Incident Description
During a takeoff from a high hover, the flight instructor heard a banging noise accompanied by an increase in engine rpm and a decrease in rotor rpm. The helicopter subsequently entered a left turn, and the pilot rolled the throttle off to initiate an autorotation. The helicopter landed hard with low rotor rpm. As a result of the hard landing, the main rotor blades contacted the tailboom, and the skid landing gear collapsed.
Post-Accident Examination
Examination of the engine, main transmission, and free wheeling clutch revealed no discrepancies that would have prevented normal flight operations. The fuel system had been filled prior to the planned dual cross-country flight.
Environmental Conditions
The density altitude at the time of the accident was calculated at 3,040 feet. The operator noted that the accident could have been prevented by avoiding hovering out of ground effect at maximum gross weight with a density altitude of 3,000 feet and by maintaining better rotor rpm control.