Engine Exhaust and Reverser Systems

Question 1

How does a leak appear in an engine exhaust system?

Answer 1

It normally looks like a gray or black streak coming from a crack or from a location where components are not in perfect alignment

Question 2

How can you check a reciprocating engine exhaust system for leaks?

Answer 2

Pressurize the exhaust system and wipe a soap solution over all joints and suspect areas. A leak will cause bubbles to form

Pressurize the exhaust system with the discharge from a vacuum cleaner and wipe a soap soliton over all joints and suspect areas. A leak will cause bubbles to form

Question 3

How do the components in the exhaust system of a turbocharged engine allow for expansion and contraction due to heat, and at the same time prevent leakage?

Answer 3

Bellows and ball joints prevent leakage while allowing contraction and expansion

Question 4

Should a turbocharged engine be started with the waste gate open or closed?

Answer 4

Open, so as much exhaust as possible will bypass the turbine

Question 5

What is the primary function of a reciprocating engine exhaust system

Answer 5

Its main function is to dispose of the gases safely with complete safety to the airframe and the occupants of the aircraft. The exhaust system can perform many useful function, but its first duty is to provide protection against the potentially destructive action of the exhaust gases

Question 6

What is a short stack exhaust system?

Answer 6

The short stack exhaust system utilizes open exhaust tubes with no mufflers. The short stack system is generally used on non-supercharged engines and low-powered engines where the noise level is not too objectionable

Question 7

What is the purpose of the exhaust system?

Answer 7

To remove high temperature noxious gases.

Question 8

Name two types of reciprocating engine exhaust systems.

Answer 8

1. Short stack
2. Collector

Question 9

What draw back in using collector type exhaust system is more than offset when used on turbocharged engines?

Answer 9

The loss of horsepower due to exhaust system back pressure.

Question 10

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

Answer 10

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

Question 11

What type of exhaust system is used on turbocharged engines?

Answer 11

Collector system

Question 12

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

Answer 12

Stainless steel

Question 13

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

Answer 13

By disassembling the exhaust system and visually inspecting the components.

Question 14

Why is an exhaust system failure considered a severe hazard?

Answer 14

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

Question 15

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

Answer 15

Can cause cracks when heated.

Question 16

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

Answer 16

There is a loss in engine power.

Question 17

What is an indication of an exhaust gas leak?

Answer 17

Flat gray or sooty black deposit in the area of the leak.

Question 18

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

Answer 18

At welded or clamped areas and at the flanges.

Question 19

What are the most common causes of turbocharger waste gate sticking?

Answer 19

Coke deposits or carbon buildup

Question 20

Why are turbocharged exhaust system leaks very damaging at high altitudes?

Answer 20

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

Question 21

What are exhaust system coke deposits?

Answer 21

Excessive carbon build up

Question 22

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

Answer 22

The engine’s performance and exhaust gas temperature change.

Question 23

Name the components of a typical turbine exhaust nozzle.

Answer 23

1. Tail cone
2. Exhaust ducts
3. Support struts

Question 24

What is the purpose of thrust reversers?

Answer 24

They decelerate an aircraft after landing.

Question 25

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

Answer 25

It converts frequency sound into high frequency sound, reducing the sound footprint

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

Question 26

What are the two most commonly used types of thrust reversers?

Answer 26

1. Clamshell
2. Cascade

Question 27

How much thrust do the thrust reversers produce compared to the engines full forward thrust

Answer 27

Substantially less. (Up to 50% of the forward thrust)

Question 28

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

Answer 28

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