TM 1-1510-224-10 dependent  upon  airspeed  and  engine  power  differential. The   boost   function   is   armed   when   the   rudder   boost switch  located  on  the  pedestal  extension  is  set  to  the RUDDER BOOST position. g. Autopilot  Controller  (PC-400).    The  autopilot controller   (fig.   3-21),   provides   a   means   of   engaging/ disengaging  the  autopilot  and  yaw  damper  as  well  as manually  controlling  the  autopilot  through  the  turn  knob and  pitch  wheel.    Whenever  the  autopilot  is  engaged,  it will fly basic roll and pitch hold or the selected lateral or vertical flight director modes. (1)   Pitch  wheel.    Rotating  the  pitch  wheel with the autopilot engaged will result in a change in pitch attitude proportional to the amount of rotation and in the direction   of   wheel   movement.      Movement   of   the   pitch wheel cancels only altitude hold (ALT HOLD) or altitude select capture (ALT SEL CAP).  With the vertical modes of   vertical   speed   (VS )   or   indicated   air   speed   (IAS ) selected   on   the   mode   selector,   rotation   of   the   pitch wheel   will   change   the   respective   air   data   command vertical    mode    reference    (with    autopilot    engaged    or disengaged) which is displayed on the EADI.  VS or  IAS modes  may  be  cancelled  by  pressing  the  mode  button on   the   mode   selector   panel.      Movement   of   the   pitch wheel   has   no   effect   with   the   autopilot   coupled   to   the glideslope. (2)   Bank  limit  switch-indicator.    The   BANK LIMIT   switch   provides   a   lower   maximum   bank   angle while  in  the  heading  select  mode.    Depressing  the  bank limit switch-indicator will illuminate the  LOW indicator on the  switch  face.    Depressing  the  switch  again  will  cause the  LOW  indicator  to  be  extinguished  and  the  autopilot to  return  to  normal  bank  limits.    The  lower  bank  limit  is inhibited   and   the   LOW   indicator   will   be   extinguished during  NAV  mode  captures.    If  heading  select  is  again engaged, LOW will again be illuminated on the bank limit switch-indicator. (3)   Soft   ride   switch-indicator.      The    SOFT RIDE   mode   provides   reduced   pitch   and   roll   autopilot gains  while  still  maintaining  stability  in  rough  air.    This mode  may  be  used  with  any  flight  director  mode,  but should only be selected   ON  in  turbulence.    Depressing the   SOFT   RIDE    switch-indicator    will    cause    the    ON indicator to illuminate on the switch face. (4)   Turn knob.  Rotation of the turn knob out of the detent results in a roll command.  The roll angle is proportional  and  in  the  direction  of  turn  knob  rotation. The  turn  knob  must  be  in  the  detent  (center  position) before  the  autopilot  can  be  engaged.    Rotation  of  the turn  knob  cancels  any  other  previously  selected  lateral mode. (5)   Yaw damper switch-indicator. Depressing the yaw damper (YD) switch will engage the yaw  damper  and  illuminate  the    ENGAGE   indicator   on the switch face.  With the autopilot (AP ) and yaw damper (YD)    engaged,    depressing    the    yaw    damper    switch- indicator  will  engage  or  disengage  the  yaw  damper  only (the autopilot will remain engaged). (6)   Autopilot   switch-indicator.      Depressing the    autopilot    (AP )    switch-indicator    will    engage    the autopilot    and    yaw    damper    simultaneously,    and    will illuminate the   AP and   YD   ENGAGE  indicators  on  the switch   face.      The   autopilot   may   be   engaged   with   the aircraft in any reasonable attitude.  With no flight director modes  selected,  the  autopilot  will  roll  the  aircraft  to  a wings level attitude upon engagement. h. Flight    Director    Mode    Selector    (MS-207). The  flight  director  mode  selector  (fig.  3-22),  provides  all mode  selection  except  go-around,  which  is  initiated  by the go-around switch located on the left power lever (fig. 2-14).    The  flight  director  command  bars  on  the  EADI provide  integrated  pitch  and  roll  guidance  to  satisfy  the selected   mode.      The   top   row   of   illuminated   switch- indicators contains the lateral modes, and the bottom Table 3-5.  Digital Flight Control System Limits (Sheet 3 of 3) Mode Control or Sensor Parameter Value ALT Preselect Air Data Encoding Preselect Capture Range 0 to 41,000 ft Altimeter and Altitude Maximum Gravitation Preselect Controller Force During Capture Maneuver + 0.20 g Pitch Limit + 20^o Pitch Rate Limit f (TAS) Rudder Boost Engine Sensors, Air Rudder Force f (Engine torque differential) Data f (IAS) BT03842 3-45