N30RKSchmidt Randall M BUSHBY MUSTANG II · 1996

The private pilot just purchased the amateur-built airplane which was reportedly equipped with two fuel tanks in each wing totaling 22 gallons, or a total capacity of 44 gallons. According to the previous owner who was an airframe and powerplant mechanic, since filling the right fuel tank more than 1 month earlier, he flew the airplane on two separate flights totaling 1.3 hours. No additional flights were made by him after fueling. During an engine run before departure of the accident flight, the left and right fuel gauges indicated about one needle width from empty and 1/2 capacity, respectively. The new owner believed the depicted fuel amount was adequate for the intended short-duration flight to a nearby airport for fuel. He departed with the fuel selector on both, then shortly after takeoff moved it to the left fuel tank. About 13 minutes later the engine quit. He declared a mayday, moved the fuel selector to both and then right tank positions but that did not restore power. He flew towards a nearby airport but realized he was unable to land there. He maneuvered for a field, but about 26 minutes since departure the airplane collided with a tree adjacent to a residence, stalled, and impacted a portion of the house, the ground, and a car before coming to rest upright. Examination of the wreckage at the accident site by a Federal Aviation Administration inspector revealed no fuel remaining in either wing fuel tanks, in the airframe fuel strainer, fuel lines, or on the ground around the wreckage. Although the carburetor was impacted damaged, there were no fuel stains on or around it. Postaccident testing of the fuel quantity indicating system was not performed.

The engine Operator’s Manual specified that the fuel consumption was about 9.0 gallons-per-hour at 65% power, or at economy cruise. Thus, for the approximate 30 minutes-long flight about 4.5 gallons of fuel were required. That value could have been reflected in any combination between the left and right fuel tanks, but it an extreme unbalance with no fuel in the left fuel tanks and all fuel in the right tanks would have reflected just under 1/4 capacity on the right fuel gauge. At no configuration based on the amount that was actually on-board should the right fuel gauge have indicated 1/2 capacity. Therefore, the right fuel quantity gauge likely indicated that the tanks contained more fuel than the amount that was actually on board, which resulted in inadequate fuel for the intended flight and a subsequent total loss of engine power due to fuel exhaustion.

As part of the airplane’s last condition inspection performed more than 12 months earlier by the previous owner, the accuracy of the fuel gauges at empty was not performed.