# Proposed AD FAA-2012-0498: The Boeing Company Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2012-22-02
- Products: Boeing
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: June 12, 2012, 77 FR 34881
- Comments due: July 27, 2012
- Became: [AD 2012-22-02](https://openairdocs.org/ad/2012-22-02)
- Docket: FAA-2012-0498 (https://www.regulations.gov/docket/FAA-2012-0498, where comments are filed)
- Project: 2011-NM-212-AD
- FR document: 2012-14253
- Official PDF: https://openairdocs.org/files/sha256/1d/e9/1de9c91934ea33f2d9dfb58cde233d6ef14b808118842b62138a4a987a271142 (from https://www.govinfo.gov/content/pkg/FR-2012-06-12/pdf/2012-14253.pdf)
- Federal Register: https://www.federalregister.gov/documents/2012/06/12/2012-14253/airworthiness-directives-the-boeing-company-airplanes
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/5529EC3827053FB386257A1B004A8829.0001
- Page: https://openairdocs.org/proposed/FAA-2012-0498

## Summary

We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-400, -400D, and -400F series airplanes. This proposed AD was prompted by reports of crown frame web cracking at left buttock line (LBL) 15.0, station (STA) 320. This proposed AD would require a measurement of the web at STA 320 and, depending on findings, various inspections for cracks and missing fasteners, web and fastener replacement, and related investigative and corrective actions. We are proposing this AD to prevent complete fracture of the crown frame assembly, and consequent damage to the skin and in-flight decompression of the airplane.

## Notices in this docket

- Jun 12, 2012: Notice of proposed rulemaking (NPRM). (first notice), FR document 2012-14253, comments due Jul 27, 2012 (https://www.federalregister.gov/documents/2012/06/12/2012-14253/airworthiness-directives-the-boeing-company-airplanes)

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.