Summary
This document proposes adopting a new airworthiness directive (AD) for Bell Helicopter Textron Canada (BHTC) Model 206L-4 helicopters. This proposal would require installing a high altitude tail rotor static stop yield indicator (indicator) to allow operators to detect excessive bending loads sustained by the tail rotor yoke. A preflight check of the indicator would also be required. This proposal is prompted by a determination that a tail rotor yoke with a high altitude rotor system is susceptible to a static and dynamic overload. Static overload could occur after the tail rotor yoke sustains an excessive bending load due to a strike from a ground vehicle. Dynamic overload could occur as a result of a hard landing. The actions specified by the proposed AD are intended to prevent failure of the tail rotor yoke in flight and subsequent loss of control of the helicopter.