raised to depress the switch. The covers pre-
clude accidental activation of the switches.
Whenever a main shutoff valve is closed, the
CAS presents a white advisory message, “L or
R FWSOV CLSD” on the EICAS display. The
white CLOSED caption will also illuminate on
the fire pushbutton switch when the switch is
depressed. If the valve fails to open/close fully
within 1.5 seconds after being selected the
CAS will display an amber caution message,
“L or R FWSOV FAULT.”
In addition to providing a means of control-
ling the shutoff valves, the switches also serve
as an indicator for engine fire or high tem-
perature in the engine nacelle area. If an en-
gine fire or high temperature occurs, the red,
FIRE PUSH annunciation on the correspond-
ing switch will illuminate. The engine fire
procedure includes depressing the FIRE PUSH
switch. This action closes the main fuel shut-
off valve, the CAS then presents the “L or R
FWSOV CLSD” message and the CLOSED
annunciator illuminates in the upper half of the
FIRE PUSH switch. Activation of the switch
also arms the fire extinguisher system and
performs some additional functions.
The main fuel shutoff valves are powered by the
left and right emergency hot busses through
the L and R FIRE FWSOV circuit breakers in
the ENGINE group on the left and right circuit
breaker panels respectively. The valves are DC
powered and will remain in their last position
should DC power fail.
FUEL LOW-PRESSURE
SWITCHES
The fuel low pressure switch is located in the
engine feed line upstream of the engine driven
pump and actuates when the pressure in the en-
gine feed line drops below 1 psig. The warn-
ing for low fuel pressure is provided through
a L/R FUEL PRESS LOW annunciator on the
crew warning panel (CWP) and through a red,
“L/R FUEL PRESS LOW” message on the
CAS. The CWP warning light extinguishes
and the CAS message is removed once pres-
sure is restored.
Illumination of the L or R FUEL PRESS LOW
warning is an indication of loss of fuel pres-
sure to an engine. The Aircraft Flight Manual
(AFM) procedure for a FUEL PRESS LOW
light includes turning on the standby pump on
the affected side to restore fuel pressure. But,
if fuel pressure cannot be restored, the en-
gine-driven pump is capable of suction-feed-
ing under most operating conditions.
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
5-15
FOR TRAINING PURPOSES ONLY
HIGH PRESSURE
LOW PRESSURE
STORAGE
LEGEND
150-420 psi
10-20 psi
Figure 5-9. Jet Pump Schematic