The control sticks, which are interconnected, are linked by push-pull rods to hydraulically operated powered flying control units (PFCU), one at each aileron and one at the tailplane. Hydraulic power for the operation of the aileron and tailplane PFCU is provided by the No. 1 and the No. 2 hydraulic systems.

If neither hydraulic system is pressurised, i.e. the engine is not running and the RAT is not available, then no control of the ailerons or tailplane is possible, with those control surfaces remaining at their previously commanded position. The control sticks will still have limited movement.

The ram-air turbine (RAT) will supply No. 2 hydraulic system pressure in-flight, ensuring control of the aileron and tailplane remains if the engine fails.

See pages 28 and 29 of the manual for more information.