Airworthiness Directives; Bell Helicopter Textron, Inc. Model 214ST Helicopters

This amendment adopts a new airworthiness directive (AD), applicable to Bell Helicopter Textron, Inc. (BHTI) Model 214ST helicopters, that requires creation of a component history card or equivalent record using a Retirement Index Number (RIN) system; establishes a system for tracking increases to the accumulated RIN; and establishes a maximum accumulated RIN for the pillow block bearing bolts (bearing bolts). This amendment is prompted by fatigue analyses and tests that show certain bearing bolts fail sooner than originally anticipated because of the unanticipated high number of takeoffs and external load lifts utilizing high-power settings in addition to the time-in-service (TIS) accrued under other operating conditions. The actions specified by this AD are intended to prevent fatigue failure of the bearing bolts, which could result in failure of the main rotor system and subsequent loss of control of the helicopter.