On March 3, 2001, at 0930 hours Pacific standard time, an experimental Christian Rans S-12, N12FC, was substantially damaged when it struck a tree during a forced landing in a ravine following a loss of engine power approximately 4 nautical miles east of the Ramona, California, airport. The private pilot was not injured. Visual meteorological conditions prevailed during the flight, which was conducted by the owner under 14 CFR Part 91. The airplane departed Barona, an uncharted private airstrip at 0900, and no flight plan was filed. According to the pilot, the engine failed while in cruise flight. He attempted to land in a small canyon, or ravine area, and was unable to avoid a single tree that was directly in front of him in the center of the ravine. The left wing struck the tree and the right wing was bent when it struck the ground. The pilot, who is also the builder of the airplane, inspected the engine and found a broken crankshaft at the number 1 piston rod attach point. The engine had oil and no other anomalies were observed. The manufacturer of the engine stated that the engine life for this model is 300 hours or 5 years. The engine in the accident airplane was manufactured on March 10, 1991. According to the manufacturer, they have no history of crankshaft failures in this engine model. The crankshaft is required to be replaced at each overhaul. According to the pilot/operator report, the engine had 20 hours since the last overhaul at the time of the accident. The engine was overhauled at a facility that only provides engines for ultralight airplanes. The owner of the facility stated that he does not approve of the use of his engines in certified airplanes. He reported that he remembered overhauling this engine, but does not recall the date, and does not believe that the crankshaft was replaced. The crankshaft was not provided for metallurgical examination.