TM 1-1510-225-10 3A-26 a.     Apply   nose   up   force   on   control wheel   –   Note   nose   down   trim motion after approximately 3 seconds. b.     Apply  nose  down  force  on  control wheel  – Note nose up trim motion after approximately 3 seconds. c. Press   right   rudder    –   Note   left rudder trim motion after approximately 3 seconds. d.     Press   left   rudder    –    Note    right rudder trim motion after approximately 3 seconds. 5.   Select   HDG   mode    –    Observe    FD commands  and  control  wheel  motion correspond to movement of the heading selector knob. 6.   AP   DISC  &   TRIM   INTRPT   –  Press and release. Note autopilot disconnection, flashing AP  annunciation,    and    aural    disconnect tone. 7.   Manual electric trim – Check. a.     Pilot and copilot control wheel trim switches – Check. Operation     of     the     electric     trim     switch system should occur only by movement of pairs  of  switches.    Any  movement  of  the elevator trim wheel while pressing only one switch    element    denotes    a    trim    system malfunction.  The AP / TRIM POWER switch must  be  turned  OFF  and  flight  conducted only by manual operation of the trim wheel.   Do not use autopilot b.     Pilot  and  copilot  trim  switches   – Check   individual   element   for   no movement    of    trim,    then    check   proper operation of both elements. c. Pilot  trim  switches   –  Check  pilot switches override copilot switches while trimming in opposite directions,    and    trim    moves    in direction commanded by pilot. d.     Pilot  and  copilot  trim  switches   – Check trim disconnects while activating     pilot     or     copilot     trim disconnect switches. 8.   AP   XFER   Switch   –  Select  copilot's side and repeat steps 2 through 7. 3A-15.  ATTITUDE     AND     HEADING     REFERENCE SYSTEM. The    attitude    and    heading    reference    system consists  of  the  vertical  gyros,  directional  gyros,  dual remote compensator, and flux valves. The vertical gyros provide the digital flight control system,    electronic    flight    instrument    system,    and weather radar antenna with pitch and roll information. The   directional   gyros,   with   the   flux   valve   and compensator, provide stabilized magnetic north referenced  heading  information  for  use  by  the  digital flight  control  computer  and  electronic  flight  instrument system. 3A-16.  AIR DATA SYSTEM. The digital air data computers are microprocessor-based   digital   computers   that  accept both     analog     and     digital     inputs,     perform     digital computations,   and   supply   both   digital   and   analog outputs.    They  receive  both  pitot  and  static  pressure for    computing    standard    air    data    functions.        They control  autopilot  gains  as  a  function  of  altitude  and airspeed.    They  contain  sensors  for  the  flight  director modes, altitude hold, vertical speed/indicated airspeed/altitude  pre-select,  and  true  airspeed  for  the flight   management   system.      They   also   include   the sensor  function  for  the  altitude  portion  of  the  altitude and  vertical  speed  indicator.    The  altitude  encoder  for the mode C function of the transponder is also in the air data computer. 3A-17.  ELECTRONIC FLIGHT INSTRUMENT SYSTEM. a.   Description.  The electronic flight instrument system  consists  of  the  pilot's  and  copilot's  EADI  and EHSI   display   units,   symbol   generators,   and   EFIS control panel. The  EFIS  electronic  displays  present  pitch  and roll   attitude,   heading,   course   orientation,   flight   path commands, radio altitude, weather radar and lightning sensor  system  presentations,  and  mode  and  source annunciations.  The displays are color coded as shown in Table 3A-2 for easier interpretation of information. WARNING