Airworthiness Directives; The Boeing Company Airplanes

DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-4000; Project Identifier AD-2025-00440-T]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; The Boeing Company 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 The Boeing Company Model 747-8F series airplanes. This proposed AD was prompted by reports of cracking in stringers and splice fittings located at stringer splices at multiple body stations. This proposed AD would require an inspection of each free flange of the stringers at the stringer splice for radius fillers at certain fastener locations, an inspection for cracking of the stringers and stringer splice fittings at certain stringer splice locations, and applicable on-condition actions. 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 January 2, 2026. </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-2025-4000; 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 Boeing material identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; telephone 562-797-1717; website <E T="03">myboeingfleet.com</E> . • 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. It is also available at <E T="03">regulations.gov</E> under Docket No. FAA-2025-4000. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Taylor Stanley, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 407-852-7677; email: <E T="03">taylor.stanley@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-2025-4000; Project Identifier AD-2025-00440-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 Taylor Stanley, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 407-852-7677; email: <E T="03">taylor.stanley@faa.gov.</E> Any commentary that the FAA receives that is not specifically designated as CBI will be placed in the public docket for this rulemaking. <HD SOURCE="HD1">Background</HD> The FAA issued AD 2023-12-18, Amendment 39-22477 (88 FR 43251, July 7, 2023) (AD 2023-12-18), for certain The Boeing Company Model 747-8 and -8F series airplanes. AD 2023-12-18 was prompted by reports of cracking in stringers and splice fittings located at stringer splices at multiple body stations. AD 2023-12-18 requires an inspection of each free flange of the stringers at the stringer splice for the presence of radius fillers at fastener locations, an inspection for cracking of the stringers and stringer splice fittings at certain stringer splice locations, and applicable on-condition actions. The agency issued AD 2023-12-18 to address cracking in stringers and splice fittings located at stringer splices, which could result in the inability of a structural element to sustain limit load and could affect structural integrity of the airplane. <HD SOURCE="HD1">Actions Since AD 2023-12-18 Was Issued</HD> Since the FAA issued AD 2023-12-18, the FAA received in-service stringer crack reports on stringers at circumferential splice joints. Recent testing indicates that certain materials are the root cause of the stringer cracks at the circumferential splice joints. Existing inspections for airplanes having line numbers 1564 through 1574 inclusive may not provide adequate damage detection before a loss of limit load capability. These airplane line numbers are not included in the effectivity of Boeing Alert Requirements Bulletin 747-53A2907 RB, dated March 3, 2022. Therefore, these affected airplanes are not included in the applicability of AD 2023-12-18, which refers to the requirements bulletin as the appropriate source of service information. Boeing has issued Boeing Alert Requirements Bulletin 747-53A2907 RB, Revision 1, dated March 14, 2025, which adds the affected airplanes to its effectivity (identified as Group 3 airplanes). To address the unsafe condition on these additional airplanes, the FAA has determined that a stand-alone AD is more appropriate as that will be a less burdensome approach for airplanes identified in AD 2023-12-18. <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 Boeing Alert Requirements Bulletin 747-53A2907 RB, Revision 1, dated March 14, 2025. This material specifies procedures for an inspection of each free flange of the stringers at the stringer splice for radius fillers at the fastener locations, a detailed inspection for cracking of the stringers and stringer splice fittings at certain stringer splice locations, and applicable on-condition actions. On-condition actions include detailed inspections for cracking or radius fillers, removal or installation of radius fillers, and contacting Boeing for repair instructions and doing the repair ( <E T="03">i.e.,</E> replacement of a cracked splice channel). 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 accomplishing the actions specified in the material already described, except for any differences identified as exceptions in the regulatory text of this proposed AD. For information on the procedures and compliance times, see this material at regulations.gov under Docket No. FAA-2025-4000. <HD SOURCE="HD1">Costs of Compliance</HD> The FAA estimates that this AD, if adopted as proposed, would affect 11 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,xs40,r50,r50"> <TTITLE>Estimated Costs</TTITLE> <CHED H="1">Action</CHED> <CHED H="1">Labor cost</CHED> <CHED H="1">Parts cost</CHED> <CHED H="1">Cost per product</CHED> <CHED H="1"> Cost on U.S. operators </CHED> <ROW> <ENT I="01">Inspection for radius filler</ENT> <ENT>Up to 124 work-hours × $85 per hour = $10,540</ENT> <ENT>None</ENT> <ENT>Up to $10,540</ENT> <ENT>Up to $115,940.</ENT> </ROW> <ROW> <ENT I="01">Inspection for cracking</ENT> <ENT>Up to 244 work-hours × $85 per hour = $20,740</ENT> <ENT>None</ENT> <ENT>Up to $20,740</ENT> <ENT>Up to $228,140.</ENT> </ROW> </GPOTABLE> The FAA estimates the following costs to do any necessary on-condition actions tha ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 19k characters. 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