Accident Description
An aircraft crashed into a field after the engine lost power during operation. The loss of power led to the accident.
Investigation Findings
Post-accident inspection of the engine fuel system identified a mechanical issue within the engine-driven fuel pump. One of the two check valves inside the pump was found unsettled and wedged between the metal pump housing and the pump diaphragm actuating plate. With the check valve in this position, no fuel flow was observed during subsequent testing. When the check valve was reset to its proper position, normal pump operation was restored, confirming that the displaced valve had prevented fuel delivery.
Additionally, the electric fuel pump was found in the 'OFF' position. The combination of the blocked check valve and the inactive electric fuel pump resulted in a complete loss of fuel flow to the engine, causing the power loss.
Fuel System Examination
During testing, the fuel system was examined to replicate the failure. With the check valve wedged as found, the pump could not generate the necessary fuel flow. After resetting the valve, the pump operated normally, indicating that the valve's displacement was the direct cause of the fuel starvation. The electric fuel pump's off position further confirmed that no auxiliary fuel supply was available at the time of the loss of power.