Textron Cessna Grand Caravan Ex 208B Pilot's Operating Handbook And Faa Approved Airplane Flight Manual page 541

CESSNA SECTION 7
MODEL 208B 867 SHP AIRPLANE AND SYSTEMS DESCRIPTION
GARMIN G1000
FUEL SYSTEM
(Continued)
The reservoir is located at the low point in the fuel system which
maintains a head of fuel around the ejector boost pump and auxiliary
boost pump which are contained within the reservoir. This head of fuel
prevents pump cavitation in low-fuel quantity situations, especially
during in-flight maneuvering. Fuel in the reservoir is pumped by the
ejector boost pump or by the electric auxiliary boost pump to the
reservoir manifold assembly. The ejector boost pump, which is driven
by motive fuel flow from the fuel control unit, normally provides fuel flow
when the engine is operating. In the event of failure of the ejector boost
pump, the electric boost pump will automatically turn on, thereby
supplying fuel flow to the engine. The auxiliary boost pump is also used
to supply fuel flow during starting. Fuel in the reservoir manifold then
flows through a fuel/oil shutoff valve located on the aft side of the
firewall. This shutoff valve enables the pilot to cut off all fuel to the
engine.
After passing through the shutoff valve, fuel is routed through a fuel
filter located on the right side of the engine. The fuel filter incorporates
a bypass feature which allows fuel to bypass the filter in the event the
filter becomes blocked with foreign material. Fuel from the filter is then
routed through the oil-to-fuel heater to the engine-driven fuel pump
where fuel is delivered under pressure to the fuel control unit. The fuel
control unit meters the fuel and directs it to the flow divider which
distributes the fuel to dual manifolds and 14 fuel nozzles located in the
combustion chamber. For additional details concerning the flow of fuel
at the engine, refer to the Engine Fuel System paragraph in this
section.
Fuel rejected by the engine during shutdown drains into the ecology
tank located on the front left side of the firewall. This unused fuel is then
drawn back into the fuel system through an ejector pump that uses flow
from the motive flow line and when the motive flow shutoff valve is
reenergized.
Fuel system venting is essential to system operation. Complete
blockage of the vent system will result in decreased fuel flow and
eventual engine stoppage. Venting is accomplished by check valve
equipped vent lines, one from each fuel tank, which protrude from the
trailing edge of the wing at the wing tips. also the fuel reservoir is
vented to both wing tanks.
208BPHCUS-01 7-77
U.S.