The pilot reported that the purpose of the flight was to demonstrate the helicopter's performance at an air show. He traveled from overseas by scheduled airline, arriving 2 days before the air show. The day before the air show he flew the helicopter for 50 minutes of demonstration practice at a similar density altitude to that anticipated for the following day's performance. The accident flight began about 1315, and the first two maneuvers were completed without incident. The third maneuver was "a standard 180-degree 'wing-over' commenced from a standard 300 feet." According to the pilot, the helicopter "failed to fully recover from the descent phase of the maneuver and struck the surface at approximately 40-50 knots." The helicopter rolled onto its left side. The pilot reported that the density altitude at the time of the accident was 8,500 feet. He stated that the accident could have been prevented "possibly by greater awareness and practice at the local density altitude conditions."