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[Federal Register Volume 90, Number 26 (Monday, February 10, 2025)]
[Rules and Regulations]
[Pages 9207-9209]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-02397]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-2023; Project Identifier MCAI-2023-01246-T; 
Amendment 39-22934; AD 2025-02-01]
RIN 2120-AA64

Airworthiness Directives; 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 Bombardier, Inc., Model BD-100-1A10 airplanes. This AD was 
prompted by uncommanded horizontal stabilizer motion during several in-
service events caused by a problem with the trim switch wiring. This AD 
requires installing the pitch/roll trim switch relays. The FAA is 
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective March 17, 2025.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of March 17, 
2025.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-2023; 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 Bombardier material identified in this AD, contact 
Bombardier Business Aircraft Customer Response Center, 400 C[ocirc]te-
Vertu Road West, Dorval, Qu[eacute]bec H4S 1Y9, Canada; phone 514-855-
2999; email bombardier.com">ac.yul@aero.bombardier.com; website bombardier.com.
     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-2024-2023.

FOR FURTHER INFORMATION CONTACT: Steven Dzierzynski, Aviation Safety 
Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; 
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 Bombardier, 
Inc., Model BD-100-1A10 airplanes. The NPRM published in the Federal 
Register on August 21, 2024 (89 FR 67577). The NPRM was prompted by AD 
CF-2023-77, dated December 7, 2023, issued by Transport Canada, which 
is the aviation authority for Canada (Transport Canada AD CF-2023-77) 
(referred to after this as the MCAI). The MCAI states that during 
several in-service events, following a STAB TRIM FAULT advisory message 
and an autopilot disconnect, both pilot and co-pilot commands to trim 
the horizontal stabilizer nose-up resulted in a nose-down movement of 
the horizontal stabilizer. In some events, the horizontal stabilizer 
reached the full travel nose-down position before the crew recognized 
the nature of the problem, and quickly recovered control of the 
airplane for safe landing. An issue with the trim switch wiring 
installation was identified as the main cause of the in-service 
unintended horizontal stabilizer motion events. The current wiring of 
the system is such that, if trim is enabled via the copilot-side trim 
switch, and the pilot-side trim switch malfunctions, it is possible for 
trim to move uncommanded or opposite to the intended direction.
    In the NPRM, the FAA proposed to require installing the pitch/roll 
trim switch relays. The FAA is issuing this AD to address the problem 
with the trim switch wiring, which is the main cause of the uncommanded 
horizontal stabilizer motion. The unsafe condition, if not addressed, 
could result in increased crew workload and reduced safety margins, and 
if the flightcrew is unable to regain control of the horizontal 
stabilizer, would result in loss of control of the airplane and high 
control forces.
    You may examine the MCAI in the AD docket at regulations.gov under 
Docket No. FAA-2024-2023.

Discussion of Final Airworthiness Directive

Comments

    The FAA received a comment from an individual. The following 
presents the comment received on the NPRM and the FAA's response to 
that comment.

Request To Develop a Preventive Maintenance Program To Assess Affected 
Airplanes

    The commenter suggested that Bombardier should develop a preventive 
maintenance program to assess if the proposed AD would apply to the 
same airplanes of different serial numbers. The commenter referenced 
another AD (PA-28 wing spar), pointing out that operators were only 
required to repair the affected part if damage or failure was detected. 
The commenter noted that a preventive replacement of the affected part 
was not required, and that is something that Bombardier should consider 
researching. The commenter further asserted that this would only be 
considered if engineers and researchers can show with evidence that 
periodic inspections outweigh the cost of a preventive repair.
    The FAA does not agree. The NPRM specifically stated that ``The FAA 
is issuing this NPRM after determining that the unsafe condition 
described previously is likely to exist or develop on other products of 
the same type design.'' Bombardier has confirmed that airplanes having 
serial number 20937 and subsequent, also subject to the unsafe 
condition addressed in this AD, were modified in production. Further, 
this AD bypasses any type of preventive maintenance inspection prior to 
modifying the trim switches because Bombardier has determined that the 
trim switches have a problem with the wiring installation, which is why 
all affected trim switches must be rewired (not simply inspected and 
repaired only if damage or failure is found). No change has been made 
to this AD in this regard.

Conclusion

    This product has been approved by the aviation authority of another 
country and is approved for operation in the United States. Pursuant to 
the FAA's bilateral agreement with this State of Design Authority, it 
has notified the FAA of the unsafe condition described in the MCAI 
referenced above. The FAA reviewed the relevant data, considered the 
comment received, and determined that air safety requires adopting this 
AD

[[Page 9208]]

as proposed. Accordingly, the FAA is issuing this AD to address the 
unsafe condition on this product. 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 Bombardier Service Bulletin 100-27-22 and 
Bombardier Service Bulletin 350-27-012, both dated December 29, 2022. 
This material specifies procedures to install the pitch/roll trim 
switch relays. The installation includes reworking the plate assembly; 
installing relay bracket assemblies, relays, ground return stacks on 
the relay bracket assemblies, wires for the relays, and line 
replaceable units and trays on the left-side and right-side avionic 
racks; and performing operational testing. These documents are distinct 
since they apply to different airplane serial numbers. 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 359 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
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Up to 45 work-hours x $85 per hour = Up        $3,582   Up to $7,407...............  Up to $2,659,113.
 to $3,825.
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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 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:

2025-02-01 Bombardier, Inc.: Amendment 39-22934; Docket No. FAA-
2024-2023; Project Identifier MCAI-2023-01246-T.

(a) Effective Date

    This airworthiness directive (AD) is effective March 17, 2025.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Bombardier, Inc., Model BD-100-1A10 
airplanes, certificated in any category, serial numbers 20003 
through 20500 inclusive and 20501 through 20936 inclusive.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by uncommanded horizontal stabilizer motion 
during several in-service events caused by a problem with the trim 
switch wiring. The FAA is issuing this AD to address the problem 
with the trim switch wiring. The unsafe condition, if not addressed, 
could result in increased crew workload and reduced safety margins, 
and if the flightcrew is unable to regain control of the horizontal 
stabilizer, would result in loss of control of the airplane and high 
control forces.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Installation of Pitch/Roll Trim Switch Relays and Tests

    Within 3,000 flight hours or 5 years, whichever occurs first, 
from the effective date of this AD, install the pitch/roll trim 
switch relays, in accordance with sections 2.B. and 2.C. of the 
Accomplishment Instructions of the applicable material specified in 
paragraph (g)(1) or (2) of this AD.
    (1) Bombardier Service Bulletin 100-27-22, dated December 29, 
2022 (for airplane serial numbers 20003 through 20500 inclusive).
    (2) Bombardier Service Bulletin 350-27-012, dated December 29, 
2022 (for airplane serial numbers 20501 through 20936 inclusive).

(h) 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, mail it to the address identified 
in paragraph (i) of this AD. Information may be emailed 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

[[Page 9209]]

by the Manager, International Validation Branch, FAA; or Transport 
Canada; or Bombardier, Inc.'s Transport Canada Design Approval 
Organization (DAO). If approved by the DAO, the approval must 
include the DAO-authorized signature.

(i) Additional Information

    For more information about this AD, contact Steven Dzierzynski, 
Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, 
Westbury, NY 11590; telephone 516-228-7300; email [email protected].

(j) 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) Bombardier Service Bulletin 100-27-22, dated December 29, 
2022.
    (ii) Bombardier Service Bulletin 350-27-012, dated December 29, 
2022.
    (3) For Bombardier material identified in this AD, contact 
Bombardier Business Aircraft Customer Response Center, 400 
C[ocirc]te-Vertu Road West, Dorval, Qu[eacute]bec H4S 1Y9, Canada; 
phone 514-855-2999; email bombardier.com">ac.yul@aero.bombardier.com; website 
bombardier.com.
    (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 January 16, 2025.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2025-02397 Filed 2-7-25; 8:45 am]
BILLING CODE 4910-13-P
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