What do switching valves do in the hydraulic system?

• A. They regulate the hydraulic fluid temperature.
• B. They allow backup hydraulic pressure to replace the primary hydraulic pressure if the primary pressure fails.
• C. They feed pressure to the APU start motor.
• D. They isolate the emergency hydraulic system.

Answer: (B)

Switching valves provide redundancy by selecting which hydraulic source powers a circuit. In the Growler’s hydraulic system, there’s a primary source and a backup (emergency) source. The switching valves route the fluid from the active source to the system outlets and can re-route the load to the backup when the primary pressure falls or fails. This keeps critical systems operating by effectively replacing the failed primary pressure with the backup, and they also prevent crossflow by isolating the unused source. So, their main role is to ensure continuous hydraulic power by switching to the backup when needed.