Proposed Rule2026-10382
Airworthiness Directives; Bombardier, Inc., Airplanes
Primary source
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Published
May 26, 2026
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA proposes to adopt a new airworthiness directive (AD) 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. This proposed AD was prompted by an in-flight uncommanded, unarrested flaps movement accompanied by a FLAPS FAIL caution message. This proposed AD would require revising the existing aircraft flight manual (AFM) to provide the flightcrew with procedures to follow in the event of an uncommanded, unarrested flap movement. The FAA is proposing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 91 Issue 100 (Tuesday, May 26, 2026)</title>
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[Federal Register Volume 91, Number 100 (Tuesday, May 26, 2026)]
[Proposed Rules]
[Pages 30516-30519]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-10382]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2026-4642; Project Identifier MCAI-2024-00705-T]
RIN 2120-AA64
Airworthiness Directives; Bombardier, Inc., Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
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. This
proposed AD was prompted by an in-flight uncommanded, unarrested flaps
movement accompanied by a FLAPS FAIL caution message. This proposed AD
would require revising the existing aircraft flight manual (AFM) to
provide the flightcrew with procedures to follow in the event of an
uncommanded, unarrested flap movement. The FAA is proposing this AD to
address the unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by July 10,
2026.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: 202-493-2251.
<bullet> 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.
<bullet> 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 <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2026-4642; 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 NPRM, 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:
<bullet> 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 <a href="/cdn-cgi/l/email-protection#a3f7e08de2cad1d4ccd1d7cbcacdc6d0d0e7cad1c6c0d7cad5c6d08ee0cccdd0cac4cdc6d0c7c6cdc2d5cac4c2c1cacfcad7c68df7e0e3d7c08dc4c08dc0c2"><span class="__cf_email__" data-cfemail="4e1a0d600f273c39213c3a2627202b3d3d0a273c2b2d3a27382b3d630d21203d2729202b3d2a2b202f3827292f2c2722273a2b601a0d0e3a2d60292d602d2f">[email protected]</span></a>. You may find this material on the
Transport Canada website at tc.canada.ca/en/aviation. It is also
[[Page 30517]]
available at <a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2026-4642.
<bullet> 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: Christopher Spencer, Aviation Safety
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
phone: 516-228-7300; email: <a href="/cdn-cgi/l/email-protection#073e2a6671742a697e6664682a6468744761666629606871"><span class="__cf_email__" data-cfemail="734a5e1205005e1d0a12101c5e101c00331512125d141c05">[email protected]</span></a>.
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
<a href="http://regulations.gov">regulations.gov</a>, 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: <a href="/cdn-cgi/l/email-protection#d7eefab6a1a4fab9aeb6b4b8fab4b8a497b1b6b6f9b0b8a1"><span class="__cf_email__" data-cfemail="271e0a4651540a495e4644480a4448546741464609404851">[email protected]</span></a>. 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
<a href="http://regulations.gov">regulations.gov</a> 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
[[Page 30518]]
compliance will be available at <a href="http://regulations.gov">regulations.gov</a> 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:
Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Labor cost Parts cost product operators
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1 work-hour x $85 per hour = $85............................. $0 $85 $51,850
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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
0
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
0
2. The FAA amends Sec. 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
[[Page 30519]]
identified in paragraph (j) of this AD and email to: <a href="/cdn-cgi/l/email-protection#26676b69656640474708414950"><span class="__cf_email__" data-cfemail="b2f3fffdf1f2d4d3d39cd5ddc4">[email protected]</span></a>.
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: <a href="/cdn-cgi/l/email-protection#82bbafe3f4f1afecfbe3e1edafe1edf1c2e4e3e3ace5edf4"><span class="__cf_email__" data-cfemail="f1c8dc908782dc9f8890929edc929e82b1979090df969e87">[email protected]</span></a>.
(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 <a href="/cdn-cgi/l/email-protection#2074630e614952574f525448494e455353644952454354495645530d634f4e5349474e455344454e415649474142494c4954450e74636054430e47430e4341"><span class="__cf_email__" data-cfemail="edb9aec3ac849f9a829f99858483889e9ea9849f888e99849b889ec0ae82839e848a83889e8988838c9b848a8c8f8481849988c3b9aead998ec38a8ec38e8c">[email protected]</span></a>. 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 <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a> or email <a href="/cdn-cgi/l/email-protection#c7a1b5e9aea9b4b7a2a4b3aea8a987a9a6b5a6e9a0a8b1"><span class="__cf_email__" data-cfemail="3a5c48145354494a5f594e5355547a545b485b145d554c">[email protected]</span></a>.
Issued on May 19, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2026-10382 Filed 5-22-26; 8:45 am]
BILLING CODE 4910-13-P
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