[Federal Register Volume 90, Number 189 (Thursday, October 2, 2025)]
[Rules and Regulations]
[Pages 47526-47529]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-19388]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2025-0206; Project Identifier MCAI-2024-00525-T;
Amendment 39-23147; AD 2025-19-07]
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.
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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 an investigation that showed a
change in the feed-through connector O-ring material at a certain frame
increased the electrical bonding resistance due to the current torque
specification being inadequate. This AD requires electrical bonding
tests between the feed-through connectors and the forward side of the
bulkhead at a certain frame, and the installation of two electrical
bonding plates, as applicable. The FAA is issuing this AD to address
the unsafe condition on these products.
DATES: This AD is effective November 6, 2025.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of November 6,
2025.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2025-0206; 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:
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 [email protected]. You may find this material on the
Transport Canada website at tc.canada.ca/en/aviation.
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 regulations.gov under
Docket No. FAA-2025-0206-T.
FOR FURTHER INFORMATION CONTACT: Steven Dzierzynski, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; telephone
516-228-7300; email [email protected].
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 February 19, 2025 (90 FR
9876). The NPRM was prompted by AD CF-2024-32, dated September 11, 2024
(Transport Canada AD CF-2024-32) (also referred to as the MCAI), issued
by Transport Canada, which is the aviation authority for Canada. The
MCAI states an Airbus Canada Limited Partnership investigation revealed
a change in the feed-through connector O-ring material at frame (FR) 51
increased the electrical bonding resistance due to the current torque
specification being inadequate, which may lead to electrical bonding
levels which exceed allowable design limits, leaving the aircraft more
susceptible to electromagnetic interference (EMI), high-intensity
radiated fields (HIRF) and lightning strikes.
In the NPRM, the FAA proposed to require electrical bonding tests
to determine the resistance between the feed-through connectors and the
forward side of the bulkhead at FR 51, and the installation of two
electrical bonding plates if any connectors have more than the
specified resistance, as specified in Transport Canada AD CF-2024-32.
The FAA is issuing this AD to
[[Page 47527]]
address the unsafe condition on these products.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2025-0206.
Discussion of Final Airworthiness Directive
Comments
The FAA received a comment from Air Line Pilots Association,
International (ALPA) who supported the NPRM without change.
The FAA received additional comments from two commenters, including
Delta Air Lines (Delta) and one anonymous commenter. The following
presents the comments received on the NPRM and the FAA's response to
each comment.
Request for Adding an Exception
Delta requested the FAA add an exception to the proposed AD to
allow all electrical bonding tests to be completed in accordance with
paragraph A. of Transport Canada AD CF-2024-32, followed, before
further flight, by installation of electrical bonding plates in
accordance with paragraph B. of Transport Canada AD CF-2024-32. Delta
stated that, in the service information referenced in Transport Canada
AD CF-2024-32, the electrical bonding test at one feed-through
connector, followed immediately by the applicable corrective action, is
repeated 21 more times for a total of 22 feed-through connectors. Delta
stated the workflow in the proposed AD would be cumbersome, requiring
multiple handoffs between skills and that multiple handoffs increase
the possibility of turnover error through miscommunication. Delta
stated Transport Canada AD CF-2024-32 allows the completion all tests,
the identification of all discrepant connectors, and turnover of all
required corrective actions to technicians for completion of that
corrective action. Delta stated this reduces turnover error by only
turning over test results one time and the end result of reviewing all
connectors and the correction of any with unsatisfactory bonding
resistance, as applicable, before further flight remains the same.
The FAA agrees to clarify. The FAA notes that compliance times in
ADs take precedence over any compliance time specified in referenced
service information. The FAA notes that the time of ``followed
immediately by the applicable corrective action'' is not specifically
stated in the service information referenced in Transport Canada AD CF-
2024-32 but is inferred. Regardless of if the service information
contains a compliance time or not, operators must accomplish the
required actions within the compliance time specified in Transport
Canada AD CF-2024-32, except as specified in paragraphs (h)(1) and (2)
of this AD.
No exception is needed to this AD because, as noted by Delta,
Transport Canada AD CF-2024-32 allows for all connectors to be
inspected first and then the replacement of the discrepant connectors
must be done before further flight as specified in paragraph B. of
Transport Canada AD CF-2024-32. Since this AD mandates the compliance
times in Transport Canada AD CF-2024-32, this AD also allows for all
connectors to be inspected first. The FAA has not revised this AD in
this regard.
Request for Revising Reporting Requirement
Delta requested that the FAA add an exception to specify that where
Airbus Canada Service Bulletin BD500-534011 states to record the
electrical bonding test result in Appendix A of the service bulletin,
the AD would permit the use of either Appendix A or an equivalent form
developed by the operator and recording the same information. Delta
commented that paragraph (i) of the proposed AD removes the reporting
requirement, but it does not remove the requirement referenced in the
service information referenced in Transport Canada AD CF-2024-32 to
record the test results in Appendix A. Delta stated that they do not
object to the requirement to record test results but prefer to use
internally developed documentation. Delta stated that operators, as a
matter of practice, frequently develop their own documentation to
accomplish work instructions in a manner which complies with mandated
work instruction documents including the recording of test results.
Delta stated the mitigation of the unsafe condition is not affected by
the use of alternative forms, provided the required information is
reported.
The FAA agrees to clarify. In excluding a reporting requirement,
the FAA is also excluding the requirement to record test results and
send them to Airbus Canada, as specified in the Airbus Canada Service
Bulletin BD500-534011. Therefore, recording the test results is not
required by this AD and no change to this AD is necessary.
Request for Additional Reporting Requirements
An anonymous commenter stated the proposed AD should require
operators to document and report the results of electrical bonding
tests to the FAA. The commenter stated this data can support compliance
verification and provide insight into broader trends in bonding
degradation. The commenter noted that FAA Advisory Circular 43-210A,
dated May 31, 2018, encourages structured data collection and reporting
to support continued airworthiness actions.
The FAA disagrees with this request. In general, the FAA only
requires reporting if the results are needed to determinate the scope
of the identified unsafe condition or to develop corrective actions.
For this AD, reporting is not necessary as the installation of the
bonding plates addresses the unsafe condition. The FAA also notes that
Transport Canada did not include reporting requirements in Transport
Canada AD CF-2024-32. The FAA has not revised this AD in this regard.
Request for Information About Diagnostic Thresholds or Engineering
Criteria for Determining Bonding Plate Installation
An anonymous commenter stated they had questions about the specific
diagnostic thresholds or engineering criteria used to determine the
need for bonding plate installation, and how it will be communicated in
the instructions for continued airworthiness. The commenter stated that
clearly defined technical criteria reduce ambiguity and ensure
consistent implementation across operators.
The FAA agrees to clarify. As specified in Transport Canada AD CF-
2024-32, the electrical bonding tests are done to determine if the
bonding plate installation is necessary and those tests are done as
specified in the procedure of the service information identified in
Transport Canada AD CF-2024-32. That procedure specifies that if the
test results show that the value is more than the specified maximum
resistance, then the installation must be done.
Request for Evaluation of Proposed Timeframe
An anonymous commenter stated the proposed timeframe of 12,000
flight hours or 48 months should be evaluated for flexibility based on
operator type and fleet utilization, particularly for lower-utilization
carriers such as regional airlines. The commenter stated that flexible
compliance windows that still prioritize safety can reduce
[[Page 47528]]
maintenance burdens and support efficient fleet management.
The FAA disagrees with this request. In developing an appropriate
compliance time for this action, the FAA considered the compliance
times specified in Transport Canada AD CF-2024-32, the urgency
associated with the subject unsafe condition, and the availability of
required parts. In consideration of these items, the FAA has determined
that the actions required by this AD must be done within the compliance
time specified in this AD to ensure an acceptable level of safety.
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 in this regard.
Request for Information About Training
An anonymous commenter stated they had questions about the FAA
providing or endorsing any specific training materials or procedural
guidance to ensure maintenance technicians are equipped to perform
bonding tests and install bonding plates correctly. The commenter
stated the FAA's Aviation Maintenance Technician Handbook outlines the
importance of tailored training for novel procedures.
The FAA notes that training requirements are outside the scope of
this AD. The FAA has determined that accomplishing the electrical
bonding tests and the installation of two electrical bonding plates, as
required by this AD, addresses the identified unsafe condition. The
service information referenced in Transport Canada AD CF-2024-32
provides appropriate procedures for accomplishing those actions. The
FAA has not changed this AD in this regard.
Request for Coordination
An anonymous commenter stated the FAA should coordinate with the
European Union Aviation Safety Agency (EASA) and Transport Canada to
harmonize compliance expectations for affected aircraft types to avoid
duplicative testing or installations for multinational operators and to
support global safety consistency. The commenter noted that
International Civil Aviation Organization (ICAO) Annex 19 supports
international alignment of airworthiness directives to improve safety
and efficiency.
The FAA acknowledges the request. The FAA has coordinated with
Transport Canada. As specified in the NPRM, pursuant to the FAA's
bilateral agreement with the State of Design Authority for the affected
aircraft, Transport Canada notified the FAA of the unsafe condition
described in the Transport Canada AD referenced above. However, the FAA
will not communicate directly with EASA regarding this AD, or the
Transport Canada AD, because Transport Canada, as the State of Design
Authority, has communicated with EASA regarding the Transport Canada
AD. The FAA has not changed this AD in this regard.
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 this product. Except for
minor editorial changes, and any other changes described previously,
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-2024-32 specifies procedures for electrical
bonding tests to determine the resistance between the feed-through
connectors and the forward side of the bulkhead at FR 51, and the
installation of two electrical bonding plates if any connectors have
more than the specified resistance. 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 36 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:
Estimated Costs for Required Actions
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Cost per Cost on U.S.
Labor cost Parts cost product operators
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23 work-hours x $85 per hour = $1,955........................ $0 $1,955 $70,380
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Estimated Costs of On-Condition Actions
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Labor cost Parts cost Cost per product
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Up to 20 work-hours x $85 per Up to $10,936 per Up to $12,636 per
hour = $1,700 per connector. connector. connector.
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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
This AD will not have federalism implications under Executive Order
13132. This AD will not have a
[[Page 47529]]
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:
2025-19-07 Airbus Canada Limited Partnership (Type Certificate
Previously Held by C Series Aircraft Limited Partnership (CSALP);
Bombardier, Inc.): Amendment 39-23147; Docket No. FAA-2025-0206;
Project Identifier MCAI-2024-00525-T.
(a) Effective Date
This airworthiness directive (AD) is effective November 6, 2025.
(b) Affected ADs
None.
(c) Applicability
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-2024-32, dated September 11, 2024 (Transport Canada AD
CF-2024-32).
(d) Subject
Air Transport Association (ATA) of America Code 92, Electrical
system installation.
(e) Unsafe Condition
This AD was prompted by an investigation that showed a change in
the feed-through connector O-ring material at frame (FR) 51
increased the electrical bonding resistance due to the current
torque specification being inadequate. The FAA is issuing this AD to
address the unsafe condition, which if not addressed, could result
in airplane susceptibility to electromagnetic interference (EMI),
high-intensity radiated fields (HIRF) and lightning strikes.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Requirements
Except as specified in paragraphs (h) and (i) of this AD: Comply
with all required actions and compliance times specified in, and in
accordance with Transport Canada AD CF-2024-32.
(h) Exception to Transport Canada AD CF-2024-32
(1) Where Transport Canada AD CF-2024-32 refers to its effective
date, this AD requires using the effective date of this AD.
(2) Where Transport Canada AD CF-2024-32 refers to hours air
time, this AD requires using flight hours.
(i) No Reporting Requirement
Although the material referenced in Transport Canada AD CF-2024-
32 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, AIR-
520, Continued Operational Safety Branch, FAA, send it to the
attention of the person identified in paragraph (k) of this AD and
email to: [email protected]. 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.
(3) Required for Compliance (RC): Except as required by
paragraph (j)(2) of this AD, if any material contains procedures or
tests that are identified as RC, those procedures and tests must be
done to comply with this AD; any procedures or tests that are not
identified as RC are recommended. Those procedures and tests that
are not identified as RC may be deviated from using accepted methods
in accordance with the operator's maintenance or inspection program
without obtaining approval of an AMOC, provided the procedures and
tests identified as RC can be done and the airplane can be put back
in an airworthy condition. Any substitutions or changes to
procedures or tests identified as RC require approval of an AMOC.
(k) Additional Information
For more information about this AD, contact Steven Dzierzynski,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; telephone 516-228-7300; email [email protected].
(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-2024-32, dated September 11, 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 [email protected]; website 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 [email protected].
Issued on September 16, 2025.
Peter A. White,
Deputy Director, Integrated Certificate Management Division, Aircraft
Certification Service.
[FR Doc. 2025-19388 Filed 10-1-25; 8:45 am]
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