What powers hydraulic system 3?

The hydraulic system 3 on the CRJ550 is powered by two electric hydraulic pumps. This choice is correct due to the design intention of system redundancy and reliability. Electric pumps provide an additional layer of capability, especially during operations when mechanical pumps may not be as effective or available, such as during certain phases of flight or on the ground when engines are not running.

Utilizing electric pumps enhances the system's responsiveness and allows for more consistent pressure and flow control, which is essential for various critical operations such as flight control surfaces and landing gear. The two electric pumps ensure that there is sufficient hydraulic power available even in case one of the pumps fails, thereby maintaining the system's operational integrity.

Other options either suggest the use of engine-driven pumps or manual pumps, which do not reflect the design of the CRJ550’s hydraulic system 3, as it specifically relies on electric pumps for its power source. This design choice aligns with modern aviation trends that emphasize electric systems for efficiency and reliability.