19970922027939A

Lost power during a spray run turn around. Hit ditch landing. Found broken crankshaft. Recent top overhaul. (.4)according to the pilot, a loss of engine power occurred, while he was applying insecticide to a farm. A force landing was made in a plowed field. During the landing, the airplane encountered a small ditch in soft terrain, and the airplane nosed over. Examination of the maintenance records revealed that a top overhaul of the engine had been accomplished, 7 days before the accident. Postaccident examination of the engine revealed a fractured crankshaft. Multiple origin sites of the fracture were found from the surface of the journal radius. There was evidence that inadequate torque had been applied to the crankcase through-bolts. The #2 main bearing had moved fore and aft in the bearing bore and had rotated in the crankcase; there was heavy fretting at the #2 and #3 main bearing boss parting surfaces; and there was evidence of severe pounding from lack of support that had started a breakup of the #2 bearing. (-23) the spray pilot was in a maneuvering turn when the engine lost power. The pilot made an emergency landing in a soft plowed field. Hitting a small ditch the plane flipped over causing substantial damage. The pilot exited the airplane through a side window with no injuries.