True-False
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1. |
Helicopter turboshaft engines develop thrust in their exhaust ducts.
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2. |
In an engine destination, a three-digit dash number means that the engine was procured after the new Army procurement system went into effect.
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3. |
Engine idling is one of the two most severe operating periods for combustion chambers.
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4. |
An axial-centrifugal-flow compressor is made up of two sets of axial-flow compressors and one centrifugal-flow compressor.
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5. |
When a number is placed after N, as is N2, it refers to a specific system in the gas turbine engine.
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Cluster True-False
(Each of the following groups of questions is related to the statement that precedes them.
FIRST GROUP
About the three basic compressors used in gas turbine engines, your text tells you that:
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6. |
An axial-flow compressor is less susceptible to foreign-object damage than a centrifugal-flow one.
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7. |
Dual compressors are mounted on the same shaft and turn at the same speed.
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8. |
The centrifugal impeller in the axial-centrifugal-flow compressor decreases the air velocity.
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9. |
A centrifugal-flow compressor is made up of two rotors and a compressor manifold.
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10. |
A series of alternating rotor and stator vane stages makes up the axial-flow compressor.
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SECOND GROUP
The turbine section of a gas turbine engine transforms energy into shaft horsepower. Which of these five statements are true and which are false about the different types of turbines?
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11. |
Axial-flow turbines are less expensive and easier to manufacture than radial-flow turbines.
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12. |
A single-rotor turbine has its power developed by one rotor.
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13. |
All gas-turbine-power aircraft in the Army today use the axial-flow turbine.
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14. |
Axial-flow turbines are invariably the single-rotor type.
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15. |
A single-rotor turbine is used where low weight and compactness are necessary.
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THIRD GROUP
The next six questions about compressor construction tell you that:
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16. |
A centrifugal-flow compressor is made of either heat-treated forged aluminum or of cast aluminum.
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17. |
All manufacturers use the split compressor case for easier inspection.
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18. |
Shrouds are used on stator vanes to provide an air seal between rotating and stationary parts.
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19. |
In an axial-flow compressor, blades fit tightly in the turbine disk to reduce vibrational stress.
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20. |
In both the axial- and centrifugal-flow compressors, the fit between the compressor and its case is important.
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21. |
In a centrifugal-flow compressor, the rotor may be balanced by using balancing weights in the hub of the compressor.
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FOURTH GROUP
Evaluate the following five statements about engine model designations by selecting true or false. |
22. |
Each engine model designation begins with a letter or two letters.
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23. |
The letters TP at the beginning of the designation identify a turboprop engine.
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24. |
Even when a production model is changed, the dash number remains the same.
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25. |
The letter or set of letters following the assigned model number identifies the manufacturer.
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26. |
The Air Force always uses even numbers, both for the assigned number and the dash number.
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FIFTH GROUP
Which of the following five questions are true and which false about the compressor section of a gas turbine engine? |
27. |
Compressor efficiency determines the power necessary to create the pressure for a given airflow and affects the temperature in the combustion chamber.
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28. |
The highest total air velocity is at the inlet of the combustion section.
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29. |
The highest static pressure is at the inlet of the diffuser.
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30. |
The volume of air pumped by the compressor is proportional to the rpm of the rotor.
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31. |
The compressor is made up of alternating rotating and stationary vane assemblies.
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