On February 13, 2004, at approximately 1345 mountain standard time, a Bell, 47G-3B-1, N83702, was substantially damaged during a hard landing at McElroy Airfield, Kremmling, Colorado. The commercial pilot, the sole occupant on board, was not injured. Visual meteorological conditions prevailed. No flight plan had been filed for the local flight being conducted under the provisions of Title 14 CFR Part 91. The flight departed approximately 1230. According to the pilot, he was practicing "power-on recovery, autorotations" from an altitude of 800 feet agl. He said he had completed two autorotations and was attempting a third autorotation when "it appeared that the aircraft had inadequate main rotor rpm." The pilot said he attempted to recover to a hover; however, "sufficient rpm was not available to recover," resulting in a hard landing. During the impact, the vertical stabilizer and both tail rotor blades were bent and the tail rotor short-shaft separated from the long shaft. An examination of the helicopters systems revealed no anomalies.