The pilot stated that, while he was on final approach at his destination airport, he caught a downdraft on short final and was unable to arrest the descent rate, even with full power. A witness at the airport advised the Safety Board however, that the wind at the airport at the time of the accident was 8-10 knots. The nearest weather reporting station also reported that the winds were from 360 degrees true at 6 knots. Another witness also advised the Safety Board that the pilot of the accident airplane would usually approach at a slow approach speed for landing. Review of a video recording that was made at the airport on the day of the accident also confirmed that there was little or no wind present during the accident, and that the airplane appeared to approach the runway at a slower airspeed than similar airplanes. Further review of the video also revealed, that while on short final, the airplane had developed a high sink rate, and had began to rapidly roll to the right just prior to impact with the turf runway. No sound of an increase of engine power was recorded until just prior to ground contact. During an interview, the pilot stated there were no mechanical malfunctions with the airplane. Examination of the airplane by a Federal Aviation Administration Inspector revealed that during the accident, the airplane had incurred substantial structural damage to the landing gear assembly bulkhead.