Engine fuel systems

Question 1

What is the purpose of strainers in a fuel system

Answer 1

They are used to prevent foreign matter from entering the carburetor

Question 2

Why do you carburetors in aircraft have a mixture control

Answer 2

The mixture control provides a means to adjust for the correct mixture at different altitudes

Question 3

What two items are adjusted when setting idling conditions on a float carburetor

Answer 3

The throttle stop for idling RPMs, and the idle mixture through the idle needle valve

Question 4

What is the purpose of fuel selector valves

Answer 4

They provide a means of shutting off fuel flow, cross feed For tank and engine selection and for fuel transfer

Question 5

What should be looked for when inspecting an engine driven fuel pump

Answer 5

Look for fuel leaks and security of mounting

Question 6

What is the purpose of an engine driven fuel pump

Answer 6

Delivers a continuous supply a fuel at the proper pressure at all times during engine operation

Question 7

What type of fuel pump is generally used with large reciprocating engines

Answer 7

A positive displacement rotary vein type pump

Question 8

What happens to the excess fuel not required by the engine in a constant displacement pump

Answer 8

The pressure relief valve opens in a fuel is routed back to the inlet side of the pump

Question 9

What is the most common type of fuel booster pump

Answer 9

The electrically driven centrifugal type pump

Question 10

What are the functions of the boost pump

Answer 10

During starting the boost pump supplies fuel to the engine pump for starting. They are also used to maintain pressure in the fuel lines to prevent the fuel from boiling off at altitudes finally boost pumps act as a back up in the event that the engine driven pump fails

Question 11

What is the purpose of the bypass valve in the engine driven fuel pump

Answer 11

The bypass valve provides a path around the pump veins for starting the engine, and to allow fuel to bypass the pump in case of pump failure

Question 12

What is the purpose of using booster pumps in a fuel system

Answer 12

Supply fuel to a pressure carburetor during engine starting and in case of engine driven pump failure. However, the main function of a Bruce pump is to keep the pressure on the suction side of the engine driven pump from becoming low enough to permit to fuel to boil when operating at a high altitudes

Question 13

What are the three general causes of vapor lock

Answer 13

Low fuel pressure, high fuel temperatures, and excessive fuel turbulence

Question 14

Turbine engine fuel pumps may be divided into what two distinct system cartridges

Answer 14

Constant displacement and variable displacement

Question 15

What category is a turbine engine driven gear type pump

Answer 15

Constant displacement

Question 16

What type of fuel pump can be made to vary the fuel flow at any speed

Answer 16

A variable displacement pump

Question 17

What part of a gas turbine engine fuel system is very susceptible to the formation of ice

Answer 17

The fuel filter

Question 18

How is the engine fuel system protected from ice formation

Answer 18

By the use of fuel heaters

Question 19

Why is a micron fuel filter provided with a bypass valve as a necessary safety factor

Answer 19

Because the small openings in this type of filter make it very susceptible to clogging

Question 20

Where are fuel filter is located

Answer 20

They are located at the fuel pump, in line with the system “last chance” filter screens are located in the fuel controls

Question 21

Can you use automotive gasoline in a reciprocating engine in place of avgas

Answer 21

Yes if you have a STC