Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Robinson Helicopter Company Model R22 series helicopters, that currently requires an inspection and repetitive visual checks for slippage of the tail rotor (T/R) drive and replacement of the T/R gearbox, if necessary. This action would require disassembly of the T/R gearbox to verify the installation of the input and output shaft keys (keys) between the input and output pinions and their respective shafts. This proposal is prompted by two incidents in which the key was not installed between the output shaft and the output pinion during assembly of the T/R gearbox at Robinson Helicopter Company. The actions specified by the proposed AD are intended to prevent slippage of the T/R drive, loss of directional control, and subsequent loss of control of the helicopter.