Airworthiness Directives; Bell Helicopter Textron, Inc. Model 205A, 205A-1, and 204B Helicopters

This amendment adopts a new airworthiness directive (AD) that is applicable to Bell Helicopter Textron, Inc. (BHTI) Model 205A, 205A- 1, and 204B helicopters. This action requires verification that the tail rotor control system is rigged in accordance with the applicable maintenance manual; a fluorescent penetrant inspection for cracks at the roots of the gear teeth on the pinion and gear of affected 42- degree tail rotor drive gearbox assemblies (42-degree gearboxes) and replacement of the 42-degree gearbox pinion or gear if cracks are found, and creation of a component history card to track the numbers of torque events. A torque event is defined as a takeoff or a lift (internal or external). This amendment is prompted by 14 accidents reported in the United States and Canada related to failure of the 42- degree gearbox. The actions specified in this AD are intended to prevent failure of the 42-degree gearbox, loss of tail rotor control, and subsequent loss of control of the helicopter.