On May 8, 1985, a Cessna 140 (registration N4034N) was involved in an aviation accident near Latrobe, PA. Investigators recorded the probable cause as: Failure of the left main landing gear spring (strut) due to a pre-existing crack that originated from a bolt hole drilled for a step. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During landing, the aircraft began to swerve right. As the pilot regained control, the left main gear spring failed, causing the aircraft to exit the runway. The left wing was damaged. Examination revealed a pre-existing crack at a bolt hole.
Incident Description
The pilot reported that during a landing, the aircraft began to swerve to the right. At approximately the time the pilot was working to regain directional control, the left main landing gear spring (strut), part number Q441138, failed. The aircraft subsequently exited the runway, and the left wing sustained damage.
Examination of the Failed Component
An examination of the failed left main landing gear strut was performed. The examination revealed that the strut had fractured at a location where a bolt hole had been drilled for the installation of a step. Evidence of a pre-existing crack was found; this crack extended about one inch on each side of the bolt hole, for a total crack length of approximately two inches. The crack was present prior to the failure event and originated from the edge of the bolt hole, propagating through the strut material.
Probable cause
Failure of the left main landing gear spring (strut) due to a pre-existing crack that originated from a bolt hole drilled for a step.