# Proposed AD FAA-2021-0653: MD Helicopters Inc. (MDHI) Helicopters

- Type: Proposed airworthiness directive (not in force)
- Status: Became AD 2021-22-11
- Products: MD Helicopters
- Product type: Aircraft
- Action: Notice of proposed rulemaking (NPRM).
- Published: August 13, 2021, 86 FR 44652
- Comments due: September 27, 2021
- Became: [AD 2021-22-11](https://openairdocs.org/ad/2021-22-11)
- Docket: FAA-2021-0653 (https://www.regulations.gov/docket/FAA-2021-0653, where comments are filed)
- Project: AD-2021-00170-R
- FR document: 2021-17032
- Official PDF: https://openairdocs.org/files/sha256/93/22/9322055b45be251f07a0ff396ff19c88deaba5a76bc8ffa2d336980bd67f963d (from https://www.govinfo.gov/content/pkg/FR-2021-08-13/pdf/2021-17032.pdf)
- Federal Register: https://www.federalregister.gov/documents/2021/08/13/2021-17032/airworthiness-directives-md-helicopters-inc-mdhi-helicopters
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/152B4DBB90E704BE862587300059E1AA.0001
- Page: https://openairdocs.org/proposed/FAA-2021-0653

## Summary

The FAA proposes to adopt a new airworthiness directive (AD) for MD Helicopters Inc. (MDHI), Model 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. This proposed AD was prompted by a report of a spiral crack in the pilot-to-copilot tail rotor torque tube (torque tube). This proposed AD would require a one- time visual and recurring borescope inspections of the torque tube and depending on the results, removing the torque tube from service. The FAA is proposing this AD to address the unsafe condition on these products.

## Notices in this docket

- Aug 13, 2021: Notice of proposed rulemaking (NPRM). (first notice), FR document 2021-17032, comments due Sep 27, 2021 (https://www.federalregister.gov/documents/2021/08/13/2021-17032/airworthiness-directives-md-helicopters-inc-mdhi-helicopters)

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