Incident Overview
The airplane was en route to its destination when, 15 miles east of the airport at 1,500 feet mean sea level (msl), the engine gauges began indicating low oil pressure and high oil temperatures. About 8 miles east of the airport, the engine lost power, accompanied by a puff of white-gray smoke and loud clanking sounds. The airplane descended to 1,200 feet msl, and the pilot directed it toward an open field above a stretch of beach. During the landing roll, the airplane reached the end of the field and nosed over the edge of a 50-foot cliff, coming to rest on the beach below.
Engine Examination
The engine had been factory rebuilt in 2002 and accumulated 1,441.5 hours since its last major overhaul. Post-accident examination revealed a 2.7-inch hole in the top of the engine case. Shiny copper fragments from the number 2 main bearing were found in the oil sump, with one bearing fragment present in the oil pickup screen. The bearing material of the number 2 main bearing had partially displaced and extruded between the crankshaft journal and the crankcase. The bearing fragments appeared shiny or polished, indicating they had received lubrication and were not exposed to extreme temperatures. Numerous fragments from the number 2 main bearing were located in the oil sump. Although the fragments were generally too large to enter the oil sump pickup tube, they could obstruct the pickup tube orifice, thereby restricting oil flow.
Oil Analysis Findings
Engine oil analysis records indicated a sudden increase in copper levels from 5.3 parts per million (ppm) to 61.2 ppm within the previous 63.1 hours of operation. Engine journal bearing material is the only component within the engine that contains a significant copper component. The source stated that this increase in copper levels was directly related to the gradual deformation and fragmentation of the number 2 main bearing.
Component Failure
The number 1 connecting rod failed under overload, which resulted from extreme temperatures at the connecting rod bearing consistent with oil starvation. The number 1 connecting rod bearing receives oil pressure from the oil pump through the number 1 main bearing and would be among the first bearings affected by reduced oil flow.