tired, Tan and Javelin,. .From my A321 FCOM:'Mechanical control of the THS is available from the pitch trim wheel at any time if either the green or yellow hydraulic system is functioning.' and: '3 independant hydraulic servojacks actuate the rudder. In automatic operation (yaw damping, turn coordination) a green servo actuator drives all 3 servojacks.. .Bottom line - you need hydraulics to stay alive!!. .Hope this helps.. .Cheers. .mcdhu