Technical data

13773-001
31-50
Page 1
INDICATING/RECORDING SYSTEMS
1. DESCRIPTION
This section describes the Central Caution/Warning System which consists of an annunciator assembly
and related sensors and switches. The annunciator assembly is mounted center, high on the flight instru-
ment panel and contains six annunciators. Each annunciator has two individual LEDs as light sources. The
annunciator panel has bright, dim, and test modes, which are activated by a toggle switch mounted to the
left of the annunciator panel. In test mode all annunciators illuminate in the bright mode, allowing the pilot
to verify that all LEDs are functional. The entire annunciator assembly is mounted on a printed circuit
board, which decodes information from the individual sensors and illuminates the necessary annunciator.
28 VDC for annunciator operation is supplied through the 2-amp ANNUNCIATOR POWER circuit breaker
on the Essential Bus.
The OIL annunciator will illuminate if the oil temperature is greater than 240° F or if the oil pressure is less
than 10 PSI. The oil pressure/oil temperature gage provides a logic low signal if either the oil pressure or
oil temperature meets the above temperature or pressure criteria. The OIL annunciator illuminates red.
The FUEL annunciator will illuminate if the fuel quantity is less than approximately 14 gallons in both tanks.
The fuel quantity gage provides a logic low signal when each tank is below approximately 14 gallons. The
annunciator decodes these two signals and illuminates when both signals are low. The FUEL annunciator
illuminates amber.
The LOW VOLTS annunciator will illuminate if the system voltage falls below 24.5 ± 0.35 volts. The MCU
provides a logic low signal when the voltage is low. The LOW VOLTS annunciator illuminates red.
The ALT 1 annunciator provides two indications. During an overload condition, when alternator 1 is gener-
ating more than maximum rated alternator amperage, the light will flash approximately 40 times per
minute. When the alternator is generating less than 2.0 ± 2.0 amps, the ALT 1 annunciator will illuminate
steady, notifying the pilot that the alternator is not generating power. The ALT 1 annunciator illuminates
amber.
The ALT 2 annunciator also provides two indications. During an overload condition, where alternator 2 is
generating more than maximum rated alternator amperage, the light will flash approximately 40 times per
minute. When the alternator is generating less than 2.0 ± 2.0 amps, the ALT 2 annunciator will illuminate
steady, notifying the pilot that the alternator is not generating power. The ALT 2 annunciator illuminates
amber.
The PITOT HEAT annunciator will illuminate if the pitot heat is inoperative. If the Pitot Heat switch is “ON”
and there is no current in the line, indicating a circuit malfunction, the PITOT HEAT annunciator will illumi-
nate. A current sensor provides a logic low signal to the annunciator when current is absent in the pitot
heat circuit and the pitot heat switch is “ON”. The PITOT HEAT annunciator illuminates amber.
A. Annunciator Panel (See Figure 31-501)
(1) Removal - Annunciator Panel
(a) Ensure BAT 1, BAT 2, and AVIONICS master switches are in OFF position.
(b) Pull ANNUNCIATOR PANEL circuit breaker.
(c) Remove glareshield. (Refer to 25-10)
(d) Remove dress nut and washers securing annunciator toggle switch to instrument panel.
(e) Disconnect electrical connector from annunciator.
(f) While supporting annunciator and toggle switch, remove screws, washers, and nuts
securing assembly to instrument panel and remove from airplane.
(2) Installation - Annunciator Panel
(a) Position annunciator on instrument panel with rear connector on top, right side, and install
screws, washers, and nuts.
30 Nov 2000