During the second flight of the homebuilt airplane, the engine lost power and the pilot made a forced landing on a residential street. Witnesses said the airplane veered off the street into a ditch and struck a mailbox. Damage included buckling of the engine mount and fuselage as well as separation of the right main gear, and approximately three feet of the outboard portion of the right wing. Due to the pilot's injuries, he had no recollection of the flight. Examination of the aircraft by Federal Aviation Administration inspectors revealed a partially crimped forward fuel tank vent tube.