Engine Fuel Systems Flashcards
What type of pump can vary the amount of fuel discharged regardless of speed?
A variable displacement pump.
What is used to keep water, sediment and foreign matter out of the carburator?
The main fuel strainer.
What is the purpose of a pressure relief valve in a constant displacement pump?
It returns excess fuel that is not required by the engine to the inlet side of the pump.
What type of engine-driven fuel pump is widely used other than gear or piston pumps?
A Rotary vane type.
What function do fuel boost pumps perform?
They supply pressurized fuel to the fuel pump, which helps prevent vapor lock and cavitation.
What is commonly used type of fuel boost pump?
The centrifugal type.
What causes vapor lock and why is it of concern?
Insufficient fuel pressure, high fuel temperatures and excessive fuel turbulence, which may completely block any fuel flow resulting in engine failure.
Why is vapor lock serious?
The fuel flow may be completely blocked.
What does the use of fuel boost pumps help prevent?
Cavitation and vapor lock.
What function does the engine-driven pump on a turbine engine perform?
It provides a continuous supply of fuel at the proper pressure while the engine is running.
Name the two categories of turbine engine pumps:
Constant and Variable displacement.
What category is a gear-type pump classified in?
Constant displacement.
When performing an external inspection of an engine-driven fuel pump, what should you look for?
Leaks and security of mounting.
What is the purpose of a shear section of the driveshaft in a dual element constant displacement pump?
If one fails the other continues working.
Where in a turbine engine fuel system is ice formation likely to occur and how is it prevented?
(1)Fuel filter is most susceptible to ice formation, (2) heat exchanger using either engine oil or bleed air to warm the fuel.
