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Rule2026-04278

Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes

Primary source

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Published

March 4, 2026

Effective

April 8, 2026

Issuing agencies

Transportation DepartmentFederal Aviation Administration

Abstract

The FAA is adopting a new airworthiness directive (AD) for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500- 1A11 airplanes. This AD was prompted by reports of certain fuel transfer float valves failing in the closed position, preventing normal fuel transfer between the center and wing fuel tanks. This AD requires replacing the existing fuel transfer float valves on airplanes approved for extended-range twin-engine operation performance standards (ETOPS). The FAA is issuing this AD to address the unsafe condition on these products.

Full Text

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<title>Federal Register, Volume 91 Issue 42 (Wednesday, March 4, 2026)</title>
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[Federal Register Volume 91, Number 42 (Wednesday, March 4, 2026)]
[Rules and Regulations]
[Pages 10510-10513]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-04278]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-2545; Project Identifier MCAI-2024-00657-T;
Amendment 39-23264; AD 2026-04-04]
RIN 2120-AA64

Airworthiness Directives; Airbus Canada Limited Partnership (Type
Certificate Previously Held by C Series Aircraft Limited Partnership
(CSALP); Bombardier, Inc.) Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-
1A11 airplanes. This AD was prompted by reports of certain fuel
transfer float valves failing in the closed position, preventing normal
fuel transfer between the center and wing fuel tanks. This AD requires
replacing the existing fuel transfer float valves on airplanes approved
for extended-range twin-engine operation performance standards (ETOPS).
The FAA is issuing this AD to address the unsafe condition on these
products.

DATES: This AD is effective April 8, 2026.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of April 8,
2026.

ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-2545; 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 final rule, the mandatory continuing airworthiness
information (MCAI), any comments received, and other information. The
address for Docket Operations is U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
<bullet> 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#0155422f406873766e737569686f647272456873646275687764722c426e6f7268666f647265646f607768666063686d6875642f55424175622f66622f6260">[email&#160;protected]</a>. You may find this material on the
Transport Canada website at tc.canada.ca/en/aviation.
<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. It is also available at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-2545.

FOR FURTHER INFORMATION CONTACT: Joseph Catanzaro, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 516-
228-7366; email: <a href="/cdn-cgi/l/email-protection#5f35302c3a2f37713c3e2b3e31253e2d301f393e3e71383029">[email&#160;protected]</a>.

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 September 15, 2025 (90 FR
44356). The NPRM was prompted by AD CF-2024-37, dated November 4, 2024
(Transport Canada AD CF-2024-37) (also referred to as the MCAI), issued
by Transport Canada, which is the aviation authority for Canada. The
MCAI states that there have been several reports of fuel transfer float
valves failing in the closed position, preventing normal fuel transfer
between the center fuel tank and wing fuel tanks. An investigation
determined that high friction of the fuel transfer float valve carbon
seal prevents the fuel transfer float valve from opening. Each wing
tank is equipped with one fuel transfer float valve. If one fuel
transfer float valve fails closed, the crew is alerted and may manually

[[Page 10511]]

transfer fuel to correct the resulting lateral fuel imbalance. A
gravity fuel transfer system provides a back-up to the manual transfer.
If both fuel transfer float valves simultaneously fail in the closed
position, the crew is alerted, and fuel in the center tank becomes
unusable as it cannot be transferred to the wing tanks. The crew may
need to divert to prevent fuel starvation before reaching the
destination airport. Simultaneous failure of both fuel transfer float
valves in the closed position is critical for ETOPS missions as fuel
starvation and engine shutdown may occur before reaching a diversion
airport.
In the NPRM, the FAA proposed to require replacing the existing
fuel transfer float valves on airplanes approved for ETOPS, as
specified in Transport Canada AD CF-2024-37. The FAA is issuing this AD
to address the simultaneous failure of both fuel transfer float valves
in the closed position during an ETOPS flight. The unsafe condition, if
not addressed, during an ETOPS flight, could lead to a forced diversion
or fuel starvation and engine shutdown before reaching a diversion
airport.
You may examine the MCAI in the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-2545.

Discussion of Final Airworthiness Directive

Comment

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

Request To Justify Forgoing Notice and Comment or Issue an NPRM

The commenter requested that the FAA either provide its
justification for finding good cause to bypass notice and comment
procedures, convert this action to an NPRM, or stay the effective date
until 30 days after close of a comment period of at least 45 days. The
commenter asserted the FAA has not adequately justified use of the good
cause exemption to bypass notice and comment and the 30-day delayed
effective date.
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 Make Incorporation by Reference (IBR) Materials Reasonably
Available

The commenter 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. They
also requested that this access be documented in the rulemaking record.
The FAA's practices comply with 5 U.S.C. 552(a) of the
Administrative Procedure Act and 1 CFR part 51. The FAA makes IBR
materials available in the AD docket when the final rule is published
in the Federal Register, following formal approval of the IBR by the
Office of the Federal Register. Materials may only be posted before the
final rule's publication if they are already publicly available or if
there is written consent from the owner of the IBR material. All
relevant materials incorporated by reference will be accessible in the
AD docket on Regulations.gov, which the public can access without
registration or fees.
The FAA also 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 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.

Request To Comply With the Paperwork Reduction Act (PRA)

The commenter 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 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 Provide Additional Cost Information

The commenter 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, and any assumption that the
manufacturer would provide parts free of charge.
The FAA recognizes that, in doing the actions required by an AD,
operators might incur indirect or incidental costs in addition to the
direct costs. The cost analysis in an AD typically describes only the
direct costs of the specific actions required by an AD, which does not
include indirect or incidental costs such as downtime, loss of revenue,
planning, or time necessitated by other administrative actions since
those costs might vary significantly among operators. The number of
work hours necessary to do the required actions of an AD is provided by
the manufacturer. This number represents the time necessary to perform
only the actions actually required by an AD. The cost of parts or
special tools, if necessary, to complete the actions required by an AD
is also provided by the manufacturer. Further, when the FAA is informed
that the manufacturer may cover some or all of the estimated costs of
an AD under warranty, the FAA indicates that in the AD.
In the Cost of Compliance section of the proposed AD, the FAA
disclosed the estimated number of work hours and the number of
airplanes affected on the U.S. registry. The FAA did not disclose an
estimated parts cost in the proposed AD but noted the parts would be
provided at no charge to all operators for a limited time. 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

[[Page 10512]]

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-2024-37 specifies procedures for replacing
the existing fuel transfer float valves and O-rings on the left and
right wing with new fuel transfer float valves and O-rings and
performing operational tests of the center-to-wing fuel transfer.
Transport Canada AD CF-2024-37 also specifies that inserting a copy of
Transport Canada AD CF-2024-37 into the ETOPS Configuration,
Maintenance, and Procedures (CMP) or using ETOPS CMP issue 009.00 or
later is an acceptable method of compliance.
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 35 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
Labor cost Parts cost Cost per product Cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
Up to 16 work-hours x $85 per Unknown *........... Up to $1,360....... Up to $47,600.
hour = $1,360.
----------------------------------------------------------------------------------------------------------------
* The FAA has received no definitive data on which to base the cost estimate for the parts specified in this AD.

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.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

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

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:

2026-04-04 Airbus Canada Limited Partnership (Type Certificate
Previously Held by C Series Aircraft Limited Partnership (CSALP);
Bombardier, Inc.): Amendment 39-23264; Docket No. FAA-2025-2545;
Project Identifier MCAI-2024-00657-T.

(a) Effective Date

This airworthiness directive (AD) is effective April 8, 2026.

(b) Affected ADs

None.

This AD applies to Airbus Canada Limited Partnership (type
certificate previously held by C Series Aircraft Limited Partnership
(CSALP); Bombardier, Inc.) Model BD-500-1A10 and BD-500-1A11
airplanes, certificated in any category, as identified in Transport
Canada AD CF-2024-37, dated November 4, 2024 (Transport Canada AD
CF-2024-37).

(d) Subject

Air Transport Association (ATA) of America Code 28, Fuel.

(e) Unsafe Condition

This AD was prompted by reports of certain fuel transfer float
valves failing in the closed position, preventing normal fuel
transfer between the center and wing fuel tanks. The FAA is issuing
this AD to address the simultaneous failure of both fuel transfer
float valves in the closed position during an extended-range twin-
engine operation performance standards (ETOPS) flight. The unsafe
condition, if not addressed, during an ETOPS flight, could lead to a
forced diversion or fuel starvation and engine shutdown before
reaching a diversion airport.

(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-2024-37.

(h) Exceptions to Transport Canada AD CF-2024-37

(1) Where Transport Canada AD CF-2024-37 refers to its effective
date, this AD requires using the effective date of this AD.

[[Page 10513]]

(2) Where Transport Canada AD CF-2024-37 refers to hours air
time, this AD requires using flight hours.
(3) Where paragraph B. of Transport Canada AD CF-2024-37
specifies ``thereafter, operating that aeroplane accordingly,'' this
AD does not require that action as that action is already required
by existing FAA operating regulations (see 14 CFR 121.374(n)).
(4) Where the material referenced in Transport Canada AD CF-
2024-37 specifies discarding parts, this AD requires removing those
parts from service.

(i) 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 (j) of this AD and email to:
<a href="/cdn-cgi/l/email-protection#0f4e42404c4f696e6e21686079">[email&#160;protected]</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 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 Designee's authorized signature.

(j) Additional Information

For more information about this AD, contact Joseph Catanzaro,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 516-228-7366; email: <a href="/cdn-cgi/l/email-protection#670d081402170f4904061306091d0615082701060649000811">[email&#160;protected]</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-2024-37, dated November 4, 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#8cd8cfa2cde5fefbe3fef8e4e5e2e9ffffc8e5fee9eff8e5fae9ffa1cfe3e2ffe5ebe2e9ffe8e9e2edfae5ebedeee5e0e5f8e9a2d8cfccf8efa2ebefa2efed">[email&#160;protected]</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#2147530f484f5251444255484e4f614f4053400f464e57">[email&#160;protected]</a>.

Issued on February 17, 2026.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft
Certification Service.
[FR Doc. 2026-04278 Filed 3-3-26; 8:45 am]
BILLING CODE 4910-13-P

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