Incident Overview
On 21 September 2014, at approximately 1600 UTC, a Robinson R22 Beta (registration G-OKEY, serial number 2004, year of manufacture 1991) was involved in an accident at Elstree Aerodrome, Hertfordshire. The helicopter was powered by one Lycoming O-320-B2C piston engine. The flight was a training sortie, with an instructor and a student on board; no passengers were carried. The instructor held a Commercial Pilot's Licence, aged 35, with 4,560 total flying hours (2,000 hours on type, 154 hours in the last 90 days, and 60 hours in the last 28 days). One crew member sustained minor injuries; the other was uninjured. The helicopter suffered substantial damage to the fuselage, windscreen, main rotor, and skids.
Sequence of Events
The instructor was conducting an introductory flying lesson. After lifting off and flying into the circuit north of the airfield, he handed control of the cyclic stick to the student upon turning onto the downwind leg. The student flew the remainder of the circuit with minimal instructor intervention until about 300 ft agl, when the instructor resumed control. The instructor then flew the helicopter to the hovering area and again gave the student control of the cyclic. After approximately one minute of hovering, the instructor applied a gentle forward pressure on the cyclic to correct a somewhat nose-high attitude. In response, the student suddenly applied a large, aggressive rearward 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 through 180°. The helicopter came to rest upright, but with the right skid collapsed.
Aftermath
No explanation was provided for the student's reaction.