Event Summary
After departure, the right engine began surging. The pilot initiated a turn back toward the departure airport, configured the airplane for landing, and attempted to secure the right engine. The engine then seized, and the propeller stopped. The airplane could not maintain sufficient altitude to clear trees at the approach end of the landing runway, so the pilot performed a forced landing to a field approximately 1 mile short of the airport.
Engine Examination
The right engine's #2 cylinder had been replaced 160 aircraft hours before the accident. Post-accident examination revealed that the crankshaft was broken between the #2 main bearing journal and the #3 connecting rod journal. The mating surfaces of both crankcase halves, in the area of the #2 and #3 main bearing saddles, displayed fretting across the entire face surface. Fracture surface examination showed damage consistent with bearing shifting and rubbing.
Manufacturer Instructions
The manufacturer's cylinder installation instructions included a warning: "Failure to torque through bolt nuts on both sides of the engine can result in a loss of main bearing crush, main bearing shift and engine failure."
Operational Guidance
According to the FAA Airplane Flying Handbook, Engine Inoperative Approach And Landing: "...neither full flaps nor the landing gear should be extended until the landing is assured."