Incident Summary
A helicopter pilot was conducting his sixth sightseeing flight of the day. After landing, three passengers disembarked and three others boarded. The accident sequence began when the pilot increased throttle to full rpm and added torque.
Sequence of Events
As torque increased, the helicopter yawed left approximately 15 degrees. The pilot applied about 3 inches of opposite pedal to correct the heading. Continuing to increase torque, the skids started to lift off; the left skid rose about 3 inches while the right skid remained on the ground. The nose then pitched up rapidly, and the helicopter rolled to the right. Despite the pilot applying full forward and left cyclic, the helicopter did not respond. The pilot subsequently lowered the collective and attempted to roll off the throttle. The helicopter continued rolling right until the main rotor blades struck the ground. A fragment of a main rotor blade impacted a nearby hangar.
Post-Accident Examination
The pilot reported no control anomalies before the event. A subsequent examination of the helicopter revealed no mechanical discrepancies.
Definition of Dynamic Rollover
The FAA's "Rotorcraft Flying Handbook" (FAA-H-8083-21) defines dynamic rollover as "the tendency of a helicopter to continue rolling when the critical angle is exceeded, if one gear is on the ground, and the helicopter is pivoting around that point."