Learjet 60 - MAN ALT Control; MODE Switch; Pressurization Controls and Indicators

Learjet 60

Pilot's Manual
"

The bleed-air shutoff
valve closes
"

The
wing anti-ice bypass circuit is deactivated
"

The EMER
PRESS annunciator illuminates
The result is that engine low-pressure bleed
air is ducted directly into
the cabin air overhead and floor diffusers .
This bypasses all bleed-air
plumbing in the tailcone area and will
stabilize cabin altitude if the
pressurization failure has occurred
in that area . The emergency pres-
surization valves are energized
to the open position and de-energized
for normal bleed-air flow . Each
valve is independent of the other and,
whenever both valves are open, temperature
control and bleed air for
wing and windshield anti-ice will be
unavailable . Operating power
for emergency
valve actuation is 28 VDC supplied
through the 7 .5-
amp L and
RBLEED AIR circuit breakers on the
pilot's and copilot's
circuit
breaker panels .
PRESSURIZATION
CONTROLS AND INDICATORS
MODE SWITCH
The MODE
switch is an alternate-action switch
located on the copi-
lot's switch
panel . The switch is used to
toggle the pressurization
sys-
tem between
the automatic and manual
modes . Upon
initial power-
up, the
system will be in automatic
mode if no faults
were revealed in
the self-test . If a fault is detected,
the system will revert to
manual and
the FAULT annunciator
(part
of
the MODE switch)
will illuminate . To
switch from automatic to
manual mode and vice
versa, the MODE
switch is depressed and
released . When manual
mode is selected, the
MANUAL annunciator
(part of the MODE
switch) will be
illuminated .
MAN
ALT CONTROL
The MAN
ALT control is a 3-position
valve located
on the copilot's
switch
panel . The control is
used to direct either
regulated vacuum or
cabin pressure to the
outflow valves positioning them
so that the de-
sired
cabin altitude results .
Moving the control to
the UP detent ap-
plies
regulated vacuum to
the outflow valves
causing them to move
toward the open position
and increasing cabin
altitude . Moving
the
control to the DN detent
applies cabin pressure
to the outflow valves
causing them to move
toward the close position
and decreasing cabin
altitude . When the control
is in the center
position, the outflow valves
PM-123
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6-27
Original