 Fuel System Components  Engine and Gearbox  The Propeller The WSC aircraft is equipped with fuel tanks usually ranging  in capacity from 5 to 20 gallons. As with any aircraft,  knowing how much fuel the tank holds is crucial to fl ight  operations. The LSA definition has no limitations on the size  of the fuel tank, unlike its ultralight vehicle predecessor. Generally, the fuel tank is located close to the CG, so fuel  burn does not affect the balance of the carriage. Some fuel  tanks are clear for visual inspection of the amount of fuel  on board  [Figure 3-50],  while others have tanks that are not  visible and require fuel level probes for instrument panel  indication of fuel.  [Figure 3-51]  A fuel shut-off valve may be installed and can be located  anywhere in the fuel line. Some designs have a fuel tank sump  drain valve to remove water and solid contaminants.  The typical WSC aircraft engine can be two or four stroke,  liquid or air cooled, and normally ranges from 50 to 100  horsepower. Some engines have electric starters and some  have pull starters. Most WSC aircraft engines have reduction  drives that, when attached, reduce the propeller rpm from  ½ to  ¼  the engine rpm.  [Figure 3-52]  A significant amount of the total aircraft empty weight  is determined by the powerplant (engine, gearbox, and  propeller) and mounting configuration. When trailering  the WSC aircraft over bumpy terrain or over long trips,  the bouncing of the carriage in the trailer can put extreme  stress on this mounting system. In addition, repeated hard  landings of the carriage can also stress the welds of the engine  mount. Consistent detailed inspections of the engine mount  should be an important part of every preflight and postfl ight  inspection. The powerplant systems are as varied as the WSC aircraft  they power. Modern technology has allowed these systems  to become lighter, quieter, more efficient, and, most  importantly, dependable.  Fuel lines exit the fuel tank, and may incorporate a primer  bulb, fuel filters, fuel pump, and/or a primer system, all of  which must be integrated into the carriage. A fuel venting  system is also required, which can be a hole in the fuel fi ller  or lines running to vent at an appropriate location.  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 WSC aircraft forward.  Aerodynamically speaking, a propeller is a rotating airfoil  and the same principles that apply to the wing applies to the  propeller, except the propeller provides a horizontal force  of thrust.  Figure 3-51. Fuel fill to fuel tank under passengers seat. Figure 3-52. Engine gearbox. Figure 3-50. Fuel tank with visible fuel quantity. Visible Fuel Level Fuel Tank Engine Gearbox Fuel fill 3-20