On September 19, 1999, at 1656 hours Pacific daylight time, a Rockwell S-2R, N4168X, collided with trees during takeoff from a private dirt airstrip near Acampo, California. The airplane, operated under the provisions of 14 CFR Part 91, was destroyed in a postimpact fire. The commercial pilot received minor injuries. Visual meteorological conditions existed for the local positioning flight, and no flight plan was filed. The flight was scheduled to terminate at the Lodi Airport, Lodi, California An on-scene investigation by a Federal Aviation Administration (FAA) inspector revealed that the airstrip is approximately the size of a single lane road. Grass, shrubs, and weeds approximately 2- to 3-feet tall, are located on both sides of the runway, with a series of trees that run along a railroad track on the left side of the runway. The inspector reported that the aircraft and engine logbooks, located onboard the airplane, were destroyed by a postimpact fire. The pilot stated in an interview with the FAA that he was moving his airplane to the Lodi airport because of the pending closure of the airstrip. The pilot stated that on the takeoff roll the left main wheel and the spreader got caught on the vegetation. This slewed the airplane to the left and then the left wing end cap struck a small tree. Before the pilot could recover directional control, the left wing struck a second tree. He stated that approximately 3 feet of the left wing was torn from the airplane, which then pitched up, turned 180 degrees, and impacted railroad tracks approximately 40 yards from the second tree. The pilot stated that the airplane had not flown since January, but the engine was started every couple of weeks to keep it lubricated. Witnesses to the accident stated that during the run-up no discrepancies were noted with the engine. They further reported that through the takeoff and accident sequence the engine sounded as if it was producing full power. Witnesses reported that during the takeoff roll the wings were level and it appeared that the spreader had become caught in the weeds. After the accident they assisted the pilot out of the airplane and noted smoke coming from the engine nacelle. They stated that there was an ensuing fire that spread from the engine nacelle downward and then up into the cockpit. The pilot did not complete the NTSB Form 6120.1/2, Pilot/Operator Aircraft Accident Report, despite repeated attempts by Safety Board investigators to obtain the information.