Airworthiness Directives; Bombardier, Inc., Airplanes

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 Bombardier, Inc., Model BD-700-2A12 airplanes. The NPRM was published in the Federal Register on March 4, 2026 (91 FR 10522). The NPRM was prompted by Transport Canada AD CF-2025-49, dated October 1, 2025 (Transport Canada AD CF-2025-49) (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states there have been reports of low clearance in the right wing between the fuel line flexible coupling and the harness support bracket clip-nut located in bay 3, between the fuel line flexible coupling and hydraulic system 3 line located in bay 18, and between the hydraulic system 3 lines and fuel vent tube located in bay 20. These low clearance conditions, if not addressed, may result in an ignition source developing in the fuel tank in the event of a lightning strike.

In the NPRM, the FAA proposed to require rectifying the low clearance condition between the fuel line flexible coupling and the harness support bracket clip-nut, rectifying the low clearance condition between the fuel line flexible coupling and the hydraulic system, and doing an inspection for adequate clearance between the hydraulic system and the fuel vent tube and applicable on-conditions actions, as specified in Transport Canada AD CF-2025-49. 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-2026-2289.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from five individuals who supported the NPRM without change.

The FAA received additional comments from two other individuals. The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Clarify Why an Emergency AD Was Not Issued

Commenter #1 requested that the FAA clarify its determination that the unsafe condition does not meet the criteria for an emergency AD, given the potential interaction between fuel transfer systems, vibration-induced wear, and adjacent hydraulic and electrical components within the affected wing structure. Additionally, the commenter asked (1) if the low clearance condition could contribute to fuel starvation scenarios under certain operational conditions; (2) if interim inspections, operational limitations, or manufacturer service bulletins should be implemented while the rulemaking process proceeds; (3) if a shortened compliance period or immediate corrective action would better mitigate the identified risk; (4) if additional technical analysis regarding system interaction between fuel, hydraulic, and electrical components should be included in the final rulemaking record.

The FAA issues an emergency AD when an unsafe condition exists that requires immediate adoption, and the risk to the flying public justifies forgoing notice and comment prior to adopting an emergency AD. In developing this rulemaking, the FAA evaluated the compliance times and all the available information provided by Transport Canada and the manufacturer. The FAA has no additional data that would support reducing the compliance time below that specified in Transport Canada AD CF-2025-49, or issuing an emergency AD to address the unsafe condition.

Further, the FAA provides the following additional information:

(1) The low clearance condition would not contribute to fuel starvation. There is no potential fouling condition of the fuel vent line and, therefore, no effect on the fuel system operation.

(2) The corrective actions and compliance times in Transport Canada AD CF-2025-49 are adequate for addressing the unsafe condition. Therefore, no interim actions, operational limitations, or additional service bulletins need to be mandated. However, operators are permitted to accomplish the requirements of this AD at an earlier time, or may voluntarily adopt service information, operational limitations, or additional inspections to address the unsafe condition.

(3) Neither a shorter compliance time nor immediate corrective action are necessary to address the unsafe condition. Based on the risk evaluation conducted by the manufacturer, the corrective actions and compliance times in Transport Canada AD CF-2025-49 are sufficient for mitigating the identified risk.

(4) There is no system failure associated with this unsafe condition; therefore, no technical analysis regarding system interaction between the fuel, hydraulic, and electrical components needs to be included in the rulemaking docket.

Request To Reopen the Comment Period or Revise the Proposed AD

Commenter #2 requested that the FAA either (1) re-open the comment period and add to the AD docket all materials incorporated by reference and the basis for the cost assumptions and warranty offset, or (2) revise the proposed AD to add the operative standard and un-offset cost estimate. The commenter stated that the FAA did not provide adequate information for the public to meaningfully evaluate and comment on the proposed requirements and costs of compliance. The commenter further stated if the FAA cannot provide these elements, the proposed AD cannot be evaluated for comment or supported as a matter of reasoned decision-making and should be withdrawn and reissued with a complete record.

The FAA disagrees with the requests. The FAA 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 incorporation by reference (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.

Further, the FAA notes that this AD incorporates by reference Transport Canada AD CF-2025-49, not the manufacturer service information referenced in Transport Canada AD CF-2025-49 ( i.e., non-IBR material). The FAA posted Transport Canada AD CF-2025-49 to the AD docket when the NPRM was published in the Federal Register . The non-IBR material 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, affected operators that must comply with the AD may obtain the non-IBR material directly from the manufacturer during the comment period through their normal course of business.

Further, the FAA based the estimated Costs of Compliance with this AD on information provided by the manufacturer. The number of estimated work hours and warranty terms are included in the manufacturer service bulletin, which is posted to the rulemaking docket upon publication of the final rule. The estimated parts cost was provided by the manufacturer. The FAA notes that no comments were received regarding the IBR material or estimated costs from any of the affected operators.

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 NPRM. 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-2025-49 specifies procedures for rectifying the low clearance condition between the fuel line flexible coupling and the harness support bracket clip-nut located in bay 3 of the right wing by replacing the clip-nut on the harness bracket in the right-hand wing between rib 3 and rib 4, rectifying the low clearance condition between the fuel line flexible coupling and the hydraulic system 3 line located in bay 18 of the right wing by replacing fuel tube assemblies in the right-hand wing between rib 17 and rib 20, doing an inspection for adequate clearance between the hydraulic system 3 lines and the fuel vent tube located in bay 20 of the right wing, and applicable on-conditions actions. On-condition actions include rectifying any low clearance condition found ( i.e., replace the hydraulic system support brackets in the right-hand wing between rib 19 and rib 21).

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 60 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 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 this on-condition action:

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:

PART 39-AIRWORTHINESS DIRECTIVES