Amateur-built GLASAIR II N61RA accident near Spanish Fork, Utah

Probable cause

A loss of engine power due to fuel starvation, which likely resulted from air being introduced into the fuel system through the worn shaft of an electric fuel boost pump.

NTSB analysis

During the en route portion of the flight, the airplane experienced fuel flow problems, which were temporarily alleviated when the fuel system boost pump was on the high-boost setting. As the pilot neared the destination airport, he reduced the engine power; the engine experienced a total loss of power. The pilot performed a forced landing in a field about 1,500 feet from the runway. During the landing roll, the airplane nosed over inverted, and the wings separated from the fuselage.

The postaccident examination of the airplane revealed that the electric boost pump would operate when the high-boost switch was selected. However, when the low-boost switch was selected, it would not operate due to a malfunctioning resistor. The significance of the anomalies with the electric boost pump on the overall fuel flow to the engine is unknown because the engine-driven fuel pump was functionally tested and was capable of providing adequate fuel delivery. Further testing revealed that when the electric boost pump was turned off and under suction, as would occur when the engine-driven pump was trying to draw fuel without the use of the electric boost pump, the electric boost pump introduced air into the fuel system through the worn shaft on the pump. The air would likely hinder the engine-driven pump from producing enough suction and starve the engine of fuel.

Text from the NTSB. Open the NTSB docket for WPR13LA147 for the full record.