Accident Description
The airplane was in level flight at 4,000 feet on a dark night in instrument conditions when the engine suddenly lost all power. The pilot executed a forced landing to a river.
Engine Examination
Following the accident, the engine was examined. Two holes were discovered on the top of the engine crankcase. The heads of three connecting rod bolts and portions of a connecting rod bearing were recovered from the bottom of the oil sump pan.
All main bearings, except for the number four and five main bearings, exhibited accelerated wear and were blackened from heat stress. The number four and five cylinder connecting rod end caps and five connecting rod bolts were sent to the Safety Board Materials Lab for further analysis.
Laboratory Findings
The five bolts exhibited severe necking at the fracture and deformation in the shafts. The large deformation and necking were consistent with a single deformation event occurring at high temperature. The connecting rod caps showed a gross amount of deformation but lacked fracture, also consistent with high-temperature deformation.
Maintenance History
The engine had been remanufactured approximately 9 years and 941 hours prior to the accident.