What is the primary function of the AUX hydraulic pump in the Challenger 300 aircraft?

The primary function of the AUX hydraulic pump in the Challenger 300 aircraft is to power the lower rudder Power Control Unit (PCU) in case of engine failure. This feature is critical because, during an engine failure, the aircraft may lose hydraulic pressure necessary for controlling the rudder. The AUX pump serves as a backup system to ensure that there is still hydraulic power available for the lower rudder, allowing pilots to maintain control of the aircraft and enhance safety during critical flight situations.

This function is essential for redundancy in hydraulic systems, which ensures that even if one engine fails, the aircraft can still maneuver effectively. Other systems like the landing gear or wing flaps might have dedicated hydraulic sources, making the AUX pump particularly important for maintaining rudder control during emergencies. Therefore, the ability of the AUX hydraulic pump to provide hydraulic power to the lower rudder PCU stands out as a vital safety mechanism in the Challenger 300.