Fuel Metering Flashcards

1
Q

What are the most common types of fuel metering systems used on small reciprocating engines

A

Float-type, pressure, and direct fuel injection systems

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2
Q

What function does the mixture control perform

A

Controls the fuel/air mixture

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3
Q

What generally causes spark plug fouling

A

an excessively rich mixture at idle

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4
Q

What is the purpose of an accelerating system

A

It provides an increase in fuel flow in the Venturi to enrich the mixture

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5
Q

What is a carburetor economizer system

A

provides a richer mixture at high power settings

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6
Q

When the mixture is placed in the idle cutoff position, a slight rise in rpm is noted prior to the engine decelerating. What does this indicate

A

Idle mixture is set correctly

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7
Q

Why should engine r.p.m be accelerated periodically when making carburetor adjustments

A

To clear the engine

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8
Q

What maintains the fuel pressure injection carburetor

A

Engine driven fuel pump

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9
Q

What purpose do turbine engine fuel control units serve

A

They automatically meter fuel to the engine

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10
Q

What are the two basic types of turbine engine fuel control units

A

Hydromechanical and electronic

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11
Q

What do turbine engine fuel spray nozzles do

A

They inject fuel into the combustion area

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12
Q

What are the different engine indications used for trimming a turbine engine

A

Either EPR or r.p.m is used depending on engine

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13
Q

What type of pump can very the amount of fuel discharged regardless of speed

A

A variable displacement pump

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14
Q

What is used to keep water, sediment, and foreign matter out of the carburetor

A

Main fuel strainer

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15
Q

What type of engine driven fuel pump is widely used other than gear or piston pumps

A

Rotary vane type

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16
Q

What is the purpose of a pressure relief valve in a constant displacement pump

A

It returns left over fuel that is not used by the engine to the inlet side of the pump

17
Q

What function do fuel boost pumps perform

A

Supples pressurized fuel to the fuel pump, which helps prevent vapor lock and cavitation

18
Q

What is a commonly used type of fuel boost pump

A

Centrifugal type

19
Q

Name two categories of turbine engine pumps

A

Constant and variable displacement

20
Q

What category is a gear type pump classified in

A

Constant displacement

21
Q

When performing an external inspection of an engine driven fuel pump, what should you look for

A

Leaks and security of mounting

22
Q

What is the purpose of a shear section of the driveshaft in a dual element constant displacement pump

A

If one Element seizes it allowing the other element to continue to operate

23
Q

What is the purpose of a duplex fuel nozzle

A

Discharges two different spray patterns

24
Q

What purpose do fuel selector valves serve

A

Allow tank and engine selection, and provide a means for shutting off fuel flow

25
What will be the result of using excessively rich idle mixtures
Cause carbon fouling of the spark plug
26
What position do you place the mixture control of a pressure injection carburetor to stop the engine
Idle cutoff position
27
What is the typical fuel pressure in a float type carburetor
3-5psi
28
What are three types of carburetor icing
Throttle, impact, and fuel evaporation icing
29
What are some of the sources used to heat the fuel in a turbine engine fuel system
Bleed air and engine lubricating oil