The instructor was conducting an introductory flying lesson. He lifted off and flew into the circuit to the north of the airfield and, after turning onto the downwind leg, he handed control of the cyclic stick to the student. The student flew the rest of the circuit with very little intervention from the instructor down to about 300 ft agl, where the instructor again took control.
The instructor then flew the helicopter to the hovering area where he again gave control of the cyclic to the student. After about a minute of hovering, the instructor applied a gentle forward pressure on the cyclic to correct a somewhat nose-high attitude, whereupon the student suddenly applied a large, aggressive rearwards input to the stick and then ‘froze’. Before the instructor could take corrective action, the helicopter impacted the ground in a nose-high, right-skid-low attitude and the main rotor struck the ground, spinning the aircraft round through 180º. The helicopter came to rest in an upright attitude, but with the right skid collapsed. No explanation was forthcoming as to why the student had reacted in this manner.