Engine Failure and Forced Landing
Shortly after switching to the chemical hopper, which had been converted to a fuel tank for the ferry flight, the aircraft's engine failed. Attempts to restart the engine were unsuccessful, and a forced landing was made in a wooded area.
Post-Crash Examination
Following the accident, the engine was operated on the ground. It would not run when using the engine-driven fuel pump. After the pump was replaced, the engine operated normally. Examination of the removed engine-driven pump revealed black rubber particle contamination under the bypass valve. Additionally, the pump was found to be worn, and these conditions prevented pressure buildup.
Fuel System Configuration
The hopper tank fuel line entered the airframe fuel system downstream of the electric boost pump. Consequently, when operating on the hopper tank, the only source of fuel pressure was the engine-driven pump. This configuration meant that any failure of the engine-driven pump would result in a loss of fuel pressure when using the hopper tank.