Module 15 Gas Turbine Engine 100 Important Sentences for Revision

 1. Basic Principles

1. A gas turbine engine operates on the Brayton cycle.
2. The Brayton cycle consists of intake, compression, combustion, expansion, and exhaust.
3. Thrust is produced by accelerating a mass of air rearward.
4. Newton’s third law is the basis of jet propulsion.
5. The faster the exhaust gases, the greater the thrust.
6. The main sections of a gas turbine are intake, compressor, combustion, turbine, and exhaust.
7. Air enters through the intake with minimum pressure loss.
8. The compressor raises the air pressure.
9. The combustion section adds heat to the compressed air.
10. The turbine extracts energy from hot gases to drive the compressor.

2. Engine Components

11. The intake directs air smoothly into the compressor.
12. The compressor may be centrifugal, axial, or mixed-flow.
13. Centrifugal compressors are common in small engines.
14. Axial compressors are used in large engines for higher pressure ratios.
15. The diffuser slows down air to increase static pressure.
16. The combustion chamber burns fuel continuously.
17. The turbine converts heat energy into mechanical work.
18. The exhaust nozzle accelerates gases to produce thrust.
19. Bearings support rotating shafts.
20. Accessory gearboxes drive pumps and generators.

3. Compressor Section

21. Compressors increase air pressure and temperature.
22. Axial compressors consist of rotating and stationary blades.
23. Rotor blades accelerate the air.
24. Stator blades convert velocity into pressure.
25. Multi-stage axial compressors achieve high pressure ratios.
26. Centrifugal compressors use impeller and diffuser action.
27. Compressor efficiency affects overall engine performance.
28. Surge is a total breakdown of airflow through the compressor.
29. Stall occurs when air separates from the blade surface.
30. Variable stator vanes and bleed valves prevent stall and surge.

4. Combustion Section

31. Combustion occurs at nearly constant pressure.
32. The air-fuel ratio must be correct for complete burning.
33. There are three types of combustion chambers: can, annular, and can-annular.
34. Igniters provide spark during engine start.
35. Fuel injectors atomize and mix fuel with air.
36. The liner directs flame and protects casing from heat.
37. Cooling air flows through liner holes to reduce temperature.
38. Combustion efficiency affects thrust and fuel economy.
39. Flameout occurs when the flame is extinguished during operation.
40. Relight systems restart combustion after flameout.

5. Turbine Section

41. The turbine extracts energy from hot gases.
42. It drives the compressor and accessories.
43. A turbine consists of rotor blades and stator vanes.
44. The stator guides gas flow onto rotor blades.
45. The high-pressure turbine drives the compressor.
46. The low-pressure turbine drives the fan or propeller.
47. Turbine blades are made of nickel-based superalloys.
48. Blade cooling prevents overheating.
49. Cooling air passes through internal passages and holes.
50. Blade creep occurs from long-term high temperatures.

6. Exhaust and Thrust

51. The exhaust system directs gases rearward efficiently.
52. Thrust is created by high-velocity gas exiting the nozzle.
53. Convergent nozzles are used on subsonic engines.
54. Convergent-divergent nozzles are used for supersonic speeds.
55. Afterburners add fuel to the exhaust for extra thrust.
56. Thrust reversers help decelerate the aircraft after landing.
57. Reversers operate hydraulically or pneumatically.
58. Bucket, cascade, and clamshell are main types of reversers.
59. Reverse thrust should not be used in flight.
60. EGT (Exhaust Gas Temperature) is an important performance indicator.

7. Engine Starting and Ignition

61. Starting provides rotation for initial air compression.
62. Air turbine starters are common in large engines.
63. Electrical starters are used on small turbine engines.
64. Ignition systems provide spark for combustion start.
65. Two igniters are used for reliability and redundancy.
66. Igniters use high-voltage discharge.
67. Ignition is required during start and for relight.
68. Exciters store and discharge energy to igniters.
69. After engine self-sustains, the starter disengages.
70. Starter cutout occurs automatically after light-up.

8. Engine Control Systems

71. Engine thrust is controlled by fuel flow.
72. The fuel control unit (FCU) meters correct fuel quantity.
73. FADEC stands for Full Authority Digital Engine Control.
74. FADEC controls fuel and engine parameters electronically.
75. FADEC removes mechanical control cables.
76. Manual reversion may be used in older systems.
77. Power levers command thrust setting to FADEC.
78. Engine control prevents over-speed and over-temperature.
79. EPR (Engine Pressure Ratio) indicates engine thrust.
80. N1 and N2 show compressor spool speeds.

9. Lubrication and Fuel Systems

81. The oil system lubricates and cools engine bearings.
82. Dry sump systems are common in turbine engines.
83. Scavenge pumps return oil to the tank.
84. Filters remove dirt and metal particles.
85. Chip detectors signal metal contamination.
86. Oil coolers maintain correct temperature.
87. The fuel system delivers fuel from tanks to combustion.
88. Boost pumps supply fuel to the engine pumps.
89. Fuel filters remove contaminants.
90. The FCU meters fuel according to throttle position and conditions.

10. Fire Protection, Performance, and Maintenance

91. Fire detection systems use continuous loops or thermal sensors.
92. Overheat detection warns of rising temperature before fire.
93. Fire extinguishing systems use Halon or clean agents.
94. Engine performance is measured by EPR, N1, and fuel flow.
95. Specific fuel consumption defines fuel efficiency.
96. Vibration monitoring detects rotor imbalance.
97. Engine trend monitoring helps predict maintenance needs.
98. Borescope inspection checks internal parts.
99. Engine removal is required for major overhauls.
100. Proper maintenance ensures reliability, safety, and efficiency.

 

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Module 14 Propulsion 100 Important Sentences for Revision

 1. Introduction to Propulsion

1. Propulsion provides the force to move an aircraft forward.
2. Thrust is the forward force produced by an engine.
3. Jet engines accelerate air to generate thrust.
4. Piston engines produce power through combustion of fuel and air.
5. Turbine engines are used on most modern aircraft.
6. Newton’s third law explains jet propulsion: action and reaction.
7. Propulsive efficiency measures how effectively thrust is used.
8. Specific fuel consumption shows fuel used per thrust output.
9. Turbofan engines have higher efficiency than turbojets.
10. Propeller engines are more efficient at low speeds.

2. Gas Turbine Engine Principles

11. A gas turbine engine works on the Brayton cycle.
12. The main sections are intake, compressor, combustion, turbine, and exhaust.
13. Air enters the intake with minimal pressure loss.
14. The compressor increases the air pressure.
15. Combustion adds heat energy to the compressed air.
16. The turbine extracts power from hot gases.
17. The exhaust accelerates gases to produce thrust.
18. The compressor and turbine are connected by a shaft.
19. Airflow must be smooth and continuous for stable operation.
20. Engine efficiency depends on pressure ratio and temperature.

3. Engine Types

21. A turbojet produces thrust only from exhaust gases.
22. A turbofan uses a fan to move extra air for more thrust.
23. A turboprop drives a propeller through a reduction gearbox.
24. A turboshaft powers helicopters and auxiliary equipment.
25. A ramjet has no moving parts and works at high speeds.
26. A pulsejet uses intermittent combustion for thrust.
27. A rocket carries both fuel and oxidizer.
28. Bypass ratio is the ratio of fan air to core air in a turbofan.
29. High-bypass engines are quieter and more efficient.
30. Low-bypass engines are used on faster aircraft.

4. Compressors

31. Compressors increase air pressure before combustion.
32. There are two main types: axial and centrifugal.
33. Axial compressors use rotating and stationary blades.
34. Centrifugal compressors use impellers and diffusers.
35. Multi-stage compressors achieve higher pressure ratios.
36. Bleed air is taken from compressor stages for aircraft systems.
37. Surge is an unstable airflow condition in compressors.
38. Stall occurs when air separates from compressor blades.
39. Variable stator vanes help control airflow and prevent surge.
40. Inter-stage bleed valves stabilize compressor operation.

5. Combustion Section

41. The combustion chamber burns fuel with compressed air.
42. The three types are can, annular, and can-annular.
43. Fuel injectors spray fuel into the airflow.
44. Igniters provide spark during engine start.
45. Continuous combustion ensures constant thrust.
46. Air cools the liner to prevent overheating.
47. Combustion efficiency affects engine performance.
48. Uneven burning can cause vibration and damage.
49. Flameout is loss of combustion during operation.
50. Relight systems restart combustion after flameout.

6. Turbine Section

51. Turbines extract energy to drive the compressor and accessories.
52. A turbine consists of rotors and stators.
53. High-pressure turbine drives the compressor.
54. Low-pressure turbine drives the fan or propeller.
55. Turbine blades are made from high-temperature alloys.
56. Cooling air flows through blade holes to reduce heat.
57. Shrouds prevent gas leakage around blades.
58. Blade creep occurs due to prolonged high temperature.
59. Over-temperature can cause turbine failure.
60. Turbine efficiency determines overall engine performance.

7. Exhaust and Thrust Reversers

61. The exhaust nozzle accelerates gases to produce thrust.
62. Convergent nozzles are used in subsonic engines.
63. Convergent-divergent nozzles are used in supersonic engines.
64. Afterburners increase thrust by burning extra fuel in exhaust.
65. Thrust reversers help slow the aircraft after landing.
66. Bucket, cascade, and clamshell are types of reversers.
67. Thrust reversers operate hydraulically or pneumatically.
68. Deploying reversers in flight is prohibited.
69. Nozzle area affects exhaust velocity and efficiency.
70. Exhaust temperature is monitored for engine health.

8. Engine Starting and Ignition

71. Engine starting turns the compressor to begin airflow.
72. Air turbine starters use compressed air to spin the engine.
73. Electrical starters are common on small engines.
74. Ignition systems provide spark for fuel ignition.
75. There are two igniters for reliability.
76. Ignition is used only during start and relight.
77. High-energy igniters produce strong sparks.
78. Dual ignition improves reliability and redundancy.
79. Ignition exciters store energy for discharge.
80. Starter cutout occurs when the engine is self-sustaining.

9. Engine Control and Monitoring

81. FADEC means Full Authority Digital Engine Control.
82. FADEC controls fuel flow and engine parameters automatically.
83. It eliminates mechanical linkages in control systems.
84. EPR (Engine Pressure Ratio) measures engine thrust.
85. N1 and N2 represent rotational speeds of compressor spools.
86. EGT (Exhaust Gas Temperature) indicates turbine temperature.
87. Oil pressure and temperature are continuously monitored.
88. Vibration sensors detect unbalance or bearing wear.
89. Engine indicating systems use digital displays in modern aircraft.
90. Over-speed protection prevents engine damage.

10. Fuel, Oil, and Fire Systems

91. The fuel system delivers fuel from tanks to the combustion chamber.
92. Fuel pumps supply pressurized fuel to the injectors.
93. Filters remove contamination from the fuel.
94. Fuel control units meter correct fuel flow.
95. Oil systems lubricate and cool engine components.
96. Scavenge pumps return oil to the tank.
97. Chip detectors indicate metal particles in oil.
98. Fire detection systems use loops or sensors.
99. Fire extinguishing systems use halon or clean agent bottles.
100. Regular inspection ensures reliable engine operation and safety.

 

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Module 13 Aircraft Aerodynamics, Structures, and Systems 100 Important Sentences for Revision

 1. Basic Aerodynamics

1. Lift is the upward force that opposes weight.
2. Drag is the air resistance acting opposite to motion.
3. Thrust moves the aircraft forward.
4. Weight acts downward through the center of gravity.
5. The four main forces on an aircraft are lift, weight, thrust, and drag.
6. Bernoulli’s principle explains lift as pressure difference.
7. Newton’s third law also contributes to lift generation.
8. The wing’s shape is called an air foil.
9. Angle of attack is the angle between chord line and airflow.
10. When angle of attack exceeds the critical angle stall occur.

2. Flight Controls

11. Primary flight controls are ailerons, elevators, and rudder.
12. Ailerons control roll about the longitudinal axis.
13. Elevators control pitch about the lateral axis.
14. The rudder controls yaw about the vertical axis.
15. Secondary flight controls include flaps, spoilers, and trim tabs.
16. The secondary Flt Control Flaps increase lift and drag for landing and takeoff.
17. Slats delay airflow separation and prevent stall.
18. Spoilers destroy lift and assist braking.
19. Trim tabs reduce pilot control effort.
20. Fly-by-wire systems use electrical signals instead of cables.

3. Aircraft Structures

21. The fuselage houses crew, passengers, and cargo.
22. The wing generates lift and supports fuel tanks.
23. The empennage includes the tailplane and fin.
24. The horizontal stabilizer provides pitch stability.
25. The vertical fin provides directional stability.
26. The landing gear supports aircraft on the ground.
27. Semi-monocoque structure uses frames, stringers, and skin.
28. Composite materials are strong and lightweight.
29. Stress is internal resistance to external load.
30. Fatigue is caused by repeated loading cycles.

4. Powerplant Systems

31. The powerplant provides thrust.
32. Turbofan engines are used in most modern airliners.
33. A propeller driven through a reduction gearbox in Turboprop engines.
34. The compressor increases air pressure.
35. The combustion chamber mixes air with fuel and burns it.
36. The turbine extracts energy to drive the compressor.
37. The exhaust nozzle accelerates the gases for thrust.
38. The accessory gearbox drives engine accessories.
39. FADEC controls engine parameters automatically.
40. Engine fire extinguishing systems use halon or clean agents.

5. Landing Gear Systems

41. The landing gear absorbs landing shock loads.
42. Main and nose gear support the aircraft on the ground.
43. Oleo struts use oil and air for shock absorption.
44. Retraction and extension are powered hydraulically or electrically.
45. Uplocks and down locks secure gear position.
46. Proximity sensors indicate gear position.
47. Anti-skid systems prevent wheel lockup.
48. Brake fans help in cooling brakes.
49. Nose wheel steering is hydraulically or electrically operated.
50. Tires are nitrogen inflated to prevent fire risk.

6. Hydraulic Systems

51. Hydraulics transmit force using pressurized fluid.
52. Pascal’s law governs hydraulic pressure transmission.
53. Typical operating pressure is 3000 psi.
54. Hydraulic pumps supply system pressure.
55. Reservoirs store hydraulic fluid.
56. Filters remove contamination.
57. Accumulators store pressure energy.
58. Relief valves protect against overpressure.
59. Actuators convert pressure to movement.
60. Skydrol is a commonly used phosphate ester hydraulic fluid.

7. Pneumatic and Air Systems

61. Pneumatic systems use compressed air.
62. Air can be supplied from the APU, engines, or ground source.
63. Pneumatics power de-icing, pressurization, and engine start.
64. Check valves prevent backflow.
65. Pressure regulators control system pressure.
66. Safety valves prevent overpressure.
67. Air cycle machines condition the cabin air.
68. Bleed air is tapped from compressor stages.
69. Leak detection systems monitor pneumatic ducts.
70. Isolation valves control system routing.

8. Electrical Systems

71. The electrical system provides power to aircraft components.
72. Power sources include generators, batteries, and external power.
73. AC and DC systems are both used in modern aircraft.
74. The constant speed drive maintains generator frequency.
75. The busbar distributes electrical power.
76. Circuit breakers protect against overloads.
77. Relays and contactors control heavy current circuits.
78. Batteries provide power during engine start.
79. Inverters convert DC to AC power.
80. TRUs convert AC to DC.

9. Air Conditioning & Pressurization

81. Cabin pressurization maintains a comfortable atmosphere.
82. Outflow valves control cabin pressure.
83. Cabin altitude should not exceed 8,000 feet.
84. Air conditioning controls temperature and humidity.
85. Air cycle machine cools bleed air using expansion.
86. Recirculation fans improve air distribution.
87. Temperature controllers regulate cabin zones.
88. Pressure relief valves prevent over pressurization.
89. Safety valves protect structure during decompression.
90. Cabin pressure differential must stay within structural limits.

10. Flight Instruments & Avionics

91. The pitot-static system provides airspeed, altitude, and VSI data.
92. Pitot tube measures dynamic pressure.
93. Static port measures atmospheric pressure.
94. Altimeter displays height above sea level.
95. Airspeed indicator shows speed relative to air.
96. Vertical speed indicator shows rate of climb or descent.
97. Attitude indicator shows aircraft pitch and roll.
98. Heading indicator shows aircraft direction.
99. Radio altimeter measures height above ground.
100. Flight data recorder and CVR record flight information for safety.

 

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