Primary finding
Probable cause
A catastrophic engine failure due to the partial blockage of the lubricating oil galley in one of the crankshaft connecting rod journals, leading to the failure of the connecting rod cap.
Investigator assessment
Analysis narrative
During the descent to the pilot's planned destination, the airplane's engine lost all power, and he was forced to make an emergency landing in a nearby open field. During the landing roll, the airplane impacted an irrigation pipe and nosed over onto its back. The nose over sequence resulted in the buckling of the fuselage and the crushing of the top one foot of the vertical stabilizer. A post-accident partial engine disassembly determined that the oil galley in the number four crankshaft connecting rod journal had became partially blocked by unidentified debris. That blockage resulted in insufficient lubrication of the number four connecting rod bearing, and the ultimate thermal destruction of the bearing. The destruction of the bearing resulted in direct contact between the connecting rod and the crankshaft journal, ultimately leading to the failure of the connecting rod cap due to thermal distress. The failure of the connecting rod cap resulted in the release of the connecting rod from the crankshaft journal, the internal failure of the engine, and the total loss of power.
Source record
Factual narrative
During the descent to the pilot's planned destination, the airplane's engine lost all power, and he was forced to make an emergency landing in a nearby open field. Although the pilot was able to make a successful touchdown in the recently plowed field, during the landing roll, the airplane impacted an irrigation pipe and nosed over onto its back. The nose over sequence resulted in the buckling of the fuselage and the crushing of the top one foot of the vertical stabilizer. A post-accident partial engine disassembly by the Investigator-In-Charge determined that the oil galley in the number four crankshaft connecting rod journal had became partially blocked by unidentified debris. That blockage resulted in insufficient lubrication of the number four connecting rod bearing, and the ultimate thermal destruction of the bearing. The destruction of the bearing resulted in direct contact between the connecting rod and the crankshaft journal, ultimately leading to the failure of the connecting rod cap due to thermal distress. The failure of the connecting rod cap resulted in the release of the connecting rod from the crankshaft journal, the internal failure of the engine, and the total loss of power.