# Proposed AD FAA-2012-0746: MD Helicopters, Inc. (MDHI) Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2013-03-03
- Products: MD Helicopter
- Product type: Aircraft
- Action: Notice of Proposed Rulemaking (NPRM).
- Published: July 19, 2012, 77 FR 42459
- Comments due: September 17, 2012
- Became: [AD 2013-03-03](https://openairdocs.org/ad/2013-03-03)
- Docket: FAA-2012-0746 (https://www.regulations.gov/docket/FAA-2012-0746, where comments are filed)
- Project: 2008-SW-35-AD
- FR document: 2012-17616
- Official PDF: https://openairdocs.org/files/sha256/53/3f/533fd15176b202beaa940eae405de7311c486b48244632f3a77de854d1adb142 (from https://www.govinfo.gov/content/pkg/FR-2012-07-19/pdf/2012-17616.pdf)
- Federal Register: https://www.federalregister.gov/documents/2012/07/19/2012-17616/airworthiness-directives-md-helicopters-inc-mdhi-helicopters
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/3AE572A730ACF84786257A40004D165E.0001
- Page: https://openairdocs.org/proposed/FAA-2012-0746

## Summary

We propose to adopt a new airworthiness directive (AD) for MDHI Model 500N, 600N, and MD900 helicopters to require determining the cure date for each NOTAR fan blade tension-torsion strap (T-T strap), establishing a calendar-time retirement life for certain T-T straps, reducing the retirement life of certain T-T straps, marking each T-T strap with the expiration date, creating a component record card for each T-T strap, and revising the airworthiness limitations section of the maintenance manual to reflect the changes to the retirement life. This proposal is prompted by a report from the T-T strap manufacturer that, over a period of time, moisture may reduce the strength of a T-T strap. The proposed actions are intended to prevent failure of a T-T strap, loss of directional control and subsequent loss of control of the helicopter.

## Notices in this docket

- Jul 19, 2012: Notice of Proposed Rulemaking (NPRM). (first notice), FR document 2012-17616, comments due Sep 17, 2012 (https://www.federalregister.gov/documents/2012/07/19/2012-17616/airworthiness-directives-md-helicopters-inc-mdhi-helicopters)

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