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EMERGENCY
PRESSURIZATION
General
The emergency pressurization system pro-
vides an alternate system of providing cabin
pressurization in the event of an emergency in-
volving the loss of cabin pressure.
The system consists of ducting for LP bleed-
air from the engines to the cabin, two emer-
gency pressurization valves, two check valves
a n d a n E M E R P R E S S s w i t c h o n t h e
Pressurization control panel.
When activated, the system diverts LP bleed-
air directly into the cabin, bypassing the ECU
and normal LP/HP ducting in the tailcone
(Figure 9-5). The system can be activated au-
tomatically by the Cabin Pressure Controller
(CPC) or manually by depressing the EMER
PRESS switch/indicator on the Pressurization
control panel.
EMER PRESS Switch
The EMER PRESS switch/indicator (S/I) is
located above the L and R BLEED switches on
the Pressurization control panel (Figure 9-1).
It has a hinged, clear plastic guard with a red
border covering the switch to prevent inad-
vertent activation. Lifting the guard and de-
pressing the EMER PRESS switch causes the
“ON” to illuminate within the S/I and signals
both channels of the ECS Controller to acti-
vate emergency pressurization on both sides.
If emergency pressurization is activated by
the CPC, the “ON” legend will also illuminate.
The L and R BLEED switches must both be on
for emergency pressurization to activate on
both sides. Emergency pressurization can be
selectively turned off on the left or right side
by turning OFF the L or R BLEED switches.
EMER PRESS Operation
The emergency pressurization valves (labeled
EMER PRESS VALVE in Figure 9-5) are lo-
cated in the tailcone and are normally closed.
The valves are energized open when emer-
gency pressurization is activated. At the same
time, the ECS PRSOVs are energized closed
and the HP SOVs are de-energized closed.
These valves are all controlled by the ECS
Controller.
When emergency pressurization is activated,
either manually or automatically, the “ON”
legend illuminates in the EMER PRESS switch
and an amber “LR EMER PRESS ON” mes-
sage is posted on the CAS (Table 9-2 and
Figure 9-6).
NOTE
Emergency pressurization cannot be
activated on a particular side if the
BLEED switch is in the OFF position
or electrical power is not available.
Emergency pressurization can be automati-
cally activated by either channel of the CPC.
The CPC will activate emergency pressuriza-
tion at a cabin altitude of 9,500' or 14,500' de-
p e n d i n g o n C P C m o d e . E m e r g e n c y
pressurization will normally be activated at
9,500'; however when the following four con-
ditions exist, emergency pressurization will not
automatically activate until the cabin reaches
14,500':
• Cabin controller is in the automatic
mode, and
• Pressurization controller set to a land-
ing field elevation above 8,000' and
• Airplane has descended at least 1,000'
from cruise altitude, and
• Airplane is below 24,500'.
With the ECS PRSOVs closed, and the emer-
gency pressurization valves open, low pressure
9-11
FOR TRAINING PURPOSES ONLY
L E A R J E T 4 5
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