# Airworthiness Directives; Bell Helicopter Textron, Inc. Model 204B Helicopters
> **Rule** · Final rule. · Published 2001-02-15 · 66 FR 10355
## Document
- **Document number:** 01-3670
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 66 FR 10355
- **Publication date:** 2001-02-15
- **FAA docket:** Docket No. 2000-SW-16-AD
## Abstract

This amendment adopts a new airworthiness directive (AD) for Bell Helicopter Textron, Inc. (BHTI) Model 204B helicopters that requires replacing any main rotor mast assembly (mast), part number (P/ N) 204-011-450-001, within 25 hours time-in-service (TIS). This amendment is prompted by the crash of a restricted category Model UH-1B helicopter due to failure of a mast, P/N 204-011-450-001. The same mast P/N is used on the Model 204B helicopters. The actions specified by this AD are intended to prevent failure of the mast and subsequent loss of control of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2001/02/15/01-3670/airworthiness-directives-bell-helicopter-textron-inc-model-204b-helicopters)
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