Chapter 4 Flashcards
Why are compressor washes performed and what methods are commonly used?
To remove any contaminants from the compressor and improve engine performance. The fluid wash and abrasive grit wash are commonly used.
How can you tell if a turbofan or turbojet engine is out of trim?
There will be high exhaust gas temperature at the target engine pressure ratio for takeoff power.
Name the different types of compressor blade damage that may be found during inspection.
Dents, cracks, galling, pitting, scratches, burrs, burns, gouges.
What kind of markers can be used to mark the parts in hot and cold sections during repair?
Layout dye, felt tip marker, chalk.
How does relative humidity affect turbine engines?
Negligible effect.
What criteria determines replacement of life limited turbine engine components?
Cycles, hours and/or calendar time.
If turbine blades are removed from a turbine disc, why should they be re-installed in the same location?
To maintain the balance of the turbine wheel.
How are gas turbine engine tachometers calibrated?
They are calibrated in percent r.p.m.
On the turbine engine, what is the engine pressure ratio and what does it indicate?
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.
On the turbine engine, what does the exhaust gas temperature (EGT) indicate and how is it obtained?
EGT is the average temperature of the turbine discharge gasses and is obtained by thermocouples placed near the turbine exit.
Can the EGT system on a turbine engine be checked without running the engine?
Yes, by checking the resistance of the thermocouples and circuits.
