Fuel Metering System

Question 1

1. Where are the fuel spray nozzles located in a turbine engine?

Answer 1

Externally or internal of combustion section chamber

Question 2

2. Name the heat sources of the operation of fuel heaters used in turbine engines.

Answer 2

Heat exchangers
Route lines through oil or bleed air to heat

Question 3

3. What engine variables are sensed by a hydro mechanical fuel control?

Answer 3

power lever position
RPM
EGT or TIT
Compressor inlet pressure temperature
Burner pressure
Compressor discharge pressure

Question 4

4. What are the two most commonly used carburetors in small reciprocating engines?

Answer 4

Float type & pressure type

Question 5

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

Answer 5

Hydro mechanical & electronic fuel control

Question 6

6. What is meant but trimming a turbine engine?

Answer 6

Adjusting fuel control

Question 7

7. When should a turbine engine be trimmed?

Answer 7

Loss of power or manufacture specifies

Question 8

8. What specifications are used to trim a turbine engine?

Answer 8

Date plate on engine

Question 9

9. What are two types of electronic fuel controls for turbine engines?

Answer 9

Supervisory ECC
FADEC

Question 10

10. What is FADEC?

Answer 10

High precision digital electronic fuel control

Question 11

11. Does a turbine engine controlled by a FADEC require manual trimming?

Answer 11

No

Question 12

12. What is the purpose of a mixture control in a float type carburetor?

Answer 12

Controls air-fuel mixture

Question 13

13. What is the purpose of an accelerating system on a float type carburetor?

Answer 13

When throttle open rapidly, accelerator pump adds fuel to compensate

Question 14

14. Describe the purpose and operation of a Venturi.

Answer 14

Increases speed decreases pressure

Question 15

15. What is the function of a metering jet?

Answer 15

Limits flow when throttle wide open

Question 16

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

Answer 16

Difference in pressure between float and discharge nozzle

Question 17

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

Answer 17

Carbon fouling of spark plug

Question 18

18. What is the purpose of the economize system in a float type carburetor?

Answer 18

Provides extra fuel for cooling the engine at high power settings

Question 19

19. Where does a pressure injection carburetor obtain fuel pressure?

Answer 19

Boost pump for starting
Engine driven pump for normal operation

Question 20

20. What operates an automatic mixture control on a pressure carburetor?

Answer 20

Sealed bellows expand & contract at different altitudes moving a needle within the carburetor

Question 21

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

Answer 21

Idle cut off position

Question 22

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

Answer 22

Slight increase in RPM followed by rpm to zero

Question 23

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

Answer 23

Soften diaphragms and make them pliable

Question 24

24. What are three types of carburetor icing?

Answer 24

Throttle icing
Impact icing
Evaporation icing

Question 25

25. What is the typical fuel pressure in a float type carburetor?

Answer 25

3-5 PSI