4 Turbine Engine Op, Instruments, Maint, And Overhaul

Question 1

1. Why are compressor washes performed and what methods are commonly used?

Answer 1

To remove any contaminants from the compressor section and improve engine performance. The fluid wash and abrasive grit wash are commonly used.

Question 2

2. How can you tell if a turbofan or turbojet engine is out of trim?

Answer 2

There will be a high EGT at the target EPR for takeoff power.

Question 3

3. Name the different types of compressor blade damage that may be found during inspection.

Answer 3

Dents, cracks, galling, pitting, scratches, burrs, burns, gouges.

Question 4

4. What kind of markers can be used to mark the parts in hot and cold sections during repair?

Answer 4

Layout dye, felt tip marker, chalk.

Question 5

5. How does relative humidity affect turbine engines?

Answer 5

Negligible effect.

Question 6

6. What criteria determines replacement of life limited turbine engine components?

Answer 6

Cycles, hours, and/or calendar time.

Question 7

7. If turbine blades are removed from a turbine disc, why should they be reinstalled in the same location?

Answer 7

To maintain the balance of the turbine wheel.

Question 8

8. How are gas turbine engine tachs calibrated?

Answer 8

In percent RPM.

Question 9

9. On a turbine engine, what is the EPR and what does it indicate?

Answer 9

It is the ratio between the total inlet pressure and total turbine exhaust pressure and is used to indicate the thrust developed by the engine.

Question 10

10. On a turbine engine, what does EGT indicate and how is it obtained?

Answer 10

EGT is the average temp of the turbine discharge gasses and is obtained by thermocouples placed near the turbine exit.

Question 11

11. Can the EGT system on a turbine engine be checked without running the engine?

Answer 11

Yes, by checking the resistance of the thermocouples and circuits.