Chapter 6 Exhaust systems

What is the purpose of the exhaust system?

To remove high temperature noxious gases.

Name two types of reciprocating engine exhaust systems.

The short stack and the collector system.

What drawback in using collector-type exhaust systems is more than offset when used on turbocharged engines?

The loss of horsepower due to exhaust system back pressure.

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

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

What type of exhaust system is used on turbocharged engines?

The collector system.

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

Stainless steel.

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

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

Why is an exhaust system failure considered a severe hazard?

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

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

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

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

There is a loss of engine power.

What is an indication of an exhaust gas leak?

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

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

At welded or clamped areas and at the flanges.

What is a common cause of turbocharger waste gate sticking?

Coke deposits or carbon buildup.

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

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

What are exhaust system coke deposits?

Excessive carbon buildup.

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

The engine's performance and exhaust gas temperature change.

Name the components of a typical turbine exhaust nozzle.

The tail cone, exhaust ducts and support struts.

What is the purpose of thrust reversers?

They help decelerate an aircraft after landing.

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

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

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

The clamshell (or mechanically blocked) and the Cascade (or aerodynamically blocked).

How much thrust do the thrust reversers produce compared to the engine's full forward thrust?

Substantially less.

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

Ingestion of foreign objects stirred up by the exhaust gases and re-ingestion of hot exhaust gases.