Learjet 60 - Bleed Air Supply; BLEED AIR Switches; CABIN AIR Light

Learjet 60

Pilot's Manual
BLEED AIR SUPPLY
SECTION VI
ANTI-ICE &
ENVIRONMENTAL
Engine
bleed
air
is used extensively
for anti-icing
and cabin
environ-
mental control
. The
source of this
air
is low- and
high-pressure
ports on
each engine compressor . From the engine compressor, the bleed air is
mixed and regulated in the mixing/ regulating valve mounted on each
engine . The bleed air is then ducted from the engines into the tailcone
where it is available for several using systems . Shutoff valves and check
valves are installed in the tailcone plumbing to control the bleed air
from the left and right engines . In addition to the plumbing, the system
includes BLEED AIR switches and an overheat warning system .
BLEED AIR SWITCHES
The L
and
R BLEED AIR
switches, located
in
the
BLEED AIR
group on
the copilot's switch
panel,
control the respective left and
right
bleed-air
shutoff valves and left and
right
emergency pressurization valves . Each
BLEED AIR
switch has three positions :
EMER,
ON and
OFF .
When a
BLEED AIR
switch is
in
the ON position, the respective bleed-air
shutoff valve
will
open and the emergency pressurization valve
will
be
closed . When a
BLEED AIR
switch is set to
OFF,
the respective bleed-
air
shutoff valve
will
be
energized
to the closed position
.
When a
BLEED AIR
switch is set to
EMER,
the respective bleed-air shutoff
valve
will
close and the emergency pressurization valve
will
be
ener-
gized
open and the high-stage bleed
air will
be shut
off . The
bleed-air
shutoff valve
will
close automatically whenever emergency pressuriza-
tion is activated or the ENG
FIRE PULL T-handle
is pulled on the
respective side .
The
bleed-air shutoff valves control bleed-air flow to
the cabin
air
distribution and temperature control systems,
wing anti-
ice system, and windshield anti-ice system
.
Bleed
air for
nacelle,
engine
anti-icing,
and windshield alcohol tank pressurization is
still
available
with the shutoff valves closed .
The
bleed-air shutoff valves and
emer-
gency pressurization valves operate on 28 VDC supplied through the
7
.5-amp
L
and
R BLEED AIR
circuit breakers on the pilot's and copilot's
circuit breaker panels .
CABIN AIR LIGHT (Aircraft 60-271 &subsequent and prior aircraft
modified by SB 60-31-1)
A white CABIN AIR advisory light indicates that either the L BLEED
AIR, R BLEED AIR or CAB AIR switches are in the off position .
PM-123
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6-1
Change 5