On May 5, 1983, a Beech E33 (registration N8314N) was involved in an aviation accident near San Angelo, TX. Investigators recorded the probable cause as: The failure of the rigid oil pressure line due to fatigue cracking, which resulted in oil starvation and the subsequent failure of the number four connecting rod. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aircraft crash-landed short of the runway after an engine failure caused by a fatigued rigid oil pressure line. The line had been installed instead of the required flexible hose, leading to oil starvation and connecting rod failure.
Accident Description
The aircraft experienced an engine failure in flight and subsequently crashed approximately one mile short of runway 18 during an emergency landing at Mathis Airport. Examination of the wreckage revealed that the fuselage was streaked with fresh oil.
Engine and Oil Line Failure
The rigid oil pressure line, which extended from the engine to the firewall, had failed due to fatigue cracking. The cracks originated from multiple points on opposite sides of the outside diameter of the line, at the beginning of a heavily flared radius. The parts catalog for the BE-E33 requires a flexible hose in this location, but it is not known when the rigid line was installed in place of the flexible hose.
Maintenance History
The engine had been overhauled on July 20, 1982, 121 hours prior to the accident. The oil starvation resulting from the line failure led to the failure of the number four connecting rod.
Probable cause
The failure of the rigid oil pressure line due to fatigue cracking, which resulted in oil starvation and the subsequent failure of the number four connecting rod.