# Airworthiness Directives; MD Helicopters, Inc.
> **Rule** · Final rule. · Published 2012-10-23 · Effective 2012-11-27 · 77 FR 64709
## Document
- **Document number:** 2012-25387
- **Category:** airworthiness
- **Manufacturer:** MD
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 77 FR 64709
- **Publication date:** 2012-10-23
- **Effective date:** 2012-11-27
- **FAA docket:** Docket No. FAA-2012-0342
## Abstract

We are adopting a new airworthiness directive (AD) to supersede an existing airworthiness directive for MD Helicopters, Inc. (MDHI), Model MD900 helicopters. The existing AD requires a visual inspection, and if necessary, an eddy current inspection of the main rotor lower hub assembly (lower hub) for a crack. If a crack exists, the AD requires replacing the lower hub with an airworthy lower hub before further flight. Because that AD was immediately effective, we declined to require certain long-term actions prior to public comment. This superseding AD will require the same inspections as the existing AD but will also require long-term recurring inspections and replacing the lower hub with an airworthy lower hub. We are issuing this AD to detect a crack in the lower hub and prevent failure of the lower hub and subsequent loss of control of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2012/10/23/2012-25387/airworthiness-directives-md-helicopters-inc)
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