# [Amended]
**AGENCY:**
Federal Aviation Administration (FAA), DOT.
**ACTION:**
Supplemental notice of proposed rulemaking (SNPRM).
**SUMMARY:**
The FAA is revising a notice of proposed rulemaking (NPRM) that would have applied to certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. This action revises the NPRM by adding a requirement to re-identify the ceiling panel liners. The FAA is proposing this airworthiness directive (AD) to address the unsafe condition on these products. Since these actions would impose an additional burden over those in the NPRM, the FAA is requesting comments on this SNPRM.
**DATES:**
The FAA must receive comments on this SNPRM by November 10, 2025.
**ADDRESSES:**
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-2025-0199; 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 SNPRM, 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-2025-0199.
• 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:**
Brenda L. Buitrago, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 516-288-7368; email: *[email protected]* .
**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-2025-0199; Project Identifier MCAI-2024-00332-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 SNPRM.
**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 SNPRM 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 SNPRM, 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 SNPRM. Submissions containing CBI should be sent to Brenda L. Buitrago, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 516-288-7368; 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.
**Background**
The FAA issued an NPRM to amend 14 CFR part 39 by adding an AD that would have applied 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 AD CF-2024-21, dated June 20, 2024 (Transport Canada AD CF-2024-21), issued by Transport Canada, which is the aviation authority for Canada. Transport Canada AD CF-2024-21 states that environmental control system (ECS) ducts, located on forward and aft cargo compartment ceiling panels, having part numbers (P/Ns) 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 prohibit the installation of ECS ducts as replacement parts under certain conditions.
**Actions Since the NPRM Was Issued**
Since the FAA issued the NPRM, Transport Canada superseded Transport Canada AD CF-2024-21 and issued Transport Canada AD CF-2025-10, dated February 27, 2025 (Transport Canada AD CF-2025-10) (also referred to as the MCAI), to correct an unsafe condition for all Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. The MCAI 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 identify the ceiling panel liners to ensure configuration control.
The FAA is proposing this AD to address noncompliant ECS ducts that could cause an inability to contain a fire within the cargo compartment. The unsafe condition, if not addressed, could result in an uncontrolled fire.
You may examine the MCAI in the AD docket at *regulations.gov* under Docket No. FAA-2025-0199.
**Comments**
The FAA received comments from the Air Line Pilots Association, International (ALPA) and two individuals who supported the NPRM without change.
The FAA received additional comments from Delta Air Lines (Delta). The following presents the comments received on the NPRM and the FAA's response to each comment.
**Request To Reference Transport Canada AD CF-2025-10**
Delta requested that the proposed AD be updated to incorporate Transport Canada AD CF-2025-10, which supersedes Transport Canada AD CF-2024-21 and requires additional identification of the ceiling panel liners in affected cargo compartments for airplanes that already incorporated corrective actions. Delta added that Transport Canada AD CF-2025-10 updates the definition of the applicable service information to reference revision 3.
The FAA agrees. As previously stated, the FAA has revised this proposed AD to reference Transport Canada AD CF-2025-10.
**Request for a 60-Day Grace Period**
Delta requested the inclusion of a 60-day grace period in paragraph (h) of the proposed AD. Delta stated the requested 60-day grace period is intended to address Delta aircraft that would be approaching/exceeding the 9,350 total flight hours compliance time when the FAA AD is published. Delta stated it owns three aircraft that need to accomplish the modification required by the proposed AD, and that without a grace period, those aircraft would be grounded. Delta noted that it found many issues with the service information that needed to be reconciled, and a 60-day grace period would allow adequate time to schedule the aircraft into a hanger and to procure parts and materials.
The FAA agrees with the commenter's request for a grace period, but has determined that a 30 day grace period will allow operators adequate time to plan and procure parts and materials. The FAA has added paragraph (h)(3) of this proposed AD to provide a 30-day grace period.
**Request To Address Discrepancies in Service Information**
Delta requested the FAA add exceptions to paragraph (h) of the proposed AD to address discrepancies in the related service information. Delta stated paragraph (g) of the proposed AD mandates accomplishing the instructions of Airbus Canada Limited Partnership Service Bulletin BD500-501003 Issue 001, or later revisions, and Safran Service Bulletin F493000-50-06, as a corrective action for the related unsafe condition. Delta stated that it discovered four discrepancies in the instructions of Safran Service Bulletin F493000-50-06 Revision 1, dated October 31, 2024. Delta suggested wording to address each of the following discrepancies:
Instructions to drill holes for inserts that are placed before instructions to mark and identify locations for those inserts.
A guidance note that could be moved to a different location to help guide maintenance personnel.
Instructions related to the installation of masking tape and inserts that could be done in a different order.
Missing instructions to drill holes for installing a sleeve assembly.
The FAA partially agrees with the commenter's request. Regarding the position of the note, the FAA clarifies that the note is guidance material, not mandatory, and may be deviated from, including applying that guidance after a different step in the referenced material. Therefore, no change to this proposed AD is needed regarding the note. For the commenter's other requests, the FAA has added paragraphs (h)(4) through (6) of this proposed AD to address the discrepancies.
**Request To Confirm Intent To Allow Use of Later Revisions of Service Information**
Delta requested the FAA include an acknowledgement in the preamble of the proposed AD to state the FAA intends to allow the use of later revisions of the service information specified in Transport Canada AD CF-2024-21. Delta stated it discovered errors that prompted Airbus to initiate two service bulletin revisions and operators should use later revisions of the service information to comply with the proposed AD.
The FAA confirms that it intends to allow the use of applicable later service bulletins revisions to comply with the requirements of this proposed AD. This proposed AD refers to Transport Canada AD CF-2025-10 as the appropriate source of service information for accomplishing the required actions. Transport Canada AD CF-2025-10 specifies acceptance of the use of later-approved revisions of the referenced Airbus Canada Limited Partnership service bulletin for compliance. Therefore, applicable later-approved service bulletin revisions are acceptable. The FAA has not changed the proposed AD regarding this request.
**Request To Address Reporting Requirement**
Delta requested a statement be added to paragraph (h) of the proposed AD to addresses the reporting requirement in Airbus Canada Limited Partnership Service Bulletin BD500-501003 Issue No. 003, dated December 18, 2024, or later revisions. Delta noted the service bulletin requires the submission of a data sheet to the Airbus customer response center for analysis. Delta stated the collection of ECS duct lot numbers does not provide public benefit or utility towards creating project scope or determining terminating action. Delta requested that the FAA revise paragraph (h) of the proposed AD to state that reporting is not required.
The FAA agrees with the commenter's request. The FAA has added paragraph (i) of this proposed AD to specify that reporting to the manufacturer is not required, and redesignated subsequent paragraphs accordingly.
**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 reidentifying 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.
**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 SNPRM after determining that the unsafe condition described previously is likely to exist or develop in other products of the same type design.
Certain changes described above expand the scope of the NPRM. As a result, it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this SNPRM.
**Proposed AD Requirements in This SNPRM**
This proposed AD would require accomplishing the actions specified in Transport Canada AD CF-2025-10 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 incorporate Transport Canada AD CF-2025-10 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with Transport Canada AD CF-2025-10 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-2025-10 for compliance will be available at *regulations.gov* under Docket No. FAA-2025-0199 after the FAA final rule is published.
**Costs of Compliance**
The FAA estimates that this AD, if adopted as proposed, would affect 11 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:
| Labor cost | Parts cost | Cost per product | Cost on U.S. operators |
| --- | --- | --- | --- |
| 12 work-hours × $85 per hour = $1,020 | $0 | $1,020 | $11,220 |
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:
| Labor cost | Parts cost | Cost per product |
| --- | --- | --- |
| 2 work-hours × $85 per hour = $170 | $4,840 | $5,010 |
The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this proposed 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**
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.
**List of Subjects in 14 CFR Part 39**
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
**The Proposed Amendment**
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
*Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.):* Docket No. FAA-2025-0199; Project Identifier MCAI-2024-00332-T.
**(a) Comments Due Date**
The FAA must receive comments on this airworthiness directive (AD) by November 10, 2025.
**(b) Affected ADs**
None.
**(c) Applicability**
This AD applies to all Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes, certificated in any category.
**(d) Subject**
Air Transport Association (ATA) of America Code 25, Equipment/furnishings.
**(e) Unsafe Condition**
This AD was prompted by certification testing that found that environmental control system (ECS) ducts manufactured using material APF1180-7781 failed the flammability test requirements established for compliance. The FAA is issuing this AD to address noncompliant ECS ducts that could cause an inability to contain a fire within the cargo compartment. The unsafe condition, if not addressed, could result in 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-2025-10, dated February 27, 2025 (Transport Canada AD CF-2025-10).
**(h) Exception to Transport Canada AD CF-2025-10**
(1) Where Transport Canada AD CF-2025-10 refers to its effective date, this AD requires using the effective date of this AD.
(2) Where Transport Canada AD CF-2025-10 refers to June 20, 2024 (the effective date of Transport Canada AD CF-2024-21), this AD requires using the effective date of this AD.
(3) Where the first paragraph under Part 1 of Transport Canada AD CF-2025-10 specifies a compliance time for the inspection and retrofit, for this AD the compliance time is at the later of the times specified in paragraphs (h)(3)(i) or (ii) of this AD:
(i) Prior to the accumulation of 9,350 total flight hours or within 60 months after the effective date of this AD, whichever occurs first.
(ii) Within 30 days after the effective date of this AD.
(4) Where the Safran material referenced in Transport Canada AD CF-2025-10 specifies to drill holes, this AD allows identifying and marking the new locations for the inserts prior to drilling the holes.
(5) Where the Safran material referenced in Transport Canada AD CF-2025-10 specifies accomplishing step 3.D.(8) after accomplishing steps 3.D.(6) and 3.D.(7), this AD allows accomplishing step 3.D.(8) concurrently with or after step 3.D.(5).
(6) Where the Safran material referenced in Transport Canada AD CF-2025-10 specifies “mark the holes position”, for this AD replace that text with “mark the holes position and drill the holes”.
(7) Where the second paragraph under Part II of Transport Canada AD CF-2025-10 specifies “The use of the Accomplishment Instructions of Safran Cabin Service Bulletin F493000-50-06 as contained within Airbus Canada SB BD500-501003 Issue 001, dated 21 December 2023, or Issue 002, dated November 15, 2024, prior to the effective date of this AD, also meet the intent of Part II of this AD”, this AD requires replacing that text with “The use of the Accomplishment Instructions of Safran Cabin Service Bulletin F493000-50-06 as contained within Airbus Canada SB BD500-501003 Issue 001, dated 21 December 2023, or Issue 002, dated November 15, 2024, prior to the effective date of this AD, also meet the intent of Part II of this AD, provided the ceiling panel liners in the cargo compartments have been re-identified in accordance with the procedure in Section 3 of Part B of the Accomplishment Instructions of the ACLP SB.”
**(i) No Reporting Requirement**
Although the material referenced in Transport Canada AD CF-2025-10 specifies to submit certain information 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: *[email protected]* . 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 Brenda L. Buitrago, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 516-288-7368; email: *[email protected]* .
**(l) 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-2025-10, dated February 27, 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 *[email protected]* ; website *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 *[email protected]* .
Issued on September 23, 2025.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft Certification Service.