# Proposed AD FAA-2012-0342: MD Helicopters, Inc.

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2012-21-01
- Products: MD Helicopter
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: March 29, 2012, 77 FR 18963
- Comments due: May 29, 2012
- Became: [AD 2012-21-01](https://openairdocs.org/ad/2012-21-01)
- Docket: FAA-2012-0342 (https://www.regulations.gov/docket/FAA-2012-0342, where comments are filed)
- Project: 2011-SW-028-AD
- FR document: 2012-7535
- Official PDF: https://openairdocs.org/files/sha256/8c/73/8c73be7d6ae1b99e44f9b7dfd2953683d8955cdecb64a34dddad9e70710a797b (from https://www.govinfo.gov/content/pkg/FR-2012-03-29/pdf/2012-7535.pdf)
- Federal Register: https://www.federalregister.gov/documents/2012/03/29/2012-7535/airworthiness-directives-md-helicopters-inc
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9BF40168B07D6A14862579D0004FBF4A.0001
- Page: https://openairdocs.org/proposed/FAA-2012-0342

## Summary

We propose to supersede an existing airworthiness directive (AD) 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 did not include in its requirements certain long-term actions that did not necessitate adoption prior to public comment. This proposed AD would require those long-term actions. This proposed AD would require the same inspections as the existing AD but would also require recurring inspections and replacing the lower hub with an airworthy lower hub. We are proposing 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.

## Notices in this docket

- Mar 29, 2012: Notice of proposed rulemaking (NPRM). (first notice), FR document 2012-7535, comments due May 29, 2012 (https://www.federalregister.gov/documents/2012/03/29/2012-7535/airworthiness-directives-md-helicopters-inc)

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