On February 29, 2004, at 1445 Pacific standard time, a Piper PA-28-180, N5205L, owned and operated by the pilot, experienced a total loss of engine power on approach to Mariposa-Yosemite Airport, Mariposa, California. The pilot made a forced landing about 4 miles south of the airport. During rollout in an open field, the airplane collided with a dirt berm and was substantially damaged. The commercial pilot was not injured, and the passenger sustained minor injuries. Visual meteorological conditions prevailed at the time of the business flight, and no flight plan had been filed. The flight was performed under the provisions of 14 CFR Part 91, and it originated from Fullerton, California, about 1215. The pilot reported that on departure the airplane's fuel tanks contained 34 gallons of fuel. He did not experience any mechanical malfunction or failure with the airplane during the climb out or cruise flight, which was performed at 10,000 feet mean sea level The pilot further reported that on approach to the destination airport the engine suddenly lost all power. After turning toward a field in preparation for a forced landing he repositioned the fuel selector to the opposite fuel tank. About 1 minute thereafter, the engine "came to life." The pilot then turned back toward his intended destination airport, which was about 4 miles away, and he entered a climb configuration. After flying for about 1 minute all engine power was again lost. The pilot made a forced landing in a nearby farmer's field. After rolling for about 30 feet in the soft field, the airplane came to a sudden stop upon impacting a berm. The pilot reported that at no time during the flight was there evidence of a rough running engine, and it had not backfired or sputtered. Subsequently, a Federal Aviation Administration (FAA) aviation safety inspector supervised an examination of the airframe and engine. The FAA inspector verbally reported to the National Transportation Safety Board investigator that an estimated 4 gallons of fuel were observed in the airplane's left wing fuel tank, and about 8 gallons were observed in the right wing fuel tank. The gascolator was devoid of foreign material. The engine was started and it operated normally. According to the Piper Aircraft Corporation, the company did not specify the quantity of unusable fuel in the PA-28-180 flight manual for the accident airplane. The FAA's type certificate data sheet indicates that the unusable fuel was a total of 2.2 pounds for PA-28-180's manufactured within the serial number group of the accident airplane.