TM 55-1510-222-10 8-45.  AUTOPILOT COUPLED APPROACHES. There  are  no  special  preparations  required  for  placing the  aircraft  under  autopilot  control.    Refer  to  Chapter  3 for procedures to be followed for automatic approaches. Section IV. FLIGHT CHARACTERISTICS 8-46.  STALLS. WARNING · Under   certain   flight   conditions, prestall  buffet  may  occur  before the stall warning horn sounds. · The RC-12K stall warning system may not provide adequate warning of impending stall. When operating under conditions where altitude loss is critical and stall recovery and aircraft control is  difficult  such  as  at  night,  IMC and     autopilot     operations,     the pilot must closely monitor airspeed. · A prestall warning in the form of light buffeting may be felt when approaching a stall.  An aural warning is also provided  by  the  warning  horn.    The  warning  horn  may begin to sound approximately 5 12 KNOTS above power off  stall  speed,  depending  on  aircraft  configuration.    If correct   stall   recovery   technique   is   used,   very   little altitude  will  be  lost  during  the  stall  recovery.    For  the purpose of this section, the term "power on" means that both engines and propellers of the aircraft are operating normally  and  are  responsive  to  pilot  control.    The  term "power off' means that both engines are operating at idle power.   Landing   gear   position   has   no   effect   on   stall speed.   During   practice,   enter   power   off   stalls   from normal   glides.      Enter   power   on   stalls   by   smoothly increasing  pitch  attitude  to  a  climb  attitude  obviously impossible  for  the  aircraft  to  maintain,  and  hold  that attitude until the stall occurs. a. Power On Stalls.  The power on stall attitude is very    steep    and    unless    this    high    pitch    attitude    is maintained,   the   aircraft   will   generally   settle   or   mush instead   of   stall.      It   is   difficult   to   stall   the   aircraft inadvertently  in  any  normal  maneuver.    A  light  buffet precedes the stall, and the first indication of approaching stall  is  generally  a  decrease  in  control  effectiveness, accompanied by a tone from the stall warning horn.  The stall  itself  is  characterized  by  a  rolling  tendency  if  the aircraft is allowed to yaw.  The proper use of rudder will minimize the tendency to roll.  A slight pitching tendency will develop if the   aircraft is held in the stall, resulting in the nose dropping slightly, then pitching up toward the horizon;  this  cycle  is  repeated  until  recovery  is  made. Control  is  regained  very  quickly  with  little  altitude  loss, providing  the  nose  is  not  lowered  excessively.    Begin recovery  with  forward  movement  of  the  control  wheel and  a  gradual  return  to  level  flight.    The  roll  tendency caused  by  yaw  is  more  pronounced  in  power  on  stalls, as is the pitching tendency; Power on stall characteristics   are   not   greatly   affected   by   wing   flap position,    except    that    stalling    speed    is    reduced    in proportion to the degree of wing flap extension. b. Power    Off    Stalls.        The    rolling    tendency    is considerably less pronounced in power off stalls (in any configuration),     and     is     more     easily     prevented     or corrected    by    adequate    rudder    and    aileron    control, respectively.      The   nose   will   generally   drop   straight through    with    some    tendency    to    pitch    up    again    if recovery  is  not  made  immediately.    The  Stall  Speed graph   (fig.      8-2)   shows   the   indicated   power   off   stall speeds  with  aircraft  in  various  configurations.    Altitude loss during a full stall may be as high as 1320 feet. c. Accelerated Stalls.  The aircraft gives noticeable stall   warning   in   the   form   of   buffeting   when   the   stall occurs.          The     stall     warning     and     buffet     can     be demonstrated    in    turns    by    applying    excessive    back pressure on the control wheel. 8-47.  SPINS. Intentional spins are prohibited.  If a spin is inadvertently entered use the following recovery procedure: NOTE Spin  demonstrations  have  not  been conducted.    The  recovery  technique is    based    on    the    best    available: information. The  first  three  actions  should  be  performed  as  nearly simultaneously as possible. 1. Power levers IDLE. 2. Apply  full  rudder  opposite  the  direction  of  spin rotation. 8-20