Probable that the helicopter sustained a mechanical failure in the cruise, resulting in loss of pitch control to one of the tail blades. During the subsequent attempt to land, the airspeed reduced to the point where directional control seems to have been insufficient to maintain heading. At a height of approx 50 ft, the helicopter yawed rapidly right before the rotation ceased and it developed a high rate of descent. The helicopter struck the ground heavily and was destroyed. The pilot sustained serious injuries. There was no fire. The investigation found fatigue cracks emanating from corrosion pits on the tail rotor blade pitch horn on one blade, which led to its failure. Also, the associated tail rotor pitch link had failed.
