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• Precheck Valve
The automatic shutoff of SPPR, when the tanks
are full, relies on the interaction of the pilot
valve and refuel shutoff valve to stop the re-
fueling. Since this is a rather important func-
tion, a precheck of these valves should be
performed before single-point pressure refu-
eling is commenced.
The Aircraft Flight Manual SPPR servicing
procedure includes a precheck before single-
point refueling. The precheck valve is manu-
ally opened with a lever located on the SPPR
adapter panel (Figure 5-14). When refueling
is initiated with the precheck valve open, fuel
will flow through the refueling shutoff valve
into the fuselage tank and simultaneously
through the precheck valve to the pilot valve.
Fuel from the precheck valve flows into the
pilot valve faster than the float basin can drain,
causing the float in the pilot valve to shut off
vented fuel through the pilot line. Fuel pres-
sure will then increase on the back side of the
refueling shutoff valve and it will close. The
fuel flow should stop automatically within 20
seconds. If fuel flow does not stop within 20 sec-
onds, do not use the SPPR system to refuel the
aircraft.
When the precheck is satisfactorily completed,
the precheck valve can be closed. This will shut
off fuel to the pilot valve, the float basin will
drain and the pilot valve will open allowing the
shutoff valve to open and refueling to resume.
GRAVITY REFUELING
Refueling the aircraft can also be accom-
plished via gravity fill through the fuselage
filler port located beneath a hinged panel on
top of the fuselage (Figures 5-2 and 5-13).
The wing tanks will fill by gravity from the
fuselage tank through the transfer lines the
same as if SPPR were used, except without the
pressure assist from the SPPR.
If the wing tanks are already full, insert the
nozzle into the gravity refill receptacle and fill
the fuselage tank. If the wings are not full and
the objective is to attain a full fuel load, the
wing vent/expansion lines must first be
drained, then the procedure remains un-
changed.
DEFUELING
Defueling may be accomplished by attaching
a suction hose to the SPPR nozzle.
Suction defuel through the refueling adapter
is accomplished through use of the DEFUEL
switch located on the refuel/defuel panel on
the aft, right side of the tail section (Figure 5-
15). The defuel valve is controlled by first
turning the FUEL SYS switch to PWR ON
and then placing the DEFUEL switch to
READY. The amber READY light should il-
luminate indicating the crossflow valve and the
defuel valve have opened (Figure 5-16).
Suction at the refueling adapter will pull fuel
from both wing tanks through the right en-
gine fuel supply line and defuel valve. If the
defuel valve does not completely close after
defueling, the CAS will generate an amber
“DEFUEL OPEN” message.
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
5-22
FOR TRAINING PURPOSES ONLY
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