Section I. GENERAL
Except for mission avionics, this chapter covers all
avionics equipment installed in the RC-12D aircraft. It
provides a brief description of equipment covered, the
technical characteristics and locations. It covers
techniques and procedures to be employed when
operating the equipment. For more detailed operational
information consult the vendor manuals that accompany
the aircraft loose tools.
3-2. AVIONICS EQUIPMENT CONFIGURATION.
The aircraft avionics covered is comprised of three
groups of electronic equipment. The Communication
group consists of the Interphone, UHF command, VHF
command and HF command systems. The Navigation
instrumentation required to establish and maintain an
accurate flight course and position, and to make an
Meteorological Conditions (IMC). The Navigation group
includes equipment for determining altitude, attitude,
position, destination, range and bearing, heading
Transponder and Radar group includes an identification,
position and emergency tracking system, and a radar
system to locate potentially dangerous weather areas
and a radar system to differentiate between friendly and
unfriendly search radar.
All avionics equipment require a
3-minute warmup period. The
weather radar has an automatic
time delay of 3 to 4 minutes.
3-3. POWER SOURCE.
a. DC Power. DC power for the avionics equipment
is provided by four sources: the aircraft battery, left and
right generators, and external power. Power is routed
through a 50-ampere circuit breaker to the avionics
power relay which is controlled by the AVIONICS
MASTER POWER SWITCH (fig. 2-18) on the overhead
control panel. Individual system circuit breakers and the
associated avionics busses are shown in fig. 2-22.
With the switch in the ON position, the avionics power
relay is de-energized and power is applied through both
the AVIONICS MASTER POWER #1 and #2 circuit
breakers to the individual avionics circuit breakers on
the overhead circuit breaker panel (fig. 2-26). In the off
(aft) position, the relay is energized and power is
removed from avionics equipment. When external
power is applied to the aircraft, the avionics power relay
is normally energized, removing power from the
avionics equipment. To apply external power to the
avionics equipment, move the AVIONICS MASTER
POWER switch to the EXT PWR position. This will de-
energize the avionics power relay and allow power to be
applied to avionics equipment.
b. AC Power. AC power for the avionics equipment
is provided by two inverters. The inverters supply 115-
volt and 26-volt single-phase AC power when operated
by the INVERTER #1 or #2 switches (fig. 2-18). Either
inverter is capable of powering all avionics equipment
requiring AC power. AC power from the inverters is
routed through fuses in the nose avionics compartment.
3-4. MICROPHONES, SWITCHES AND JACKS.
Boom, and oxygen mask microphones can be utilized in
a. Microphone Switches. The pilot and copilot are
provided with individual MIC control switches, placarded
wheels. A foot-actuated mic switch is also positioned on
the floorboards forward of each pilot's seat.
b. Controls and Functions. Microphone switches
and jack functions are as follows:
(1) Control wheel switches (fig. 2-16).
Keys selected facility.
(Not depressed) Microphone is