What happened
Shortly after takeoff, while the aircraft was climbing to its cruise altitude, the engine failed. In response to the loss of power, the pilot executed a forced landing into a field. The impact of the landing was described as hard.
The investigation
An examination of the engine identified that the crankshaft had failed at the connecting rod thrust face, specifically just above the rear fillet radius of the no.5 crankpin journal. A metallurgical examination determined that the failure was caused by fatigue.
Review of the engine logbooks provided additional context regarding the engine's maintenance history. Following a previous overhaul, a cam follower failed during the run-in period. This necessitated the disassembly of the engine, at which time the crankshaft was subjected to a Magnaflux inspection. No defects were identified during that inspection. The engine underwent a second overhaul and had accumulated approximately 372 hours of operation since that subsequent maintenance event.