Powerplant Systems & Components: Engine Fuel Systems 🔊 Flashcards
What is the purpose of filters in the fuel system?
To prevent foreign matter from entering the carburetor
Why do carburetors in aircraft have a mixture control?
Air density changes with altitude which affects the fuel-air mixture. Mixture controls provide a means to adjust for the correct mixture at different altitudes
What two items are adjusted when setting idling conditions on a float carburetor?
The throttle stop for idling RMP and the idle mixture through the idle needle valve
What is the purpose of fuel selector valves?
They provide a means of shutting off fuel flow, cross-feed for tank and engine selection and for fuel transfer
What should be looked for when inspecting an engine driven fuel pump?
Look for fuel leaks and security of mounting
What is the purpose of an engine driven fuel pump?
It always delivers a continuous supply of fuel at the proper pressure during engine operations
What type of fuel pump is generally used with large reciprocating engines?
A positive displacement rotary-vane type pump
What happens to excess fuel not required by the engine in a constant displacement pump?
The pressure relief valve opens and the fuel is routed back to the inlet side of the pump
What is the most common type of fuel boost pump?
The electrically driven centrifugal type pump
What are the functions of the boost pump?
First, the boost pumps supply fuel to the engine pump for starting. Then, they are used to maintain pressure in the fuel lines to prevent the fuel from boiling off at altitude. Finally, the act as a backup if the engine driven pump fails.
What is the purpose of the bypass valve in the engine driven fuel pump?
The bypass valve provides a path around the pump vanes for starting the engine and to allow fuel to bypass the pump in case of a pump failure
What is the purpose of using boost pumps in a fuel system?
Electric boost pumps are used to supply fuel to a pressure carburetor during engine starting and in case of engine driven pump failure. However, a main function of a boost pump is to keep the pressure on the suction side of the engine driven pump from becoming low enough to permit the fuel to boil when operating at high altitudes.
What are the three general causes of vapor lock?
Low fuel pressure, high fuel temperatures, and excessive fuel turbulence
Turbine engine fuel pumps may be divided into what two distinct system categories?
Constant displacement and variable displacement
What category is a turbine engine driven gear type pump?
Constant displacement
