On July 22, 1995, at 1130 hours Pacific daylight time, a Piper PA-28-151, N41521, collided with a fence during an off-airport takeoff from a field near San Luis Obispo, California. The airplane was being operated as a personal flight by the pilot. The airplane was substantially damaged. The certificated private pilot received minor injuries, and the passenger was not injured. Visual meteorological conditions prevailed. The preceding flight departed Fresno, California, earlier in the day and was destined for Oceano, California. The pilot changed her destination to San Luis Obispo after learning weather conditions at Oceano did not clear as forecasted. While on final approach to San Luis Obispo Airport, the air traffic control tower specialist requested that the pilot accomplish a 360-degree turn for spacing of traffic. The pilot stated she was in the process of completing the before-landing check, and inadvertently switched the fuel selector switch to the off position. The engine lost power and the pilot accomplished an uneventful off-airport landing in a field short of the airport. About 1 hour later, the pilot decided to attempt a takeoff from the field. The pilot told her passenger that he need not go along, however, the passenger insisted he accompany her. The pilot attempted a short/soft field takeoff, but the airplane did not get airborne before colliding with a chain link fence. The pilot stated to the Safety Board that she did not extend the flaps for the takeoff. According to the Pilot Operating Handbook for the Piper PA-28-151, the flaps should be extended 25 degrees for obstacle clearance short field and soft field takeoffs.