AVIONICS (COMMON) C D T1 T2
Section I. GENERAL
3-1. GENERAL DESCRIPTION.
This chapter covers the avionics equipment
installed common to the C12C, C -12D1, C-12D2,
C-12T1, and C-12T2 aircraft. It includes a brief
description of the avionics equipment, its technical
characteristics, capabilities, and locations. Avionics
installed in the C-12C and D1 aircraft are covered in
Chapter 3A. Avionics installed in the C-12D2 aircraft
are covered in Chapter 3B. Avionics installed in C-
12T1 and T2 aircraft are covered in Chapter 3C.
3-2. AVIONICS EQUIPMENT CONFIGURATION.
The avionics configuration of the aircraft is
comprised of three groups of electronic equipment.
The communication equipment group consists of the
interphone, UHF command C D , V/UHF command
T , and HF command systems. The navigation
equipment group provides the pilot and copilot with the
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 reference, groundspeed, and drift angle. The
transponder and radar group includes an identification
capability, a position and emergency tracking system,
and a radar system to locate potentially dangerous
weather areas. A Ground Proximity Altitude Advisory
System (GPAAS) is also installed.
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 that is controlled by the
AVIONICS MASTER POWER switch on the overhead
control panel, Figure 2-15. Individual system circuit
breakers and the associated avionics buses are shown
in Figures 2-27 and 2-28 and Tables 2-6, 2-7, 2-8, and
2-9. With the switch in the ON position, the avionics
power relay is deenergized 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, Figure
2-16. 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 deenergizes the avionics power relay and allows
power to be applied to avionics equipment.
b. AC Power. Two inverters provide ac power
for the avionics equipment. The inverters supply 115-
volt and 26-volt single-phase ac power when operated
by the INVERTER #1 or #2 switches. Either inverter is
capable of powering all avionics equipment requiring
ac power. 115 Vac power from the inverters is routed
through fuses and transformers in the nose avionics
compartment. The transformers provide the required
26 Vac needed by avionics equipment.
Section II. COMMUNICATIONS
3-4. COMMUNICATIONS DESCRIPTION.
The common avionics in the communications
equipment group consists of the microphone switches,
microphone jacks, and headset jacks.
JACKS, AND HEADSET JACKS.
microphone switch, placarded INTPH XMIT / MIC, is
located on the pilot's and copilot's control wheels,
Figure 2-22, and copilot's floor.
(1) MIC INTPH / XMIT Switch. Keys
(a) INTPH. When pressed to first detent,
keys interphone facility regardless of position of
transmitter selector switch.
(b) XMIT. When pressed fully, keys
facility indicated on transmitter selector switch.