On May 8, 2004, at 1245 central daylight time, a Robinson R22 Beta, N215WW, piloted by a private pilot, sustained substantial damage during a hard landing near Genesee Depot, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 without a flight plan. The pilot and his pilot-rated passenger were not injured. The flight departed the pilot's private residence near Dousman, Wisconsin, approximately 1240. According to the pilot's written statement, after departure he assumed control of the helicopter from the pilot-rated passenger in order to practice a hover landing. The pilot reported he selected a sand/gravel pit approximately 1 1/2 miles from his residence to practice the landing. The pilot stated that during the landing attempt, approximately 20 feet above ground level, the low rotor RPM horn sounded along with the corresponding warning light. The pilot reported the helicopter "settled rapidly" as he lowered the collective and increased the throttle. The pilot stated that the helicopter was too low for a successful recovery and impacted left skid first. The pilot reported "It may have been possible that I delayed throttle governor by initially holding throttle/collective control too tightly." The pilot also stated that the accident could have been prevented by "closer observation of [the] main rotor RPM."