MANUAL PRESSURIZATION
SWITCH
The airplane pressurization system may be
operated manually by crew selection after de-
pressing the MANUAL PRESS switch on the
pressurization control panel (Figure 12-1).
When selected, an ON caption illuminates
within the S/I to indicate manual operation.
The S/I is blank during automatic mode, as this
is the normal configuration. Depressing the S/I
a second time returns the CPCS to automatic
mode.
The CPCS, under conditions whereby both
ADC’s fail to provide valid input to the cabin
pressure controller, enters the manual mode au-
tomatically. When this occurs, crew selection
is unnecessary and the ON caption illuminates
automatically to indicate the system has re-
verted to manual mode.
EMERGENCY
DEPRESSURIZATION SWITCH
The EMER DEPRESS switch, located on the
pressurization control panel, is guarded with
a hinged cover. Lifting the cover and de-
pressing the switch causes the airplane cabin
to rapidly depressurize to a maximum alti-
tude of 13,700 feet.
The cabin pressure controller drives both out-
flow valves to the full open position. The
cabin altitude climbs at a rapid rate until the
airplane is unpressurized or the cabin reaches
13,700 feet, whichever comes first. If the
cabin altitude reaches 13,700 feet, altitude
limiters on each outflow valve cause the valves
to move towards a closed position, keeping the
cabin from climbing higher. Depressing the
EMER DEPRESS switch a second time re-
turns the system to the previous mode, auto-
matic or manual, and the ON caption within
the switch is extinguished. When activated, a
white advisory CAS message, “EMER DE-
PRESS” is annunciated.
LANDING ALTITUDE
SELECTOR KNOB
The landing altitude selector knob is located
on the pressurization control panel (Figure
12-1) and is used to set the elevation of the des-
tination landing runway. Labeled LDG ALT,
with UP and DN arrows, and used only in the
automatic CPCS mode. When the LDG ALT
knob is rotated, “LA” and the presently set
landing altitude will appear on the LCD where
CAB ALT is normally displayed. “LA” and the
landing field altitude remain on the LCD dis-
play for 5 seconds after the switch was last ro-
tated. LDG ALT is also displayed on the ECS
system schematic display on the EICAS/MFD
(Figure 12-2).
The destination field elevation is normally se-
lected before takeoff and the crew should in-
sure that field elevation is set, not the field
pressure altitude. The CPCS automatically
compensates for non-standard field pressure
through ADC input to the cabin pressure con-
troller. The ADCs receive this information
when the crew enters the altimeter setting on
the primary flight display (PFD).
12-3
FOR TRAINING PURPOSES ONLY
LEARJET 45 PILOT TRAINING MANUAL
FlightSafety
international
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