Wing anti-ice valves require both electrical signal and pneumatic pressure to operate.

Wing anti-ice valves require both electrical signal and pneumatic pressure to operate.

• A. They require only electrical
• B. They require only pneumatic
• C. They require electrical signal and pneumatic pressure to open
• D. They operate without power

Answer: (C)

Wing anti-ice valves are electrically commanded pneumatically actuated devices. The electrical signal from the ice protection system tells the valve to open or close, but the actual movement of the valve is powered by pneumatic pressure from the bleed air system. So both parts are essential: the electrical command to initiate motion, and the bleed-air pressure to drive the actuator. If electrical power is lost, the command is not issued; if bleed air is unavailable, the actuator cannot move even with a command. This ensures the anti-ice system only operates when both systems are functional.

Wing anti-ice valves are electrically commanded pneumatically actuated devices. The electrical signal from the ice protection system tells the valve to open or close, but the actual movement of the valve is powered by pneumatic pressure from the bleed air system. So both parts are essential: the electrical command to initiate motion, and the bleed-air pressure to drive the actuator. If electrical power is lost, the command is not issued; if bleed air is unavailable, the actuator cannot move even with a command. This ensures the anti-ice system only operates when both systems are functional.