Stinson 108-2 N373C accident near Salt Lake City, Utah

Probable cause

A total loss of engine power during cruise flight due to the failure of the crankshaft gear.

NTSB analysis

During cruise flight, the pilot experienced a complete loss of engine power and initiated a forced landing to an open field. During the landing roll, the airplane encountered a ditch, which resulted in substantial damage to the airplane's fuselage. A Federal Aviation Administration airworthiness inspector reported damage to the accessory section of the engine. A subsequent postaccident examination of the engine by a second inspector revealed that the crankshaft gear had failed, which resulted in significant damage to all the gears in the accessory section of the engine. Over 50 percent of the crankshaft gear could not be found, and the crankshaft gear appeared to have fractured and failed through both dowel pin slots. The engine was manufactured in 1947 and was the original engine installed by the factory at the time of the airframe's manufacture. The engine had accumulated 2,520 hours time in service and was overhauled 147 hours prior to the accident.

Text from the NTSB. Open the NTSB docket for WPR09LA382 for the full record.