If N2 reaches the overspeed threshold, which component engages to shut down the engine?

If N2 reaches the overspeed threshold, which component engages to shut down the engine?

• A. Manual shutdown
• B. NR shuts down
• C. Indicator lamp only
• D. Overspeed solenoid valve activates to shut down the engine

Answer: (D)

When N2 reaches the overspeed limit, the overspeed protection circuit triggers the overspeed solenoid valve in the fuel control system. This valve closes, cutting fuel to the combustor. With no fuel, combustion ceases, the engine cannot sustain the high speed, and it decelerates to a safe stop. The indicator lamp may warn of the condition, and manual shutdown is an operator action, but neither automatically stops the engine. The automatic shutdown mechanism for overspeed is specifically the overspeed solenoid valve that interrupts fuel supply.

When N2 reaches the overspeed limit, the overspeed protection circuit triggers the overspeed solenoid valve in the fuel control system. This valve closes, cutting fuel to the combustor. With no fuel, combustion ceases, the engine cannot sustain the high speed, and it decelerates to a safe stop. The indicator lamp may warn of the condition, and manual shutdown is an operator action, but neither automatically stops the engine. The automatic shutdown mechanism for overspeed is specifically the overspeed solenoid valve that interrupts fuel supply.