TM 1-1510-225-10 2-74 2-39.  TRIM TABS. Trim    tabs    are    provided    for    all    flight-control surfaces.      These   tabs   are   manually   actuated,   and mechanically controlled by a cable-drum and jackscrew   actuator   system,   except   the   right   aileron tab,  which  is  of  the  fixed,  pliable  type.    Elevator  and aileron trim tabs incorporate neutral, non-servo action, i.e., as the elevators or ailerons are displaced from the neutral position, the trim tab maintains an as-adjusted position.    The  rudder  trim  tab  incorporates  anti-servo action, i.e., as the rudder is displaced from the neutral position,  the  trim  tab  moves  in  the  same  direction  as the   control   surface.      This   action   increases   control pressure  as  the  rudder  is  deflected  from  the  neutral position. a.   Elevator  Trim  Tab  Control.    The  elevator- trim  tab  control  wheel,  placarded  PITCH  TRIM  DN  / UP,  is  located  on  the  left  side  of  the  control  pedestal and  controls  a  trim  tab  on  each  elevator.    A  position arrow  indicates  the  amount  of  elevator  tab  deflection, in units from a neutral setting. b.  Electric Elevator Trim.  Dual element thumb switches   on   the   control   wheels   control   the   electric elevator trim system, and a trim disconnect switch on each  control  wheel.    The  system  is  protected  by  two 10-ampere   circuit   breakers,   placarded   NO.   1   and NO. 2 AP TRIM POWER, located on the right sidewall circuit breaker panel.  The dual element thumb switch is  moved  forward  for  trimming  nose  down  and  aft  for nose  up.    When  released,  the  switch  returns  to  the center (off) position.  Any activation of the trim system through the copilot's trim switch can be over-ridden by activation    of    the    pilot’s    switch.        Simultaneously operating the pilot's and copilot's switches in opposing directions   results   in   the   pilot's   having   priority.      An annunciator,   placarded   ELEC   TRIM   OFF,   on   the caution/advisory annunciator panel indicates failure or disconnect of the electric trim system. c.   A  preflight  check  of  the  switches  should  be accomplished   before   flight   by   moving   the   switches individually  on  both  control  wheels.    No  one  switch alone should operate the system; operation of elevator trim   should   occur   only   by   movement   of   pairs   of switches   on   each   control   wheel.      The   trim   system disconnect  is  a  bi-level  push  button  momentary-type switch,  located  on  the  outboard  grip  of  each  control wheel, placarded AP DISC & TRIM INTRPT.  Pressing the  switch  to  the  first  of  two  levels  disconnects  the autopilot   and   yaw  damper  system,  and  the  second level disconnects the electric trim system. d.  Aileron  Trim  Tab  Control.    The  aileron-trim tab control, placarded AILERON TRIM LEFT / RIGHT, located on the control pedestal, adjusts the aileron trim tab.      The   amount   of   aileron   tab   deflection   from   a neutral setting, as  indicated by a  position  indicator,  is relative only and is not in degrees. e.   Rudder Trim  Tab  Control.    The  rudder  trim tab  control  knob,   placarded   RUDDER  TAB  LEFT  / RIGHT,    located    on    the    control    pedestal,    controls adjustment of the rudder trim tab.  A position indicator denotes  the  amount  of  rudder  tab  deflection,  in  units from a neutral setting. 2-40.  WING FLAPS. The slot-type wing flaps are electrically operated and  consist  of  two  sections  for  each   wing.    These sections  extend  from  the  inboard  end  of  each  aileron to   the   junction   of   the   wing   and   fuselage.      During extension  or  retraction,  the  flaps  are  operated  as  a single  unit,  with  each  section  actuated  by  a  separate jackscrew actuator.  The actuators are driven through flexible  shafts  by   a  single  reversible  electric  motor. Wing flap position is indicated in percent of travel by a flap position indicator on the center subpanel.  Full flap extension and retraction time is approximately 11 seconds.  The flap control switch is located on the control  pedestal.    No  emergency  wing  flap  actuation system  is  provided.    With  flaps  extended  beyond  the APPROACH  position,  the  landing  gear  warning  horn will   sound,   unless   the   landing   gear   is   down   and locked.      The   flap   motor   circuit   is   protected   by   a 20-ampere  circuit  breaker,  placarded  FLAP  MOTOR, located on the left sidewall circuit breaker panel.  The flap system control circuit is protected  by  a  5-ampere circuit  breaker,  placarded  FLAP  CONTROL,  located on the left sidewall circuit breaker panel. a.   Wing Flap Control Switch.  A three-position switch    controls    flap    operation    with    a    flap-shaped handle  on  the  control  pedestal.    The  handle  of  this switch   is   placarded   FLAP.      Switch   positions   are placarded  FLAP  /  UP  /  APPROACH  /  DOWN.    The amount of extension of the flaps is established by the position   of   the   flap   switch   as   follows:   UP   –   0%, APPROACH   –   40%,   and   DOWN   –   100%.      Limit switches, mounted  on the right  inboard flap,  establish the flap travel.  Intermediate flap positions between UP and  APPROACH  cannot  be  selected.    To  return  the flaps to full UP, place the flap switch to the UP detent position.  To return the flaps to APPROACH, move the flap    switch    to    the    UP    position    and    then    to    the APPROACH detent position.  In the event that any two adjacent  flap  sections  extend  3°  to  5  out  of  phase with   the   other,   a   safety   mechanism   is   provided   to discontinue power to the flap motor. b.  Wing Flap Position Indicator.  Flap position in percent of travel from 0% (UP) to 100% (DOWN) is shown  on  an  indicator,  placarded  FLAPS,  located  on