Accident Overview
On July 26, 2020, at about 1110 mountain daylight time, a Vans RV7, registration N514BS, was substantially damaged during a forced landing near Henefer, Utah. The pilot sustained minor injuries. The aircraft was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
Sequence of Events
The pilot reported that while flying at an altitude of about 10,000 ft mean sea level, he switched fuel tanks. Shortly thereafter, the engine began to sputter. The pilot turned on the electric fuel boost pump and moved the fuel selector valve back to the original position, after which the engine began to operate normally. A short time later, the engine began to sputter a second time. Despite the pilot's attempts, he was unable to restore engine power and initiated a forced landing to a nearby road. During the landing, the left wing struck the ground, causing the airplane to veer left off the road surface and impact rising terrain. Both wings and the fuselage sustained structural damage.
Examination Findings
A Federal Aviation Administration inspector examined the Lycoming IO-540-C4B5 engine. The examination revealed that the crankshaft idler gear shaft had separated from its mount, and the idler gear was disengaged from the crankshaft and camshaft. The idler gear shaft bolts were separated, and no locking tabs or safety wire were present. Photographs supplied by the inspector showed that both left idler gear shaft bolt holes were elongated, and the entire mounting area was severely worn with areas of fretting. The left idler gear interconnects the crankshaft, camshaft, left magneto, and fuel pump drive gears.