Narrative
The flight proceeded normally until shortly after climbing and leveling at 6,000 feet, when the right engine bmep gauge indicated a rapid power loss. Concurrently, the right engine rpm increased out of control to about 3,100 rpm. The aircrew retarded the right throttle and reduced the engine to 2,100 rpm using the prop increase/decrease toggle switch. Attempts to feather the right propeller were unsuccessful, and the aircraft could not maintain altitude. The crew diverted to the nearest airport, Walker County.
While turning downwind for runway 09, the right engine fire indicator activated, and the copilot confirmed the presence of a fire. Both fire bottles were discharged, and the right propeller stopped rotating. The injection water for the left engine was exhausted, causing the left engine to begin backfiring. The captain maneuvered the aircraft and landed on runway 27 instead.
After touchdown, the right main tires failed, and the aircraft veered off the right side of the runway. It struck a ditch, causing the landing gear to collapse. Post-accident examination revealed that the #6 cylinder link rod and/or piston in the right engine had failed, leading to further engine damage. Fire and heat caused the right engine to seize and also damaged the right main tires, which failed at touchdown. All 39 occupants were evacuated; two passengers sustained serious injuries.
Findings
The official investigation identified multiple contributing occurrences: loss of engine power in cruise due to total failure of the #6 cylinder connecting rod and piston, resulting in engine assembly failure and inability to feather the propeller. An engine fire ensued in cruise, during which the fire extinguishing system was activated. The landing gear tires experienced overtemperature. During the forced landing, anti-detonation injection fluid for the left engine was exhausted. After landing, the right main tires failed, making directional control impossible and leading to an uncontrolled ground loop/swerve. The subsequent ground encounter with a ditch resulted in landing gear overload.