Chapter 3C Avionics T1 T2; General - Beechcraft C-12C Operator And Technical Reference Manual

3C-1. DESCRIPTION.
This chapter covers the avionics equipment
configuration installed in C-12T1 and C-12T2 aircraft.
It includes a brief description of the avionics
equipment, its technical characteristics, capabilities,
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's loose tools.
3C-2. AVIONICS EQUIPMENT CONFIGURATION.
The avionics configuration of the aircraft consists
of three groups of electronic equipment.
communication equipment group consists of the
interphone and V/UHF, VHF, and HF communications
transceivers and an Emergency Locator Transponder
(ELT). 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 approach on instruments in
Instrument Meteorological Conditions (IMC).
navigation group includes equipment for determining
altitude, attitude, position, destination, range, bearing,
heading, groundspeed,
transponder and radar group includes an identification,
position, a emergency tracking system, and a radar
system to locate potentially dangerous weather areas.
A Ground Proximity
(GPAAS), Traffic Alert and Avoidance System (TCAS-
II), and Stormscope are also installed.
3C-3. POWER SOURCE.
a. DC Power.
supplied with DC power from the aircraft battery, left
and right generators, and external power. Power is
routed through two 50-ampere circuit breakers to the
avionics power relay, which is controlled by the
avionics master power switch, located on the overhead
control panel, Figure 2-15. Individual system circuit
breakers and the associated avionics buses are shown
in Figure 2-28. A three-position switch, placarded
AVIONICS MASTER POWER ON / EXT PWR,
CHAPTER 3C
AVIONICS
Section I. GENERAL
and drift angle.
Altitude Advisory System
The avionics equipment is
T1 T2
located on the overhead control panel controls a relay
which applies power to two 35-ampere circuit
breakers, placarded AVIONICS MASTER PWR #1 /
#2, located on the overhead circuit breaker panel,
Figure 2-16. When the AVIONICS MASTER POWER
switch is set to the ON (center) position, the avionics
power relay is de-energized and power is applied
through two 35-ampere circuit breakers, placarded
AVIONICS MASTER PWR #1 / #2, located on the
overhead circuit breaker panel.
If the AVIONICS MASTER POWER switch
fails to operate, power to the individual
avionics circuit breakers can be provided
The
by pulling the 5-ampere circuit breaker,
placarded AVIONICS MASTER CONTR,
located on the overhead circuit breaker
panel.
In the off (aft) position, the relay is energized and
power is removed from avionics equipment.
external power is applied to the aircraft, the avionics
power relay is normally energized, automatically
The
removing power from the avionics equipment.
apply external power to the avionics equipment, move
the AVIONICS MASTER POWER switch to the EXT
The
PWR position, which overrides the automatic avionics
lockout system.
power relay and allow power to be applied to the
avionics equipment.
b. AC Power.
equipment and ac engine instruments is provided by
two 400 Hz 750 volt-ampere single-phase inverters.
During normal operation, the number 1 inverter
supplies 115 Vac and 26 Vac to the number 1 avionics
and navigation system and the left engine ac
instruments, while the number 2 inverter supplies
115 Vac and 26 Vac to the number 2 avionics and
navigation system and the right ac engine instruments.
If either inverter fails, the total ac load will be switched
to the remaining inverter automatically, unless a
ground fault exists. The inverters are controlled by two
switches, placarded
INVERTER #2/ON, located on the overhead control
panel.
TM 1-1510-218-10
NOTE
This will de-energize the avionics
AC power for the avionics
INVERTER #1/ON
When
To
and
3C-1