Cessna 210L N2263S accident near Tampa, Florida

Probable cause

The total loss of engine power due to inadequate torgue on the crankcase bolts. Contributing to the accident was the inadequate inspection performed 19.5 hours prior to the accident.

NTSB analysis

The airplane was climbing when the engine lost partial power. The pilot turned back toward the departure airport and the engine lost total power. During the subsequent forced landing, the airplane struck a fence, which resulted in substantial damage to the fuselage and left wing. Examination of the engine crankcase halves revealed fretting at the No. 2 main bearing saddle surfaces, which indicated insufficient clamping force during assembly due to inadequate torque on the bolts. The No. 2 main bearing was broken into pieces, which were observed in the oil sump. Examination of the crankshaft revealed a fatigue fracture that initiated in the fillet between the No. 2 main journal and the cheek at the aft end of the journal. The fatigue crack features observed in the No. 2 main bearing were secondary and were a result of high stresses on the bearing as it shifted. This most likely resulted from insufficient bearing crush due to insufficient clamping force on the crankcase saddle surfaces. According to the engine logbooks, a 100-hour maintenance inspection occurred 19.5 hours prior to the accident, which required a mechanic to verify that the crankcase bolts did not exhibit looseness.

Text from the NTSB. Open the NTSB docket for ERA10LA307 for the full record.