What happened
While performing the base-to-final turn approximately 1 to 1.5 miles from the runway threshold, the left engine of the twin-engine airplane suffered a loss of power. This was immediately followed by a loss of power in the right engine. In response to the dual engine failure, the pilot feathered both propellers. The aircraft subsequently struck a tree measuring 70 feet in height and crashed into the ground roughly 1,000 feet before reaching the runway.
Prior to the incident, about 17 miles from the destination, the pilot had engaged the electric fuel boost pumps and transitioned the fuel selectors from the auxiliary tanks to the main tanks. At that time, the pilot noted approximately 70 gallons remained in the main tank and between 10 and 15 gallons were in the auxiliary tanks. Post-accident inspections of the cockpit revealed the left fuel shutoff valve was set to the left outboard position with the boost pump off, while the right valve was set to the right outboard position with the boost pump on. The airframe fuel shutoff valves for the main tanks were found in the closed position.
Findings
Investigation of the wreckage and historical records revealed a complex fuel configuration. While the original system utilized a center tank and two outboard tanks, the aircraft had been modified with an extended range system, though documentation for these changes was incomplete. The total usable capacity was estimated at 244 gallons, consisting of a 156-gallon center tank, 67 gallons in the outboard wing tanks, and 21 gallons in auxiliary tanks.
Although the flight manual's landing procedures required the fuel selector valves to be set to the center tank position before approach, the investigation determined that the simultaneous loss of power was likely caused by the unporting of the outboard fuel tanks. No mechanical defects were identified in the engines or the airframe, and sufficient usable fuel remained in the center tank at the time of the accident.