Cessna T210N N6278C accident near Oakland, California

Probable cause

A loss of engine power while maneuvering due to the disintegration of the number two main bearing, which resulted in a fracture of the crankshaft. Contributing to the accident was inadequate maintenance.

NTSB analysis

During a local photo flight at an altitude of 1,500 feet mean sea level (msl), the pilot reported a decrease in engine power followed by a complete loss of engine oil pressure. The pilot determined that due to his location and altitude, he was forced to make a landing on the water. During the landing, the airplane sustained substantial damage to the horizontal stabilizers and to the bottom of the fuselage. During the post-accident investigation, it was determined that the number two and three cylinders had been replaced 137.1 flight hours prior to the accident. During the engine examinations, thermal discoloration of the crankshaft main journals and damage to various other internal components were noted. The crankshaft was fractured just forward of the number two main bearing. The fracture surfaces of the crankshaft were mechanically damaged due to rotational forces. The number two main bearings were not found in the main bearing support diameters. Several bearing fragments were found in the oil sump and on the bearing support diameter. The crankcase itself had been compromised just above the number one cylinder. A review of the maintenance logbooks noted that the engine was beyond manufacturers' recommendations for time between overhaul. Several maintenance discrepancies and non-compliance with manufacturers' recommendations were also noted.

Text from the NTSB. Open the NTSB docket for LAX08LA292 for the full record.