CHAPTER 2 AIRCRAFT AND SYSTEMS DESCRIPTION AND OPERATION

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.