Accident Overview
During cruise flight, a Cessna 210 suffered a complete loss of engine power. The pilot executed a descent through an overcast cloud layer and performed a forced landing in an open field. The landing was made with the landing gear retracted. During the subsequent ground slide, the aircraft passed over a creek and sustained substantial damage.
Engine Examination
Prior to engine disassembly, a torque check was conducted. This check revealed low torque values on a nose case bolt and on several cylinder through bolts for the front and middle cylinders. Subsequent disassembly of the engine disclosed that the crankshaft had fractured near the rear of the number 2 main bearing, which is located between the middle and rear cylinders.
Inspection Findings
The investigation determined that the number 2 main bearing had shifted toward the rear of the engine. This movement caused the bearing to make contact with the short cheek of the crankshaft. The number 4 cylinder had been replaced 469 flight hours before the accident. The remaining cylinders—numbers 1, 2, 3, 5, and 6—had been replaced 367 flight hours prior to the accident.