# Airworthiness Directives; MD Helicopters, Inc. (MDHI) Model MD- 900 Helicopters
> **Rule** · Final rule. · Published 1999-08-06 · Effective 1999-09-10 · 64 FR 42824
## Document
- **Document number:** 99-20182
- **Category:** airworthiness
- **Manufacturer:** MD
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 64 FR 42824
- **Publication date:** 1999-08-06
- **Effective date:** 1999-09-10
- **FAA docket:** Docket No. 98-SW-42-AD
## Abstract

This amendment supersedes an existing airworthiness directive (AD), applicable to MDHI Model MD-900 helicopters, that currently requires applying specified serial numbers and establishing life limits for certain parts. This amendment is prompted by additional analysis that supports an increase in the life limit of certain parts. The actions specified by this AD are intended to increase the life limits for various parts.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1999/08/06/99-20182/airworthiness-directives-md-helicopters-inc-mdhi-model-md--900-helicopters)
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