On April 18, 1997, at 0900 Pacific daylight time, a Rockwell International S-2R, N4978X, registered to and operated by Shupe Flying Service, as a 14 CFR Part 137 aerial application flight, collided with the terrain near Prescott, Washington. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The airplane was substantially damaged and the commercial pilot, the sole occupant, was seriously injured. The flight originated from a private airstrip near the accident site about 30 minutes prior to the accident. Documentation at the accident site by a Federal Aviation Administration inspector from the Spokane, Washington, Flight Standards Field Office, reported that it appeared that the airplane was spraying a field from east to west. The inspector reported that the right side wing tip struck sharply rising terrain approximately three feet from the top. Evidence appears that the wing tip dragged on the ground for about 75 feet prior to the aircraft nosing over. At the point where the aircraft nosed over, a ground impact mark indicated propeller marks in the soil. The aircraft continued to travel for another 150 feet before coming to rest inverted. The engine broke away from the airframe and came to rest over the top of a knoll approximately 200 yards down into a ravine. Another agricultural pilot, operating in the area, reported that he had observed the aircraft make a turn and start the spray run from east to west when it went out of sight behind a hill. Shortly thereafter, the pilot observed smoke and went to investigate, assuming that the aircraft had crashed. As the pilot arrived at the accident location, he observed the accident pilot exiting the burning wreckage. The other agricultural pilot reported that the winds had been blowing from time-to-time in the ravines. Further inspection of the wreckage and engine did not reveal evidence of a mechanical failure or malfunction. The accident pilot was hospitalized for several days after the accident and was unable to make a statement. The National Transportation Safety Board Pilot Operator Accident Report Form 6120.1/2 was sent to the pilot's home address on April 23, 1997. The pilot did not respond and another request for the pilot to complete the form was sent out on July 23, 1997. To this date, the pilot has not responded.