On June 30, 2002, at approximately 1000 central daylight time, an amateur-built, single-place Grenier Acro Sport, N1419, piloted by a private pilot, was substantially damaged when it experienced a hard landing at the Jacksonville Municipal Airport (IJX), Jacksonville, Illinois. The pilot was practicing takeoffs and landings on runway 22 (4,001 feet x 75 feet, asphalt) when the accident occurred. Visual meteorological conditions prevailed. The flight was being conducted under the provisions of 14 CFR Part 91 and was not on a flight plan. The pilot reported no injuries. The pilot stated: "I was on final approach on runway 220, attempting a wheel landing when I caused the aircraft to hit the runway too hard. I heard and felt the left wheel give way, bounced a small distance, and then skidded on the runway . . .. The aircraft skidded to the left off the runway into the grass area." In a phone interview, the pilot stated that he had attempted to land three (3) times previously, each time initiating a go-around after touching down at an excessive rate of descent and becoming airborne again. The pilot holds a private pilot certificate, with an airplane - single-engine land rating, and a valid third class medical certificate. He last completed a biennial flight review in September 2000, and has accumulated 600 hours total time. Of that flight time, one (1) hour was in the same make and model as the accident aircraft. The Grenier Acro Sport, S/N 499, involved in the accident had completed an inspection on June 28, 2002, and accumulated one (1) hour since then. Total time on the aircraft was not reported. The pilot did not report any malfunctions prior to the accident. Evaluation of the aircraft after the accident indicated that the left main landing gear attachment bolt failed at the strut-to-fuselage fitting. A review of the airplane by the FAA inspector on-scene revealed that the wing spar had been broken and a fuselage longeron was bent in the area of the left main landing gear attachment fitting. Weather conditions at the scene were reported by the pilot as clear skies, light winds (040 degrees at five (5) knots), and no turbulence. The Jacksonville airport (IJX) AWOS, at 1007 cdt, reported clear skies and calm winds.