Fuel Flow Indication; Fuel Caution Light; Boost Pump Switch - Cirrus DESIGN SR20 Information Manual

Section 7
Airplane Description
When the fuel tanks are 1/4 full or less, prolonged
uncoordinated flight such as slips or skids can uncover the
fuel tank outlets. Therefore, if operating with one fuel tank dry
or if operating on LEFT or RIGHT tank when 1/4 full or less, do
not allow the airplane to remain in uncoordinated flight for
periods in excess of 30 seconds.

Fuel Flow Indication

Fuel flow indication is integral to the combination Fuel Flow/Manifold
Pressure Gage. Refer to preceding discussion on Fuel Flow and
Manifold Pressure Gage for complete description of fuel flow
indication.

Fuel Caution Light

The amber FUEL caution light in the annunciator panel comes on to
indicate a low fuel condition. The light is illuminated by switches in the
fuel quantity gages if the fuel quantity in both tanks drops below
approximately 8.5 gallons (17 gallons total with tanks balanced in level
flight). Since both tanks must be below 8.5 gallons to illuminate the
light, the light could illuminate with as little as 8.5 gallons in one tank
during level flight if the other tank is allowed to run dry.
If the FUEL caution light comes on in flight, refer to the Fuel Quantity
gages to determine fuel quantity. The light is powered by 28 VDC
through the 2-amp ANNUNC circuit breaker on the Essential Bus.

Boost Pump Switch

Boost pump operation and engine prime is controlled through the Fuel
Pump BOOST-PRIME switch located adjacent to the fuel selector
valve. The PRIME position is momentary and the BOOST position is
selectable. A two-speed prime allows the fuel pressure to rapidly
achieve proper starting pressure.
Serials 1005 thru 1227 before SB 20-73-02: For engine starting,
pressing PRIME causes the boost pump to operate at high speed until
the fuel pressure reaches 2-4 psi. When the fuel pressure reaches the
2-4 psi range, a pressure switch in the fuel injection line switches the
boost pump to the low-speed mode to provide a 4-6 psi fuel pressure
boost. Selecting BOOST energizes the boost pump in low-speed
7-44
Cirrus Design
P/N 13999-002 Info Manual
September 2011
SR20