Airworthiness Directives; Bell Helicopter Textron, Inc. Model 214B, 214B-1, and 214ST Helicopters

This amendment adopts a new airworthiness directive (AD) that is applicable to Bell Helicopter Textron, Inc. (Bell) Model 214B, 214B- 1, and 214ST helicopters. This action requires a visual inspection of thin-flanged attachment barrel nuts (barrel nuts) manufactured by Kaynar Technologies, Inc. for cracks or lubrication residue, and replacement of the barrel nuts and corresponding attaching bolts, as necessary. These barrel nuts have been installed in main rotor grips, pitch horns, and tailboom assemblies. This amendment is prompted by a report of a cracked barrel nut, which was discovered on a helicopter being prepared for shipment. The actions specified in this AD are intended to detect cracks in a barrel nut, which could lead to failure of a main rotor grip, pitch horn, or tailboom, and subsequent loss of control of the helicopter.