What happened
During the sixth sightseeing flight of the day, the pilot prepared for departure after three passengers had disembarked and three new passengers boarded the helicopter. As the pilot increased torque and brought the throttle to full RPM, the aircraft initially turned left by approximately 15 degrees. The pilot applied about 3 inches of opposite pedal to correct the heading.
As the pilot continued to increase torque and the skids began to lift from the ground, the nose pitched up rapidly and the helicopter rolled to the right. During this yaw, the left skid was approximately 3 inches off the ground while the right skid remained in contact with the surface. The pilot attempted to use full forward and left cyclic, but these inputs had no effect. The pilot then lowered the collective and attempted to reduce throttle, but the aircraft continued to roll to the right until the main rotor blades struck the ground. During the event, a piece of a main rotor blade struck a nearby hangar.
The investigation
The pilot reported that there were no control anomalies during the flight. A subsequent examination of the aircraft revealed no discrepancies.