What happened
During the takeoff phase, the aircraft experienced a loss of engine power. Witnesses observed the engine losing power as the aircraft entered a sharp right bank, which subsequently led to a collision with obstacles and terrain.
The investigation
Post-accident examination of the engine revealed that debris had coated the inlet side of the fuel manifold valve. This component features a screen separating the inlet from the outlet, through which fuel passes to reach the fuel injector nozzles. Due to the accumulation of debris on the inlet side, fuel pressure at the injectors could not exceed 213 psi, whereas the required specification was 250 psi.
While the fuel pump pressure was measured at 83 psi (exceeding the specification of 32.5 psi), the investigation determined that at engine speeds above 1,500 RPM, fuel pressure may have become excessive depending on how debris moved within the valve. An aviation maintenance technician and a family member reported that the pilot had previously encountered engine trouble during takeoff similar to this accident, and would adjust the mixture setting to compensate. This adjustment was likely necessitated by excessive fuel pump pressure resulting from the contaminated manifold valve. Because debris could shift within the valve, the pilot likely experienced erratic fuel flow pressures.
Findings
- The accumulation of debris on the inlet side of the fuel manifold valve prevented proper fuel pressure at the injectors.
- There were no maintenance entries regarding adjustments to the fuel pump or maintenance of the manifold valve.
- Both the fuel pump and the manifold valve had been remanufactured during an engine overhaul approximately 6.5 years before the accident.