Airworthiness Directives; General Electric Company Engines

DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2024-1883; Project Identifier AD-2023-01120-E]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; General Electric Company 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 all General Electric Company (GE) Model CF34-10E2A1, CF34-10E6, CF34-10E6A1, CF34-10E7, and CF34-10E7-B engines with certain part-numbered high-pressure turbine (HPT) shroud/low pressure turbine (LPT) nozzle assemblies installed. This proposed AD was prompted by a report of failed retention features of the inner and outer support air ducts (commonly referred to as spoolies) discovered during engine disassembly. This proposed AD would require a visual inspection of the combustion case for wear and gouges, repair if necessary, and rework of the affected HPT shroud/LPT nozzle assemblies. 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 26, 2024. </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-2024-1883; 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 GE service information, contact General Electric Company, 1 Neumann Way, Cincinnati, OH 45215; phone: (513) 552-3272; email: <E T="03">aviation.fleetsupport@ge.com;</E> website: <E T="03">ge.com.</E> • You may view this service information that is incorporated by reference 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> Alexei Marqueen, Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: (781) 238-7178; email: <E T="03">alexei.t.marqueen@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 <E T="02">ADDRESSES</E> . Include “Docket No. FAA-2024-1883; Project Identifier AD-2023-01120-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 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 Alexei Marqueen, 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 received a report from the manufacturer that during disassembly, the retention features of the inner and outer support air ducts on GE Model CF34-10E series engines were found to have failed. The retention features include a retaining ring, which becomes plastically deformed during installation. Vibrations loosen the retaining ring until it disengages. With the retaining ring disengaged, the outer support air duct has no radial constraint, and releases and migrates due to gravity, impacting the inner wall of the combustion case causing case wall damage. If this damage has been repaired in the past and after the repair the support air duct liberates and causes more damage, then the remaining wall thickness is not sufficient to sustain the loading from a fan-blade-out or other extreme event. This condition, if not addressed, could result in the inner surface of the combustion case having reduced load carrying capability for fan blade out or other extreme event with possible engine separation 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">Related Service Information Under 1 CFR Part 51</HD> The FAA reviewed GE Service Bulletin (SB) 72-0351 R01, dated July 17, 2019, which provides instructions for a visual inspection of the combustion case for wear and gouges, repair if necessary, and rework of the affected HPT shroud/LPT nozzle assemblies. This service bulletin also introduces a new HPT shroud/LPT nozzle assembly P/N 2205M38G07 with welded retaining rings. 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 <E T="02">ADDRESSES</E> . <HD SOURCE="HD1">Proposed AD Requirements in This NPRM</HD> This proposed AD requires a visual inspection of the combustion case for wear and gouges, repair if necessary, and rework of the affected HPT shroud/LPT nozzle assemblies to add a positive retention of the support air duct. <HD SOURCE="HD1">Costs of Compliance</HD> The FAA estimates that this AD, if adopted as proposed, would affect 300 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,i1" CDEF="s50,r50,12,12,12"> <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">Visual inspection of the combustion case inner shell surface</ENT> <ENT>8 work-hours × $85 per hour = $680</ENT> <ENT>$0</ENT> <ENT>$680</ENT> <ENT>$204,000</ENT> </ROW> <ROW> <ENT I="01">Rework of the affected HPT shroud/LPT nozzle assembly</ENT> <ENT>8 work-hours × $85 per hour = $680</ENT> <ENT>0</ENT> <ENT>680</ENT> <ENT>204,000</ENT> </ROW> </GPOTABLE> The FAA estimates the following costs to do any necessary repairs that would be required based on the results of the proposed inspection. The agency has no way of determining the number of engines that might need these repairs. <GPOTABLE COLS="4" OPTS="L2,i1" CDEF="s50,r50,12,12"> <TTITLE>On-Condition Costs</TTITLE> <CHED H="1">Action</CHED> <CHED H="1">Labor cost</CHED> <CHED H="1">Parts cost</CHED> <ENT I="01">Repair the combustion case</ENT> <ENT>8 work-hours × $85 per hour = $680</ENT> <ENT>$0</ENT> <ENT>$680</ENT> </ROW> <ROW> <ENT I="01">Replace the combustion case</ENT> <ENT>8 work-hours × $85 per hour = $680</ENT> <ENT>647,000</ENT> <ENT>647,680</ENT> </ROW> </GPOTABLE> <HD SOURCE="HD1">Authority for This Rulemaking</HD> 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. <HD SOURCE="HD1">Regulatory Findings</HD> Th ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 17k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━