troller to operate the following:
• ECS PRSOV (energized to closed)
• HP SOV (energized to open)
• EMER PRESS valve (energized to open)
Electrical failure to either channel of the ECS
Controller will cause each of the above valves
on that side to go to the de-energized position.
With electrical failure to both channels of the
ECS Controller, only LP bleed-air will be
available for pressurization. In this case, HP
bleed-air will not be available for pressuriza-
tion and emergency pressurization will not be
available. If only one BLEED circuit breaker
opens or one essential bus fails, only the valves
on that side will be affected.
ECS PRESSURE REGULATOR
SHUTOFF VALVES (ECS PRSOV)
When the L and R BLEED switches are in the
ON position, the solenoid controlled ECS
PRSOVs are de-energized open (Figure 9-2).
These valves will normally remain open dur-
ing flight. Flight manual procedures call for
closing an ECS PRSOV only for certain mal-
functions, such as Engine Shutdown Inflight
or L/R Bleed Air Leak. When the L BLEED
or R BLEED is selected OFF, the corre-
sponding ECS PRSOV is energized closed,
the HP SOV is de-energized closed, and the
EMER PRESS valve is de-energized closed.
There are two cases where the ECS PRSOVs
are closed other than through the L and R
BLEED switches. The corresponding ECS
PRSOV is automatically energized closed by
the ECS Controller when an engine FIRE
PUSH switch/indicator is depressed and both
ECS PRSOVs are energized closed when emer-
gency pressurization is activated.
HP SHUTOFF VALVES (HP SOV)
The left and right HP SOVs are independently
controlled by the left and right channels of the
ECS controller (Figure 9-3). When the con-
troller determines the low pressure bleed-air
supply is not adequate, the HP SOVs are com-
manded open to replace the LP bleed-air.
Thrust lever position (angle) and airplane al-
titude are used by the ECS controller in de-
termining if the HP SOV should be closed or
open.
Also, each channel of the ECS Controller uses
input from a 130 psi pressure switch located
in the corresponding HP duct (Figure 9-3). If
the pressure switch in the HP duct detects
p r e s s u r e i n ex c e s s o f 1 3 0 p s i , t h e E C S
Controller will de-energize the HP SOV
solenoid causing the valve to close.
The HP SOVs are automatically de-energized
closed anytime the corresponding L or R
BLEED switch is OFF and anytime emergency
pressurization is activated on the corre-
sponding side. Loss of electrical power through
the L or R BLEED circuit breakers will also
cause the corresponding HP SOV to close.
9-4
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
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