On August 23, 1996, approximately 1435 mountain daylight time, a Bell 206-B3 helicopter, N206FT, sustained substantial damage while maneuvering near Greybull, Wyoming. The airline transport pilot and his passenger were uninjured. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed, and there was no report of an ELT actuating. The pilot stated that he was demonstrating autorotations to his passenger. At 800 feet above the ground and about 80 knots airspeed, he rolled off the throttle and initiated the maneuver, planned to be a power-on recovery. At the time he flared to recover, he heard a horn and had a light on the panel. The aircraft touched down easy on the nearly level surface and slid less than one yard. The main rotor separated the tailboom. The pilot did not believe that the aircraft had sustained a loss of power, and he surmised that he may have made a pitch change application at too high an altitude.