Incident Details
A flight instructor and a commercial pilot were practicing autorotations. On the fourth maneuver, the flight instructor was demonstrating an autorotation that would terminate with a full touchdown. The flight instructor reported that he began the maneuver at 800 feet above ground level (AGL) and initiated the deceleration about 50 feet AGL. At approximately 10-15 feet AGL, he leveled the helicopter and began the descent to touchdown.
When collective was to be applied, the pilot felt a forward pressure on the cyclic and a tendency for the helicopter to nose down. He reacted by centering the cyclic. When the collective reached 50 percent of travel, the pilot realized that the rate of descent was greater than normal. He applied more collective and advanced the throttle in an attempt to minimize the rate of descent, but the helicopter landed hard in a tail-low attitude.
The accident was videotaped by a witness. Review of the videotape revealed that the helicopter appeared to stop its descent about 20-25 feet AGL and assume a tail-low attitude. The helicopter then descended and landed on the tailskid, followed by the aft portion of the main landing gear skids. When the tailskid contacted the ground, the tail boom fractured. The tail assembly was then struck by a main rotor blade, and the helicopter rocked forward on the main landing gear skids, causing the left strut to fail.
Post-Accident Examination
Examination of the helicopter revealed that there were no mechanical deficiencies.