Summary
This document proposes to supersede an existing airworthiness directive (AD) for the Bell Model 412, 412CF, and 412EP helicopters. The AD currently requires reidentifying each affected part-numbered main rotor yoke (yoke) on its data plate, reducing the retirement life of the reidentified yoke, and revising the Airworthiness Limitations section of the maintenance manual or the Instructions for Continued Airworthiness (ICAs) accordingly. Since we issued the AD, we have discovered that the affected yokes do not have a data plate, making compliance with the part-marking requirements of the existing AD impossible. This proposed AD would retain the current requirements with the exception of the P/N marking location. The actions specified in this AD are intended to prevent fatigue cracking of a yoke, failure of the yoke, and subsequent loss of control of the helicopter.