# Airworthiness Directives; Sikorsky Aircraft Model S-76B Helicopters
> **Rule** · Final rule; request for comments. · Published 1996-07-19 · Effective 1996-08-19 · 61 FR 37675
## Document
- **Document number:** 96-18294
- **Category:** airworthiness
- **Manufacturer:** Sikorsky
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 61 FR 37675
- **Publication date:** 1996-07-19
- **Effective date:** 1996-08-19
- **FAA docket:** Docket No. 96-SW-16-AD
## Abstract

This amendment supersedes an existing Airworthiness Directive (AD), applicable to Sikorsky Aircraft Model S-76B helicopters, that requires an inspection of the drive shaft for cracks or loose balance weights. This amendment also supersedes a Priority Letter AD that currently requires repetitive inspections for cracks in the driveshaft in helicopters with certain engine drive shaft assemblies (drive shafts) installed. This amendment is prompted by a report of a fatigue crack found in a drive shaft that was caused by fretting of a balance weight rivet washer. The actions specified by this AD are intended to prevent failure of the drive shaft, loss of power to the rotor system, and a subsequent forced landing of the helicopter.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1996/07/19/96-18294/airworthiness-directives-sikorsky-aircraft-model-s-76b-helicopters)
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