Field in Sight; absolutely correct old bean.
Mechanical back-up of pitch and yaw on the A320/321/330 STILL requires a hydraulic source - green or yellow for the THS, (blue or yellow on the 330), and green, or yellow or blue for the rudder. Mechanical back-up does not mean that the rudder pedals or THS trim wheel can wind the control surfaces alone in the absence of all hydraulic power - it merely commands the hydraulic motors in the case of the THS or the servos in the case of the rudder, to move.
This is possibly the most commonly misunderstood part of the A320 family control architecture.
U
Last edited by Uplinker; 22nd October 2012 at 13:30.