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operating handbook for specific engine specifica - tions). 

Generally, the fuel tank is located close to the center of gravity, so fuel burn does not affect the balance of the aircraft. Some fuel tanks are clear for visual in - spection of the amount of fuel on board while others are dark. Dark tanks or hidden tanks generally have a sight tube to assist the pilot in determining the actual amount of fuel. [Figure 3-14] Some powered para - chute manufacturers offer optional fuel level probes and instrument panel analog gauges or incorporate this information into the EIS. As fuel is used by the engine, air needs to enter the tank and take its place; otherwise a vacuum will form inside the fuel tank preventing the fuel pump from drawing fuel. This is usually accomplished with a  fuel venting system. This can be a vent in the fuel cap or some other means that vents elsewhere, providing the ability for the fuel tank to breathe. Any vent system must be free of debris or it will cause fuel starvation in flight. This is especially true when a small hole is in the fuel cap that can be easily plugged. Check the fuel venting system during each preflight inspection. 

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The fuel shut-off valve can be located anywhere in the fuel line. It is important to make sure the fuel valve is open and stays open for normal operation. Most designs have a fuel tank sump drain valve to remove water and solid contaminants. Each design is differ- ent and the PPC POH will specify how to conduct this check. 

## Throttle System 

The throttle is the pilot’s hand control to regulate the power provided by the engine. The configuration of the throttle control varies from one cart manufacturer to another. Refer to the POH of each individual PPC for function reference. [Figure 3-15] 

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## The Powerplant 

The typical powered parachute engine can be two- or four-stroke, liquid- or air-cooled, 50 to 100 horsepow- er. Some engines have electric starters and some have pull starters. Most PPC engines have reduction drives that, when attached, reduce the propeller RPM to half to one quarter the engine RPM. [Figure 3-16] The en - gines are as varied as the powered parachutes they power. Modern technology has allowed the powered parachute engine to become lighter, more efficient and, most importantly, dependable. Chapter 4 covers the powerplant in more detail. 

## The Propeller 

Propellers are “power converters” that change the engine horsepower into “thrust.” Thrust is the force that propels the aircraft through the air by pushing the powered parachute forward. Aerodynamically speaking, a propeller is a rotating airfoil and the same principles that apply to the wing will apply to the pro- peller. [Figure 3-17] Engine power is transferred to the propeller through a rotating crankshaft that turns the propeller through the air, producing thrust in the same way as wings produce lift. The shape of the blade cre - ates thrust vectors because it is cambered like the air foil of a wing. Consequently, as the air flows past the propeller, the pressure on one side is less than that on the other. As in a wing, this produces a reaction force in the direction of the lower pressure. In the case of the propeller, which is mounted in a vertical plane, the 

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