AIRCRAFT AND SYSTEMS DESCRIPTION AND OPERATION
The purpose of this chapter is to describe the
aircraft and its systems and controls which contrib-
ute 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 contains descriptive information and does
not describe procedures for operation of the aircraft.
These procedures are contained within appropriate
chapters in the 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 suffi-
ciently complete to allow for its safe and efficient
The RC-12H is a pressurized, low wing, all
metal aircraft, powered by two PT6A-41 turboprop
engines (fig. 2-1 and 2-11), and has all weather capa-
bility. Distinguishable features of the aircraft are the
slender, streamlined engine nacelles, an aft rotating
boom antenna, mission antennas, wing tip pods, a
T-tail and a ventral tin below the empennage. The
basic mission of the aircraft is radio reconnaissance.
Cabin entrance is made through a stair-type door
(fig. 2-2) on the left side of the fuselage.
Overall aircraft dimensions are shown in figure
2-4. GROUND TURNING RADIUS.
Minimum ground turning radius of the aircraft
is shown in figure 2-4.
2-5. MAXIMUM WEIGHTS.
Maximum takeoff gross weight is 15,000
pounds. Maximum landing weight is 15,000 pounds.
Maximum ramp weight is 15,090 pounds. Maxi-
mum zero fuel weight is 11,500 pounds.
2-6. EXHAUST DANGER AREA.
Danger areas to be avoided by personnel while
aircraft engines are being operated on the ground are
depicted in figure 2-5. Distance to be maintained
with engines operating at idle are also shown. Tem-
perature 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 landing gear is a retractable, tricycle type,
electrically operated by a single DC motor. This
motor drives the main landing gear actuators
through a gear box and torque tube arrangement,
and also drives a chain mechanism which controls
the position of the nose gear. Positive down-locks
are installed to hold the drag brace in the extended
and locked position. The down-locks are actuated by
overtravel of the linear jackscrews and are held in
position by a spring-loaded overcenter mechanism.
The jackscrew in each actuator holds all three gears
in the UP position, when the gear is retracted. A
friction clutch between the gearbox and the torque
shafts protects the motor from electrical overload in
the event of a mechanical malfunction. A 150-
ampere current limiter, located on the DC distribu-
tion bus under the center floorboard, protects
against electrical overload. Gear doors are opened
and closed through a mechanical linkage connected
to the landing gear. The nose wheel steering mecha-
nism is automatically centered and the rudder ped-
als relieved of the steering load when the landing
gear is retracted. Air-oil type shock struts, filled with
compressed air and hydraulic fluid, are incorporated
with the landing gear. Gear retraction or extension
time is approximately six seconds.
(1.) Landing Gear Control Switch. Land-
ing gear system operation is controlled by a manu-
ally actuated, wheel-shaped switch placarded LDG
GEAR CONTR - UP - DN, located on the left sub-
panel (fig. 2-6). The control switch and associated
relay circuits are protected by a S-ampere circuit
breaker, placarded LANDING GEAR RELAY on
the overhead circuit breaker panel (fig. 2-26).