TM 1-1510-224-10 CHAPTER 2 AIRCRAFT AND SYSTEMS DESCRIPTION AND OPERATION Section I.  AIRCRAFT 2-1. INTRODUCTION. The   purpose   of   this   chapter   is   to   describe   the aircraft  and  its  systems  and  controls  which  contribute  to the  physical  act  of  operating  the  aircraft.    It  does  not contain   descriptions   of   avionics   or   mission   equipment covered   elsewhere   in   this   manual.      This   chapter   also contains    the    emergency    equipment    installed.        This chapter  is  not  designed  to  provide  instructions  on  the complete    mechanical    and    electrical    workings    of    the various   systems;   therefore,   each   is   described   only   in enough  detail  to  make  comprehension  of  that  system sufficiently    complete    to    allow    for    safe    and    efficient operation. 2-2. GENERAL The   RC-12P   and   RC-12Q   are   pressurized,   low wing, all metal aircraft and are powered by two PT6A-67 turboprop  engines  (fig.    2-1  and  2-2).    The  aircraft  have all-weather   capability.      Distinguishable   features   of   the aircraft   are   the   slender,   streamlined   engine   nacelles, four-bladed     propellers,     aft     rotating     boom     antenna, mission  antennas,  wing  tip  pods,  stabilons,  T-tail,  and  a ventral  fin  below  the  empennage.    The  RC-12Q  aircraft is  distinguished  by  the  large  SATCOM  radome  located on top of the fuselage. a. RC-12P Basic Mission.  The basic mission of the aircraft is radio reconnaissance. b. RC-120 Basic Mission.  The basic mission of   the   aircraft   is   Direct   Air   to   Satellite   Relay   (DASR) communications. Cabin  entrance  is  made  through  a  stair-type  door aft  of  the  wing  on  the  left  side  of  the  fuselage  (fig.    2-1 and   2-2).      The   interior   configuration   of   the   aircraft   is shown in figure 2-3 and 2-4. 2-3. DIMENSIONS. Overall aircraft dimensions are shown in figure 2-5. 2-4. GROUND TURNING RADIUS. Minimum  ground  turning  radius  of  the  aircraft  is shown in figure 2-6. 2-5. MAXIMUM WEIGHTS. a. Takeoff.  Maximum gross takeoff weight is 16,500 pounds. b. Landing.    Maximum  gross  landing  weight is 15,675 pounds. c. Maximum  Ramp  Weight.    Maximum  ramp weight is 16,620 pounds. d. Maximum   Zero   Fuel   Weight.      Maximum zero fuel weight is 13,100 pounds. 2-6. EXHAUST AND PROPELLER DANGER AREAS. Exhaust and propeller danger areas to be avoided by  personnel  while  aircraft  engines  are  being  operated on the ground are depicted in figure 2-7.  Distance to be maintained    with    engines    operating    at    idle    are    also shown.    Temperature  and  velocity  of  exhaust  gases  at varying locations aft of the exhaust stacks are shown for maximum power.  The danger area extends to 40 feet aft of  the  exhaust  stack  outlets.    Distance  to  be  maintained with   engines   operating   at   idle   and   propeller   danger areas are also shown. 2-7. LANDING GEAR SYSTEM. The  retractable  tricycle  landing  gear  is  electrically controlled  and  hydraulically  actuated.    The  landing  gear are  extended  and  retracted  by  a  hydraulic  power  pack, located  in  the  left  wing  center  section,  forward  of  the main   spar.      The   power   pack   consists   primarily   of   a hydraulic  pump,  a  28  VDC  motor,  a  gear  selector  valve and solenoid, a two section fluid reservoir, filter screens, a  gear-up  pressure-switch  and  a  low  fluid  level  sensor. Engine  bleed  air,  regulated  to  18  to  20  PSI,  is  plumbed into    the    power    pack    reservoir    and    the    system    fill reservoir  to  prevent  cavitation  of  the  pump.    The  fluid level   sensor   activates   an   amber   caution   annunciator, placarded HYD FLUID LOW, located on the caution/advisory  annunciator  panel,  whenever  the  fluid level  in  the  power  pack.    is  low.    The  annunciator  is tested   by   pressing   the   HYD   FLUID   SENSOR   TEST switch located on the pilot's subpanel (fig.  2-8). Power  for  the  hydraulic  power  pack  is  supplied  through the   landing   gear   motor   relay   and   a   60-ampere   circuit breaker located under the floorboard forward of the main spar.    The  motor  relay  is  energized  by  power  furnished through    the    2-ampere    LANDING    GEAR    CONTROL circuit  breaker  located  on  the  overhead  circuit  breaker panel (fig.  2-9).  The power pack motor is protected by a time    delay    module    which    senses    operation    voltage through  a  5-ampere  circuit  breaker.    Both  are  located beneath  the  aisleway  floorboards,  forward  of  the  main spar.  Landing 2-1