In the event of an over-speed, which valves activate to shut down the engine?

• A. Overspeed and drain
• B. Primary and secondary
• C. Relief and check
• D. Bleed and isolation

Answer: (A)

When an engine overspeeds, the immediate goal is to stop fuel from reaching the engine and remove any remaining fuel so combustion can’t continue. The overspeed valve is the one that acts to shut off the fuel supply, and the drain valve opens to purge or remove the fuel in the lines so there’s nothing left to burn. Together, they rapidly halt engine operation and prevent damage from running at too high a speed.

Relief and check valves deal with pressure and one-way flow, not the rapid shutdown of fuel in an overspeed event. Bleed and isolation pertain to venting or separating parts of a system rather than stopping the engine by cutting fuel and draining it. Primary and secondary don’t describe the shutdown action needed in an overspeed situation.