On July 21, 1996, a Boeing A75N1 (registration N58712) was involved in an aviation accident near East Troy, WI. Investigators recorded the probable cause as: corrosion and fracture of the rudder control horn. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During the landing roll on runway 8, the airplane drifted right; gentle braking led to a nose-over. Examination found a fractured left rudder horn with overstress separation and corrosion pits that reduced wall thickness.
Incident Summary
A pilot reported a normal approach to land on runway 8. During the landing roll, the airplane began to drift to the right. The pilot applied the brakes gently, and the airplane nosed over.
Examination Findings
Post-incident examination of the airplane revealed that the left rudder horn was fractured. No other evidence of mechanical malfunction was reported. A metallurgical examination of the rudder horn showed no evidence of progressive cracking, such as fatigue. The fracture was typical of an overstress separation. The examination also found thinning of the wall and corrosion pits on the inside surface of the tube. Measurements of some of the corrosion pits indicated that the thickness of the 0.035-inch wall tubing was corroded to a thickness of 0.008 inches in some areas. There was no indication that any of the corrosion pits had penetrated through the tube to the outside surface.