# Proposed AD 99-NM-88-AD: Boeing Model 747-100 and -200 Series Airplanes

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2000-03-01
- Action: Notice of proposed rulemaking (NPRM).
- Published: August 20, 1999, 64 FR 45481
- Comments due: October 4, 1999
- Became: [AD 2000-03-01](https://openairdocs.org/ad/2000-03-01)
- Docket: 99-NM-88-AD
- FR document: 99-21686
- Official PDF: https://openairdocs.org/files/sha256/a9/8a/a98af84a843f6a50952d86911104a56a305dd01184b1fd266ad3974b866efc9a (from https://www.govinfo.gov/content/pkg/FR-1999-08-20/pdf/99-21686.pdf)
- Federal Register: https://www.federalregister.gov/documents/1999/08/20/99-21686/airworthiness-directives-boeing-model-747-100-and--200-series-airplanes
- Page: https://openairdocs.org/proposed/99-NM-88-AD

## Summary

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-100 and - 200 series airplanes. This proposal would require repetitive inspections of the upper and lower chords of the wing front spar for cracks, and corrective action, if necessary. For airplanes on which no cracking is detected, this proposal would also provide optional terminating action in lieu of repetitive inspections. This proposal is prompted by reports of cracks in the upper chord of the wing front spar. The actions specified by the proposed AD are intended to detect and correct fatigue cracking of the upper and lower chords of the wing front spar, which could result in reduced structural capability and possible fuel leakage onto an engine and a resultant fire.

## Notices in this docket

- Aug 20, 1999: Notice of proposed rulemaking (NPRM). (first notice), FR document 99-21686, comments due Oct 4, 1999 (https://www.federalregister.gov/documents/1999/08/20/99-21686/airworthiness-directives-boeing-model-747-100-and--200-series-airplanes)

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