Accident Overview
The pilot filed a company flight plan for a VFR flight from Boise to Salmon, Idaho. During initial climb, the engine surged, then seemed to return to normal operation. The pilot reduced power to 33 inches of manifold pressure and set the propeller to 2,550 rpm. Shortly thereafter, the engine began losing power again, experienced a second surge, and then the propeller stopped.
Emergency Landing
During the emergency landing, the pilot elected to cross over a road and land in an open field. He saw a power line along the road at the edge of the field and chose to cross under it. However, he did not see a single telephone pole on the opposite side of the road. The left wing struck the pole, causing the aircraft to cartwheel and crash. Three occupants escaped with minor injuries; four others were uninjured.
Investigation Findings
An investigation revealed that the crankshaft had failed from fatigue. The official findings identified four occurrences: loss of engine power due to mechanical failure (crankshaft fatigue), a forced landing, an in-flight collision with an object (utility pole), and an in-flight collision with terrain. The pilot performed the maneuver during the approach phase, and terrain conditions included high obstructions (utility pole).