This September 2008 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Cessna 210. Injuries: None. Location: Oakland, Calif. Aircraft damage: Substantial.
What reportedly happened: During a photo flight at an altitude of 1,500 feet MSL, the engine lost power and oil pressure. The pilot determined that the safest thing to do was to land in water. During the post-accident 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 several maintenance discrepancies and non-compliance with manufacturers’ recommendations. The engine was beyond manufacturers’ recommendations for time between overhaul.
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. Inadequate maintenance was a factor.
For more information: NTSB.gov