On July 23, 1998, a Cessna 140 (registration N76601) was involved in an aviation accident near Falls City, NE. Investigators recorded the probable cause as: the main landing gear leg fracturing and separating from the portion mounted to the fuselage for undetermined reasons. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During landing roll, the left landing gear leg of a tailwheel airplane fractured at the step bolt hole, causing a ground loop. The pilot's seat belt mounting bracket, made of aluminum instead of specified steel, separated, ejecting the pilot through the left door.
Incident Summary
During the landing roll of a tailwheel airplane, the left landing gear leg fractured and separated at the point where the entrance step bolt hole passes through the leg. The fracture led to the aircraft ground looping to the left.
Seat Belt Mounting Bracket Failure
During the ground loop event, the pilot's seat belt mounting bracket separated. The bracket was constructed from aluminum, whereas the manufacturer had specified that it should be made from steel. The separation of the bracket resulted in the pilot being ejected through the left door.
Landing Gear Leg Fracture Characteristics
Examination of the separated landing gear leg revealed fracture surfaces with a grainy texture. All four edges of the fracture exhibited shear lips. A series of small arrowhead-shaped markings originated from the leading edge of the gear and progressed aft to a point approximately midway between the bolt hole and the leading edge.