5 Induction Systems

Question 1

1. Name the 3 components on the induction system of a reciprocating engine.

Answer 1

The air scoop, carburetor or fuel control, and the intake mani.

Question 2

2. What could happen if the induction system becomes obstructed?

Answer 2

The engine may not be able to produce its rated power or it may not run at all. This may also be an indication of a dirty air inlet filter.

Question 3

3. How does induction icing affect engine performance?

Answer 3

It causes a reduction in power and possible erratic operation.

Question 4

4. How is induction icing categorized?

Answer 4

As impact ice, fuel evaporation ice, and throttle ice.

Question 5

5. What is the common method used to prevent induction system ice in a reciprocating engine?

Answer 5

Raise the temp of induction air with a preheater.

Question 6

6. What causes fuel evaporation ice?

Answer 6

Fuel evaporation ice is formed because of the decrease in air temp resulting from evaporation of the fuel after it is introduced into the air stream.

Question 7

7. Is carburetor throttle ice more likely to occur at a higher or lower power setting? Why?

Answer 7

Lower power setting because the throttle is partly closed, offering a larger surface area for ice accumulation.

Question 8

8. What may be the indication of leaking intake pipes?

Answer 8

The engine runs rough at low RPM.

Question 9

9. What happens to engine power when the carbon heat is applied?

Answer 9

There is a noticeable drop in power.

Question 10

10. What could happen if carb heat is applied at high engine power settings?

Answer 10

Detonation.

Question 11

11. What are 2 types of supercharged induction systems?

Answer 11

Internally driven and externally driven.

Question 12

12. How and at what point does an internally driven supercharger boost air pressure?

Answer 12

An engine driven impeller compresses the fuel/air mixture after it leaves the carburetor.

Question 13

13. What is used to power a turbo?

Answer 13

Engine exhaust gas directed onto the turbo turbine.

Question 14

14. What could result if the wastegate on a turbo system doesn’t fully close?

Answer 14

The engine may not be able to produce its rated power at certain altitudes and the aircraft may not be capable of reaching critical altitude.

Question 15

15. What function does a turbo wastegate perform?

Answer 15

It controls the amount of exhaust gas either into or around the turbo, thus controlling the boost pressure of the turbo.

Question 16

16. What could cause a turbo engine to surge?

Answer 16

There could be a wastegate or controller malfunction.

Question 17

17. What are the most common ways to control a wastegate?

Answer 17

Either mechanically with linkages to the throttle or a separate control, or by an actuator that is driven by oil pressure.

Question 18

18. In a pressurized reciprocating aircraft, what component in the turbo system is used to limit the amount of turbo airflow used for cabin pressurization?

Answer 18

The sonic venturi.

Question 19

19. What is the function of a divergent shaped jet engine inlet during subsonic flight?

Answer 19

It causes the air velocity to decrease with a subsequent increase in air pressure.

Question 20

20. Where are bellmouth inlet ducts typically found?

Answer 20

On helicopter engines.

Question 21

21. How do venturi type particle separators, found on many turbine powered helicopters, function?

Answer 21

A venturi is used to accelerate the flow of incoming air and debris through a curved intake. The debris gains too much inertia to allow it to follow the curved intake towards the engine, and is channeled away from the compressor.

Question 22

22. What are the most common methods used for anti-icing of turbine engine inlet ducts?

Answer 22

Engine bleed air and electric heating elements.