Fuel And Fuel Metering

Front 1

What are some of the sources used to heat the fuel in a turbine engine fuel system?

Back 1

Bleed air and engine lubricating oil.

Front 2

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

Back 2

Float type carburetors, pressure injection carburetors and direct fuel injection systems.

Front 3

What function does the mixture control perform?

Back 3

Controls the fuel/air mixture.

Front 4

What generally causes spark plug Fouling?

Back 4

Operating the engine with an excessively rich mixture at idle.

Front 5

What is the purpose of an accelerating system?

Back 5

It provides an immediate but brief increase in fuel flow in the Venturi to enrich the mixture.

Front 6

What is a carburetor economizer system?

Back 6

It is a power enrichment system that provides a richer mixture at high power settings, where the excess fuel aids in engine cooling. This system functions at throttle settings above cruise power settings.

Front 7

When the mixture is placed in the idle-cut off position, a slight rise in RPM is noted prior to the engine decelerating. What does this indicate?

Back 7

The idle mixture is set correctly.

Front 8

Why should engine RPM be accelerated periodically when making carburetor adjustments?

Back 8

To clear the engine.

Front 9

What maintains the fuel pressure in a pressure injection carburetor?

Back 9

And engine driven fuel pump.

Front 10

What happens if the manual mixture control of a pressure injection carburetor is moved to the idle cut off position?

Back 10

The engine stops

Front 11

How does an automatic mixture control (AMC) function?

Back 11

A sealed brass Bellows connected to the fuel metering system, expands and contracts with changes in pressure and temperature, adjusting the mixture accordingly.

Front 12

What are some of the advantages of fuel injection systems over carburetor systems?

Back 12

Less danger of induction icing, better acceleration, better fuel distribution, better fuel economy, reduced overheating of individual cylinders.

Front 13

What purpose do turbine engine fuel control units serve?

Back 13

They automatically meter fuel to the engine.

Front 14

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

Back 14

Hydro mechanical and electronic.

Front 15

What are the engine variables detected by the fuel control unit?

Back 15

Power lever position, engine RPM, compressor inlet temperature, compressor inlet pressure, compressor discharge pressure, burner pressure.

Front 16

What are the two major components of a supervisory electronics engine control?

Back 16

The electronic control unit (computer), and the Hydro mechanical fuel control.

Front 17

What are some of the advantages of a full authority digital engine control (FADEC) over a Hydro mechanical fuel control?

Back 17

Better fuel economy, improve starts, requires no engine trimming, provides engine limit protection, provides constant idle speed‘s regardless of atmospheric conditions or bleed air requirements, fully modulates the active clearance control, and allows more repeatable engine transients.

Front 18

What do turbine engine fuel spray nozzles do?

Back 18

They inject fuel into the combustion area.

Front 19

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

Back 19

Either EPR or RPM is used depending on the particular engine.

Front 20

What maintenance adjustments are normally allowed on an installed hydromechanical fuel control?

Back 20

Specific gravity for fuel, idle RPM, and maximum RPM (or maximum EPR).

Front 21

What type of pump can vary the amount of fuel discharged regardless of speed?

Back 21

A variable displacement pump.

Front 22

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

Back 22

The Main fuel strainer.

Front 23

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

Back 23

It returns excess fuel that is not required by the engine to the inlet side of the pump.

Front 24

What type of engine driven fuel pump is widely used other than gear or piston pump’s?

Back 24

A rotary vane type.

Front 25

What function do fuel boost pumps perform?

Back 25

They supply pressurized fuel to the fuel pump, which helps prevent vapor lock and cavitation.

Front 26

What is a commonly used type of fuel boost pump?

Back 26

The centrifugal type.

Front 27

What causes vapor lock and why is it of concern?

Back 27

Vapor lock is caused by insufficient fuel pressure, high fuel temperatures and excessive fuel turbulence, which may completely block any fuel flow resulting in engine failure.

Front 28

What function does the engine driven pump on a turbine engine perform?

Back 28

It provides a continuous supply of fuel at the proper pressure while the engine is running.

Front 29

Name the two categories of turbine engine pumps.

Back 29

Constant and variable displacement.

Front 30

Name the two categories of turbine engine pumps.

Back 30

Constant and variable displacement.

Front 31

What category is a gear type pump classified in?

Back 31

Constant displacement

Front 32

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

Back 32

Leaks and security of mounting.

Front 33

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

Back 33

Leaks and security of mounting.

Front 34

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

Back 34

If one element seizes, a portion of the driveshaft seizes, allowing the other element to continue to operate.

Front 35

Where in a turbine engine fuel system is ice formation likely to occur and how is it prevent it?

Back 35

The fuel filter is most susceptible to ice formation, so a fuel heater is used that consist of a heat exchanger using either engine oil or bleed air to warm the fuel.

Front 36

What is the purpose of a bypass valve in an engine fuel system micron filter?

Back 36

It is a safety feature that allows fuel to flow to the engine if the filter becomes blocked.

Front 37

What is the purpose of a duplex feel nozzle?

Back 37

A duplex Fuel noxxle discharges two different spray patterns. The spray pattern is wider during start up and acceleration and Narrows when engine speed increases above idle.

Front 38

What are the functions of the pressurizing and dump portions of a pressurizing and dump valve?

Back 38

The pressurizing portion provides primary and secondary fuel flow to dual-line duplex fuel nozzles, and the dump portion allows fuel to drain from the manifolds after engine shut down.

Front 39

What purpose do fuel selector valves serve?

Back 39

They allow tank and engine selection, and provide a means for shutting off fuel flow.

Front 40

A

Back 40

B