# Airworthiness Directives; Boeing Model 707 and 720 Series Airplanes
> **Rule** · Final rule; request for comments. · Published 2001-04-23 · Effective 2001-05-08 · 66 FR 20383
## Document
- **Document number:** 01-9663
- **Category:** airworthiness
- **Manufacturer:** Boeing Model 707 and 720 Series
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 66 FR 20383
- **Publication date:** 2001-04-23
- **Effective date:** 2001-05-08
- **FAA docket:** Docket No. 2001-NM-42-AD
## Abstract

This amendment supersedes two existing airworthiness directives (AD), applicable to all Boeing Model 707 and 720 series airplanes, that currently require inspections of the upper chords of the wing front and rear spars, repair, if necessary, and application of corrosion inhibitor to the inspected areas. This amendment requires repetitive inspections of the upper and lower chords on the wing front and rear spars, repair, if necessary, and application of corrosion inhibitor to the inspected areas. These actions are necessary to find and fix stress corrosion cracking of the upper and lower chords on the wing front and rear spars, which could result in reduced structural integrity of the wing. This action is intended to address the identified unsafe condition.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2001/04/23/01-9663/airworthiness-directives-boeing-model-707-and-720-series-airplanes)
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