Loss of hydraulic system _____ will cause the nosewheel steering to go into free castoring mode.

Loss of hydraulic system 3 results in the nosewheel steering going into free castoring mode. This is due to the design of the CRJ550's hydraulic systems and their associated functionalities. In the CRJ550, the nosewheel steering system relies on hydraulic pressure supplied by system 3 for proper operation. When this hydraulic system is compromised, it loses the ability to control the nosewheel's position actively, which transitions it into a free castoring state.

This means the nosewheel can swivel freely without steering input from the crew because the hydraulic assist that helps in steering has been lost. It is important for pilots to understand this functionality, as losing hydraulic system 3 could affect ground handling during taxiing, requiring adjustments in how the aircraft is maneuvered on the ground.

The other hydraulic systems may have their own roles in various other aircraft operations, but they do not directly influence the steering of the nose gear in this particular way. This highlights the crucial nature of hydraulic System 3 in the overall operation of the CRJ550's nosewheel steering system.