On August 31, 2007, a Mooney M20K (registration N231BQ) was involved in an aviation accident near Fort Wayne, IN. Investigators recorded the probable cause as: A total loss of engine power due to the fatigue failure of one of the number two cylinder connecting rod bolts. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Shortly after leveling off at 6500 feet, the engine vibrated and lost power. The pilot attempted a return but chose a forced landing in a corn field, substantially damaging the airplane. Investigation revealed a connecting rod bolt failed due to metal fatigue.
Incident Summary
The airplane had just leveled off at 6500 feet after departure when the engine began to vibrate and subsequently lost all power. The pilot attempted to return to the departure airport but realized that none of the runways could be reached. A forced landing was executed into a corn field, which resulted in substantial damage to the airplane.
Investigation Findings
A postaccident disassembly of the engine was conducted. Examination revealed that the number two connecting rod had separated from the crankshaft. One of the connecting rod bolts had sheared. Microscopic inspection of the fracture surface showed distinct signature marks of metal fatigue across the bolt shear face. These fatigue marks had initiated at the surface of the bolt.
It was noted that the number two cylinder had been replaced approximately 8 hours prior to the accident. However, the connecting rod had not been removed from the crankshaft during the cylinder replacement procedure.