Airworthiness Directives; Bell Helicopter Textron Model 204B, 205A, 205A-1, 205B, and 212 Helicopters

This amendment supersedes an existing airworthiness directive (AD), applicable to Bell Helicopter Textron Model 204B, 205A, 205A-1, and 212 helicopters, that currently establishes a retirement life for the main rotor masts (masts) and main rotor trunnions (trunnions) based on time-in-service (TIS) and types of operations. This amendment adds Model 205B helicopters to the applicability; requires creation of component history cards or equivalent records using a Retirement Index Number (RIN) system; establishes a system for tracking increases to the accumulated RIN; and establishes a maximum accumulated RIN for certain masts and trunnions. This amendment is prompted by an accident involving a Model 205A-1 helicopter, in which a mast failure caused a separation of the main rotor from the helicopter. The actions specified by this AD are intended to prevent fatigue failure of the mast or trunnion and subsequent loss of control of the helicopter.