Cirrus SR22 Pilot Operating Handbook page 468

Section 9 Cirrus Design
Supplements SR22
Fuel System
An 92-gallon usable wet-wing fuel storage system provides fuel for
engine operation. The system consists of a 47.25-gallon capacity (46-
gallon usable) vented integral fuel tank and a fuel collector/sump in
each wing, a three position selector valve, an electric boost pump, and
an engine-driven fuel pump. Fuel is gravity fed from each tank to the
associated collector sumps where the engine-driven fuel pump draws
fuel through a filter and selector valve to pressure feed the engine fuel
injection system. The electric boost pump is provided for engine
priming and vapor suppression. Each integral wing fuel tank has a filler
cap in the upper surface of each wing for fuel servicing. Access panels
in the lower surface of each wing allow access to the associated wet
compartment (tank) for inspection and maintenance. Float-type fuel
quantity sensors in each wing tank supply fuel level information to the
fuel quantity indicators. Positive pressure in the tank is maintained
through a vent line from each wing tank. Fuel, from each wing tank,
gravity feeds through strainers and a flapper valve to the associated
collector tank in each wing. Each collector tank/sump incorporates a
flush mounted fuel drain and a vent to the associated fuel tank. The
engine-driven fuel pump pulls filtered fuel from the two collector tanks
through a three-position (LEFT-RIGHT-OFF) selector valve.
The selector valve allows tank selection. From the fuel pump, the fuel
is metered to a flow divider, and delivered to the individual cylinders.
Excess fuel is returned to the selected tank. A dual-reading fuel-
quantity indicator is located in the center console next to the fuel
selector in plain view of the pilot. Fuel shutoff and tank selection is
positioned nearby for easy access. Fuel system venting is essential to
system operation. Blockage of the system will result in decreasing fuel
flow and eventual engine fuel starvation and stoppage. Venting is
accomplished independently from each tank by a vent line leading to a
NACA-type vent mounted in an access panel underneath the wing
near each wing tip. The airplane may be serviced to a reduced
capacity to permit heavier cabin loadings. This is accomplished by
filling each tank to a tab visible below the fuel filler, giving a reduced
fuel load of 30.0 gallons usable in each tank (60 gallons total usable in
all flight conditions). Drain valves at the system low points allow
draining the system for maintenance and for examination of fuel in the
system for contamination and grade. The fuel must be sampled prior
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Revision 03: 05-09-11