On May 31, 1997, approximately 1845 Pacific daylight time, a Cessna 150H, N50348 impacted the terrain between the runways at Roberts Field, Redmond, Oregon. The private pilot, who was the sole occupant, was not injured, but the aircraft sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which departed Madras, Oregon about 20 minutes earlier, was being operated in visual meteorological conditions. No flight plan had been filed, and there was no report of an ELT activation. The pilot said that he had measured the fuel with a dipstick prior to leaving Madras, and he estimated that he had about eight gallons of total fuel remaining for the 18 to 20 minute trip. While on a 45 degree entry for the downwind leg at Roberts Field, the aircraft's engine experienced a total power loss. At that time the tower cleared the pilot to land on any runway, but he was unable to maneuver to land on a runway, so he elected to make a forced landing on a level area within the lateral boundary of the airport. The pilot made a successful touchdown, but the aircraft collided with sagebrush and rocks during the landing roll. According to an FAA inspector from Portland FSDO, after the accident, both wing tanks were drained and a total of 2.3 gallons was recovered. According to the Owner's Manual, 3.3 gallons of the total fuel load is unusable.