Fuel System - Cirrus DESIGN SR20 Information Manual

Cirrus Design Section 7
SR20 Airplane Description

Fuel System

A 56-gallon usable wet-wing fuel storage system provides fuel for
engine operation. The system consists of a 30.3-gallon capacity (28-
gallon usable) vented integral fuel tank in each wing, 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. An access panel in the lower surface of
each wing provides access to the associated wet compartment (tank)
for general inspection and maintenance. Float-type fuel quantity
sensors in each wing tank provide 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 check valve to the associated collector
tank/sump 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
proportioned to the induction airflow, metered to a flow divider, and
delivered to the individual cylinders. Excess fuel is returned to the
selected tank.
Fuel quantity indicators for each tank are 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.
P/N 13999-002 Info Manual 7-41
September 2011