Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Robinson Helicopter Company (Robinson) Model R22 helicopters. This proposal would require replacement of the upper V-belt sheave (sheave). This proposal is prompted by three reports of cracks in the flange of the sheave. The actions specified in this AD are intended to prevent failure of the sheave, which could result in damage to other drive system components, and subsequent loss of control of the helicopter.