# Airworthiness Directives; MD Helicopters, Inc. (MDHI) Helicopters
> **Rule** · Final rule. · Published 2013-10-31 · Effective 2013-12-05 · 78 FR 65195
## Document
- **Document number:** 2013-25702
- **Category:** airworthiness
- **Manufacturer:** MD
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 78 FR 65195
- **Publication date:** 2013-10-31
- **Effective date:** 2013-12-05
- **FAA docket:** Docket No. FAA-2013-0486
## Abstract

We are adopting a new airworthiness directive (AD) for MDHI Model MD900 helicopters with certain main rotor blade (MRB) retention bolts (bolts) installed. This AD requires a daily check of the position of each bolt, a daily check and a repetitive inspection for a gap in each bolt, and, if necessary, removing and inspecting the bolt for a crack and replacing any cracked bolt with an airworthy bolt. This AD was prompted by multiple reports of in-service bolt failures. The actions are intended to prevent failure of a bolt, which could lead to loss of MRB structural integrity and subsequent loss of control of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2013/10/31/2013-25702/airworthiness-directives-md-helicopters-inc-mdhi-helicopters)
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