Airworthiness Directives; Bell Textron Inc. Helicopters

The FAA is adopting a new airworthiness directive (AD) for certain Bell Textron Inc. Model 212, 412, 412CF, and 412EP helicopters. This AD was prompted by reports of cracked tail boom attachment barrel nuts (barrel nuts). This AD requires replacing all steel alloy barrel nuts with nickel alloy barrel nuts, replacing or inspecting other tail boom attachment point hardware, repetitively inspecting torque, and repetitively replacing tail boom attachment bolts (bolts). This AD also prohibits installing steel alloy barrel nuts. The FAA is issuing this AD to address the unsafe condition on these products.