The pilot reported that, during cruise flight, the Cessna 210’s engine began running roughly with smoke developing inside the cabin, followed by oil covering the windshield.
He said the engine continued to run and that his attempts to increase the power setting resulted in severe shaking and more smoke.
He initiated a forced landing in a field near Jacksonville, Ore. During the landing roll, the nosewheel landing gear dug into mud, and the airplane subsequently nosed over.
A post-accident examination of the engine revealed that the Nos. 5 and 6 connecting rods were liberated from the crankshaft. The No. 6 connecting rod was thermally discolored and fractured, which was likely caused by oil starvation to the No. 6 connecting rod journal and bearing.
The No. 5 connecting rod was also fractured; however, the connecting rod and bearing did not exhibit thermal discoloration or distress; the fracture likely resulted due to damage sustained when the No. 6 connecting rod fractured.
The Nos. 1 and 2 connecting rods also exhibited thermal discoloration and distress, which likely resulted from the engine’s continued operation after the liberation of the No. 6 connecting rod.
The NTSB determined the probable cause as a loss of engine power during cruise flight due to the failure of the No. 6 connecting rod, which resulted from oil starvation.
NTSB Identification: WPR15LA032
This November 2014 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.