Summary
This document proposes the supersedure of an existing airworthiness directive (AD) applicable to Bell Helicopter Textron, A Division of Textron Canada (BHTC) Model 206L, L-1, L-3, and L-4 helicopters. This action would require the same type of actions required by the existing AD. In addition, the proposal would require an increase in the Retirement Index Number (RIN) multiplier for the mast, a correction in the model number, and other nonsubstantive changes. This proposal is prompted by further tests and analyses that indicate the RIN multiplier for the Model 206L-4 needs to be increased and the discovery of other errors in the existing AD. The actions specified by the proposed AD are intended to prevent fatigue failure of the mast or trunnion, which could result in loss of the main rotor system and subsequent loss of control of the helicopter.