| Yaw Damper The Yaw Damper System consists of a main and standby yaw damper. Both yaw
dampers are controlled through Stall Management / Yaw Damper (SMYD) computers. The SMYD
computers receive inputs from both ADIRUs, both control wheels and the YAW DAMPER
Switch.
SMYDs provide yaw damper inputs to the Main Rudder Power Control Unit (PCU) or Standby Rudder PCU, as appropriate. Either yaw damper is capable of providing dutch roll prevention, gust damping and turn coordination. Yaw damper operation does not result in rudder pedal movement. Only main yaw damper inputs are shown on the YAW DAMPER Indicator. The pilot can override either main or standby yaw damper inputs using either the rudder pedals or trim inputs. During normal operation the main yaw damper uses Hydraulic System B and the SMYD computers provide continuous system monitoring. The YAW DAMPER Switch automatically moves to OFF, the amber YAW DAMPER Light illuminates and the YAW DAMPER Switch cannot be reset to ON when any of the following conditions occur:
During manual reversion flight (loss of Hydraulic System A and B pressure), both FLT CONTROL Switches are positioned to STBY RUD. In this case, the YAW DAMPER Switch can be reset to ON and the standby hydraulic system powers the standby yaw damper. During Standby Yaw Damper operation, movement of the control wheel sends a signal to the standby rudder PCU to move the rudder. This gives rudder assist to help tum the airplane when control of the ailerons is through manual reversion. |