Engine Fuel Systems

Question 1

1. During what period does the fuel pump bypass valve open and remain open?

a. When the fuel pump pressure is greater than the demand of the engine.
b. When the boost pump pressure is greater than the fuel pump pressure.
c. When the fuel pump output is greater than the demand of the carburetor.

Answer 1

b.

Question 2

2. Which of the following statements concerning a centrifugal-type fuel boost pump located in a fuel supply tank is NOT true?

a. Air and fuel vapors do not pass through a centrifugal-type pump.
b. Fuel can be drawn through the impeller section of the pump when it is not in operation.
c. The centrifugal-type pump is classified as a positive displacement pump.

Answer 2

c.

Question 3

3. Where is the engine fuel shutoff valve usually located?

a. Aft of the firewall.
b. Adjacent to the fuel pump.
c. Downstream of the engine-driven fuel pump.

Answer 3

a.

Question 4

4. Boost pumps in a fuel system

a. operate during takeoff only.
b. are primarily used for fuel transfer.
c. provide a positive flow of fuel to the engine pump.

Answer 4

c.

Question 5

6. What is the purpose of an engine-driven fuel pump bypass valve?

a. To divert the excess fuel back to the main tank.
b. To prevent a damaged or inoperative pump from blocking the fuel flow of another pump in series with it.
c. To divert the excess fuel from the pressure side of the pump to the inlet side of the pump.

Answer 5

b.

Question 6

7. Most large aircraft reciprocating engines are equipped with which of the following types of engine-driven fuel pumps?

a. Rotary-vane-type fuel pump.
b. Centrifugal-type fuel pump.
c. Gear-type fuel pump.

Answer 6

a.

Question 7

8. When an electric primer is used, fuel pressure is built up by the

a. internal pump in the primer solenoid.
b. suction at the main discharge nozzle.
c. booster pump.

Answer 7

c.

Question 8

9. The fuel pump relief valve directs excess fuel to the

a. fuel tank return line.
b. inlet side of the fuel pump.
c. inlet side of the fuel strainer.

Answer 8

b.

Question 9

10. Which type of pump is commonly used as a fuel pump on reciprocating engines?

a. Gear.
b. Impeller.
c. Vane.

Answer 9

c.

Question 10

11. The purpose of the diaphragm in most vane-type fuel pumps is to

a. maintain fuel pressure below atmospheric pressure.
b. equalize fuel pressure at all speeds.
c. compensate fuel pressures to altitude changes.

Answer 10

c.

Question 11

12. The primary condition(s) that allow(s) microorganisms to grow in the fuel in aircraft fuel tanks is (are)

a. warm temperatures and frequent fueling.
b. the presence of water.
c. the presence of dirt or other particulate contaminants.

Answer 11

b.

Question 12

13. It is desirable that fuel lines have a gentle slope upward or downward and not have sharp curves or sharp rises and/or falls in order to

a. prevent vapor lock.
b. prevent stagnation or ‘pooling’ of fuel in the fuel lines.
c. minimize the generation of static electricity by decreasing fluid friction the lines.

Answer 12

a.

Question 13

14. The fuel systems of aircraft certificated in the standard classification must include which of the following?

a. An engine-driven fuel pump and at least one auxiliary pump per engine.
b. A positive means of shutting off the fuel to all engines.
c. A reserve supply of fuel, available to the engine only after selection by the flightcrew, sufficient to operate the engines at least 30 minutes at METO power.

Answer 13

b.

Question 14

15. Where should the main fuel strainer be located in the aircraft fuel system?

a. Downstream from the wobble pump check valve.
b. At the lowest point in the fuel system.
c. At any point in the system lower than the carburetor strainer.

Answer 14

b.

Question 15

16. Where physical separation of the fuel lines from electrical wiring or conduit is impracticable, locate the fuel line

a. below the wiring and clamp the line securely to the airframe structure.
b. above the wiring and clamp the line securely to the airframe structure.
c. inboard of the wiring and clamp both securely to the airframe structure.

Answer 15

a.

Question 16

17. What is a characteristic of a centrifugal-type fuel boost pump?

a. It separates air and vapor from the fuel.
b. It has positive displacement.
c. It requires a relief valve.

Answer 16

a.

Question 17

18. The Federal Aviation Regulations require the fuel flow rate for gravity systems (main and reserve) to be

a. 125 percent of the takeoff fuel consumption of the engine.
b. 125 percent of the maximum, except takeoff, fuel consumption of the engine.
c. 150 percent of the takeoff fuel consumption of the engine.

Answer 17

c.

Question 18

19. Fuel boost pumps are operated

a. to provide a positive flow of fuel to the engine.
b. during takeoff only.
c. primarily for fuel transfer to another tank.

Answer 18

a.

Question 19

20. A pilot reports that the fuel pressure fluctuates and exceeds the upper limits whenever the throttle is advanced. The most likely cause of the trouble is

a. a ruptured fuel pump relief-valve diaphragm.
b. a sticking fuel pump relief valve.
c. an air leak at the fuel pump relief-valve body.

Answer 19

b.

Question 20

21. A fuel strainer or filter must be located between the

a. boost pump and tank outlet.
b. tank outlet and the fuel metering device.
c. boost pump and engine-driven fuel pump.

Answer 20

b.

Question 21

22. Fuel pump relief valves designed to compensate for atmospheric pressure variations are known as

a. compensated-flow valves.
b. pressurized-relief valves.
c. balanced-type relief valves.

Answer 21

c.

Question 22

23. Fuel lines are kept away from sources of heat, and sharp bends and steep rises are avoided to reduce the possibility of

a. liquid lock.
b. vapor lock.
c. positive lock.

Answer 22

b.

Question 23

24. Fuel crossfeed systems are used in aircraft to

a. purge the fuel tanks.
b. jettison fuel in an emergency.
c. maintain aircraft stability.

Answer 23

c.

Question 24

25. If an engine equipped with a float-type carburetor backfires or misses when the throttle is advanced, a likely cause is that the

a. float level is too high.
b. main air bleed is clogged.
c. accelerating pump is not operating properly.

Answer 24

c.

Question 25

26. A fuel pressure relief valve is required on

a. engine-driven diaphragm-type fuel pumps.
b. engine-driven vane-type fuel pumps.
c. centrifugal fuel boost pumps.

Answer 25

b.

Question 26

27. A rotary-vane pump is best described as a

a. positive-displacement pump.
b. variable-displacement pump.
c. boost pump.

Answer 26

a.

Question 27

28. Fuel pressure produced by the engine-driven fuel pump is adjusted by the

a. bypass valve adjusting screw.
b. relief valve adjusting screw.
c. engine-driven fuel pump adjusting screw.

Answer 27

b.

Question 28

29. Kerosene is used as a turbine engine fuel because

a. kerosene has very high volatility which aids in ignition and lubrication.
b. kerosene has more heat energy per gallon and lubricates fuel system components.
c. kerosene does not contain any water.

Answer 28

b.

Question 29

30. What are the principal advantages of the duplex fuel nozzle used in many turbine engines?

a. Restricts the amount of fuel flow to a level where more efficient and complete burning of the fuel is achieved.
b. Provides better atomization and uniform flow pattern.
c. Allows a wider range of fuels and filters to be used.

Answer 29

b.

Question 30

31. It is necessary to control acceleration and deceleration rates in turbine engines in order to

a. prevent blowout or die-out.
b. prevent overtemperature.
c. prevent friction between turbine wheels and the case due to expansion and contraction.

Answer 30

a.

Question 31

32. Which of the following turbine fuel filters has the greatest filtering action?

a. Micron.
b. Small wire mesh.
c. Stacked charcoal.

Answer 31

a.

Question 32

33. What is the purpose of the flow divider in a turbine engine duplex fuel nozzle?

a. Allows an alternate flow of fuel if the primary flow clogs or is restricted.
b. Creates the primary and secondary fuel supplies.
c. Provides a flow path for bleed air which aids in the atomization of fuel.

Answer 32

b.

Question 33

34. What causes the fuel divider valve to open in a turbine engine duplex fuel nozzle?

a. Fuel pressure.
b. Bleed air after the engine reaches idle RPM.
c. An electrically operated solenoid.

Answer 33

a.

Question 34

35. How often should float carburetors be overhauled?

a. At engine overhaul.
b. Annually.
c. At engine change.

Answer 34

a.

Question 35

36. What is the final authority for the details of carburetor overhaul?

a. The local FAA safety inspector.
b. The Type Certificate Data Sheets for the engine.
c. The manufacturer’s recommendations.

Answer 35

c.

Question 36

37. Excessively rich or lean idle mixtures result in

a. too rapid completion of combustion.
b. incomplete combustion.
c. incomplete cylinder scavenging.

Answer 36

b.

Question 37

38. Which statement is true regarding proper throttle rigging of an airplane?

a. The throttle stop on the carburetor must be contacted before the stop in the cockpit.
b. The stop in the cockpit must be contacted before the stop on the carburetor.
c. The throttle control is properly adjusted when neither stop makes contact.

Answer 37

a.

Question 38

39. What precaution should be taken when putting thread lubricant on a tapered pipe plug in a carburetor float bowl?

a. Put the thread lubricant only on the first thread.
b. Do not use thread lubricant on any carburetor fitting.
c. Engage the first thread of the plug, then put a small amount of lubricant on the second thread and screw the plug in.

Answer 38

c.

Question 39

40. Maximum power is normally considered to be developed in a reciprocating engine with a fuel/air mixture ratio of approximately

a. 8:1
b. 12:1
c. 15:1

Answer 39

b.