Airworthiness Directives; Bell Helicopter Textron Inc. Model 412, 412CF, and 412EP Helicopters

This amendment adopts a new airworthiness directive (AD) for the specified Bell Helicopter Textron Inc. (Bell) model helicopters. This action requires reidentifying a certain part-numbered main rotor yoke (yoke) based on whether it was ever installed on a Model 412CF helicopter or on a Model 412 or 412EP helicopter with a slope landing kit. This AD also requires reducing the retirement life of the reidentified yokes from 5,000 hours time-in-service (TIS) to 4,500 hours TIS. Also, this AD requires recording the reidentified yoke part number (P/N) and the reduced retirement life on the component history card or equivalent record. This amendment is prompted by fatigue analysis that shows that the retirement life should be reduced on certain yokes. The actions specified in this AD are intended to prevent fatigue cracking of a yoke, failure of a yoke, and subsequent loss of control of the helicopter.