# Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Helicopters
> **Rule** · Final rule; request for comments. · Published 2015-02-25 · Effective 2015-03-12 · 80 FR 9985
## Document
- **Document number:** 2015-03703
- **Category:** airworthiness
- **Manufacturer:** Sikorsky
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 80 FR 9985
- **Publication date:** 2015-02-25
- **Effective date:** 2015-03-12
- **FAA docket:** Docket No. FAA-2015-0397
## Abstract

We are adopting a new airworthiness directive (AD) for certain Sikorsky Model S-76A, B, C, and D helicopters. This AD requires inspecting the tail rotor drive shaft (TDS) flange-to-shaft attachment hardware for correct assembly and correct torque of the fasteners. If there is a discrepancy, this AD requires, before further flight, applying an index mark to the flange and TDS, inspecting the flange and shaft for a crack, fracture, wear, and certain measurements, and replacing any part that does not meet the approved criteria before further flight. This AD is prompted by a partial loss of tail rotor drive resulting in a forced landing. The actions specified by this AD are intended to prevent failure at the flange-to-shaft attachment, loss of a tail rotor drive, and subsequent loss of control of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2015/02/25/2015-03703/airworthiness-directives-sikorsky-aircraft-corporation-sikorsky-helicopters)
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