TM 1-1510-218-10 8-15 (b)   Control wheel – Overpower slowly in  both   pitch  and  roll   axis.      AP ENGAGE annunciator stops flashing.  FD flag on ADI retracts. If   autopilot   or   yaw   damper   disengages during overpower test or if AP ENGAGE or YD    ENGAGE    annunciator    continues    to flash,    the    system    is    considered    non- operative  and  should  not  be  used.    The elevator  trim  system  must  not  be  forced beyond the limits indicated on the elevator trim tab indicator. (7)   Elevator trim follow-up – Check. (a)   Control  wheel  –  Hold  aft  of  mid travel.      Trim   wheel   should   run nose    down    after    approximately 3 seconds. Trim down annunciator should illuminate after approximately 8 seconds. (b)   Control  wheel  –  Hold  forward  of mid travel.  Trim wheel should run nose up after approximately 3 seconds,    trim    up    annunciator should illuminate after approximately 8 seconds, and AP TRIM FAIL annunciator and MASTER WARNING lights should illuminate after approximately 15 seconds. (8)   AP/YD & TRIM DISC Button – Press through  second  level.    Autopilot  and yaw  damper  should  disengage  and ELEC TRIM OFF annunciator should illuminate.     AP  ENG  and  YD  ENG annunciators    on    instrument    panel should flash five times. (9)   Elevator  trim  control  switch  –  OFF, then on. ELEC TRIM OFF annunciator should extinguish. (10)   AP    –    Re-engage    and    overpower another time. (11)   Turn  controller  –  Check  that  control wheel follows in each applied direction, then center. (12)   Pitch     wheel     –     Check     that     trim responds  to  pitch  wheel  movement. UP TRIM and DN TRIM annunciators may illuminate. (13)   Heading  bug  –  Center  and  engage HDG.    Check  that  control  follows  a turn in each direction. (14)   Disengage    AP    by    selecting    GA. Check  that  AP  disengages  and  FD commands  7°  nose  up,  wings  level attitude. 10.  Electric elevator trim D2 – Check. a.   Elevator trim switch – On. b.   Pilot  and  copilot  trim  switches  –  Check operation. Operation    of    the    electric    trim     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   system   malfunction. The   electric   elevator   trim   control   switch must    then    be    turned    OFF    and    flight conducted  by  operating  the  elevator  trim wheel manually.  Do not use autopilot. (1)  Pilot    and    copilot    trim    switches    – Check    individual    element    for    no movement of trim and proper operation of both elements. (2)  Pilot trim switches –  Check that pilot trim switches override copilot switches  while  trimming  in  opposite directions and trim moves in direction commanded by pilot. c.   Pilot  and  copilot  trim  switches.    Check trim disconnects while activating pilot's or copilot's trim switches. d.   Elevator   trim   switch   –   OFF   then   ON. ELEC TRIM OFF annunciator extinguishes. 11.  Ground Proximity Altitude Advisory System (GPAAS) – Check as follows: NOTE The  GPAAS  voice  advisory  must  produce an    operational    volume    at    the     lowest setting. a.   GPAAS   voice   advisory   VOL   control   – Full counterclockwise. b.   VOICE OFF switch-indicator – Extinguished. c.   Audio control panel – Set listening audio level. WARNING WARNING