On August 21, 1996, at 1330 central daylight time, a Beech C-23, N18780, operated by General Aviation Services, sustained substantial damage during a hard landing at the Flying Cloud Airport, Eden Prairie, Minnesota. The instructor pilot and student pilot reported no injuries to themselves or to the one passenger . The 14 CFR Part 91 flight departed Flying Cloud Airport, on a local instructional flight. Visual meteorological conditions prevailed and no flight plan was filed. The instructor pilot reported that he had been instructing the student in short field takeoffs and landings at Winsted Municipal Airport, Winsted, Minnesota. They returned to Flying Cloud Airport and were going to practice two more short field takeoffs and landings. The instructor pilot reported that on the first approach, the airspeed got too slow. The instructor tried to take control and recover. The instructor lowered the nose to gain airspeed and do a go-around. The airplane landed hard on the main landing gear, which bent the left wing spar.