Incident Summary
A pilot reported that while in cruise at 10,500 feet, the oil pressure dropped to zero and the oil temperature increased. Shortly thereafter, the engine ceased operating. During an attempted forced landing uphill in mountainous terrain, the aircraft collided with ground obstructions.
Engine Examination
External inspection of the engine showed that the number 2 connecting rod had failed and was protruding through the engine case. Internal examination revealed that the number 2 main bearing had spun in its journal. Severe abrasion was observed under the bearing inserts. The oil channel in the number 2 main bearing journal was completely obstructed with metal particles. Further downstream in the oiling path of the number 2 main bearing, progressive heat discoloration and component distress were noted.
Technical Assessment
A technical representative from Continental Engines examined the engine and bearings. The representative opined that the bearing had been intermittently spinning on the journal for approximately 10 hours. The failure of the number 2 connecting rod was attributed to oil starvation resulting from restrictions in the oil path. According to the representative, the most likely cause of the bearing spin condition was under-torque of the case through bolts in the area of the number 2 main bearing.
Additional Information
The engine had been overhauled 70 hours prior to the event.