On May 19, 2001, at about 0930 central daylight time, a Cessna 172R, N9532K, piloted by a private pilot, sustained substantial damage during landing on runway 35 (6,500 feet by 100 feet, asphalt), at the St. Louis Regional Airport, Alton, Illinois. The 14 CFR Part 91 personal flight was operating in visual meteorological conditions and was not on a flight plan. The pilot, who was the sole occupant, was not injured. The local flight originated about 0900. The pilot said in a written report, "Doing touch and gos in pattern. On 4th circuit bounced landing [and] sudden vibration in nose wheel. Nose pulled up - power added [and] uneventful go around. Landed on 5th circuit's incident. When nose wheel touched down, again had heavy vibration. [Aircraft] stopped on runway...After shutdown discovered 1-2 [inch] bend in prop tips....Subsequently informed that firewall had been bent [and] required replacement." The pilot stated "Blow out nose wheel" in the section of the report titled, "Mechanical Malfunction Failure".