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AGENCY:
Federal Aviation Administration (FAA), DOT.
ACTION:
Final rule.
SUMMARY:
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SP, and 747SR series airplanes. This AD was prompted by a report indicating cracks at eight fastener hole locations in the fuselage skin lap splice between certain stations (STAs) at certain stringers. This AD requires repetitive inspections of the upper fastener row of the fuselage skin lap splice in a certain area for any crack, and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.
DATES:
This AD is effective November 15, 2024.
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of November 15, 2024.
ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2024-1882; 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 final rule, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Material Incorporated by Reference:
- For Boeing material identified in this 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; websitemyboeingfleet.com.
- 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 atregulations.gov under Docket No. FAA-2024-1882.
FOR FURTHER INFORMATION CONTACT:
Stefanie Roesli, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-3964; email: Stefanie.N.Roesli@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SP, and 747SR series airplanes. The NPRM published in the Federal Register on July 3, 2024 (89 FR 55128). The NPRM was prompted a report indicating cracks at eight fastener hole locations in the fuselage skin lap splice between STAs 1450 and 1470 at stringers S-23L and S-23R.
In the NPRM, the FAA proposed to require repetitive inspections of the upper fastener row of the fuselage skin lap splice in a certain area for any crack, and applicable on-condition actions. The FAA is issuing this AD to detect and correct cracking of the upper fastener row of the fuselage skin lap splice between STAs 1350 and 1480 at stringers S-23L and S-23R. The unsafe condition, if not addressed, could result in an in-flight rapid decompression and a loss of structural integrity of the fuselage.
Discussion of Final Airworthiness Directive
Comments
The FAA received a comment from Boeing who supported the NPRM without change.
Conclusion
The FAA reviewed the relevant data, considered the comment received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed Boeing Alert Requirements Bulletin 747-53A2912 RB, dated April 5, 2024. This material specifies procedures for repetitive external surface high frequency eddy current inspections of the upper fastener row of the fuselage skin lap splice between STAs 1350 and 1480 at stringers S-23L and S-23R for any crack, and applicable on-condition actions. On-condition actions include obtaining and following repair instructions.
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 ADDRESSES section.
Costs of Compliance
The FAA estimates that this AD affects 170 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:
Estimated Costs
| Action | Labor cost | Parts cost | Cost per product | Cost on U.S. operators |
|---|---|---|---|---|
| Inspections | 8 work-hours × $85 per hour = $680 per inspection cycle | $0 | $680 per inspection cycle | $115,600 per inspection cycle. |