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the crew with the Master Caution light and an
amber “FUEL XFLO” message (Table 5-1).
The crossflow valve is powered by the rear hot
bus and/or the right essential bus through the
“XFLOW VALVE CTRL” circuit breaker lo-
cated in the FUEL group of circuit breakers on
the copilot's circuit breaker panel. The crossflow
valve is a DC electrical motor-driven valve;
therefore, if electrical power is lost to the valve,
it will fail in the position it was last in.
STANDBY PUMPS
The standby pumps are located at the low point
next to the main jet pumps in each wing col-
lector tank area (Figure 5-1). The standby
pumps are used:
• For engine start (automatically energized
ON with starter switch activation).
• As a backup for the main jet pumps.
• For wing-to-wing fuel transfer.
• For defueling.
• APU operation (right pump).
The standby pumps can be activated by de-
pressing the L STBY and R STBY switches on
the fuel control panel (Figure 5-8). The cor-
responding standby pump operates automat-
ically during engine start. Whenever power is
applied to the standby pumps, whether it is
turned on by crew action or if it is automati-
cally activated, a white advisory message (“L
or R STBY PUMP ON”) is presented by the
CAS. The “ON” caption within the standby
pump switch also illuminates. In the event ei-
ther standby pump continues to run after being
selected to off, the “ON” caption will remain
illuminated in the S/I, and the “L or R STBY
PUMP ON” CAS will remain illuminated. The
AFM
provides an abnormal procedure for this
event.
Each standby pump has an associated STBY
PUMP PWR and STBY PUMP CTRL circuit
breaker located in the FUEL group of circuit
breakers on each circuit breaker panel.
The standby pumps are powered from the re-
spective L/R essential buses. The essential
buses remain powered by the aircraft batter-
ies in the event of the loss of both aircraft
generators.
FUSELAGE TRANSFER LINES
Two, 2 inch transfer lines (one on each side)
connect the fuselage fuel tank and the wing
tanks (Figure 5-1). Anytime there is fuel in the
fuselage tank, it automatically flows into the
wing tanks to replenish fuel that has been
used.
A check valve and a series of baffled flap
valves are installed in each transfer line to
prevent inadvertent back-flow of fuel from
the wing tanks into the fuselage tank during
nose high pitch attitude. A transfer jet pump
is located in each fuselage tank transfer line,
outboard of the collector tanks.
The engine driven motive flow pumps route
fuel under pressure to the jet pumps. Motive
flow through the jet pumps draws fuel through
the transfer lines from the fuselage tank when
the engines are running. There are no motor
driven valves in these lines and there are no
motor driven pumps in the fuselage tank. Also,
fuel cannot be transferred from the wing tanks
to the fuselage tank through the fuselage trans-
fer lines.
ENGINE FUEL SUPPLY
SYSTEM
GENERAL
Each engine (Figure 5-8) is automatically pro-
vided with fuel from the respective wing tank.
The standby pump automatically supplies pres-
surized wing fuel to the engine for starting and
the main jet pump provides pressurized wing
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
5-12
FOR TRAINING PURPOSES ONLY
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