When L/R ENGINE FIRE pushbutton is pressed, which valves are closed?

When L/R ENGINE FIRE pushbutton is pressed, which valves are closed?

• A. Fuel Firewall shutoff valve and Hydraulic Firewall shutoff valve
• B. APU Fuel Valve
• C. Main Fuel Valve
• D. Hydraulic Pump Valve

Answer: (A)

When an engine fire pushbutton is pressed, the system isolates that engine by closing the dedicated firewall shutoff valves for both fuel and hydraulic circuits. For the engine in question, this means the fuel firewall shutoff valve and the hydraulic firewall shutoff valve are closed. Stopping fuel flow and hydraulic pressure to the engine helps prevent the fire from spreading and allows the fire suppression system to work more effectively. The APU fuel valve isn’t affected by this action, and the main fuel valve or hydraulic pump valve aren’t closed by the engine fire pushbutton—those have separate controls and logic.

When an engine fire pushbutton is pressed, the system isolates that engine by closing the dedicated firewall shutoff valves for both fuel and hydraulic circuits. For the engine in question, this means the fuel firewall shutoff valve and the hydraulic firewall shutoff valve are closed. Stopping fuel flow and hydraulic pressure to the engine helps prevent the fire from spreading and allows the fire suppression system to work more effectively. The APU fuel valve isn’t affected by this action, and the main fuel valve or hydraulic pump valve aren’t closed by the engine fire pushbutton—those have separate controls and logic.