TM 55-1510-220-10
CHAPTER 3
AVIONICS
Section I. GENERAL
3-1. INTRODUCTION.
Except for mission avionics, this chapter covers all
avionics equipment installed in the RC12G aircraft. It provides
a brief description of equipment covered, the technical
characteristics and locations. It covers systems and controls
and provides the proper 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 consists of three groups of
electronic equipment. The communication group consists of
the interphone, UHF command, VHF command and HF
command systems. The navigation group provides the pilot
and copilot with the instrumentation required to establish and
maintain an accurate flight course and position, and to make an
approach on instruments under Instrument 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,
position, emergency tracking system, a radar system to locate
potentially dangerous weather areas, and a radar system to
differentiate between friendly and unfriendly search radar.
NOTE
Avionics equipment requires a 3-minute
warm-up period. The weather radar
has an automatic time delay of 60 to 70
seconds.
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 on the
overhead control panel (fig. 2-12). Individual system circuit
breakers and the associated avionics busses are shown in fig.
223. With the switch in the ON (forward) position, the
avionics power relay is de-energized and power is applied
through both the AVIONICS MASTER POWER No.1 and
No.2 circuit breakers to the individual avionics circuit breakers
on the overhead circuit breaker panel (fig. 2-27). 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 the avionics equipment.
b.
Single-Phase 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 No.1 or No.2 switches (fig. 2-12).
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.
c.
Three-Phase AC Power. Three phase AC electrical
power for operation of the inertial navigation system and
mission avionics is supplied by either of two DC powered 3000
voltampere solid state three phase inverters. The three phase
inverters are controlled by a three-position switch located on
the mission control panel (fig. 4-1) placarded No. 1 MSN OFF
No. 2 MSN.
Change 2 3-1
