Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes

DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-2545; Project Identifier MCAI-2024-00657-T]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Notice of proposed rulemaking (NPRM). <SUM> <HD SOURCE="HED">SUMMARY:</HD> The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. This proposed AD was prompted by reports of certain fuel transfer float valves failing in the closed position, preventing normal fuel transfer between the center and wing fuel tanks. This proposed AD would require replacing the existing fuel transfer float valves on airplanes that are approved for extended-range twin-engine operation performance standards (ETOPS). The FAA is proposing this AD to address the unsafe condition on these products. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> The FAA must receive comments on this proposed AD by October 30, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods: • <E T="03">Federal eRulemaking Portal:</E> Go to <E T="03">regulations.gov</E> . Follow the instructions for submitting comments. • <E T="03">Fax:</E> 202-493-2251. • <E T="03">Mail:</E> U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. • <E T="03">Hand Delivery:</E> Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. <E T="03">AD Docket:</E> You may examine the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-2545; 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. <E T="03">Material Incorporated by Reference:</E> • For Transport Canada material identified in this proposed AD, contact Transport Canada, Transport Canada National Aircraft Certification, 159 Cleopatra Drive, Nepean, Ontario K1A 0N5, Canada; telephone 888-663-3639; email <E T="03">TC.AirworthinessDirectives-Consignesdenavigabilite.TC@tc.gc.ca</E> . You may find this material on the Transport Canada website at <E T="03">tc.canada.ca/en/aviation.</E> It is also available at <E T="03">regulations.gov</E> under Docket No. FAA-2025-2545. • 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. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Joseph Catanzaro, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: 516-228-7366; email: <E T="03">joseph.catanzaro@faa.gov</E> . </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Comments Invited</HD> The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under the <E T="02">ADDRESSES</E> section. Include “Docket No. FAA-2025-2545; Project Identifier MCAI-2024-00657-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 this 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 <E T="03">regulations.gov</E> , including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM. <HD SOURCE="HD1">Confidential Business Information</HD> 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; phone: 516-228-7366; email: <E T="03">joseph.catanzaro@faa.gov.</E> Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking. <HD SOURCE="HD1">Background</HD> Transport Canada, which is the aviation authority for Canada, has issued Transport Canada AD CF-2024-37, dated November 4, 2024 (Transport Canada AD CF-2024-37) (also referred to as the MCAI), to correct an unsafe condition for certain Airbus Canada Limited Partnership Model BD-500-1A10 and BD-500-1A11 airplanes. The MCAI states that there have been several reports of fuel transfer float valves failing in the closed position, preventing normal fuel transfer between the center fuel tank and wing fuel tanks. An investigation determined that high friction of the fuel transfer float valve carbon seal prevents the fuel transfer float valve from opening. Each wing tank is equipped with one fuel transfer float valve. If one fuel transfer float valve fails closed, the crew is alerted and may manually transfer fuel to correct the resulting lateral fuel imbalance. A gravity fuel transfer system provides a back-up to the manual transfer. If both fuel transfer float valves simultaneously fail in the closed position, the crew is alerted, and fuel in the center tank becomes unusable as it cannot be transferred to the wing tanks. The crew may need to divert to prevent fuel starvation before reaching the destination airport. Simultaneous failure of both fuel transfer float valves in the closed position is critical for ETOPS missions as fuel starvation and engine shutdown may occur before reaching a diversion airport. The FAA is proposing this AD to address the unsafe condition on these products. You may examine the MCAI in the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-2545. <HD SOURCE="HD1">Material Incorporated by Reference Under 1 CFR Part 51</HD> Transport Canada AD CF-2024-37 specifies procedures for replacing the existing fuel transfer float valves and O-rings on left- and right-wing with new fuel transfer float valves and O-rings and performing operational tests of the center to wing fuel transfer. Transport Canada AD CF-2024-37 also specifies that inserting a copy of Transport Canada AD CF-2024-37 into the ETOPS Configuration, Maintenance, and Procedures (CMP) or using ETOPS CMP issue 009.00 or later is an acceptable method of compliance. 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 <E T="02">ADDRESSES</E> section. <HD SOURCE="HD1">FAA's Determination</HD> These products have been approved by the civil aviation authority of another country and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, that authority has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop in other products of the same type design. <HD SOURCE="HD1">Proposed AD Requirements in This NPRM</HD> This proposed AD would require accomplishing the actions specified in Transport Canada AD CF-2024-37 described previously, except for any differences identified as exceptions in the regulatory text of this proposed AD. <HD SOURCE="HD1">Compliance With CMP Revisions</HD> Transport Canada AD CF-2024-37 requires operators to “operate the aeroplane accordingly” after accomplishing the optional method of compliance specified in paragraph B. of Transport Canada AD CF-2024-37. However, this proposed AD would not specifically require those actions as those actions are already required by FAA regulations. FAA regulations (14 CFR 121.374(n)) require airplanes to be operated using a system that ensures compliance with the operator's CMP document. Therefore, including a requirement in this proposed AD to operate the airplane according to the revised CMP would be redundant and unnecessary. <HD SOURCE="HD1">Explanation of Required Compliance Information</HD> In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some civil aviation authority (CAA) ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, the FAA ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 20k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━