Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bell Textron Inc., Model 212, 412, 412CF, and 412EP helicopters. This proposed AD was prompted by reports of cracked tail boom attachment barrel nuts (barrel nuts). This proposed AD would require replacing all steel alloy barrel nuts with nickel alloy barrel nuts and, replacing or inspecting other tail boom attachment point hardware and depending on the results, replacing hardware, stabilizing torque, and applying torque stripes. This proposed AD would also require repetitively inspecting torque and, depending on the results, corrective action. This proposed AD would require repetitively replacing the upper left-hand (LH) tail boom attachment bolt (bolt) and repetitively inspecting the other tail boom attachment point bolts. Lastly, this proposed AD would prohibit installing steel alloy barrel nuts. The FAA is proposing this AD to address the unsafe condition on these products.