The stab trim brakes are controlled by which unit?

• A. Spoiler Stabilizer Control Unit (SSCU)
• B. Flight Control Computer 2
• C. Rudder PCU
• D. Yaw Damper Unit

Answer: (A)

Stabilizer trim brakes are part of the stabilizer control function, and on this aircraft the Spoiler Stabilizer Control Unit is the component that commands both stabilizer trim and its braking. The SSCU serves as the centralized processor for stabilizer position, trim actuation, and the braking that keeps the stabilizer from moving unexpectedly or drifting from the commanded trim. It coordinates with the flight control system and hydraulic circuits to apply these brakes as needed.

The other units are focused on different parts of the flight control system: the Rudder PCU handles rudder hydraulic actuation, the Yaw Damper Unit manages yaw damping signals, and Flight Control Computer 2 provides broader flight-control logic but does not directly control the stab trim brakes. Therefore, the Spoiler Stabilizer Control Unit is the correct source for the stab trim brakes.