6 Exhaust Systems

Question 1

1. What is the purpose of the exhaust system?

Answer 1

To remove high temp noxious gases.

Question 2

2. Name 2 types of reciprocating engine exhaust systems.

Answer 2

The short stack and the collector system.

Question 3

3. What drawback in using collector type exhaust systems is more than offset when used on turbo engines?

Answer 3

The loss of horsepower due to exhaust system back pressure.

Question 4

4. What could result if the internal baffles or diffusers in an exhaust system fail?

Answer 4

The flow of the exhaust gasses could be restricted, resulting in a loss of engine power.

Question 5

5. What type of exhaust system is used on turbo engines?

Answer 5

The collector system.

Question 6

6. What kind of material is normally used to make the muffler shrouds found in the exhaust system?

Answer 6

Stainless steel.

Question 7

7. How do you inspect the internal baffles and diffusers of an exhaust system?

Answer 7

By disassembling the exhaust system as necessary and visually inspecting the components.

Question 8

8. Why is an exhaust system failure considered a severe hazard?

Answer 8

It can result in carbon monoxide poisoning, loss of engine power, or fire.

Question 9

9. What could happen if lead, zinc, or galvanized marks are made on an exhaust system?

Answer 9

They cause a change in molecular structure, which could result in cracks when heated.

Question 10

10. What happens if the heat exchanger leaks exhaust gasses into the induction system?

Answer 10

There is a loss of engine power.

Question 11

11. What is an indication of an exhaust gas leak?

Answer 11

A flat gray or sooty black deposit in the area of the leak.

Question 12

12. Where are the most common places to find cracks in an exhaust system?

Answer 12

At welded or clamped areas and at the flanges.

Question 13

13. What is a common cause of turbo wastegate sticking?

Answer 13

Coke deposits or carbon buildup.

Question 14

14. Why are turbo exhaust system leaks very damaging at high altitudes?

Answer 14

Pressure differential will cause the leak to escape with torch like intensity.

Question 15

15. What are exhaust system coke deposits?

Answer 15

Excessive carbon buildup.

Question 16

16. What is the result of changing the exhaust nozzle area of a turbine engine?

Answer 16

The engine’s performance and EGT change.

Question 17

17. Name the components of a typical turbine exhaust nozzle.

Answer 17

The tail cone, exhaust ducts, and support struts.

Question 18

18. What is the purpose of thrust reversers?

Answer 18

They help decelerate an aircraft after landing.

Question 19

19. How does a noise suppressor found on older turbojet engines work?

Answer 19

It converts low frequency sound, which is audible over great distance, into high frequency sound, thus reducing the sound footprint.

Question 20

20. What are the 2 most commonly used types of thrust reversers?

Answer 20

The clamshell and the Cascade.

Question 21

21. How much thrust did the thrust reversers produce compared to the engine’s full forward thrust?

Answer 21

Substantially less.

Question 22

22. What are the hazards of operating some thrust reversers at low ground speeds?

Answer 22

Ingestion of foreign objects stirred up by the exhaust gasses and reingestion of hot exhaust gasses.