# Proposed AD 99-NM-56-AD: Boeing Model 747 Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2000-08-14
- Action: Notice of proposed rulemaking (NPRM).
- Published: September 2, 1999, 64 FR 48120
- Comments due: October 18, 1999
- Became: [AD 2000-08-14](https://openairdocs.org/ad/2000-08-14)
- Docket: 99-NM-56-AD
- FR document: 99-22921
- Official PDF: https://openairdocs.org/files/sha256/46/62/4662faeae9830e9bead3ed1439e93d496d3f8cd15396bc084166492c8872f14d (from https://www.govinfo.gov/content/pkg/FR-1999-09-02/pdf/99-22921.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/09/02/99-22921/airworthiness-directives-boeing-model-747-series-airplanes
- Page: https://openairdocs.org/proposed/99-NM-56-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This proposal would require repetitive inspections or checks to detect broken H-11 steel bolts at the wing rear spar side-of-body on the lower chord splice plate and kick fitting; and corrective actions, if necessary. This proposal also would require eventual replacement of the existing bolts with new inconel bolts, which would constitute terminating action for the repetitive inspections. This proposal is prompted by a report of broken bolts at the wing rear spar side-of-body on the lower chord splice plate. The actions specified by the proposed AD are intended to prevent cracking of the bolts due to stress corrosion, which could result in reduced structural integrity of the wing-to-body joint structure.

## Notices in this docket

- Sep 2, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-22921, comments due Oct 18, 1999 (https://www.federalregister.gov/documents/1999/09/02/99-22921/airworthiness-directives-boeing-model-747-series-airplanes)

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