Accident Summary
A flight instructor was demonstrating an autorotation to his student when the accident occurred. The instructor initiated a straight-in autorotation to runway 30 from 600 feet above ground level (AGL). The descent rate was stabilized until 200 feet AGL, at which point he felt a sudden increase in the rate of descent.
Sequence of Events
The instructor began the flare at 50 feet AGL, but the vertical speed did not decrease at the rate he was accustomed to, resulting in a hard landing. The tail boom contacted the ground first during a right yawing moment. Subsequently, the helicopter rolled to the right, crushing the right skid, severing the tail boom, and allowing the rotor blades to contact the ground.
Pilot Observations
The instructor noted that no mechanical problems existed with the helicopter during the flight and that he did not notice any mechanical anomalies during the autorotation demonstration. The engine was running normally during the autorotation and the landing flare. The pilot stated that wind shear may have been a factor. He had observed the winds to be from the northwest at 8 knots, with gusts to 12 knots and light turbulence.