annunciator lights within the control switch of the malfunctioning system or
installation. Labels within each system or component control switchlight will
illuminate whenever the associated system or component is not in the
commanded operating state. In normal cockpit operations, all switchlights
are dark (unless there is a known malfunction). A malfunction will power the
light(s) within the switchlight illuminating the text label (typically ON, OFF or
FAULT) to annunciate the failure. The switchlight will remain in the
previously selected position until manually repositioned by the flight crew.
The lamp elements within the annunciator lights are powered by direct
current (DC) through circuit breakers labelled either ANN LTS PWR or
WARN LTS PWR. The circuits for most (but not all) annunciator lights are
controlled by an Annunciator Lights Test and Dim relay that both allows the
lights to be tested with a single pushbutton on the overhead console
labelled ANN LIGHTS TEST, and connects the lights to the dimming
function of the cockpit lighting control knobs to adjust annunciator
illumination levels. (A complete discussion of annunciator lights and cockpit
lighting controls is contained in Section 2A-33-20: Flight Compartment
Lighting System.) The annunciators in the engine fire handles, fuel control
switches and the thrust reverser manual stow switches are not dimmable
and illuminate at full brightness regardless of cockpit lighting control
settings.
Six (6) warning lights power (WARN LTS PWR) circuit breakers are
incorporated to control L and R ESS 28v DC bus power distribution to
numerous system signals and/or indications. The circuit breaker names,
locations, power sources and signals and/or indications they control are
listed in the following tables and shown in schematic form in Figure 12.
NOTE:
Twenty eight volt (28v) power sources for warning and
annunciator lights are intermixed. The lighting power
and control sources for symmetrical systems /
installations (e. g. left and right) may be from either
warning lights or annunciator lights power or from an
unrelated power source circuit breaker. Circuit breaker
/ power source wiring is dependent upon load carrying
ability, physical proximity or redundancy requirements.
WRN LTS PWR #1 Circuit Breaker (REER A-23)
Signals / Indications
Right and left engine LOOP A / LOOP B
FIRE TEST switch
Right cowl anti-ice relay and valve
Cabin Pressure Control Panel
FAULT light in FAULT / MANUAL switch
Right engine Fuel Pressure Low relay
and switch data to MAU #3
GPWS / GND SPLR FLAP ORIDE
switch ON legend
Switch position data to MAUs #1 and
#3
Copilot MASTER WARN “W” switch
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS
2A-31-00
Page 28
July 15/04
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