Beech F33 N80WH accident near Hobe Sound, Florida

Probable cause

A bearing shift, which resulted in a loss of lubrication to the crankshaft, the failure of the crankshaft, and a total loss of engine power.

NTSB analysis

During low-altitude cruise flight, the engine lost total power and the pilot performed a forced landing on an embankment next to a road, resulting in substantial damage to the right wing, right tip tank, and right elevator. Postaccident examination of the engine revealed that the crankshaft was fractured between the No. 2 main bearing journal and the No. 2 connecting rod journal and exhibited evidence of lubrication distress. Additionally, the No. 2 bearing had shifted, and a large portion of the bearing had extruded from the bearing support. The bearing support mating surfaces displayed fretting and the lock tab had completely worn away. Based on the observed damage, it is likely that the No. 2 main bearing shifted, resulting in inadequate lubrication to, and subsequent failure of, the crankshaft.

While the crankcase mating surfaces displayed unapproved sealant material with no signs of silk thread, which was not consistent with the engine manufacturer’s guidance for engine assembly, the breakaway through bolt torque remained at or above the manufacturer’s specification. It could not be definitively determined, based on available evidence, if the use of an unapproved sealant contributed to the bearing shift.

Text from the NTSB. Open the NTSB docket for ERA19LA258 for the full record.