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AUTOMATIC MODE
The airplane pressurization system powers up
in the automatic mode and requires no fur-
ther crew action after the following require-
ments are met:
• Electrical power applied
• MANUAL PRESS not selected
• Landing elevation selected
When the PACK switch is selected ON before
takeoff and the thrust levers are still below
MCR, the cabin pressure controller is in the
ground mode (Figure 12-6). The controller
will drive the outflow valves full open. The
CPCS remains in the ground mode until any
of the following occurs:
• Left throttle advanced to MCR or higher.
• WOW switch indicates airborne.
• Airspeed is greater than 90 knots.
When the left thrust lever is advanced past
MCR for takeoff, the system enters the take-
off pre-pressurization mode (Figure 12-6).
The controller begins rating the cabin down
150 (+50) feet, at 600 fpm. This pre-pressur-
ization reduces any pressure transients during
rotation.
If the thrust levers are retarded below MCR
prior to lift-off, as in an aborted takeoff, the
cabin controller enters the takeoff abort mode
(Figure 12-6). In this mode, cabin altitude is
rated back to the takeoff field elevation at a rate
of 500 fpm for 20 seconds, after which the sys-
tem re-enters the ground mode.
When the airplane becomes airborne, the sys-
tem enters the climb pressurization mode
(Figure 12-7).
For normal takeoff procedures, the cabin pres-
sure control system transfers directly from
the takeoff mode to the climb mode. This trans-
fer is initiated when the CPCS receives an air-
borne signal from the squat switches, or
airspeed exceeds 90 knots. During the climb
mode, a schedule of cabin altitude versus air-
plane altitude is calculated based upon the
12-14
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
(20 SECONDS)
GROUND
MODE
TAKEOFF ABORT
MODE
TAKEOFF (PREPRESSURE)
MODE
GROUND
MODE
CABIN SEALED
AIRFLOW ON
0.10 psid max
THROTTLES
ADVANCED
RATE OF
600 fpm
(1,000 fpm MAX)
150 ft
500 fpm
THROTTLES
RETARDED
2,000 fpm
FIELD LEVEL
CABIN ALTITUDE
Figure 12-6. Controller — Takeoff Abort