DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1003; Project Identifier MCAI-2023-00712-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 supersede Airworthiness Directive (AD)
2023-11-01, which applies to certain Bombardier, Inc., Model BD-100-
1A10 airplanes. AD 2023-11-01 requires a records check and replacement
of affected left-hand (LH) direct current power center (DCPC) units. AD
2023-11-01 also provides optional terminating action for the records
check and replacement. However, it has been determined that certain LH
DCPC units require additional modification. This proposed AD would
require checking maintenance records of certain airplanes, replacing
certain DCPC units, and modifying certain DCPC units. This proposed AD
would also expand the applicability of AD 2023-11-01. This proposed AD
would also prohibit the installation of affected parts. 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 June 10,
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.
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-2024-1003; 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 service information identified in this NPRM, contact
Bombardier Business Aircraft Customer Response Center, 400 Cote-
Vertu Road West, Dorval, Quebec H4S 1Y9, Canada; telephone 514-
855-2999; email ac.yul@aero.bombardier.com; website bombardier.com.
You may view this service information 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 9-avs-nyaco-cos@faa.gov.

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-2024-1003; Project Identifier
MCAI-2023-00712-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
9-avs-nyaco-cos@faa.gov. Any commentary that the FAA receives which is not
specifically designated as CBI will be placed in the public docket for
this rulemaking.

Background

The FAA issued AD 2023-11-01, Amendment 39-22446 (88 FR 44042, July
11, 2023) (AD 2023-11-01), for certain Bombardier, Inc., Model BD-100-
1A10 airplanes. AD 2023-11-01 was prompted by an MCAI originated by
Transport Canada, which is the aviation authority for Canada. Transport
Canada issued AD CF-2022-28, dated May 26, 2022 (Transport Canada AD
CF-2022-28), to correct an unsafe condition.
AD 2023-11-01 requires a records check and replacement of affected
LH DCPC units, and provides optional terminating action for those
actions. The FAA issued AD 2023-11-01 to address erratic indications,
which could cause the flightcrew to turn off fully operational
electrical power sources, leading to partial or complete loss of
electrical power. The unsafe condition, if not addressed, could result
in loss of flight displays and reduced controllability of the airplane.

Actions Since AD 2023-11-01 Was Issued

The preamble to AD 2023-11-01 explains that the FAA considers the
requirements ``interim action'' and was considering further rulemaking.
The FAA has now determined that further rulemaking is indeed necessary,
and this NPRM follows from that determination.
Transport Canada superseded AD CF-2022-28, dated May 26, 2022
(Transport Canada AD CF-2022-28), and issued Transport Canada AD CF-
2023-35, dated May 26, 2023 (Transport Canada AD CF-2023-35) (referred
to after this as the MCAI), to correct an unsafe condition on all
Bombardier, Inc., Model BD-100-1A10 airplanes. The MCAI states that
airplanes could experience misleading electrical system status
indications (push button annunciators (PBA) and engine indicating and
crew alerting system (EICAS)) as a result of contamination of
electrical contacts in the LH DCPC internal communication data bus.
These erratic indications could cause the flightcrew to turn off fully
operational electrical power sources, leading to partial or complete
loss of electrical power. Loss of electrical power could result in the
loss of flight displays and reduced controllability of the airplane.
The MCAI retains the requirement to verify the airplane records,
requires removal of certain LH DCPC units for cleaning, and requires
modification of certain LH DCPC units by adding a protective layer of
tape to prevent the ingress of contaminants into the printed circuit
board cage. The MCAI also prohibits installation of affected parts. The
FAA is proposing this AD to address the unsafe condition on these
products.
You may examine the MCAI in the AD docket at regulations.gov under
Docket No. FAA-2024-1003.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Bombardier Service Bulletins 100-24-29 and 350-24-
004, both Revision 01, both dated July 27, 2023. This service
information specifies procedures for a records check to determine the
total flight hours and replacement of affected LH DCPC units (part
numbers 975GC02Y04, 975GC0Y05, 975GC02Y06, and 975GC02Y07). These
documents are distinct since they apply to different airplane
configurations.
The following documents specify procedures for removing LH DCPC
units.
Task 24-61-01-000-801, Removal of the DC Power Center
(DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation,
Bombardier Challenger 300 Aircraft Maintenance Manual, Part Two--
Publication No. CH 300 AMM, Revision 82, dated November 9, 2023. (For
obtaining the task for the Bombardier Challenger 300 Aircraft
Maintenance Manual, Part Two--Publication No. CH 300 AMM, use Document
Identification No. CH 300 AMM.)
Task 24-61-01-000-801, Removal of the DC Power Center
(DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation,
Bombardier Challenger 350 Aircraft Maintenance Manual, Part Two--
Publication No. CH 350 AMM, Revision 38, dated November 9, 2023. (For
obtaining the task for the Bombardier Challenger 350 Aircraft
Maintenance Manual, Part Two--Publication No. CH 350 AMM, use Document
Identification No. CH 350 AMM.)
The following documents specify procedures for installing LH DCPC
units.
Task 24-61-01-400-801, Installation of the DC Power Center
(DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation,
Bombardier Challenger 300 Aircraft Maintenance Manual, Part Two--
Publication No. CH 300 AMM, Revision 82, dated November 9, 2023. (For
obtaining the task for the Bombardier Challenger 300 Aircraft
Maintenance Manual, Part Two--Publication No. CH 300 AMM, use Document
Identification No. CH 300 AMM.)
Task 24-61-01-400-801, Installation of the DC Power Center
(DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation,
Bombardier Challenger 350 Aircraft Maintenance Manual, Part Two--
Publication No. CH 350 AMM, Revision 38, dated November 9, 2023. (For
obtaining the task for the Bombardier Challenger 350 Aircraft
Maintenance Manual, Part Two--Publication No. CH 350 AMM, use Document
Identification No. CH 350 AMM.)
The following documents specify procedures for testing LH DCPC
units.
Task 24-61-01-720-801, Functional Test of the DC Power
Center (DCPC), Subject 24, 61-01, DC Power Center (DCPC), Adjustment/
Test, Bombardier Challenger 300 Aircraft Maintenance Manual, Part Two--
Publication No. CH 300 AMM, Revision 82, dated November 9, 2023. (For
obtaining the task for the Bombardier Challenger 300 Aircraft
Maintenance Manual, Part Two--Publication No. CH 300 AMM, use Document
Identification No. CH 300 AMM.)
Task 24-61-01-720-801, Functional Test of the DC Power
Center (DCPC), Subject 24, 61-01, DC Power Center (DCPC), Adjustment/
Test, Bombardier Challenger 350 Aircraft Maintenance Manual, Part Two--
Publication No. CH 350 AMM, Revision 38, dated November 9, 2023. (For
obtaining the task for the Bombardier Challenger 350 Aircraft
Maintenance Manual, Part Two--Publication No. CH 350 AMM, use Document
Identification No. CH 350 AMM.)
This proposed AD would also require the following service
information, which the Director of the Federal Register approved for
incorporation by reference as of August 15, 2023 (88 FR 44042, July 11,
2023).
Bombardier Service Bulletin 100-24-29, dated April 9,
2021.
Bombardier Service Bulletin 100-24-30, dated November 29,
2022.
Bombardier Service Bulletin 350-24-004, dated April 9,
2021.
Bombardier Service Bulletin 350-24-005, dated November 29,
2022.
This service information 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 service information referenced above. The FAA is issuing this NPRM
after determining that 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 expand the applicability of AD 2023-11-01
and require the actions specified in the service information described
previously, except as discussed under ``Differences Between this
Proposed AD and the MCAI.''

Differences Between This Proposed AD and the MCAI

Although the MCAI only requires LH DCPC P/N 975GC02Y07 that have
been cleaned or replaced to be modified to P/N 975GC02Y08, this
proposed AD would also require that LH DCPC P/N 975GC02Y04, 975GC02Y05,
and 975GC02Y06 that have been cleaned or replaced, as required by
Transport Canada AD CF-2022-28 (which corresponds to AD 2023-11-01), to be
replaced with LH DCPC P/N 975GC02Y08.
Additionally, although the MCAI only requires the test of the DCPC
logic and protections after modification of P/N 975GC02Y07 that have
been cleaned or replaced, as required by Transport Canada AD CF-2022-
28, to P/N 975GC02Y08, this proposed AD also requires the functional
test of the LH DCPC unit.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 356 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
AD:

Estimated Costs for Required Actions

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:

Estimated Costs of On-Condition Actions

According to the manufacturer, some or all of the costs of this
proposed AD may be covered under warranty, thereby reducing the cost
impact on affected individuals. The FAA does not control warranty
coverage for affected individuals. As a result, the FAA has included
all known costs in the cost estimate.

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 has 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) 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 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

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]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive (AD) 2023-11-01, Amendment 39-22446
(88 FR 44042, July 11, 2023); and

b. Adding the following new AD: