Engine Failures
During climb to cruise altitude, the left engine experienced a loss of power. The failure was attributed to exhaust and intake valve failures of the No.6 cylinder. The pilot responded by feathering the left propeller and initiating a return to the departure airport.
Right Engine Loss
During the descent, the right engine also lost power. The airplane subsequently entered a steep descent and crashed in a wooded area. A massive postcrash fire ensued.
Fuel Selector Examination
Post-accident examination of the fuel selector valves revealed that the left engine fuel selector valve was in the 'on' position, while the right engine fuel selector valve was in the 'off' position.
Left Engine Inspection
Investigation of the valve failure in the left engine showed extensive rocker arm wear.