On May 9, 1994, at 0845 eastern daylight time, a Schweizer 300C, N220MS, collided with the ground, during an autorotation after a complete loss of engine power near Randleman, North Carolina. The aerial observation flight operated under 14 CFR Part 91, with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The helicopter sustained substantial damage; and the pilot received serious injuries. The flight departed Randleman at 0843 hours. The pilot's normal preflight inspection included draining the fuel system to check for contaminants. During this phase of the preflight,the pilot normally drained a small quantity of fuel from the fuel system. The fuel samples were not collected in a container and checked for contaminants. Approximately an hour after the preflight, the flight departed and the pilot established a left climbing turn to 1000 feet agl (feet above the ground). As the pilot continued the left turn, engine rpm dropped, and the pilot lowered the collective to maintain rotor RPM. As the emergency continued, rotor rpm continued to drop and the pilot established a final approach for the emergency landing. The helicopter touched down hard and rolled over on the right side. During the post-crash examination of the helicopter two gallons of water were recovered from the fuel system.