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-2026-4642; Project Identifier MCAI-2024-00705-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 Christopher Spencer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: 9-avs-nyaco-cos@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

Transport Canada, which is the aviation authority for Canada, has issued Transport Canada AD CF-2024-39, dated November 29, 2024 (Transport Canada AD CF-2024-39) (also referred to as the MCAI), to correct an unsafe condition for all Bombardier, Inc., Model CL-600-1A11 (600), CL-600-2A12 (601), and CL-600-2B16 (601-3A, 601-3R, and 604 Variants) airplanes. The MCAI states that a Model CL-600-2B16 airplane experienced an in-flight uncommanded, unarrested flaps movement from 0 to 45 degrees accompanied by a FLAPS FAIL caution message. The airplane returned to the departure airport without further incident. The flaps control system should have stopped the flaps at 3 degrees; however, a failed retract relay prevented the system from arresting the uncommanded movement. The uncommanded and unarrested flap movement, if not addressed, could result in loss of control of the airplane.

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-2026-4642.

Related Actions

Transport Canada issued related Transport Canada AD CF-2023-07, dated February 10, 2023 (Transport Canada AD CF-2023-07), as an interim action to address the failure of the flap control system to arrest the uncommanded flap extension. The FAA issued AD 2023-17-06, Amendment 39-22532 (88 FR 63004, September 14, 2023) (AD 2023-17-06), to address Transport Canada AD CF-2023-07. AD 2023-17-06 requires initial and repetitive operational tests of the flap control system. The FAA issued this AD as a standalone AD as the required actions are separate from each other.

Material Incorporated by Reference Under 1 CFR Part 51

Transport Canada AD CF-2024-39 specifies procedures for revising the AFM to provide the flightcrew with procedures to follow in the event of an uncommanded, unarrested flap movement. 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-2024-39 described previously, except for any differences identified as exceptions in the regulatory text of this proposed AD.

Compliance With AFM Revisions

Transport Canada AD CF-2024-39 requires operators to “advise all flight crews” of revisions to the AFM, and “thereafter operate the aeroplane accordingly.” However, this proposed AD would not specifically require those actions as those actions are already required by FAA regulations. FAA regulations require operators furnish to pilots any changes to the AFM (for example, 14 CFR 121.137), and to ensure the pilots are familiar with the AFM (for example, 14 CFR 91.505). As with any other flightcrew training requirement, training on the updated AFM content is tracked by the operators and recorded in each pilot's training record, which is available for the FAA to review. FAA regulations also require pilots to follow the procedures in the existing AFM including all updates.

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-2024-39 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with Transport Canada AD CF-2024-39 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-2024-39 for ( printed page 30518) compliance will be available at regulations.gov under Docket No. FAA-2026-4642 after the FAA final rule is published.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would affect 610 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed 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

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 adding the following new airworthiness directive:

Bombardier, Inc.: Docket No. FAA-2026-4642; Project Identifier MCAI-2024-00705-T.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by July 10, 2026.

(b) Affected ADs

None.

(c) Applicability

This AD applies to all Bombardier, Inc., Model CL-600-1A11 (600), CL-600-2A12 (601), and CL-600-2B16 (601-3A, 601-3R, and 604 Variants) airplanes, certificated in any category.

(d) Subject

Air Transport Association (ATA) of America Code 27, Flight Controls.

(e) Unsafe Condition

This AD was prompted by a Model CL-600-2B16 airplane that experienced an in-flight uncommanded, unarrested flaps movement from 0 to 45 degrees accompanied by a FLAPS FAIL caution message. The FAA is issuing this AD to provide the flightcrew with procedures to follow in the event of an uncommanded, unarrested flap movement. The unsafe condition, if not addressed, could result in loss of control of the airplane.

(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-2024-39, dated November 29, 2024 (Transport Canada AD CF-2024-39).

(h) Exceptions to Transport Canada AD CF-2024-39

(1) Where Transport Canada AD CF-2024-39 refers to its effective date, this AD requires using the effective date of this AD.

(2) Where Transport Canada AD CF-2024-39 refers to “the applicable Transport Canada approved AFM”, this AD requires replacing that text with “the existing AFM”.

(3) Where Table 1 of Transport Canada AD CF-2024-39 refers to “Temporary Revision (TR) No. 600/35 dated June 28, 2024”, this AD requires replacing that text with “Temporary Revision (TR) No. 600/34 dated June 28, 2024”.

(4) Where the AFM Procedure column for the Model CL-600-1A11 (Challenger 600) Airplanes in Table 1 of CF-2024-39 refers to “Emergency Procedures, Abnormal Procedures, Supplement 14”, this AD requires replacing that text with “Emergency Procedures, Supplement 14”.

(5) Where Table 1 of Transport Canada AD CF-2024-39 refers to “Temporary Revision (TR) No. 600-1/31 dated June 28, 2024”, this AD requires replacing that text with “Temporary Revision (TR) No. 600-1/29, dated June 28, 2024”.

(6) Where Table 1 of Transport Canada AD CF-2024-39 refers to “Temporary Revision (TR) No. 601/42 dated June 28, 2024”, this AD requires replacing that text with “Temporary Revision (TR) No. 601/40, dated June 28, 2024”.

(7) Where Table 1 of Transport Canada AD CF-2024-39 refers to “Temporary Revision (TR) No. 601/34 dated June 28, 2024”, this AD requires replacing that text with “Temporary Revision (TR) No. 601/32, dated June 28, 2024”.

(8) Where paragraph B. of Transport Canada AD CF-2024-39 specifies to “advise all flight crews” and “thereafter operate the aeroplane accordingly”, this AD does not require those actions as those actions are already required by existing FAA operating regulations (see 14 CFR 91.505 and 121.137).

(i) Additional AD Provisions

The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, International Validation 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 International Validation Branch, send it to the attention of the person ( printed page 30519) 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, International Validation Branch, FAA; or Transport Canada; or Bombardier's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature.

(j) Additional Information

For more information about this AD, contact Christopher Spencer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7300; email: 9-avs-nyaco-cos@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-2024-39, dated November 29, 2024.

(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.

91 FR 30516