SECTION 7
CESSNA
AIRPLANE AND SYSTEMS DESCRIPTION
MODEL 172S NAV III
ENGINE
(Continued)
FUEL INJECTION SYSTEM
The engine is equipped with a fuel injection system. The system is
comprised of an engine-driven fuel pump, fuel/air control unit, fuel
manifold, fuel flow indicator, and air-bleed type injector nozzles.
Fuel is delivered by the engine-driven fuel pump to the fuel/air
control unit. The fuel/air control unit correctly proportions the fuel
flow to the induction air flow. After passing through the control unit,
induction air is delivered to the cylinders through the intake manifold
tubes and metered fuel is delivered to a fuel manifold (flow divider).
The fuel manifold, through spring tension on a diaphragm and
valve, evenly distributes the fuel to an air-bleed type injector nozzle
in the intake valve chamber of each cylinder. A turbine-type fuel
flow transducer mounted between the fuel/air control unit and the
fuel distribution unit produces a digital signal that displays fuel flow
on the EIS pages.
COOLING SYSTEM
Ram air for engine cooling enters through two intake openings in
the front of the engine cowling. The cooling air is directed around
the cylinders and other areas of the engine by baffling, and is then
exhausted through an opening at the bottom aft edge of the cowling.
No manual cowl flap cooling system control is required.
PROPELLER
The airplane is equipped with a two bladed, fixed pitch, one-piece
forged aluminum alloy propeller which is anodized to retard
corrosion. The propeller is 76 inches in diameter.
FUEL SYSTEM
The airplane fuel system (see Figure 7-6) consists of two vented
integral fuel tanks (one tank in each wing), a three-position selector
valve, auxiliary fuel pump, fuel shutoff valve, fuel strainer, engine
driven fuel pump, fuel/air control unit, fuel distribution valve and fuel
injection nozzles.
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7-36 U.S.
172SPHAUS-03