Jeppesen Chapter 3 - Turbine Engines - (23 items) Flashcards

0
Q

Q2. Name the major components in a gas turbine engine.

A

A2. (1)Air inlet, compressor section, (2)combustion section, (3)turbine section, (4)exhaust section, (5)gearbox and accessory section.

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1
Q

Q1. Explain the main difference and advantage of turbofan over turbojet engines.

A

A1. A turbofan engine uses a fan to bypass some air around the engine air core to provide thrust. The advantage is that this provides additional thrust without increasing fuel flow.

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2
Q

Q3. What determines the amount of airflow through a turbine engine?

A

A3. (1)The forward speed speed of the aircraft, (2)Compressor speed, (3)Air density

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3
Q

Q4. Name the two types of compressors commonly used in turbine engines.

A

A4. Axial and Centrifugal flow compressors.

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4
Q

Q5. Name two different methods for attaching turbine engine rotor blades to the rotor disks.

A

A5. Dovetail-type root, or Bulb-type root, or Fir tree-type root.

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5
Q

Q6. What is a split compressor system?

A

A6. Also called dual or twin compressors, these are connected to the turbine section with two rotor shafts, one inside the other.

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6
Q

Q7. What are the different types of combustion chambers used in turbine engines?

A

A7. (1)Can, (2)Annular, (3)Can-Annular, and (4)reverse flow annular

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7
Q

Q8. What prevents the combustion chambers from from burning?

A

A8. Cooling air along the inside of the liner.

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8
Q

Q9. What is the purpose of the interconnecting tubes attached between can-type combustion chambers?

A

A9. For flame propagation during the start.

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9
Q

Q10. What functions do axial flow turbine nozzles perform?

A

A10. They direct the mass airflow to drive the turbine rotor at a specific angle.

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10
Q

Q11. How is the thermal stress relieved on a turbine disc?

A

A11. By directing bleed air into onto the face of the disk, or by grooves being cut in the disk.

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11
Q

Q12. What are carbon seals used for in turbine engines?

A

A12. They are used as oil seals for the rotor shaft bearings.

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12
Q

Q13. What is shaft horsepower?

A

A13. It is an indication of the torque developed by a turboprop or turboshaft engine.

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13
Q

Q14. Name the main components of a typical APU.

A

A14. A small power turbine for power and bleed air, and an electrical generator.

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14
Q

Q15. When is the greatest demand placed on an APU?

A

A15. When supplying bleed air.

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15
Q

Q16. How is an APU generally started?

A

A16. With its own electrical starter and battery power.

16
Q

Q17. Where does the APU get its fuel supply?

A

A17. From one of the aircraft’s main fuel tanks.

17
Q

Q18. At what speed does a gas turbine APU operate and how is this speed maintained?

A

A18. At or near its rated speed regardless of electrical or pneumatic loads imposed. The APU fuel control automatically adjusts thefuel flow to maintain the rated speed.

18
Q

Q19. What is used to prevent a heavily loaded APU from exceeding its maximum EGT?

A

A19. A load control valve modulates the pneumatic load to maintain EGT’s within limits.

19
Q

Q20. How is an APU shut down and why is this procedure used?

A

A20. After the APU is unloaded by closing the bleed air valve, it is run for a specified amount of time to allow the EGT to cool and stabilize. This cool down period is typically three minutes. If a heavily loaded APU is abruptly shut down without any cooling down period, damage could occur as a result of thermal shock.

20
Q

Q21. What powers the variable inlet guide vanes used on some APU’s to regulate compressor intake airflow?

A

A21. Fuel Pressure.

21
Q

Q22. What is fan blade shingling?

A

It is the overlapping of the midspan shrouds of the fan blade.

22
Q

Q23. When a turbofan or turbojet engine is shut down, what should a mechanic listen for during a coast coastdown?

A

A23. Any rubbing sound or other unusual noises from the engine.