On August 21, 1997, at 1515 eastern daylight time (edt), a Beech G35, N4630D, operated by a commercial pilot collided with a fence, and a ditch prior to nosing over near the Willow Run Airport, Belleville, Michigan. The engine started when the pilot moved the propeller by hand. Both the pilot and passenger who were outside the airplane when the engine started were not injured. The airplane was substantially damaged. Visual meteorological conditions prevailed. The 14 CFR Part 91 flight was to have originated from the Willow Run Airport. The pilot stated that the engine was hot and he could not get it srated. He reported that the throttle was set at 1,000 rpm, the mixture was full rich, the battery and generator switches were on, and the magnetos were on; however, the recalled turning the magnetos off prior to exiting the airplane. He stated he and the passenger departed the airplane so he could "...manually turn the propeller off of the starter's "dead" spot." He stated that he moved the propeller slightly at which time the engine started. The pilot reported that the airplane which was not tied down or secured with chocks started moving toward an FBO flight line. He stated he put pressure on the right wing in order to turn the airplane away from the flight line. He stated he turned the airplane 200 to 240 degrees to the right. The airplane traveled approximately one mile prior to contacting a chain link fence and a six foot deep ditch at which time it nosed over. The airplane's ignition system was inspected by a Federal Aviation Administration Airworthiness Inspector. He reported that the "...magneto switch worked normally and that all magneto P-leads were properly installed and functional."