On July 21, 1996, at 1011 central daylight time, a Boeing A75N1, N58712, sustained substantial damage when it nosed over during the landing roll at the East Troy Municipal Airport, East Troy, Wisconsin. The private pilot and one passenger reported no injuries. The personal, 14 CFR Part 91 flight originated in Staughton, Wisconsin, about 0940. Visual meteorological conditions prevailed and no flight plan was filed. The pilot reported that he flew a "normal" approach to land on runway 08. During the landing roll, the airplane began to "drift" to the right. He "applied the brakes gently" and the airplane nosed over. The airplane was inspected by a Federal Aviation Administration (FAA) inspector. He reported that the left rudder horn was fractured. No other evidence of mechanical malfunction was reported. The rudder horn was examined by an engineering technician in the NTSB materials laboratory. In his factual report, the technician reported that the fracture "showed no evidence of progressive cracking, such as fatigue. The fracture was typical of an overstress separation. There was thinning of the wall and corrosion pits on the inside surface of the tube... ." Measurements of some of the corrosion pits revealed that the thickness of the .035 inch wall tubing was corroded to a thickness of .008 inches in some areas. "There was no indication that any of the corrosion pits had penetrated through the tube to the outside surface."