Cessna T210F N6195R accident near Monticello, New York

Probable cause

Maintenance personnel’s improper torque of the engine through-bolts during maintenance, which resulted in a bearing shift, oil starvation, and a total loss of engine power.

NTSB analysis

The pilot was descending toward the destination airport when the engine began losing power and “making noises.” The pilot switched fuel tanks, but the power loss continued. He subsequently began looking for a place to land the airplane. The pilot then heard what sounded like an “explosion” from the engine. The oil service door blew open and began spewing oil and smoke from the service door opening, covering the windscreen. Smoke then began entering the cabin. The pilot landed on a road with the landing gear retracted, and the airplane slid to a stop. The airplane caught on fire, and the pilot egressed before the cockpit was consumed.

Postaccident examination of the engine revealed that the Nos. 5 and 6 connecting rods were fractured. The No. 5 connecting rod was missing and the No. 6 connecting rod exhibited thermal discoloration consistent with a loss of lubrication. The crankshaft and camshaft were fractured at the No. 5 cylinder. Review of the engine logbook revealed that about 100 flight hours (5 months) before the accident flight, engine through-bolt nuts were removed and resealed for oil leaks. Given this information, it is likely that maintenance personnel did not properly torque the crankcase through-bolts, which allowed the No. 5 main bearing to shift, resulting in loss of lubrication to that area and subsequent engine failure.

Text from the NTSB. Open the NTSB docket for ERA22LA317 for the full record.