In a runaway trim situation, which action disconnects the trim?

• A. Stab trim switch lights on the center pedestal
• B. Depress the stab trim switch on the control wheel
• C. Trim bus tie switch
• D. Use the Trim Disc red button on the top of each control wheel

Answer: (D)

When trim starts moving on its own, you want a fast, positive way to stop it so you can regain manual control. The red Trim Disc on top of each control wheel is designed for just that. Pressing this disc directly disconnects the stabilizer trim from the trim system, and it stops any further trim movement even if the system is trying to command it. That immediate disconnection is what lets you take back control of the elevator without fighting against runaway trim.

The other actions don’t provide that quick, guaranteed stop. Standby indicators on the center pedestal only show a trim condition; they don’t stop the movement. Depressing the stab trim switch on the control wheel may still command trim rather than cut it off. The trim bus tie switch isolates the trim power path but doesn’t deliver the same direct, positive disconnection as the Trim Disc.