2024-08347. Airworthiness Directives; Bombardier, Inc., Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

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: [phone].

• 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 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone [phone]; email [e-mail]; 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 [phone]; email [e-mail].

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 [phone]; email [e-mail]. 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

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Records check	1 work-hours × $85 per hour = $85	$0	$85	$30,260
New proposed actions (modification)	2 work-hours × $85 per hour = $170	0	170	60,520

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

Labor cost	Parts cost	Cost per product
7 work-hours × $85 per hour = $595	Up to $35,000	Up to $35,595.

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.

§ 39.13

[Amended]

2. The FAA amends § 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:

Bombardier, Inc.: Docket No. FAA-2024-1003; Project Identifier MCAI-2023-00712-T.

(a) Comments Due Date

The FAA must receive comments on this airworthiness directive (AD) by June 10, 2024.

(b) Affected ADs

This AD replaces AD 2023-11-01, Amendment 39-22446 (88 FR 44042, July 11, 2023) (AD 2023-11-01).

(c) Applicability

This AD applies to all Bombardier, Inc., Model BD-100-1A10 airplanes, certificated in any category.

(d) Subject

Air Transport Association (ATA) of America Code 24, Electrical Power.

(e) Unsafe Condition

This AD was prompted by multiple reports of erratic electrical system status on the push button annunciators (PBAs) and the engine instrument and crew alerting system (EICAS) while on-ground and during flight, and by the determination that certain direct current power center (DCPC) units require additional modification or replacement. The FAA is issuing this AD 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.

(f) Compliance

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

(g) Records Check

For any left-hand (LH) DCPC unit having part number (P/N) 975GC02Y04, 975GC02Y05, 975GC02Y06, or 975GC02Y07 that was not cleaned before the effective date of this AD as specified in Safran Service Bulletin 975GC02Y-24-018 or replaced before the effective date of this AD as specified in Bombardier Service Bulletin 100-24-29 or Bombardier Service Bulletin 350-24-004: Within 60 days after the effective date of this AD, verify the total flight hours of the LH DCPC unit since the date of manufacture by doing a records check in accordance with paragraph 2.B.(1) of the Accomplishment Instructions of the applicable service bulletin identified in paragraphs (g)(1) and (2) of this AD.

(1) For airplanes having serial numbers 20001 through 20500 inclusive, use Bombardier Service Bulletin 100-24-29, dated April 9, 2021, or Revision 01, dated July 27, 2023. As of the effective date of this AD, use only Bombardier Service Bulletin 100-24-29, Revision 01, dated July 27, 2023.

(2) For airplanes having serial numbers 20501 through 20999 inclusive, use Bombardier Service Bulletin 350-24-004, dated April 9, 2021, or Revision 01, dated July 27, 2023. As of the effective date of this AD, use only Bombardier Service Bulletin 350-24-004, Revision 01, dated July 27, 2023.

(h) Replacement of the LH DCPC

If, during the records check required by paragraph (g) of this AD, the total flight hours since date of manufacture of the LH DCPC unit is equal to or more than 3,500 total flight hours as of the effective date of this AD, and the LH DCPC was not previously cleaned as specified in Safran Service Bulletin 957GC02Y-24-018, or replaced as specified in Bombardier Service Bulletin 100-24-29 or Bombardier Service Bulletin 350-24-004: Within 12 months after the effective date of this AD, remove, replace with LH DCPC P/N 975GC02Y08, test the DCPC logic and protection cards, and do the functional test for the LH DCPC unit, in accordance with the applicable service information specified in paragraphs (h)(1) through (8) of this AD. If any test fails, do corrective actions and repeat the test before further flight until the test passes.

(1) 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.

(2) 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.

(3) 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.

(4) 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.

(5) For airplanes having serial number 20001 through 20500 inclusive, use paragraph 2.D. of the Accomplishment Instructions of Bombardier Service Bulletin 100-24-30, dated November 29, 2022.

(6) For airplanes having serial number 20501 through 20999 inclusive, use paragraph 2.D. of the Accomplishment Instructions of Bombardier Service Bulletin 350-24-005, dated November 29, 2022.

(7) 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.

(8) 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.

(i) Exception to the Service Information

Although the note in paragraph 2.B.(4) of the Accomplishment Instructions of Bombardier Service Bulletin 100-24-29, dated April 9, 2021, and Revision 01, dated July 27, 2023, and Bombardier Service Bulletin 350-24-004, dated April 9, 2021, and Revision 01, dated July 27, 2023, specify that actions will reset “the unit total flight hours to zero at date of incorporation,” this AD does not include that requirement.

(j) Modification

For LH DCPC P/N 975GC02Y07 units that were cleaned before the effective date of this AD as specified in Safran Service Bulletin 975GC02Y-24-018, or replaced before the effective date of this AD as specified in Bombardier Service Bulletin 100-24-29 or Bombardier Service Bulletin 350-24-004: Within 12 months after the effective date of this AD, modify each LH DCPC P/N 975GC02Y07 into LH DCPC P/N 975GC02Y08, in accordance with paragraph 2.C. of the Accomplishment Instructions of the applicable service bulletin identified in paragraph (j)(1) or (2) of this AD. Before further flight after the modification, test the DCPC logic and protection cards in accordance with paragraph 2.D. of the Accomplishment Instructions of the applicable service bulletin identified in paragraph (j)(1) or (2) of this AD, and do the functional test for the LH DCPC unit, in accordance with the applicable service information specified in paragraphs (j)(3) or (4) of this AD. If any test fails, do corrective actions and repeat the test before further flight until the test passes.

(1) For airplanes having serial number 20001 through 20500 inclusive, use Bombardier Service Bulletin 100-24-30, dated November 29, 2022.

(2) For airplanes having serial number 20501 through 20999 inclusive, use Bombardier Service Bulletin 350-24-005, dated November 29, 2022.

(3) 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.

(4) 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.

(k) Replacement of Certain LH DCPC P/N 975GC02Y04, 975GC02Y05, and 975GC02Y06

For LH DCPC P/N 975GC02Y04, 975GC02Y05, and 975GC02Y06 that were cleaned before the effective date of this AD as specified in Safran Service Bulletin 975GC02Y-24-018, or replaced before the effective date of this AD as specified in Bombardier Service Bulletin 100-24-29 or Bombardier Service Bulletin 350-24-004: Within 12 months after the effective date of this AD, remove, replace with LH DCPC P/N 975GC02Y08, test the DCPC logic and protection cards, and do the functional test for the LH DCPC unit, in accordance with the applicable service information specified in paragraphs (h)(1) through (8) of this AD. If any test fails, do corrective actions and repeat the test before further flight until the test passes.

(l) Parts Installation Prohibition

As of 60 days from the effective date of this AD, it is prohibited to install a LH DCPC with P/N 975GC02Y04, 975GC02Y05, 975GC02Y06, or 975GC02Y07, on any airplane.

(m) Additional AD Provisions

(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 (n)(2) of this AD. Information may be emailed to: [e-mail].

(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.

(n) Additional Information

(1) Refer to Transport Canada AD CF-2023-35, dated May 26, 2023, for related information. This Transport Canada AD may be found in the AD docket at regulations.gov under Docket No. FAA-2024-1003.

(2) For more information about this AD, contact Steven Dzierzynski, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone [phone]; email [e-mail].

(o) Material Incorporated by Reference

(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use this service information as applicable to do the actions required by this AD, unless this AD specifies otherwise.

(3) The following service information was approved for IBR on [DATE 35 DAYS AFTER PUBLICATION OF THE FINAL RULE].

(i) Bombardier Service Bulletin 100-24-29, Revision 01, dated July 27, 2023.

(ii) Bombardier Service Bulletin 350-24-004, Revision 01, dated July 27, 2023.

(iii) Bombardier Challenger 300 Aircraft Maintenance Manual, Part Two, Publication No. CH 300 AMM, Revision 82, dated November 9, 2023.

(A) Task 24-61-01-000-801, Removal of the DC Power Center (DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation.

Note 1 to paragraph (o)(3)(iii)(A): For obtaining the tasks specified in paragraphs (o)(3)(iii)(A) through (C) of this AD for the Bombardier Challenger 300 Aircraft Maintenance Manual, Part Two, Publication No. CH 300 AMM, use Document Identification No. CH 300 AMM.

(B) Task 24-61-01-400-801, Installation of the DC Power Center (DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation.

(C) Task 24-61-01-720-801, Functional Test of the DC Power Center (DCPC), Subject 24, 61-01, DC Power Center (DCPC), Adjustment/Test.

(iv) Bombardier Challenger 350 Aircraft Maintenance Manual, Part Two, Publication No. CH 350 AMM, Revision 38, dated November 9, 2023.

(A) Task 24-61-01-000-801, Removal of the DC Power Center (DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation.

Note 2 to paragraph (o)(3)(iv)(A): For obtaining the tasks specified in paragraphs (o)(3)(iv)(A) through (C) of this AD for the Bombardier Challenger 350 Aircraft Maintenance Manual, Part Two—Publication No. CH 350 AMM, use Document Identification No. CH 350 AMM.

(B) Task 24-61-01-400-801, Installation of the DC Power Center (DCPC), Subject 24-61-01, DC Power Center (DCPC), Removal/Installation.

(C) Task 24-61-01-720-801, Functional Test of the DC Power Center (DCPC), Subject 24, 61-01, DC Power Center (DCPC), Adjustment/Test.

(4) The following service information was approved for IBR on August 15, 2023 (88 FR 44042, July 11, 2023).

(i) Bombardier Service Bulletin 100-24-29, dated April 9, 2021.

(ii) Bombardier Service Bulletin 100-24-30, dated November 29, 2022.

(iii) Bombardier Service Bulletin 350-24-004, dated April 9, 2021.

(iv) Bombardier Service Bulletin 350-24-005, dated November 29, 2022.

(5) For service information identified in this AD, contact Bombardier Business Aircraft Customer Response Center, 400 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone [phone]; email [e-mail]; website bombardier.com.

(6) 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.

(7) 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 [e-mail].

Issued on April 15, 2024.

Victor Wicklund,

Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.