The Magnetic Compass

Question 1

26.32.2 Distinguish between gravity­fed and pump­fed fuel systems.

Answer 1

gravity fed is when the sole reliance of the fuel being fed to the engine is through gravity. A pump

fed system is where a fuel pump is required to pump the fuel towards the engine and oppose

gravity.

Question 2

26.32.4 For a typical fuel system, explain the function, and where appropriate, the correct handling of the following: (a) fuel strainers and filters;

Answer 2

The fuel required by the engine is fed through a system of pipes or ‘lines’ from the tank to the carburetor or injection pump. These lines and the other system components are bonded together to avoid the build up of static electrical charge and the dangers of inherent in sparking occurring from that. On its way through the system, the fuel is strained, usually at three points. The first is at the tank outlet where straining is aimed at removing the major portions of any water or foreign matter which may be present in the tank. A second, and master, straining point will usually be situated at the lowest point in the system where another drain is also provided to enable checking and clearing of foreign matter. The third and final point will usually be located at the carburetor or fuel control unit. Here, fuel will be filtered through a fine gauze which, in some systems is suspended in a glass bowl which allows for a ready inspection for foreign matter to be made without dismantling.

Question 3

26.32.4 For a typical fuel system, explain the function, and where appropriate, the correct handling of the following: (b) engine­ driven fuel pump;

Answer 3

The engine ­driven mechanical fuel pump operates automatically and provides fuel under pressure to the carburetor whenever the engine is running.

Question 4

26.32.4 For a typical fuel system, explain the function, and where appropriate, the correct handling of the following: (c) boost (auxiliary) pump(s);

Answer 4

boost pumps are used to: ­provide fuel for starting at the required pressure to the carburetor or to the fuel metering unit of a fuel injection system. ­purge the fuel lines of any vapor to reduce the possibility of vapor lock ­prime the cylinders of fuel injected engines for start up
­supply fuel if the engine driven pump fails it is therefore used at all critical stages of flight

Question 5

26.32.4 For a typical fuel system, explain the function, and where appropriate, the correct handling of the following: (d) engine primers and priming systems.

Answer 5

priming fuel pumps it directly into the inlet manifold of one or more cylinders to help start the engine. The primer must be locked when the engine is running.