What happened
While cruising at 6,000 feet, the crew of the aircraft experienced a sudden loss of power in the right engine, accompanied by an uncontrolled increase in RPM to approximately 3,100. The flight crew attempted to stabilize the engine by reducing the throttle and adjusting the propeller pitch, but they were unable to feather the propeller or sustain their altitude. This necessitated an immediate diversion to Walker County airport.
During the downwind approach for runway 09, a fire was confirmed in the right engine. Although the crew discharged both fire extinguishing bottles and successfully stopped the rotation of the right propeller, the left engine began backfiring after its water injection fluid was depleted. The pilot executed a landing on runway 27.
Upon touchdown, the right main tires failed, causing the aircraft to veer off the right side of the runway and strike a ditch, which subsequently led to a landing gear collapse. All 39 occupants were evacuated from the aircraft; while most escaped without major harm, two passengers sustained serious injuries.
Findings
Investigations into the mechanical failures revealed that the primary cause was the failure of the #6 cylinder link rod and/or piston within the right engine. This internal component failure caused significant damage to the engine assembly and led to an engine fire. The intense heat from the fire eventually caused the right engine to seize and contributed to the failure of the right main tires during the landing phase. Additionally, the loss of directional control on the ground was exacerbated by the exhaustion of anti-ice fluid and the impact with the terrain.