On July 14, 1996, at 1700 central daylight time, a Smith RV4, N83FS, owned and operated by a private owner, was substantially damaged during a forced landing following a loss of engine power near Mandeville, Louisiana. The commercial pilot and his passenger were not injured. Visual meteorological conditions prevailed for the personal flight operated under Title 14 CFR Part 91. A flight plan was not filed for the cross country flight that originated near Stennis, Missouri at 1645. According to the pilot, the airplane was about 1/2 mile from the end of runway 18 when he "added additional power to maintain glide path. There was no response from the engine." The airplane impacted the water about 200 yards from the approach end of the runway. The lower fuselage and leading edge of both wings were damaged. An engine tear down was not performed, and the cause of the loss of engine power could not be determined.