On August 23, 2000, at 0715 mountain daylight time, a Phelps Rans S-12 Airaile experimental homebuilt airplane, N586WP, experienced a loss of power and was destroyed during a forced landing near Buffalo, Wyoming. The private pilot and his passenger were both seriously injured. The pilot was operating the airplane under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the local flight that originated from Johnson County Airport, Buffalo, Wyoming, approximately 15 minutes before the accident. No flight plan had been filed. The pilot said that he was flying approximately 1,000 feet above the ground when the engine lost power. He selected a landing site for a forced landing, but an unexpected downdraft changed his glide path. He turned to avoid a house, and landed hard on a road. The airplane subsequently slid approximately 50 feet into a fence. Postaccident examination of the Rotax 582UL engine by a mechanic revealed that a rod bearing had failed, and subsequently its associated piston rod bent.