On August 3, 2002, approximately 0900 Pacific daylight time, an Aero Commander 100, N3766X, registered to and operated by the pilot as a 14 CFR Part 91 personal flight, collided with a fence short of the runway at Quincy Municipal Airport, Quincy, Washington, and subsequently nosed over. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was substantially damaged and the private pilot received minor injuries. The two passengers were not injured. The flight departed from Tonasket, Washington, about one hour and 30 minutes prior to the accident. In a written statement, the pilot reported that the aircraft was slightly above glide path while on final approach for runway 27, at 80 MPH indicated airspeed. The aircraft had 10 degrees of flaps extended. The pilot increased flap extension to 20 degrees, and noted a sudden and severe descent rate. The pilot added power, however, the descent rate was not arrested and the aircraft touched down approximately 150 feet short of the runway. During the landing roll, the aircraft collided with a fence. The nose gear separated and the aircraft nosed over. The pilot reported the weather at the time of the accident as calm winds and no turbulence. No mechanical failures or malfunctions were reported with the aircraft at the time. At 0852, Moses Lake, Washington, METAR located 17 nautical miles southwest of Quincy, was reporting the weather as clear with winds from 190 degrees at 5 knots.