On August 21, 1998, at 1315 hours Pacific daylight time, a Robinson R22B, N2335Q, experienced a hard landing at the Ramona, California, airport. The aircraft sustained substantial damage. The commercial pilot and student pilot, the sole occupants, were not injured. The flight originated at the Carlsbad, California, airport at 1145, and no flight plan was filed. Visual meteorological conditions prevailed. A Federal Aviation Administration (FAA) inspector from the San Diego Flight Standards District Office interviewed the two pilots on August 24. The student pilot reported that he was in the helicopter solely as a passenger with the commercial pilot, who was preparing for his flight instructor check ride the following day. The commercial pilot performed several maneuvers to the taxiway parallel to runway 27. The last maneuver was a 180-degree autorotation. The pilot reported that he initiated the maneuver abeam his intended touchdown zone with the governor in the "on" position. The helicopter nosed over and the rotor rpm began to decrease. The pilot attempted to recover to a level flight attitude, but the rotor rpm decreased to 73 percent. He reported that he "waited for [the] engine to help me, to bring back my rotor rpm." The helicopter landed hard and rolled onto its left side and the main rotor blades severed the tail boom. The FAA inspector examined the helicopter and established flight control continuity. He stated that the pilots did not report experiencing any problems with the aircraft or powerplant prior to the accident. The owner of the flight school reported that the pilot had signed an agreement that stated he would not perform autorotations without an instructor onboard except in an actual emergency.