On August 9, 2004, at 1640 central daylight time, a Schweizer 269C-1 single-engine helicopter, N204LH, was substantially damaged following a loss of control while hovering at the Denton Municipal Airport (DTO) near Denton, Texas. The flight instructor and the pilot receiving instruction were not injured. The helicopter was registered and operated by Longhorn Helicopters, Inc., of Trophy Club, Texas. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 91 instructional flight for which a flight plan was not filed. The local flight originated from DTO about 1540. The 2,800-hour flight instructor reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that while practicing hovering autorotations, the student pilot applied full forward cyclic and full collective while reducing throttle. As the flight instructor applied full aft cyclic and lowered the collective, the helicopter pitched forward and the main rotor blades impacted the ground. Subsequently, the helicopter rolled to the left and came to rest on its left side. The rated pilot receiving instruction stated that he "did not knowingly apply forward cyclic or full collective." The operator reported that all main rotor blades were destroyed and the skid landing gear, tailboom and the left side of the fuselage were also damaged. The 2004-model helicopter was reported to have accumulated a total of 224 hours since new. The flight instructor reported that the pilot receiving instructions performed two hovering autorotations with no drift. On the third hovering autorotation, accomplished at a skid height of 12 to 18 inches off the ground, the student applied full forward cyclic with full collective while reducing throttle. The flight instructor added that the maneuver was initiated with the helicopter into the wind, while hovering over level grassy area. The wind at the time of the accident was from 360 degrees at 2 knots.