On July 17, 1994, approximately 1120 Pacific daylight time, an experimental Black RV-4, N144US, sustained substantial damage while landing at Twisp, Washington. The private pilot, who owned the aircraft and was the sole occupant, was uninjured. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed for the flight from Methow Valley Airport, Winthrop, Washington. The pilot, who built the aircraft and had approximately 800 hours in the aircraft, stated that on short final the "bottom dropped out," and the aircraft landed hard, bending the gear and engine mount, and buckled the firewall. The wing was also damaged by impact with a fence post that was apparently near the runway threshold. The pilot stated that the aircraft ended up back in the air. He did not know if he pushed the throttle forward during the impact sequence, but he had a stuck throttle and mixture control. He said that he flew the aircraft back to Methow Valley Airport and landed successfully.