TM 55-1510-219-10 e. Autopilot Operation. (1) Engaging    autopilot.        AP    mode    select panel ENG/DIS switch to ENG position. NOTE When   the   autopilot   is   engaged, the yaw damper is also automatically engaged as indicated    by    the    lighted    YAW DAMP button (AP pitch/turn control panel). The  autopilot  and  flight  director  are  coupled  when both  units  are  engaged.    When  coupled,  the  autopilot accepts   guidance   commands   from   the   flight   director. When  the  flight  director  is  not  engaged,  the  autopilot accepts   pitch   and   roll   commands   from   the   pitch/turn control knobs as selected by the pilot. The  autopilot  may  be  engaged  in  any  reasonable attitude  and  in  either  the  coupled  or  uncoupled  mode. The    autopilot    will    smoothly    acquire    the    command attitude.    When  uncoupled,  the  autopilot  will  maintain the bank and pitch attitude at the time of engagement. (2) Disengaging autopilot. (a)    The autopilot may be disengaged by any of the following: 1.    Actuating compass INCREASE/DECREASE switch. 2.    Pressing TEST button on AP mode select panel. 3.    Pressing      GO        AROUND  switch on left power lever. 4.    Pressing control wheel DISC switch to AP YD position. (b)    The   following   functions   will   cause the autopilot to automatically disengage: 1.    Vertical gyro failure. 2.    Directional gyro failure. 3.    Autopilot power or circuit failure. 4.    Torque limiter failure. (3)    Maneuvering. 1.    To change flight functions, press the desired    mode    button    on    the    AP mode   selector   panel.      The   button will  illuminate  along  its  edges  and autopilot   annunciator   lights   on   the instrument     panel     will     illuminate, indicating  the  respective  modes  in operation. 2.    In any function except "after glideslope capture", use the autopilot   pitch   control   for   climbing or   descending.      Movement   of   the pitch control establishes a pitch rate that is proportional to knob displacement.      If      any      vertical mode  button  has  been  selected,  it will  automatically  release  when  the pitch control knob is rotated. 3.    When  HDG  mode  is  selected,  the autopilot  will  command  the  aircraft to execute a turn then maintain the heading set by the heading marker. 4.    Use   the   autopilot   turn   control   to command    a    roll    rate    when    the autopilot  is  engaged.    At  the  time control   is   returned   to   detent,   the autopilot  maintains  the  bank  angle (up   to   approximately   30   degrees). Rotating  the  turn  control  when  the autopilot  is  engaged  and  a  lateral mode    is    selected    will    cause    the selected lateral modes to release. (4) Control     wheel     synchronization.          The PITCH SYNC & CWS button on the pilot's control wheel can be used instead of the pitch/turn control to establish the aircraft in a desired attitude.  Depressing this button causes     autopilot     elevator     and     aileron     servos     to disengage from the control surfaces.  The pilot then flies the  aircraft  manually  to  a  desired  attitude,  releases  the PITCH  SYNC  &  CWS  button  to  re-engage  the  servos, and the autopilot holds the established attitude. The ALT and IAS mode will immediately disengage (if  selected)  when  the  PITCH  SYNC  &  CWS  button  is pressed.    Upon  release  of  the  PITCH  SYNC  &  CWS button,    the    autopilot    will    couple    to    the    previously selected lateral mode. NOT The   APPR   mode   will   not disengage  when  the  PITCH  SYNC &     CWS     button     is     depressed. When  the  button  is  released,  the aircraft  will  return  to  the  localizer course and glideslope. 3-39