TM 55-1510-222-10 thumb switches on the control wheels, a trim disconnect switch on each control wheel and a circuit breaker in the overhead circuit breaker panel.  The ELEV TRIM - OFF - RESET switch must be in the ELEV TRIM (on) position to operate the system.  The dual element thumb switch is  moved  forward  for  trimming  nose  down,  aft  for  nose up,   and   when   released   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.      Operating   the   pilot's   and   copilot's switches in opposing directions simultaneously results in the pilot having priority. 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. The trim system disconnect is a bi-level, r12pushbutton, momentary type switch, located on the outboard grip of each control wheel.  Depressing the switch to the first of two   levels   disconnects   the   autopilot   and   yaw   damp system,  and  the  second  level  disconnects  the  electric trim  system.    The  system  can  be  reset  by  moving  the ELEV TRIM switch toggle on the pedestal (fig. 2-11) to OFF/RESET position, then back to ELEV TRIM again. c.  Aileron Trim Tab Control.  The aileron trim tab control,     placarded     AILERON     TAB     LEFT,     RIGHT, located  in  the  control  pedestal,  adjusts  the  aileron  trim tab  (fig.  2-11).    The  amount  of  aileron  tab  deflection from a neutral setting, as indicted by a position indicator, is relative only and is not in degrees. d.  Rudder Trim Tab Control.  The rudder trim tab control  knob,  placarded  RUDDER  TAB  LEFT,  RIGHT, located  in  the  control  pedestal,  controls  adjustment  of the rudder trim tab (fig. 2-11).  The amount of rudder tab deflection, in units from a neutral setting, is indicated by a position indicator. 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, each  section  being  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 in 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 circuit is  protected  by  a  20-ampere  circuit  breaker,  placarded FLAP  MOTOR,  located  in  the  overhead  circuit  breaker panel (fig. 2-6). a.    Wing  Flap  Control  Switch.    Flap  operation  is controlled  by  a  three-position  switch  with  a  flapshaped handle on the control pedestal (fig. 2-11).  The handle of this   switch   is   placarded   FLAP.      Switch   positions   are placarded:  FLAP  UP,  APPROACH  and  DOWN.    The amount   of   extension   of   the   flaps   is   established   by 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.    The  flap  control  switch,  limit  switch,  and  relay circuits   are   protected   by   a   5-ampere   circuit   breaker, placarded FLAP CONTR located in the overhead circuit breaker   panel   (fig.   2-6).      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   degrees   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  O  percent  (UP)  to  100  percent (DOWN)  is  shown  on  an  indicator,  placarded  FLAPS, located  in  the  center  subpanel  (fig.  2-5).  The  approach and  full  down  flap  positions  are  14  and  35  degrees, respectively.  The flap position indicator is protected by the 5-ampere circuit breaker, placarded FLAP CONT'R, located in the overhead circuit breaker panel (fig..  2-6). Section VI.  PROPELLERS 2-41.  DESCRIPTION. A  four-blade  aluminum  propeller  is  installed  on each  engine.    The  propeller  is  of  the  full  feathering, constant speed, variable-pitch, counterweighted, 2-42