Which valve is designed to shut off flow to prevent fire spread?

• A. Jettison Valve
• B. Firewall Shutoff Valve
• C. Cross-Feed Valve
• D. Refuel or Fill Valve

Answer: (B)

When trying to keep a fire from spreading, isolating the fuel supply at the firewall is essential. The firewall shutoff valve is placed in the fuel line at the firewall, so when a fire is detected or a shutdown is commanded, the valve closes to stop fuel from reaching the engine or from feeding fuel into the fire on the engine side. This containment reduces the fuel available to burn and helps prevent the fire from crossing the firewall into other compartments. The other valves have different roles: a jettison valve dumps fuel to reduce weight, a cross-feed valve lets fuel move between tanks to balance or supply engines, and a refuel/fill valve controls bringing fuel into the system.