TM 55-1510-220-10 and   locked.      The   circuit   is   protected   by   a   20-ampere circuit  breaker,  placarded  FLAP  MOTOR,  located  on  the overhead circuit breaker panel (fig.  2-27). a. Wing   Flap   Control   Switch.      Flap   operation   is controlled  by  a  three-position  switch  with  a  flapshaped handle on the control pedestal (fig.  2-8).  The handle of this  switch  is  placarded  FLAP  and  switch  positions  are placarded:   FLAP   UP,   APPROACH,   and   DOWN.      The amount of downward extension of the flaps is established by  position  of  the  flap  switch,  and  is  as  follows:  UP  0%, APPROACH   40%,   and   DOWN   100%.      Limit   switches, mounted on the right inboard flap, control flap travel.  The flap   control   switch,   limit   switch,   and   relay   circuits   are protected  by  a  5ampere  circuit  breaker,  placarded  FLAP CONTR  located  on  the  overhead  circuit  breaker  panel (fig.  2-27).    Flap  positions  between  UP  and  APPROACH cannot   be   selected.      For   intermediate   flap   positions between   APPROACH   and   DOWN,      The   APPROACH position acts as an off position.  To return the flaps to any position between full DOWN and APPROACH, place the flap   switch   to   UP   and   when   desired   flap   position   is obtained, return the switch to the APPROACH detent.  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 on the control pedestal (fig.  2-6).  The approach and   full   down   or   extended   flap   position   is   14   and   34 degrees,   respectively.      The   flap   position   indicator   is protected  by  a  5ampere  circuit  breaker,  placarded  FLAP CONTR,  located  on  the  overhead  circuit  breaker  panel (fig.  2-27). Section VI.  PROPELLERS 2-43.  DESCRIPTION. A   three-blade   aluminum   propeller   is   installed   on each   engine.      The   propeller   is   of   the   full   feathering, constant speed, counterweighted, reversible type, controlled  by  engine  oil  pressure  through,  single  action, engine driven propeller governors.  The propeller is flange mounted to the engine shaft.  Centrifugal counterweights, assisted  by  a  feathering  spring,  move  the  blades  toward the  low  RPM  (high  pitch)  position  and  into  the  feathered position.    Governor  boosted  engine  oil  pressure  moves the  propeller  to  the  high  RPM  (low  pitch)  hydraulic  stop and  reverse  position.    The  propellers  have  no  low  RPM (high  pitch)  stops;  this  allows  the  blades  to  feather  after engine    shutdown.        Low    pitch    propeller    position    is determined by the low pitch stop which is a mechanically actuated, hydraulic stop.  Beta and reverse blade angles are controlled by the power levers in the beta and reverse range. 2-44.  FEATHERING PROVISIONS. Both   manual   and   automatic   propeller   feathering systems are provided.  Manual feathering is accomplished by  pulling  the  corresponding  propeller  lever  aft  past  a friction detent.  To unfeather, the propeller lever is pushed forward     into     the     governing     range.          An     automatic feathering   system,   will   sense   loss   of   torque   and   will feather  an  unpowered  propeller.    Feathering  springs  will feather the propeller when it is not turning. a. Automatic  Feathering.    The  automatic  feathering system   provides   a   means   of   immediately   dumping   oil from  the  propeller  servo  to  enable  the  feathering  spring and counterweights to start feathering action of the blades in the event of an engine failure.  Although the system is armed    by    a    switch    on    the    overhead    control    panel, placarded AUTOFEATHER ARM OFF TEST, the completion of the arming phase occurs when both power levers  are  advanced  above  90%  N1  at  which  time  both indicator lights on the caution/ advisory annunciator panel indicate  a  fully  armed  system.    The  annunciator  panel lights are green and are placarded No.1 AUTOFEATHER (left   engine)   and   No.2   AUTOFEATHER   (right   engine). The   system   will   remain   inoperative   as   long   as   either power  lever  is  retarded  below  90%  N1  position,  unless TEST    position    of    the    AUTOFEATHER    SWITCH    is selected  to  disable  the  power  lever  limit  switches.    The system is designed for use only during takeoff and landing and  should  be  turned  off  when  establishing  cruise  climb. During   takeoff   or   landing,   should   the   torque   for   either engine    drop    to    an    indication    between    16    21%,    the autofeather    system    for    the    opposite    engine    will    be disarmed.        Disarming    is    confirmed    when    the    No.1 AUTOFEATHER   or   No.2   AUTOFEATHER   annunciator light of the 2-39