Airworthiness Directives; CFM International, S.A. Engines

DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-1115; Project Identifier AD-2024-00797-E]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; CFM International, S.A. Engines</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 CFM International, S.A. (CFM) Model LEAP-1A23, LEAP-1A24, LEAP-1A24E1, LEAP-1A26, LEAP-1A26CJ, LEAP-1A26E1, LEAP-1A29, LEAP-1A29CJ, LEAP-1A30, LEAP-1A32, LEAP-1A33, LEAP-1A33B2, and LEAP-1A35A engines. This proposed AD was prompted by a report of multiple aborted takeoffs and air turn-backs (ATBs) caused by high-pressure compressor (HPC) stall, which was induced by high levels of non-synchronous vibration (NSV). Additional manufacturer investigation revealed that wear on the No. 3 bearing spring finger housing can lead to high levels of NSV. This proposed AD would require initial and repetitive calculations of the levels of NSV, inspection of the stage 2 high-pressure turbine (HPT) nozzle assembly honeycomb and HPT stator stationary seal honeycomb and, depending on the results of the calculations and inspections, replacement of certain parts. This AD also requires replacement of certain No. 3 bearing spring finger housings at a certain time. 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 August 11, 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-2025-1115; 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, any comments received, and other information. The street address for Docket Operations is listed above. <E T="03">Material Incorporated by Reference:</E> • For CFM material identified in this proposed AD, contact CFM, GE Aviation Fleet Support, 1 Neumann Way, M/D Room 285, Cincinnati, OH 45215; phone: (877) 432-3272; email: <E T="03">aviation.fleetsupport@ge.com.</E> • You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 1200 District Avenue, Burlington, MA 01803. For information on the availability of this material at the FAA, call (817) 222-5110. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Mehdi Lamnyi, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (781) 238-7743; email: <E T="03">mehdi.lamnyi@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 to an address listed under the <E T="02">ADDRESSES</E> section. Include “Docket No. FAA-2025-1115; Project Identifier AD-2024-00797-E” 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 revise 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 Mehdi Lamnyi, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198. 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> The FAA was notified by the engine manufacturer of three aborted takeoffs and two ATBs caused by HPC stall on CFM Model LEAP-1A engines. Additional manufacturer investigation revealed that wear on the No. 3 bearing spring finger housing can lead to high levels of NSV, which could induce HPC stall. As a result of its investigation, the manufacturer published service material that specifies procedures for addressing this situation. The FAA previously published AD 2024-07-06, Amendment 39-22727 (89 FR 33211, April 29, 2024) to address this condition for parts from one specific supplier whose parts have shown increased susceptibility to premature wear. Since the publication of that AD, the manufacturer has identified another supplier whose parts are also susceptible to the same type of premature wear. This condition, if not addressed, could result in engine power loss at a critical phase of flight such as takeoff or climb, loss of engine thrust control, reduced controllability of the airplane, and loss of the airplane. <HD SOURCE="HD1">FAA's Determination</HD> 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. <HD SOURCE="HD1">Material Incorporated by Reference Under 1 CFR Part 51</HD> The FAA reviewed CFM Service Bulletin (SB) LEAP-1A-72-00-0536-01A-930A-D, Issue 001, dated July 22, 2024. This service material specifies procedures for replacing the No. 3 bearing spring finger housings, inspecting the stage 2 HPT nozzle assembly honeycomb, and inspecting the HPT stator stationary seal honeycomb. The FAA also reviewed CFM SB LEAP-1A-72-00-0562-01A-930A-D, Issue 001-00, dated April 30, 2025. This service material identifies the affected No. 3 bearing spring finger housings and specifies procedures for monitoring NSV during engine operation, replacing the stage 2 HPT nozzle assembly honeycomb, and replacing the HPT stator stationary seal. 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">Proposed AD Requirements in This NPRM</HD> This proposed AD would require repetitive calculations of the levels of NSV and, depending on the results of the calculations, replacement of the No. 3 bearing spring finger housing. This proposed AD would require, following the removal and replacement of the No. 3 bearing spring finger housing, inspection of the stage 2 HPT nozzle assembly honeycomb and HPT stator stationary seal honeycomb for rubs and, depending on findings, replacement of the stage 2 HPT nozzle assembly honeycomb and HPT stator stationary seal. This proposed AD would also require replacement of the No. 3 bearing spring finger housing regardless of calculated level of NSV, at a certain time. <HD SOURCE="HD1">Costs of Compliance</HD> The FAA estimates that this AD, if adopted as proposed, would affect three engines installed on airplanes of U.S. registry. The FAA estimates the following costs to comply with this proposed AD: <GPOTABLE COLS="5" OPTS="L2,nj,i1" CDEF="s50,r50,10,10,12"> <TTITLE>Estimated Costs</TTITLE> <CHED H="1">Action</CHED> <CHED H="1">Labor cost</CHED> <CHED H="1">Parts cost</CHED> Cost on U.S. operators </CHED> <ROW> <ENT I="01">Calculate NSV data</ENT> <ENT>1 work-hours × $85 per hour = $85</ENT> <ENT>$0</ENT> <ENT>$85</ENT> <ENT>$255</ENT> </ROW> <ROW> <ENT I="01">Inspect stage 2 HPT nozzle assembly honeycomb and HPT stator stationary seal honeycomb</ENT> <ENT>4 work-hours × $85 per hour = $340</ENT> <ENT>0</ENT> <ENT>340</ENT> <ENT>1,020</ENT> </ROW> <ROW> <ENT I="01">Replace No. 3 bearing spring finger housing</ENT> <ENT>17 work-hours × $85 per hour = $1,445</ENT> <ENT>64,590</ENT> <ENT>66,035</ENT> <ENT>198,105</ENT> </ROW> </GPOTABLE> The FAA estimates the following costs to do any necessary replacements and inspections that would be required based on the results of the proposed calculation. The agency has no way of determining the number of engines that might need these replacements and inspections: <GPOTABLE COLS="4" OPTS="L2,nj,i1" CDEF="s50,r50,12,15"> <TTITLE>On-Condition Costs</TTITLE> <CHED H="1">Actio ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 22k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━