The airplane lost power and collided with objects during a forced landing at 1130 Pacific time, sustaining substantial damage. The Commercial pilot received minor injuries. Visual conditions prevailed. The airplane was on a left downwind and the pilot had completed the before-landing checklist when the engine quit producing power. The pilot performed the emergency checklist but the engine did not restart. According to FAA inspectors, approximately inch of fuel or less remained in the left wing when it was placed in a level position. Slightly more remained in the right fuel tank. According to the pilot, the recovery personnel drained three gallons of fuel from the left fuel tank and five gallons from the right; however, he noted that some had spilled out during the recovery process.