[Federal Register Volume 89, Number 162 (Wednesday, August 21, 2024)]
[Proposed Rules]
[Pages 67577-67580]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-18478]


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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]
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 certain Bombardier, Inc., Model BD-100-1A10 airplanes. This 
proposed AD was prompted by uncommanded horizontal stabilizer motion 
during several in-service events caused by a problem with the trim 
switch wiring. This proposed AD would require installing the pitch/roll 
trim switch relays. 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 October 7, 
2024.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:

     Federal eRulemaking Portal: Go to regulations.gov. Follow 
the instructions for submitting comments.

[[Page 67578]]

     Fax: 202-493-2251.
     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.
     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 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 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:
     For Bombardier material identified in this proposed 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.

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:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2024-2023; Project Identifier 
MCAI-2023-01246-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 
the 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 
regulations.gov, 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 
Steven Dzierzynski, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, 
Suite 410, Westbury, NY 11590; telephone 516-228-7300; email [email protected]. Any commentary that the FAA receives that 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-2023-77, dated December 7, 2023 
(Transport Canada AD CF-2023-77) (also referred to after this as the 
MCAI), to correct an unsafe condition on certain Bombardier, Inc., 
Model BD-100-1A10 airplanes. The MCAI states that during several in-
service events, following a STAB TRIM FAULT advisory message and an 
auto-pilot 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. Transport Canada issued AD CF-2022-03, dated 
February 1, 2022 (Transport Canada AD CF-2022-03) (which corresponds to 
FAA AD 2022-12-02 (87 FR 34125, June 6, 2022)), as a mitigating action 
to require the use of an Expanded Pitch Trim Pre-Flight Check, the use 
of Trim Malfunction procedures, the revision of the AP STAB TRIM FAIL 
caution and STAB TRIM FAULT advisory procedures to address this unsafe 
condition. During the ongoing investigation by Bombardier and the 
supplier of the horizontal stabilizer pitch/roll trim switch (trim 
switch), Bombardier determined that one of the springs within the trim 
switch had failed. The supplier of the spring was changed in 2019. The 
majority of observed trim switch failures occurred in trim switches 
that were manufactured after 2019. Consequently, Transport Canada 
issued AD CF-2022-24, dated May 2, 2022 (Transport Canada AD CF-2022-
24) (which corresponds to FAA AD 2023-02-01 (88 FR 7856, February 7, 
2023)), to remove and replace the defective springs in the affected 
fleet. At that time, Bombardier also found an existing issue with the 
trim switch wiring installation. The problem with the trim switch 
wiring was identified as the main cause of the in-service unintended 
horizontal stabilizer motion events. On this airplane model, manual 
trim is accomplished by enabling the trim function by both pressing 
down on the trim switch and simultaneously moving the switch up, down, 
left, or right, as required to command trim in pitch or roll. The 
current wiring of the system is such that an enable signal originating 
from either the pilot-side or the copilot-side trim switch will enable 
both sides. By design, the pilot-side trim commands have priority over 
the copilot-side trim commands. Thus, 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. Transport Canada AD CF-2023-77 requires changes to the trim 
switch wiring installation to ensure the pilot and co-pilot trim 
Enable/Arm switch signals remain segregated in both roll and pitch 
axes.
    The FAA is proposing 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.

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. 
The material specifies procedures to install the pitch/roll trim switch 
relays. The

[[Page 67579]]

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.

FAA's Determination

    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 and 
material referenced above. 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.

Proposed AD Requirements in This NPRM

    This proposed AD would require accomplishing the actions specified 
in the material already described.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 359 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

                                      Estimated Costs for Required Actions
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               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

    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-2024-2023; Project Identifier MCAI-
2023-01246-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by October 7, 2024.

(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

[[Page 67580]]

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 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 August 12, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-18478 Filed 8-20-24; 8:45 am]
BILLING CODE 4910-13-P