Airworthiness Directives; Bell Helicopter Textron Inc. Model 205A-1, 205B, 212, 412, and 412CF Helicopters

摘要

This amendment adopts a new airworthiness directive (AD) for Bell Helicopter Textron Inc. (BHTI) Model 205A-1, 205B, 212, 412, and 412CF helicopters. This action requires inspecting the locking washer on each main rotor actuator (actuator) for twisting or damage to the tab and replacing any locking washer that has a twisted or damaged tab. Replacing certain locking washers, regardless of condition, is also required within a specified time period. Installing a certain airworthy locking device on each actuator constitutes terminating action for the requirements of this AD. This amendment is prompted by an incident in which a damaged locking washer allowed the rod end to detach from the collective actuator, causing loss of collective control of the main rotor. The current locking washer is subject to mechanical damage and failure, which allows the actuator piston to unthread itself from its rod end. This condition, if not corrected, could cause loss of control of the main rotor and subsequent loss of control of the helicopter.