Summary
This document proposes superseding an existing airworthiness directive (AD) for Bell Helicopter Textron, Inc. (BHTI) Model 212 helicopters. That AD currently requires, at specified intervals, inspecting for a cracked tail boom and replacing any cracked tail boom. That AD also requires modifying the tail fin and tail boom within 100 hours time-in-service (TIS). This action would require modifying and visually inspecting certain vertical fin left-hand spar caps for cracking, loose fasteners, corrosion, or disbonding. If corrosion or loose fasteners are found, this AD would require repairing the vertical fin left-hand spar cap (spar cap) and if a crack or disbonding is found, replacing any cracked or disbonded part with an airworthy part. This proposed AD would also require replacing certain spar caps within 24 months. This proposal is prompted by an accident and four failures of the spar cap involving helicopters of similar type design. The actions specified by the proposed AD are intended to prevent failure of a vertical fin spar, loss of a tail rotor, and subsequent loss of control of the helicopter.