AD FAA-2014-0385

We are adopting a new airworthiness directive (AD) for Columbia Helicopters, Inc. (Columbia) Model 234 helicopters. This AD requires visually and tap inspecting each fore and aft rotor blade for any defect, damage, or a disbond and, if necessary, repairing or replacing the blade. Also, this AD requires dye-penetrant inspecting the aft pylon structure for fatigue cracking in certain areas near the attachment fittings and, if there is a crack, repairing or replacing the aft pylon. This AD is prompted by an accident caused by fatigue failure of an aft pylon fitting attach structure combined with aft rotor blade damage. The actions specified by this AD are intended to detect fatigue cracks in the aft pylon attach structure to prevent overload of the aft pylon structure and failure of the rotor blade, rotor blade vibration, departure of the aft pylon, and subsequent loss of control of the helicopter.