# Airworthiness Directives; Boeing Model 747-400 Series Airplanes
> **Rule** · Final rule. · Published 2000-10-18 · Effective 2000-11-22 · 65 FR 62276
## Document
- **Document number:** 00-26308
- **Category:** airworthiness
- **Manufacturer:** Boeing Model 747-400 Series
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 65 FR 62276
- **Publication date:** 2000-10-18
- **Effective date:** 2000-11-22
- **FAA docket:** Docket No. 99-NM-248-AD
## Abstract

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 series airplanes, that requires removal of existing inertial reference units (IRU) and installation of modified IRU's. This amendment is prompted by a report of the failure of the left and center IRU's on a single flight. The actions specified by this AD are intended to prevent loss of multiple IRU's in flight, which could result in the loss of navigation data during flight. This could compromise the ability of the flight crew to maintain the safe flight and landing of the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2000/10/18/00-26308/airworthiness-directives-boeing-model-747-400-series-airplanes)
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