Accident Details
On August 3, 2009, at approximately 1315 mountain daylight time, a Stinson 108-2, registration N373C, made a forced landing about 2 miles east of the Salt Lake City International Airport (SLC), Salt Lake City, Utah, following a total loss of engine power. The commercial pilot was not injured, and the sole passenger sustained minor injuries. Visual meteorological conditions prevailed for the cross-country flight, which was operated under Title 14 Code of Federal Regulations Part 91. No flight plan was filed.
The flight departed from Rock Springs-Sweetwater County Airport (RKS), Rock Springs, Wyoming, at about 1130, and was destined for Bolinder Field-Tooele Valley Airport (TVY), Tooele, Utah.
Pilot Report
The pilot reported that while in cruise flight at 10,500 feet mean sea level, the engine suffered a catastrophic failure. He set up a glide for SLC but realized he would not make it and elected to land in a field east of the airport. The aircraft sustained substantial damage to the fuselage in the area where both main landing gear were attached.
Engine Examination
A Federal Aviation Administration (FAA) airworthiness inspector who responded to the accident site reported damage to the accessory section of the Franklin 6A4-165 engine. A subsequent post-accident examination by a second inspector revealed that the crankshaft gear had failed, resulting in damage to the accessory section. All accessory gears exhibited mechanical damage. Over 50 percent of the crankshaft gear could not be found, and the crankshaft gear appeared to have failed at both dowel pin slots.
The engine was a Franklin 6A4-165B-3 manufactured in 1947 and was the original engine installed by the Stinson factory at the time of airframe manufacture. The engine had accumulated 2,520 hours time in service and was overhauled 147 hours prior to the accident.