TM 1-1510-223-10 Change 3          2-1 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 de- signed to provide instructions on the complete mechani- cal   and   electrical   workings   of   the   various   systems; therefore,  each  is  described  only  in  enough  detail  to make  comprehension  of  that  system  sufficiently  com- plete to allow for its safe and efficient operation. 2-2. GENERAL. The RC-12N is a pressurized, low wing, all metal air- craft, powered by two PT6A-67 turboprop engines (fig. 2-1), having all weather capability. Distinguishable fea- tures of the aircraft are the slender, streamlined engine nacelles, four-bladed propellers, aft rotating boom an- tenna, mission antennas, wing tip pods, stabilons, T-tail, and a ventral fin below the empennage. The basic mis- sion of the aircraft is radio reconnaissance. Cabin en- trance is made through a stair-type door aft of the wing on the left side of the fuselage (fig. 2-1). The interior con- figuration of the aircraft is shown in figure 2-2. 2-3. DIMENSIONS. Overall aircraft dimensions are shown in figure 2-3. 2-4. GROUND TURNING RADIUS. Minimum  ground  turning  radius  of  the  aircraft  is shown in figure 2-4. 2-5. MAXIMUM WEIGHTS. a.   Takeoff.  Maximum gross takeoff weight is 16,200 pounds. b.   Landing. Maximum gross landing weight is 15,400 pounds. c.   Maximum Ramp Weight.  Maximum ramp weight is 16,320 pounds. d.   Maximum Zero Fuel Weight. Maximum zero fuel weight is 13,100 pounds. 2-6. EXHAUST AND PROPELLER DANGER AREA. Danger areas to be avoided by personnel while air- craft engines are being operated on the ground are de- picted  in  figure  2-5.  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. 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 assemblies are extended and retracted by a hydraulic power pack, located in the left wing center section, for- ward 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, gear-up pressure switch and low fluid level sen- sor.  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,  plac- arded 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  pilot’s subpanel (fig. 2-6). 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 fur- nished  through  the  2-ampere  LANDING  GEAR  CON- TROL  circuit  breaker  located  on  the  overhead  circuit breaker panel (fig. 2-7). The power pack motor is pro- tected by a time delay module which senses operation voltage through a 5-ampere circuit breaker. Both are lo- cated beneath the aisleway floorboards, forward of the main spar. Landing gear extension or retraction is nor- mally  accomplished  in  6  to  7  seconds.  Voltage  to  the power pack is terminated after the fully extended or re- tracted position is reached. If electrical power has not ter- minated within 14 seconds, a relay and 2-ampere landing gear circuit breaker will open, and electrical power to the system power pack will be interrupted.