Accident Overview
After approximately 20 minutes of flight, while on final approach for landing, the airplane experienced a loss of engine power on both engines. The pilot-in-command (PIC) executed a forced landing into trees about half a mile from the airport. The left and right boost pumps and the left and right transfer pumps were observed in the "OFF" position. According to the PIC, after exiting the airplane, he returned to the cockpit and "shut off the fuel panel." The fuel quantity indicator toggle switch was observed in the "TOTAL" position.
Flight and Fuel Records
The accident flight was the third flight of the day for the flight crew and airplane. A flight log located in the cockpit indicated that the flight crew recorded 750 lbs of fuel remaining at the time of takeoff.
Fuel System Examination
Examination of the fuel system revealed that both engine nacelle tanks, both wing center section tanks, and the right wing fuel tanks were not compromised. Approximately one quart of fuel was drained from the left and right engine nacelle tanks, respectively. Less than a quart of fuel was drained from the right wing tanks. The left wing tanks were compromised during the accident, but there was no evidence of a fuel spill. Examination of the left and right wing center tanks revealed approximately 27 gallons (approximately 181 lbs) of fuel present in each tank. Battery power was connected to the airplane, and when the fuel transfer pump switches were turned to the "ON" position, fuel was observed being pumped from the left and right wing center tanks to their respective nacelle tanks.
According to the airplane flight manual (AFM), "Fuel for each engine is supplied from a nacelle tank and four interconnected wing tanks...The outboard wing tanks supply the center section wing tank by gravity flow. The nacelle tank draws its fuel supply from the center section tank. Since the center section tank is lower than the other wing tanks and the nacelle tank, the fuel is transferred to the nacelle tank by the fuel transfer pump in the low spot of the center section tank...." Additionally, with the transfer pumps inoperative, all wing fuel except 28 gallons from each wing will transfer to the nacelle tank through gravity feed.
Probable Cause
The official probable cause was determined to be the pilot’s failure to activate the fuel transfer pumps in accordance with the checklist, which resulted in fuel exhaustion.