What does the FLAP INTERRUPT switch do if a flap runaway occurs, and how can the system be reset for the remainder of the flight?

• A. Disengages the Power Drive Unit motor and cannot be reset until on the ground.
• B. Disables the flaps but allows immediate reset in flight.
• C. Reduces flap speed to 0 and reverts automatically.
• D. Puts the system into standby mode and can be reset from the cockpit.

Answer: (A)

The main idea here is how the flap protection works when a flap runaway happens. The FLAP INTERRUPT switch acts as an emergency shutoff for the flap drive system by disengaging the Power Drive Unit (PDU) motor. That immediate power cut stops any further movement of the flaps, preventing damage or control problems from a runaway.

This design intentionally requires a ground reset. In flight, the motor is isolated to avoid re-energizing a potentially jammed or misbehaving system, so you can’t reset the flap drive while airborne. To restore normal operation for the rest of the flight, you bring the airplane to a safe landing, then perform the reset procedure on the ground as specified in the flight manual.

In short, the switch stops the flap motor to halt a runaway, and it cannot be reset until you’re on the ground.