Home/Federal/Federal Register/2026-10486

Rule2026-10486

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

Primary source

Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.

Published

May 27, 2026

Effective

July 1, 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 the discovery that titanium fasteners had been incorrectly installed in the butt strap at the outer wing box lower skin to center wing box interface in lieu of the correct nickel alloy fasteners. This AD requires the identification of fasteners installed in the butt strap at the outer wing box lower skin to center wing box interface, and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.

Full Text

<html>
<head>
<title>Federal Register, Volume 91 Issue 101 (Wednesday, May 27, 2026)</title>
</head>
<body><pre>
[Federal Register Volume 91, Number 101 (Wednesday, May 27, 2026)]
[Rules and Regulations]
[Pages 31341-31345]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-10486]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-2543; Project Identifier MCAI-2025-00215-T;
Amendment 39-23347; AD 2026-10-07]
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.

-----------------------------------------------------------------------

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 the discovery that titanium
fasteners had been incorrectly installed in the butt strap at the outer
wing box lower skin to center wing box interface in lieu of the correct
nickel alloy fasteners. This AD requires the identification of
fasteners installed in the butt strap at the outer wing box lower skin
to center wing box interface, and applicable on-condition actions. The
FAA is issuing this AD to address the unsafe condition on these
products.

DATES: This AD is effective July 1, 2026.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of July 1,
2026.

ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2025-2543; 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#47130469062e35302835332f2e29223434032e352224332e3122346a042829342e2029223423222926312e2026252e2b2e3322691304073324692024692426">[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-2025-2543.

FOR FURTHER INFORMATION CONTACT: Bill Ashforth, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3520; email: <a href="/cdn-cgi/l/email-protection#80e2e9ececaee1f3e8e6eff2f4e8c0e6e1e1aee7eff6">[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
44337). The NPRM was prompted by AD CF-2025-09, dated February 24, 2025
(Transport Canada AD CF-2025-09) (also referred to as the MCAI), issued
by Transport Canada, which is the aviation authority for Canada. The
MCAI states that titanium fasteners (part number (P/N) B0206003GD) had
been incorrectly installed in the butt strap at the outer wing box
lower skin to center wing box interface in lieu of the correct nickel
alloy fasteners (P/N B0206033GD). The use of titanium fasteners could
result in a reduction in joint strength, and the risk of a fuel leak if
the fastener fails and falls free from the joint. This condition, if
not corrected, could cause damage to and loss of principal structure
and fatigue critical structure.
In the NPRM, the FAA proposed to require the identification of
fasteners installed in the butt strap at the outer wing box lower skin
to center wing box interface, and applicable on-condition actions, as
specified in Transport Canada AD CF-2025-09. The FAA is issuing 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-2025-2543.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from an anonymous commenter who
supported the NPRM without change.
The FAA received additional comments from Delta Air Lines (Delta)
and the Citizens Rulemaking Alliance. The following presents the
comments

[[Page 31342]]

received on the NPRM and the FAA's response to each comment.

Request To Remove the Requirement To Contact the Manufacturer for
Disposition

Delta requested that the FAA add an exception to paragraph (h) of
the proposed AD to allow use of an existing, approved Airbus Canada
Limited Partnership (ACLP) disposition instead of contacting ACLP for
an approved disposition via the instructions in the service information
referenced in Transport Canada AD CF-2025-09. Delta noted that ACLP is
changing the contact method specified in the service information, so
operators may need to request an alternative method of compliance
(AMOC) to use an alternative contact method. Delta also noted that ACLP
has already issued two Generic Repair Engineering Orders (GREOs) to
address discrepant fasteners found during the inspection, and that the
GREOs meet the provisions of paragraph (j)(2) of the proposed AD for
obtaining an approved disposition.
The FAA agrees that operators may use existing repair instructions,
including GREOs, for compliance with this AD provided the repair
instructions were approved under the provisions of paragraph (j)(2) of
this AD. No change to this AD is necessary in regard to that part of
Delta's comment.
The FAA also agrees with removing the requirement to obtain an
approved disposition in accordance with the contact method specified in
the service information referenced in Transport Canada AD CF-2025-09
and has added a new exception in paragraph (h)(3) of this AD
accordingly. The FAA notes that under paragraph (j)(2) of this AD
operators must contact the Manager, AIR-520, Continued Operational
Safety Branch, FAA; or Transport Canada; or ACLP's Transport Canada
Design Approval Organization (DAO) to obtain an approved disposition
for any requirement in this AD to obtain instructions from a
manufacturer.

Request To Extend the Compliance Times

Delta requested that the FAA revise paragraph (h)(2) of the
proposed AD to allow the required inspection to be accomplished within
11,400 total flight cycles, 22,800 total flight hours, or 500 flight
cycles from the effective date of this AD, whichever occurs later,
instead of performing the inspections within 500 flight cycles from the
effective date of the AD or before accumulating 10,000 total flight
cycles, whichever occurs later. Delta stated that ACLP has already
issued two approved GREOs to address discrepant fasteners found during
the inspection, and that one of the GREOs authorizes continued flight
with the discrepant fasteners up to 11,400 total flight cycles or
22,800 total flight hours, whichever occurs first. Delta asserted that
if replacement of the discrepant fasteners can be deferred to those
later thresholds, then deferring the inspection to the same thresholds
provides an acceptable level of safety.
The FAA disagrees with extending the compliance time for performing
the inspection to determine if serviceable fasteners are installed.
Transport Canada, as the state of design authority for these airplanes,
analyzed the data, considered the recommendations of the manufacturers,
and determined that the inspection must be accomplished before
accumulating 10,000 total flight cycles or within 500 flight cycles
from the effective date of the AD, whichever occurs later; and the FAA
concurs with Transport Canada's determination. However, under the
provisions of paragraph (j)(1) of this AD, the FAA will consider
requests for approval of an extension of the compliance time if
sufficient data are submitted to substantiate that the new compliance
time would provide an acceptable level of safety. The FAA has not
changed this AD as a result of this comment.

Request To Justify Forgoing Notice and Comment or Issue an NPRM

The Citizens Rulemaking Alliance requested that the FAA either
provide its justification for finding good cause to bypass notice and
comment procedures and the 30-day delayed effective date, or convert
this action to an NPRM with a 30-day comment period. 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 Comply With the Paperwork Reduction Act (PRA)

The Citizens Rulemaking Alliance 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 paragraph (i) of this AD specifies that 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 Consider Impact on Small Entities

The Citizens Rulemaking Alliance requested that the FAA either
provide the factual basis for its certification under the Regulatory
Flexibility Act (RFA) that the AD will not have a significant economic
impact on a substantial number of small entities, or prepare an initial
regulatory flexibility analysis that identifies potentially affected
small entities and considers alternatives that minimize impact.
The FAA provides the following clarification. The RFA of 1980 (5
U.S.C. 601-612), as amended by the Small Business Regulatory
Enforcement Fairness Act of 1996 (Pub. L. 104-121) and the Small
Business Jobs Act of 2010 (Pub. L. 111-240), requires Federal agencies
to consider the effects of the regulatory action on small business and
other small entities and to minimize any significant economic impact.
The term ``small entities'' comprises small businesses and not-for-
profit organizations that are independently owned and operated and are
not dominant in their fields, and governmental jurisdictions with
populations of less than 50,000.
The FAA identified three air carriers that will be affected by this
AD. Based on the Small Business Administration size standard, all three
entities are large businesses:

[[Page 31343]]

Small Business Size Standards \1\
------------------------------------------------------------------------
NAICS \2\ code Description Size standard
------------------------------------------------------------------------
481111.......................... Scheduled 1,500 employees.
Passenger Air
Transportation.
------------------------------------------------------------------------
\1\ Source: <a href="http://sba.gov">sba.gov</a>: Table of Small Business Size Standards.
\2\ North American Industrial Classification System.

If an agency determines that a rulemaking will not result in a
significant economic impact on a substantial number of small entities,
the head of the agency may so certify under section 605(b) of the RFA.
Therefore, as provided in section 605(b) and based on the foregoing,
the head of the FAA certifies that this AD will not result in a
significant economic impact on a substantial number of small entities.
The FAA did not change this AD as a result of this comment.

Request To Provide Additional Cost Information

The Citizens Rulemaking Alliance requested that the FAA augment the
economic analysis to include downtime and scheduled disruption costs,
parts availability constraints, and cumulative fleet impacts, and
adjust the compliance times to align with scheduled maintenance
intervals and broaden AMOC pathways accordingly. The commenter stated
that the FAA should also provide the per airplane and fleet costs,
including labor hours, parts, engineering, software loads, and special
tools.
The FAA recognizes that, in doing the actions required by an AD,
operators might incur indirect costs (such as engineering work or loss
of revenue due to airplane downtime, scheduled disruptions, parts
availability constraints, etc.) 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
costs since the FAA lacks data on those costs and they vary
significantly among operators. Additionally, the FAA determined that
there may be no downtime costs for some of the affected operators
because the compliance times required by this AD would allow the
required inspection to be performed during regularly scheduled
maintenance. Further, special tools and software are not necessary to
complete the actions required by this AD.
In the Costs of Compliance section of the proposed AD, the FAA
disclosed the number of affected airplanes on the U.S. registry,
estimated number of work hours and parts costs provided by the
manufacturer, and the fleet cost. 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 provide additional information in the
AD docket.
Further, in developing an appropriate compliance time for this AD,
the FAA considered the compliance time in Transport Canada AD CF-2025-
09, the urgency associated with the subject unsafe condition, the
availability of required parts, and the practical aspect of
accomplishing the required actions within a period of time that
corresponds to the normal scheduled maintenance for most affected
operators. However, under the provisions of paragraph (j)(1) of this
AD, the FAA will consider requests for approval of an extension of the
compliance time if sufficient data are submitted to substantiate that
the new compliance time would provide an acceptable level of safety.
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 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

The FAA reviewed Transport Canada AD CF-2025-09, which specifies
procedures for a detailed inspection to identify the part markings on
the head of the fasteners, and applicable on-condition actions. On-
condition actions include replacing non-serviceable fasteners (those
not identified as HST54, HST154, HST254, B0201074, B0201074 with
oversize code X, or B0201074 with oversize code Y). For non-serviceable
fasteners, the replacement includes a detailed inspection to make sure
that the fastener heads are not damaged; the fastener heads are
installed within requirements; and there are no signs of loose
fasteners, fasteners that rotated, or fasteners that moved.
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 71 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Labor cost Parts cost product operators
----------------------------------------------------------------------------------------------------------------
29 work-hours x $85 per hour = $2,465........................... $0 $2,465 $175,015
----------------------------------------------------------------------------------------------------------------

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 this on-condition action:

[[Page 31344]]

Estimated Costs of On-Condition Actions *
------------------------------------------------------------------------
Labor cost Parts cost Cost per product
------------------------------------------------------------------------
Up to 4 work-hours x $85 per Up to $11,550..... Up to $11,890.
hour = $340.
------------------------------------------------------------------------
* For replacement of 11 fasteners.

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:

2026-10-07 Airbus Canada Limited Partnership (Type Certificate
Previously Held by C Series Aircraft Limited Partnership (CSALP);
Bombardier, Inc.): Amendment 39-23347; Docket No. FAA-2025-2543;
Project Identifier MCAI-2025-00215-T.

(a) Effective Date

This airworthiness directive (AD) is effective July 1, 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-2025-09, dated February 24, 2025 (Transport Canada AD
CF-2025-09).

(d) Subject

Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

This AD was prompted by the discovery that titanium fasteners
had been incorrectly installed in the butt strap at the outer wing
box lower skin to center wing box interface in lieu of the correct
nickel alloy fasteners. The FAA is issuing this AD to address the
use of titanium fasteners. The unsafe condition, if not addressed,
could result in a reduction in joint strength, potential damage to
and loss of principal structure and fatigue critical structure, and
the risk of a fuel leak if the fastener fails and falls free from
the joint.

(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-2025-09.

(h) Exceptions to Transport Canada AD CF-2025-09

(1) Where Transport Canada AD CF-2025-09 refers to its effective
date, this AD requires using the effective date of this AD.
(2) Where Transport Canada AD CF-2025-09 refers to ``10 000
flight cycles'', this AD requires replacing that text with ``10,000
total flight cycles''.
(3) Where Transport Canada AD CF-2025-09 specifies to ``contact
ACLP for an approved disposition in accordance with the ACLP SB
procedure and perform the ACLP disposition instructions'', this AD
requires replacing that text with ``contact ACLP for an approved
disposition and perform the ACLP disposition instructions''.

(i) No Reporting Requirement

Although the material referenced in Transport Canada AD CF-2025-
09 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:
<a href="/cdn-cgi/l/email-protection#a3e2eeece0e3c5c2c28dc4ccd5">[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 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.

(k) Additional Information

For more information about this AD, contact Bill Ashforth,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des

[[Page 31345]]

Moines, WA 98198; phone: 206-231-3520; email: <a href="/cdn-cgi/l/email-protection#d8bab1b4b4f6b9abb0beb7aaacb098beb9b9f6bfb7ae">[email&#160;protected]</a>.

(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-2025-09, dated February 24, 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 <a href="/cdn-cgi/l/email-protection#da8e99f49bb3a8adb5a8aeb2b3b4bfa9a99eb3a8bfb9aeb3acbfa9f799b5b4a9b3bdb4bfa9bebfb4bbacb3bdbbb8b3b6b3aebff48e999aaeb9f4bdb9f4b9bb">[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#deb8acf0b7b0adaebbbdaab7b1b09eb0bfacbff0b9b1a8">[email&#160;protected]</a>.

Issued on May 11, 2026.
Brian Knaup,
Acting Deputy Director, Integrated Certificate Management Division,
Aircraft Certification Service.
[FR Doc. 2026-10486 Filed 5-26-26; 8:45 am]
BILLING CODE 4910-13-P

</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>

View on FederalRegister.gov →Plain-text source

Indexed from Federal Register on May 27, 2026.

This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.