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

This amendment supersedes an existing airworthiness directive (AD) for Bell Helicopter Textron Inc. (BHTI) Model 205A-1, 205B, 212, 412, and 412CF helicopters. That AD currently 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 that AD. This amendment requires the same actions as the existing AD but adds the BHTI Model 412EP helicopters to the applicability. This amendment is prompted by the discovery that the BHTI Model 412EP helicopter was inadvertently omitted from the existing AD. The actions specified by this AD are intended to prevent an actuator piston from unthreading from its rod end, loss of control of the main rotor, and subsequent loss of control of the helicopter.