What happened
During a night flight in a snowstorm, the pilot of an air ambulance reported mechanical difficulties involving the right engine. In response to the issue, the pilot feathered the right propeller. After reviewing the most recent weather information for the nearest suitable airport, the pilot decided to abort the diversion and return to the original base.
While executing a left turn, the aircraft reentered instrument meteorological conditions (IMC). The plane struck a mountainside while flying on a magnetic heading of 092°, which was a significant deviation from the 272° heading required to reach the intended landing site. Despite the impact, all five occupants survived the crash and were successfully rescued the following afternoon.
Findings
Investigations into the mechanical failure revealed that heavy grease on the right engine's fuel control camshaft hindered a spring from returning the 3d cam to its proper lower altitude position. The cam remained stuck on the shaft at a position corresponding to roughly 15,000 feet. Additionally, the fuel flow schedule for flight idle was found to be below the required specifications. The inspection also identified that shroud material had delaminated from the second stage compressor housing of the left engine.