# [Amended]
**AGENCY:**
Federal Aviation Administration (FAA), DOT.
**ACTION:**
Notice of proposed rulemaking (NPRM).
**SUMMARY:**
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier, Inc., Model BD-700-2A12 airplanes. This proposed AD was prompted by reports that the pivot door pressure seals on the thrust reverser fixed structure were found disbonded or missing on several airplanes. This proposed AD would require inspecting the pivot door pressure seals and accomplishing applicable corrective actions. This proposed AD would also require a functional test of the thrust reversers. 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 July 8, 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-2024-1468; 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, Inc. service information, contact Bombardier Business Aircraft Customer Response Center, 400 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone 514-855-2999; email *[email protected];* website: *bombardier.com.*
• You may view this service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th Street, Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195.
**FOR FURTHER INFORMATION CONTACT:**
Joseph Catanzaro, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7366; 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-2024-1468; Project Identifier MCAI-2023-00975-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 Joseph Catanzaro, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7366; email *[email protected].* Any commentary that the FAA receives which 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-2023-61, dated August 16, 2023 (Transport Canada AD CF-2023-61) (also referred to after this as the MCAI), to correct an unsafe condition on certain serial-numbered Bombardier, Inc., Model BD-700-2A12 airplanes. The MCAI states that the pivot door pressure seals on the thrust reverser fixed structure were found disbonded or missing on several airplanes. The investigation revealed that the seal disbond condition was caused by the variation in the installation process of the seals during bonding surface preparation and sealant application. The unsafe condition, if not addressed, could result in engine thrust loss due to flow path overboard leakage during forward thrust operation and reduce airplane performance during one-engine inoperative conditions in climb margin and ceiling altitude.
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-2024-1468.
**Related Service Information Under 1 CFR Part 51**
The FAA reviewed Bombardier Service Bulletin 700-78-7501, Revision 01, dated July 13, 2023. This service information specifies procedures for a one-time general visual inspection for discrepant (missing, damaged, or disbonded) thrust reverser pivoting door pressure seals, a bonding check of the pivoting door seals, and repair or replacement of discrepant seals. This service information also specifies procedure for performing a functional test of the thrust reverser.
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 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 service information already described.
**Costs of Compliance**
The FAA estimates that this AD, if adopted as proposed, would affect 53 airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD:
| Labor cost | Parts cost | Cost per | Cost on U.S. |
| --- | --- | --- | --- |
| 6 work-hours × $85 per hour = $510 | $0 | $510 | $27,030 |
The FAA estimates the following costs to do any necessary on-condition action 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:
| Labor cost | Parts cost | Cost per product |
| --- | --- | --- |
| Up to 24 work-hours × $85 per hour = $2,040 | $4,850 | Up to $6,890. |
The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected operators.
**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**
1. The authority citation for part 39 continues to read as follows:
**Authority:**
49 U.S.C. 106(g), 40113, 44701.
§ 39.13
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
*Bombardier, Inc.:* Docket No. FAA-2024-1468; Project Identifier MCAI-2023-00975-T.
**(a) Comments Due Date**
The FAA must receive comments on this airworthiness directive (AD) by July 8, 2024.
**(b) Affected ADs**
None.
**(c) Applicability**
This AD applies to Bombardier, Inc., Model BD-700-2A12 airplanes, certificated in any category, serial numbers 70007, 70008, 70010, 70012 through 70047 inclusive, 70049, 70051, 70052, 70053, 70055 through 70077 inclusive, 70079, 70080, 70081, 70083 through 70133 inclusive, 70135, 70136, 70137, 70138, 70142 through 70148 inclusive, 70150, 70152, and 70158.
**(d) Subject**
Air Transport Association (ATA) of America Code 78, Engine exhaust.
**(e) Unsafe Condition**
This AD was prompted by reports that the pivot door pressure seals on the thrust reverser fixed structure were found disbonded or missing on several airplanes. The FAA is issuing this AD to address the pivot door pressure seals on the thrust reverser fixed structure. The unsafe condition, if not addressed, could result in engine thrust loss due to flow path overboard leakage during forward thrust operation and reduce airplane performance during one-engine inoperative conditions in climb margin and ceiling altitude.
**(f) Compliance**
Comply with this AD within the compliance times specified, unless already done.
**(g) Inspection and Functional Test**
(1) Within 750 flight hours or 18 months, whichever comes first from the effective date of this AD, perform a general visual inspection for discrepancies (missing, damaged, or disbonding) of the 4 pivot door pressure seals on the thrust reverser door of each engine, and perform a bonding check as applicable, and repair or replace each discrepant seal as applicable, in accordance with Part 2.B of the Accomplishment Instructions of Bombardier Service Bulletin 700-78-7501, Revision 01, dated July 13, 2023. Applicable corrective actions must be done before further flight.
(2) Before further flight after accomplishing the actions specified in paragraph (g)(1) of this AD: Perform a functional test of the thrust reverser in accordance with Part 2.C of the Accomplishment Instructions of Bombardier Service Bulletin 700-78-7501, Revision 01, dated July 13, 2023.
**(h) Credit for Previous Actions**
This paragraph provides credit for actions required by paragraph (g) of this AD, if those actions were performed before the effective date of this AD using Bombardier Service Bulletin 700-78-7501, dated April 12, 2023.
**(i) No Reporting Requirement**
Although the service information referenced in Bombardier Service Bulletin 700-78-7501, Revision 01, dated July 13, 2023, 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, 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 (k) 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.
**(k) Additional Information**
For more information about this AD, contact Joseph Catanzaro, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 516-228-7366; email *[email protected].*
**(l) 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.
(i) Bombardier Service Bulletin 700-78-7501, Revision 01, dated July 13, 2023.
(ii) [Reserved]
(3) For Bombardier, Inc. service information, contact Bombardier Business Aircraft Customer Response Center, 400 Côte-Vertu Road West, Dorval, Québec H4S 1Y9, Canada; telephone 514-855-2999; email *[email protected];* website *bombardier.com.*
(4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th Street, 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 May 14, 2024.
James D. Foltz,
Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.