Stab

Stabilizer

The stabilizer is controlled manually by the stab trim wheels in the pedestal. This control is mechanical and overrides the PRIM computer signals.

The actual stabilizer position is shown by a small white triangular indicator by the side of the trim wheels. The position is also displayed on the flight controls system page on the system display.

For the A330 PC simulation there is also a digital display that gives a more accurate and observable stabilizer position.

Indications

On the flight controls system page, the stabilizer position is shown above the Rudder position.

The Trimable Horizontal Stabilizer (THS) is moved by a hydraulic screw jack.

The hydraulic screw jack is powered by the blue and yellow hydraulic systems. Only one hydraulic system is needed to move the stabilizer, the other is a back up.

The hydraulic screw jack is controlled by 3 electrical motors, commanded by the PRIM computers.

After landing, the THS is automatically controlled to 4 deg aircraft nose up.