Engine Fuel And Fuel Metering System

Question 1

Gasoline and other liquid fuels do not burnt at all, unless they are mix with what other elements 

Answer 1

Mix with air

Question 2

Where are the fuel spray nozzle located in a turbine engine?

Answer 2

Either externally or internally on the combustion chamber in such a way that fuel can be sprayed into the combustion area

Question 3

name the heat sources for operation of fuel heaters used in turbine engines

Answer 3

Bleeder as air to liquid heat exchanger, engine lubricating oil as liquid to liquid heat exchanger

Question 4

What engine variables are sensed by Hydro mechanical fuel control

Answer 4

Power lever position, rpm, compressor inlet pressure temperature, burner pressure or compressor Discharge pressure and EGT or TIT

Question 5

In an electrical fuel control system,what are the two import components

Answer 5

Electrical and fuel

Question 6

What are the two most commonly used carburetor in a small reciprocating engine?

Answer 6

Float type and pressure type

Question 7

What type of fuel control unit is used in a turbine engine

Answer 7

Both Hydro mechanical and electronic fuel control. Most common unit control is the Hydro mechanical type.

Question 8

What is meant by trimming a turbine engine?

Answer 8

 adjusting fuel control for proper specific gravity of the fuel and for proper idle and full throttle rpm

Question 9

When should a turbine engine be trimmed?

Answer 9

When there is a loss of engine, power or manufacturer specified

Question 10

What specification are used to trim a turbine engine

Answer 10

 Data plate on engine typically contains trimming specification

Question 11

What are the three type of fuel controls for turbine engines?

Answer 11

Supervisory EEC (electronic engine control) ,FADEC and mechanical

Question 12

What is FADEC

Answer 12

full authority digital electronic control is high precision digital electronic fuel control that use electronic engine control and a flight management computer to measure the fuel nozzle that prevent over temperature and over speed conditions. It also sends information to the education system for the aircraft crew.

Question 13

Does an engine control by FADEC required manual trimming

Answer 13

 No, it is self-trimming

Question 14

What is the purpose of a mixer control in a float type carburetor?

Answer 14

Controls the fuel air mixture as air density change with altitude change

Question 15

What is the purpose of an accelerating system on a flow type carburetor

Answer 15

When the throttle is open rapidly, the fuel air mixture will lean out momentarily, to overcome tendency a charge of fuel from the accelerating pump will temporarily enrich the mixture in the Venturi

Question 16

Describe the purpose and operation of Venturi

Answer 16

Is an example of Bernoulli principle as the velocity of a gas or liquid increases, the pressure decrease. Venturi performs three function. 1-proportion to fuel air mixture .
2-lower the pressure at discharge nozzle.
3-and limit the airflow at full throttle. The carburetor depends on differential between the atmospheric pressure, and decreased pressure offered by Venturi

Question 17

What is the function of a metering jet

Answer 17

To limit the fuel flow when the throttle valve is wide open

Question 18

What is the fuel metering force in a float type carburetor?

Answer 18

The differential pressure between the pressure in a flow chamber and at the nozzle

Question 19

What will be the result of using excessively rich idle mixtures?

Answer 19

Carbon fouling of spark plug

Question 20

What is the purpose of economizer system in float type carburetor

Answer 20

Valve, which is closed at throttle setting below 60% to 70% rate power, by provide additional fuel for engine cooling to prevent detonation a higher throttle setting above 60%to 70%

Question 21

Where does the pressure injection carburetor obtain fuel pressure

Answer 21

Form boost pump for starting and engine driven pump during normal operation

Question 22

What operates an automatic mixture control on a pressure carburetor

Answer 22

Seal bellows that expand or contract with changes in atmospheric pressure. The movement of the Bellow operate a Tapered needle that controls the impact air pressure into A chamber of carburetor

Question 23

In what position do you place the mixture control of a pressure injection carburetor to stop engine ?

Answer 23

Idle cutoff position

Question 24

What rpm indication should result when the mixture control is placed in the idle cutoff position when the idle mixture is set correctly ?

Answer 24

Should be slight drop in rpm, follow by a rapid drop of rpm to zero

Question 25

What is the purpose of filling a pressure injection carburetor full of fuel and allowing it to soak for a period of about eight hours prior to installation

Answer 25

To soften the diaphragms and make them as pliable as they were when the carburetor was originally calibrated

Question 26

What are three type of carburetor icing

Answer 26

Throttle icing, impact icing and fuel evaporation icing

Question 27

What is the typical fuel pressure in a float type carburetor

Answer 27

3-5 psi

Question 28

Name some advantage of direct fuel injection system system over conventional carburetor system

Answer 28

Less danger of induction system icing , improve acceleration , improved fuel distribution, reduced overheating of individual cylinders, better fuel economy

Question 29

What is the purpose of filter in a fuel system

Answer 29

Prevent foreign matter from entering the carburetor

Question 30

Why do carburetor in aircraft have a mixture control

Answer 30

Air density changes with altitude, which affect the air fuel mixture. Mixture control provides a means to adjust for the correct mixture at different attitude

Question 31

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

Answer 31

Throttle stop for idle rpm and idle mixture though the idle needle valve

Question 32

What should be looked for when inspecting engine driven pump

Answer 32

Look for fuel leak and security of mounting

Question 33

What is the purpose of fuel selector valve?

Answer 33

Shutting off fuel flow, crossfeed for tank, engine selection, and for fuel transfer

Question 34

What is the purpose of an engine driven fuel pump?

Answer 34

Always deliver continuous supply of fuel add the proper pressure during engine operation

Question 35

What type of fuel pump is generally use with large reciprocating engine

Answer 35

Positive displacement, rotary vane type

Question 36

What are the function of the boost pump?

Answer 36

Supplies fuel to the engine pump for starting, maintain pressure in the fuel line to prevent fuel from boiling off at altitude and act as a back up if engine driven pump fails

Question 37

What are the three general causes of vapor lock?

Answer 37

Low fuel pressure, high fuel temperatures, excessive fuel turbulence

Question 38

Turbine engine fuel pumps may be divided into two distinct system categories

Answer 38

Constant displacement and variable displacement

Question 39

What category is a turbine engine driven gear type pump?

Answer 39

Constant displacement

Question 40

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

Answer 40

Variable displacement pump

Question 41

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

Answer 41

Fuel filter

Question 42

How is the engine fuel system protected from ice formation?

Answer 42

Use fuel heaters

Question 43

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

Answer 43

Small opening in this type of filter makes it very easy to clogging

Question 44

Where are the fuel filter located?

Answer 44

At the fuel pump in line with the system. Last chance filter screens are in the fuel control

Question 45

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

Answer 45

Yes, if you have a STC

Question 46

What is the purpose of pressurizing portion of a pressurizing and dump valve?

Answer 46

To provide primary and secondary fuel flow to dual line duplex fuel nozzle

Question 47

What is the divided fuel flow of a turbine engine duplex fuel nozzle produce in the fuel

Answer 47

Two spray pattern