# Airworthiness Directives; Sikorsky Aircraft Corporation Model S-76A, B, and C Helicopters
> **Rule** · Final rule; request for comments. · Published 2007-05-31 · Effective 2007-06-15 · 72 FR 30247
## Document
- **Document number:** E7-10126
- **Category:** airworthiness
- **Manufacturer:** Sikorsky
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 72 FR 30247
- **Publication date:** 2007-05-31
- **Effective date:** 2007-06-15
- **FAA docket:** Docket No. FAA-2007-28241
## Abstract

This amendment adopts a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, B, and C helicopters. This action requires a one-time ultrasonic inspection of the main rotor shaft assembly (M/R shaft) for cracking. This amendment is prompted by the discovery of cracking that occurred during the manufacturing of certain M/R shafts. The actions specified in this AD are intended to detect cracking in the M/R shaft, which could result in separation of the main rotor and subsequent loss of control of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2007/05/31/E7-10126/airworthiness-directives-sikorsky-aircraft-corporation-model-s-76a-b-and-c-helicopters)
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