What important precaution should be taken before using the pressure fueling method?

Before employing the pressure fueling method, it is crucial that the fuel truck's engine is turned off. This precaution significantly reduces the risk of fire or explosion due to potential fuel vapors igniting. An operational truck engine creates heat and may produce sparks that can pose a danger in the vicinity of flammable materials like aviation fuel. Ensuring that the engine is off creates a safer working environment during the fueling operation, allowing for a more controlled and secure process.

While other precautions such as checking atmospheric temperature, verifying the pump pressure, and inspecting hoses for leaks are indeed important in the overall refueling procedure, the immediate safety concern tied to the engine being off directly addresses risk management in a more direct manner during pressure fueling.