On May 27, 2001, at 1255 hours Pacific daylight time, a Cessna 337G, N337GD, sustained substantial damage when it impacted and severed an electrical power transmission wire about 5 miles south of Temecula, California. The owner/pilot was operating the airplane under the provisions of 14 CFR Part 91. The private pilot and one passenger were not injured. The personal cross-country flight departed Brown Field, San Diego, California, about 1235, and was destined for the French Valley Airport, Temecula. Instrument meteorological conditions prevailed, and no flight plan had been filed. According to a Federal Aviation Administration inspector, the airplane impacted power transmission wires approximately 120 feet above ground level, approximately 2 miles east of Interstate highway 15. The wires cross the highway about 9 miles south of the French Valley airport. The top (skyline) wire was marked; however, the wire the aircraft severed was lower. A person who was present in the area at the time told the inspector that conditions of low clouds and poor visibility prevailed. Inspection of the airplane revealed the windshield was broken out, the cabin ceiling and a doorpost were bent, and a wing strut was damaged. The inspector located a GPS antenna skin doubler on the ground near the severed wire. He was able to match the piece to damage on the aircraft. A Sempra Energy Company employee told the Safety Board investigator that the power interruption occurred at 1255. In his statement to the Safety Board, the pilot reported he was en route from Brown Field to French Valley "in VFR [visual flight rules] conditions." When approximately 10 miles south of French Valley and with the airport in sight, there was a loud bang, after which the windshield was broken and the cabin ceiling was broken open. The pilot continued the flight to his intended destination at French Valley. The nearest weather reporting point was at MCAS Camp Pendleton (KNFG), 14 miles south-southwest, and approximately 1,500 feet lower elevation. At 1255, their reported weather was scattered clouds at 1,000 feet agl and overcast ceiling at 1,500 feet agl.