# Airworthiness Directives; Boeing Model 747-400 Series Airplanes
> **Rule** · Final rule; request for comments. · Published 2001-09-06 · Effective 2001-09-21 · 66 FR 46512
## Document
- **Document number:** 01-22087
- **Category:** airworthiness
- **Manufacturer:** Boeing Model 747-400 Series
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 66 FR 46512
- **Publication date:** 2001-09-06
- **Effective date:** 2001-09-21
- **FAA docket:** Docket No. 2001-NM-119-AD
## Abstract

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747-400 series airplanes, that currently requires repetitive inspections to detect damage or deflection of the crew rest heat exchanger, and follow-on actions, if necessary. This amendment adds a new requirement for a one-time inspection to determine the part number and shop code of the shell of the crew rest heat exchanger; and follow-on actions, if necessary; which terminate the currently required repetitive inspections. This action is necessary to prevent cracking and buckling of the front edge of the crew rest heat exchanger, which could result in a jam of the rudder or elevator control cables, and consequent reduced controllability of the airplane. This action is intended to address the identified unsafe condition.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2001/09/06/01-22087/airworthiness-directives-boeing-model-747-400-series-airplanes)
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