What happened
During a sprayer calibration test, the engine of the aircraft suffered a substantial loss of power. At the time of the power loss, the pilot was operating at an altitude of approximately 50 feet above ground level (agl). The pilot reported being at too low an altitude to troubleshoot the power loss or maneuver the aircraft into an open field.
Upon touchdown, the left main gear dug into soft mud. This caused the left main gear to collapse, which subsequently led to the left wing impacting the terrain. The pilot stated that the aircraft rotated approximately 80 degrees about the left wing before coming to a complete stop. The pilot was not injured.
The investigation
Post-accident investigation focused on the engine's performance and the fuel system. Investigators found that the engine would not sustain power at idle or any other power setting when the fuel boost pump was in the 'Off' position.
An examination of the fuel system revealed that a 'B' nut on the fuel line, running from the firewall to the back of the engine, was loose. Following the tightening of this nut, the engine performed correctly at all power settings with the fuel pump in the 'Off' position. No other anomalies were identified in the aircraft or engine.