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when a channel of the controller is operating
in the degraded mode.
System failure is annunciated by an amber
CAS caution message, “L or R WSHLD
FAIL.” This message is displayed if the wind-
shield temperature is below 50° F while the
system is turned on. The excessively low tem-
perature could be due to failure of an alternator
or loss of DC electrical power to the associ-
ated channel of the controller. There is no
cockpit indication of alternator failure other
than the loss of windshield heat on that side.
A system overheat condition is annunciated by
display of an amber CAS message, “L or R
WSHLD OVHT.” This occurs when the sen-
sors detect a temperature that exceeds ap-
proximately 160° F. The corresponding wind-
shield heat should be selected OFF in this
case.
Although AC electrical power is provided by
the engine-driven alternators to heat the wind-
shield heating elements, the two channel
WSHLD controller is powered by 28 VDC re-
ceived from the left and right essential buses
respectively. The left system control is pow-
ered through the L HEAT WSHLD circuit
breaker and the right system is powered
through the R HEAT WSHLD circuit breaker.
They are located in the ANTI-ICE group of cir-
cuit breakers on the left and right panels re-
spectively.
10-8
FOR TRAINING PURPOSES ONLY
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
FlightSafety
international
L WSHLD
CONTROLLER
R WSHLD
CONTROLLER
5 KVA
ALTERNATOR
5 KVA
ALTERNATOR
HEATING ELEMENT
HEATING ELEMENT
PDP*
PDP*
OFF
R WSHLD
L ESS BUS
R ESS BUS
OFF
L WSHLD
L HEAT
WSHLD
R HEAT
WSHLD
*PDP
NORMAL SENSOR
OVHT SENSOR
POWER
DISTRIBUTION
PANEL
L WSHLD OVHT
L WSHLD HT FAIL
R WSHLD OVHT
R WSHLD HT FAIL
Figure 10-5. Windshield Anti-Ice Schematic