Induction and Engine Airflow Systems

Study Materials

Aviation Maintenance Technician Series Powerplant textbook ASA Chapters 4 and 10

Aviation Maintenance Technician Powerplant Handbook FAA-H-8083-32 Vol. 1 FAA Chapter 3

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Typical Oral Questions

1. Where is the heat taken from that is used to heat the induction air in a reciprocating engine?

From a muff that is installed around some part of the exhaust system.

2. Where does the alternate air come from that is used with a pressure carburetor or a fuel injection ­system?

From inside the engine cowling.

3. Where does carburetor ice normally form in a carburetor?

In the throat of the carburetor, on and around the throttle valve.

4. Does the application of carburetor heat cause the fuel-air mixture to become richer or to become leaner?

Heated air causes the fuel-air mixture to become richer.

5. What is used to drive most of the external superchargers used on modern reciprocating engines?

Exhaust gases.

6. What controls the speed of a turbocharger com­pressor?

The amount of exhaust gas that is forced to flow through the turbine. This is controlled by the position of the waste gate.

7. What is meant by a convergent inlet duct for a turbine engine?

A convergent duct is one whose cross-sectional area becomes smaller in the direction the air flows.

8. What is meant by a divergent inlet duct for a turbine engine?

A divergent duct is one whose cross-sectional area becomes greater in the direction the air flows.

9. What kind of inlet duct is often used on turbine-powered helicopters?

A bell-mouthed inlet duct.

10. What is the danger of operating an aircraft reciprocating engine with too high a carburetor air temperature?

Too high a carburetor air inlet temperature can cause the fuel-air mixture to reach its critical temperature and detonate.

11. Why do some turbine engines use variable inlet guide vanes?

These variable inlet guide vanes are automatically adjusted to direct the air into the engine in such a way that it keeps the RPM vs. velocity proper for the most efficient operation.

12. How do some turbine engines prevent ice formation on the inlet guide vanes?

Hot compressor bleed air flows through hollow inlet guide vanes.

13. What is usually installed in a large reciprocating engine between the turbosupercharger and the carburetor?

An intercooler. This is an air-to-air heat exchanger.

14. In what position should the carburetor heat control be placed when starting a reciprocating engine?

In the Cold position.

15. How does an engine air inlet vortex destroyer help prevent foreign object damage to the engine?

A high-velocity stream of compressor bleed air is blown out in front of the engine to break up the vortices that form in front of the engine when it is operating at high power on the ground.

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Typical Practical Projects

1. Demonstrate to the examiner the correct way to clean the carburetor air filter for an aircraft engine.

2. Inspect a carburetor heater air box, and explain to the examiner the things that should be checked.

3. Demonstrate to the examiner the things that should be inspected on a turbocharger installation.

4. Inspect the induction system of a reciprocating engine for condition. Explain to the examiner the things that could cause a loss of engine power.

5. Locate and identify the components in the control system of a turbocharger.

6. Using a diagram of the ice control system for a turbine engine, explain to the examiner the way each component removes or prevents the formation of ice.

7. Explain to the examiner the correct way to check the operation of a turbocharger system on an aircraft engine.

8. Using a diagram of a turbocharger installation, explain to the examiner the operation of the type of controller that is installed.

9. Using a diagram of the clutch system of a two-speed internal supercharger, explain to the examiner the way the clutches operate to change the speed of the impeller.

10. Explain to the examiner the correct way to use a two-speed supercharger to maintain the maximum engine power as the airplane gains altitude.

11. Explain to the examiner the way the antisurge bleed system in a turbojet engine prevents compressor stall.

12. Explain the way an induction system fire should be extinguished in an aircraft reciprocating engine.

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