If an uncommanded displacement of an aileron PCU occurs, what happens?

• A. A bungee breakout switch sends a signal to the spoiler stabilizer control unit.
• B. Hydraulic lock engages to protect the wing.
• C. Flight control computer isolates the PCU.
• D. Pilot input overrides the control surface.

Answer: (A)

When a PCU moves without a pilot command, the system has a rapid protection path to prevent a surface from running away. The bungee breakout switch detects this unexpected displacement and immediately sends a signal to the spoiler-stabilizer control unit. That unit then acts to counter the unintended aileron movement, using the spoilers and stabilizer to restore or maintain safe roll control. This provides a fast, automatic handoff of control away from a faulty PCU to the surfaces designed to stabilize the wing. The other options describe different protective ideas, but they don’t represent the immediate fail-safe behavior activated by the breakout switch in this situation.