Cessna 210N N5307A accident near Tampa, Florida

Probable cause

A total loss of engine power due to the fatigue failure of the No. 4 connecting rod. Contributing to the accident was a likely loss of lubrication for reasons that could not be determined during a postaccident engine examination.

NTSB analysis

As the on-demand air cargo flight approached the destination airport, the pilot advised air traffic control that the airplane's engine had "lost oil pressure." Subsequently, an air traffic controller cleared the flight to land on an alternate runway. The airplane impacted a berm short of the runway threshold, which resulted in serious injury to the pilot and substantial damage to the airframe.

Postaccident examination of the wreckage revealed that engine oil was present from the windscreen to the vertical stabilizer and that the engine case had been breached near the Nos. 4 and 6 cylinders. Detailed examination of the engine revealed signatures consistent with oil starvation and a fatigue failure of the No. 4 connecting rod and connecting rod cap. Although the metallurgical hardness of one of the No. 4 connecting rod bolts was slightly below its specified value, this likely did not contribute to its separation, and it likely failed in overstress after the fatigue-related separation of the mating connecting rod. The engine's oil sump was breached and only contained residual traces of engine oil; the preaccident quantity of oil within the engine could not be determined. Examination of the engine's oil galleys and passages revealed that they were intact, clear, and unrestricted. The root cause for the loss of lubrication and subsequent fatigue failure of the No. 4 connecting rod could not be determined.

Text from the NTSB. Open the NTSB docket for ERA14LA076 for the full record.