Overview
A company certified flight instructor (CFI) and a mechanic were conducting a maintenance test flight when the engine lost power, leading to a forced landing in a cornfield.
Sequence of Events
Earlier on the day of the accident, the same airplane experienced a loss of engine power during an instructional flight. The student pilot switched fuel tanks, engine power was regained, and the airplane landed without further incident. Subsequent maintenance inspection revealed no fuel flow when fuel was drained through the gascolator with the right fuel tank selected. The mechanic inspected the airplane and called the CFI to perform a maintenance test flight in the airport traffic pattern. No anomalies were noted during the engine runup for the maintenance test flight. The test flight was planned to be conducted in the airport traffic pattern at traffic pattern altitude.
During the test flight, on the turn to base leg, the CFI adjusted the throttle to 1,700 rpm, and the engine started to sputter and ran rough at an engine speed of 500 rpm. The CFI reported running the engine-out checklist by memory, but it did not accomplish an engine restart. The CFI decided the best option was to land in a cornfield to avoid trees and power lines.
Postaccident Investigation
A postaccident investigation revealed that there were no detents evident in the fuel selector and that it was difficult to turn. The fuel selector did not possess safety wire on its mounting screws. The carburetor drain valve exhibited a brown colored material consistent with rust. The carburetor float had a green line around the float and rested above its minimum level. The green line was consistent with a reaction of the bronze float with water. The accelerator pump check valve was stuck and material consistent with water corrosion was noted within the accelerator pump. The bottom portion of the carburetor bowl contained a material consistent with rust and shiny gouges consistent with recent tooling marks adjacent to the area possessing rust at the bottom of the bowl. The airplane was operated without shoulder harnesses while providing rental/flight instruction.