must also be re-identified, then JetBlue requests that the unaffected parts be re-identified at the next scheduled heavy maintenance visit instead of before further flight after the inspection. JetBlue noted that Issue 001 of the ACLP Service Bulletin does not specify to re-identify the relevant ECS ducts or ceiling panel liners, for airplanes determined to not be affected. JetBlue stated if ECS ducts or ceiling panel liners are found to be affected, a change to the part number is required because repairs and modification are necessary to comply with the applicable fireproofing requirements, and the repairs are considered major changes to ensure continued compliance with the type certificate. JetBlue further stated, if the ECS ducts and ceiling panel liners are determined to not be affected, no modification or repair is performed, and the part re-identification is not necessary because the inspection and verification are considered minor, and the type certificate remains valid with amendment.

The FAA disagrees with both requests. The FAA notes that although Issue 001 of the ACLP Service Bulletin does not specify re-identifying unaffected ceiling panel liners, Transport Canada AD CF-2025-10 specifies to accomplish the actions in Part I of the Transport Canada using Issue 003 of the ACLP Service Bulletin, which does require re-identifying all ceiling panel liners regardless of findings. Re-identifying the ceiling panel lining provides assurance that an affected ECS duct has been inspected in compliance with this AD. However, the FAA will consider requests for an alternative method of compliance or extension of the compliance time, under the provisions of paragraph (j)(1) of this AD. The FAA has not changed this AD in this regard.

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, or convert this action to an NPRM to extend the comment period. The commenter asserted the FAA has not adequately justified use of the good cause exemption.

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 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 paragraph (i) of this AD specifies that 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 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 notes that this AD incorporates by reference Transport Canada AD CF-2025-10, not the manufacturer service information referenced in that Transport Canada AD. The FAA posted Transport Canada AD CF-2025-10 to the AD docket when the NPRM was published in the Federal Register . The material referenced in Transport Canada AD CF-2025-10 may only be posted before the final rule's publication if it is already publicly available or if there is written consent from the owner of that material. Additionally, the FAA provided notice in the NPRM that the material referenced in Transport Canada AD CF-2025-10 will be available in the AD docket after this AD is published. Therefore, the FAA did not change this AD as a result of this comment.

Request To Consider Impact on Small Entities

The Citizens Rulemaking Alliance requested that the FAA either provide the factual basis for its Regulatory Flexibility Act (RFA) certification that the AD will not have a significant economic impact on a substantial number of small entities, or prepare an initial regulatory flexibility analysis.

The FAA provides the following clarification. 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. ( printed page 31347)

The FAA identified three air carriers and one commercial aircraft lessor that will be affected by this AD. Based on the Small Business Administration (SBA) size standard, all four entities are large businesses:

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 under section 605(b) of the RFA. Therefore, as provided in section 605(b) and based on the foregoing, the head of the 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 fleet size, per airplane labor and parts cost, any assumed downtime or out-of-service impacts, aggregate costs, and any assumption that the manufacturer would provide parts free of charge.

In the Costs of Compliance section of the proposed AD, the FAA disclosed the number of airplanes affected on the U.S. registry, estimated number of work hours provided by the manufacturer, and the aggregate costs. The FAA did not disclose an estimated parts cost since this AD does not require any parts. Additionally, the FAA considered the impact that this AD will have on affected operators and determined this AD will not trigger any downtime costs because the requirements of this AD can be performed during regularly scheduled maintenance. 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 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 SNPRM. None of the changes will increase the economic burden on any operator.

Material Incorporated by Reference Under 1 CFR Part 51

Transport Canada AD CF-2025-10 specifies procedures for inspecting to determine the lot numbers of affected ECS ducts, installing a fire-resistant sleeve assembly over any non-compliant ECS duct, and re-identifying the ceiling panel liners in the cargo compartments. Transport Canada AD CF-2025-10 also prohibits the installation of ECS ducts as replacement parts under certain conditions. 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 200 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

The FAA estimates the following costs to do any necessary on-condition actions 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:

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.

The Amendment

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