On August 11, 2005, about 1215 eastern daylight time, a Robinson R22 Beta, N8320A, registered to a private individual, operated by Airman Testing & Training, Inc., dba Palm Beach Helicopters, experienced a hard landing during a practice autorotative landing at Palm Beach County Park Airport, Lantana, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 local, instructional flight from Palm Beach County Park Airport. The helicopter was substantially damaged and the certified flight instructor (CFI) and commercial-rated student (student) were not injured. The flight originated about 24 minutes earlier from Palm Beach County Park Airport. The CFI stated that the student had previously demonstrated two practice, straight-in autorotative landings which concluded with a power recovery, and entered a third at 700 feet above ground level (agl) and 70 knots, with the main rotor and engine rpm needles "split", and the throttle in the detent. The student maintained 65 knots during the approach, and flared at 40 feet agl. He (CFI) noted that the helicopter was drifting away from the taxiway centerline so he advised the student to recover. The helicopter was leveled, and he (CFI) applied throttle slowly. While descending, he heard the low rotor warning horn just before impact, and believed the student pulled collective control just before touchdown. The helicopter impacted the ground "hard" on left side, spun to the right, and came to rest upright. The CFI also stated that there were no mechanical failures or malfunctions to the helicopter, or any of its systems. The student reported the flare was normal and the main rotor rpm was still in the green. When the helicopter was leveled off, "...before we could roll the throttle back on, the left skid make contact with the ground."