Which hydraulic system is primarily pressurized by an electric motor driven pump?

The blue hydraulic system on the A320 is primarily pressurized by an electric motor-driven pump, which distinguishes it from the other hydraulic systems. This system is designed to ensure that the aircraft maintains hydraulic pressure even when engine-driven pumps may not be operational, providing a critical backup for essential control systems. The electric motor-driven pump provides greater reliability and responsiveness during various phases of flight, particularly when engine power may be less available during specific scenarios such as an engine failure or during ground operations.

In contrast, the red, green, and yellow systems utilize different methods for maintaining hydraulic pressure and do not rely primarily on an electric motor-driven pump for their operation.