Learjet 60 - Page 227

Pilot's Manual
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Leaqet6o
The green WSHLD
FIT
light, located on the glareshield annunciator
anel, provides the crew with a visual indication
of
windshield heat
. The light is
extinguished when the WSHLD HEAT switch is
FR The light will illuminate when the WSHLD HEAT switch is
out of the OFF position and remain
illuminated until either the
switch is set to OFF or an overheat thermoswitch
trips
shutting airflow
off and extinguishing
the green WSHLD HT light .
D HT
LIGHT
LD OV HT LIGHT
Illumination of the
amber WSHLD
OV FIT caution
light, on the
glareshield annunciator panel, indicates that the bleed air
temperature
in one or both of the windshield outlet nozzles has reached the respec-
tive low- or high-limit thermoswitch settings and the windshield anti-
ice system has been
shutdown by either the low- or high-limit ther-
moswitches . During ground operations, the light is controlled by the
low-limit switches . In flight, the light is controlled by the high-limit
switches .
If the
bleed air temperature in
either
outlet nozzle
rea
25YF (12VC) during ground operation,
the low-limit overheat ther-
moswitches will close
the anti-ice
shutoff valve and illuminate the
WSHLD OV HT caution light . If the outlet nozzle bleed air temperature
hi either nozzle reaches 347 1 F (175 1 C) in flight, the high-limit overheat
thermoswitches will perform the same function . When the nozzle
bleed
air temperature drops to 240'F (115'C) during ground
operations, or
311 - F (155 - C) in
flight, the overheat thermoswitches will reset allowing
the anti-ice shutoff
valve
to open and extinguish the WSHLD OV HT
caution light . To avoid a false WSHILD OV HT indication upon landing,
the low-limit overheat thermoswitch
circuitry
is
disabled for 10 sec-
onds after touchdown, after
which normal functioning will resume .
INDSHIELD DEFOG
Windshield internal defogging is accomplished using electrically
heated windshield
panel
. The system is deigned so that
if
deli
it may be activated before takeoff and remain an
until
shutdown .
system consists of two windshield panels with
integral heaters,
windshield
heat control
unit,
system switch, L and R WS DEFOG aann-
nunciators, and associated aircraft wiring . The system utilizes the 115
VAC output from be inverter system to
power the integral heaters .
The control circuit receives 28 VDC
through the 5-amp L WSHLD
DEFOG and R WISHLUD DEFOG circuit breakers on the pilot's and co-
pilot's circuit breaker panels . The 115 VAC
input
to the system
is pro-
vided through the 10-amp
L and R WSHLD DEFOG circuit breakers
on the
pilot's and copilot's circuit breaker panels .
642
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