On August 9, 2008, about 1514 Pacific daylight time, a Smith Stewart S51D, amateur built experimental airplane, N51VS, experienced a loss of engine power while on approach to land at Oxnard Airport, Oxnard, California. During the subsequent forced landing, the airplane sustained substantial damage when it collided with a fence and building. The private pilot, who was the owner and builder of the airplane, received serious injuries. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 91 personal cross-country flight, and no flight plan was filed. The flight departed from Tehachapi, California, at 1415, with an intended destination of Oxnard. The pilot reported that the flight was made at a cruise altitude of 9,500 feet mean sea level (msl). As he neared his destination, he descended to 2,500 feet msl at low power with the mixture enrichened progressively. He entered the traffic pattern for runway 25 on the right base leg as instructed by the tower local controller. After turning final, the pilot increased power and the engine began to run rough. According to the pilot, "the engine was producing little or no power and descent rate was in excess of 2,500 feet per minute." He switched from the right to the left ignition module, which resulted in a momentary increase in power. After a few seconds, the engine again stopped producing power, and he executed an approach to a baseball field. Oxnard Fire Department personnel reported that the airplane impacted the chain link fence backstop of the baseball field and then struck a school bus barn. The wing separated from the fuselage and fuel was observed leaking from the wing. A Federal Aviation Administration inspector examined the wreckage of the airplane and reported that the airplane was powered by a Chevrolet V-8 engine. The reason for the loss of engine power was not determined.