Module 09 Human Factors 100 Important Sentences for Revision

1. Introduction to Human Factors

1. Human factors study how people interact with machines and environments.
2. Around 80% of aircraft accidents involve human error.
3. Human factors aim to improve safety and efficiency.
4. Maintenance errors can have serious consequences in aviation.
5. The “SHELL” model explains human interaction in aviation systems.
6. “SHELL” stands for Software, Hardware, Environment, Liveware, Liveware.
7. Liveware represents the human element in the system.
8. The goal of human factors is to reduce human error.
9. Human performance depends on physical, mental, and emotional states.
10. Aviation safety relies on teamwork and communication.

2. Human Performance and Limitations

11. Human capability has physical and psychological limits.
12. Physical factors include strength, vision, and hearing.
13. Mental factors include perception, attention, and memory.
14. Human short-term memory holds information for only a few seconds.
15. Long-term memory stores knowledge and experience.
16. Working memory processes current information.
17. Attention can only focus on a limited number of tasks.
18. Multitasking increases the risk of error.
19. Fatigue reduces attention and reaction time.
20. Stress can affect decision-making and performance.

3. Environment and Workplace Factors

21. Lighting affects accuracy in visual inspections.
22. Poor lighting may cause eye strain or missed defects.
23. Noise interferes with communication and concentration.
24. Excessive noise can cause hearing loss over time.
25. Temperature extremes reduce work efficiency.
26. High temperature causes dehydration and fatigue.
27. Low temperature affects hand coordination and tools handling.
28. Humidity can lead to corrosion and discomfort.
29. Vibration causes long-term physical health issues.
30. Workspace layout should support safe and efficient work.

4. Communication in Maintenance

31. Communication ensures the correct transfer of information.
32. Miscommunication is a major cause of maintenance errors.
33. Verbal communication must be clear and precise.
34. Written communication includes logs, worksheets, and reports.
35. Handovers between shifts must be accurate and complete.
36. Standard phraseology reduces misunderstanding.
37. Feedback confirms that the message was understood.
38. Language barriers can cause misinterpretation.
39. Use of checklists supports communication clarity.
40. Always document work performed and work pending.

5. Teamwork

41. Teamwork enhances safety and problem-solving.
42. Teams should have clear roles and responsibilities.
43. Leadership provides direction and motivation.
44. Good teams have open communication.
45. Mutual respect builds trust among team members.
46. Poor teamwork can result in missed errors.
47. Conflict should be managed constructively.
48. Regular briefings improve coordination.
49. Cooperation between departments ensures smoother workflow.
50. Team decision-making reduces individual bias.

6. Stress and Fatigue

51. Stress is the body’s reaction to demands and pressure.
52. Stress can be positive (motivating) or negative (harmful).
53. Chronic stress reduces concentration and performance.
54. Common causes of stress are workload, time pressure, and conflicts.
55. Fatigue is extreme tiredness resulting from long hours or poor rest.
56. Fatigue reduces alertness and reaction time.
57. Sleep deprivation affects decision-making and mood.
58. Fatigue can accumulate over several days.
59. Proper rest and work schedules prevent fatigue.
60. Awareness of personal limits prevents unsafe decisions.

7. Human Error

61. Human error is an unintentional action that results in undesired outcome.
62. Errors can be active or latent.
63. Active errors occur immediately and have direct effects.
64. Latent errors lie hidden until triggered by conditions.
65. Slips occur when actions do not go as planned.
66. Lapses are memory failures.
67. Mistakes result from wrong decisions or incorrect knowledge.
68. Violations are intentional deviations from procedures.
69. The “Dirty Dozen” are twelve common causes of human error.
70. Awareness of error traps helps prevent mistakes.

8. The Dirty Dozen

71. The Dirty Dozen were identified by Gordon Dupont.
72. The twelve factors include: lack of communication, complacency, and knowledge.
73. Other factors include distraction, teamwork, and fatigue.
74. Lack of resources leads to unsafe shortcuts.
75. Pressure causes rushing and missed checks.
76. Lack of assertiveness prevents speaking up about safety.
77. Stress and norms also influence errors.
78. Distraction is the most common cause of maintenance error.
79. Always return to the job after interruption to recheck progress.
80. Recognizing these factors helps prevent accidents.

9. Safety Culture

81. Safety culture is the attitude and behavior toward safety.
82. A good safety culture encourages reporting of errors.
83. A blame-free culture promotes learning from mistakes.
84. Just culture balances accountability and learning.
85. Management commitment is essential for safety culture.
86. Safety meetings improve awareness and feedback.
87. Reporting systems help identify recurring problems.
88. Safety is everyone’s responsibility.
89. A positive safety attitude prevents risk-taking.
90. Continuous training supports a strong safety culture.

10. Human Factors in Maintenance Tasks

91. Maintenance errors can be reduced by using checklists.
92. Documentation ensures traceability of work.
93. Double inspection is required for critical tasks.
94. Job rotation reduces fatigue and boredom.
95. Use of approved tools prevents damage or injury.
96. Time pressure should never compromise safety.
97. Always follow the aircraft maintenance manual.
98. Record all defects, even minor ones.
99. Training improves awareness and competence.
100. Human factors knowledge improves safety, teamwork, and performance.

 

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Module 05 Digital Techniques 100 Important Sentences for Revision

1. Basics of Digital Systems

1. Digital systems work with discrete values, usually 0 and 1.
2. Analog systems work with continuous values.
3. Binary number system is used in all digital circuits.
4. A bit is a binary digit, either 0 or 1.
5. A byte consists of 8 bits.
6. Nibble is a group of 4 bits.
7. Binary numbers are converted to decimal for interpretation.
8. The octal number system uses base 8.
9. The hexadecimal system uses base 16.
10. Hexadecimal is often used in computer memory addressing.

2. Logic Gates

11. Logic gates perform basic logic operations.
12. AND gate output is 1 only if all inputs are 1.
13. OR gate output is 1 if any input is 1.
14. NOT gate inverts the input signal.
15. NAND gate output is opposite of AND gate.
16. NOR gate output is opposite of OR gate.
17. XOR gate output is 1 when inputs are different.
18. XNOR gate output is 1 when inputs are the same.
19. Truth tables show input-output logic relationships.
20. Boolean algebra simplifies digital circuits.

3. Number Systems and Codes

21. Binary addition follows 1+1 = 10 rule.
22. Binary subtraction follows 10−1 = 1 rule.
23. BCD stands for Binary-Coded Decimal.
24. ASCII code represents letters and numbers in computers.
25. Parity bits are used for error detection.
26. Even parity means total number of 1s is even.
27. Odd parity means total number of 1s is odd.
28. Gray code changes only one bit between adjacent numbers.
29. Excess-3 code is used in digital counters.
30. Codes help reduce data transmission errors.

4. Logic Circuits

31. Combinational logic depends only on current inputs.
32. Sequential logic depends on current and past inputs.
33. Flip-flops store one bit of data.
34. SR flip-flop has Set and Reset inputs.
35. JK flip-flop eliminates invalid states.
36. D flip-flop transfers input at clock edge.
37. T flip-flop toggles its state when triggered.
38. Latches are used for temporary data storage.
39. Counters count pulses in digital circuits.
40. Shift registers move data in serial or parallel form.

5. Microprocessors and Computers

41. A microprocessor is the brain of a digital system.
42. Microprocessor performs arithmetic and logic operations.
43. CPU stands for Central Processing Unit.
44. CPU includes ALU, control unit, and registers.
45. ALU stands for Arithmetic Logic Unit.
46. Memory stores data and instructions.
47. RAM is volatile memory that loses data when power is off.
48. ROM is non-volatile memory that retains data permanently.
49. EEPROM can be electrically erased and reprogrammed.
50. Cache memory speeds up processor operations.

6. Computer Systems

51. Hardware includes physical components like CPU, keyboard, and monitor.
52. Software is a set of instructions for hardware.
53. Operating system manages computer resources.
54. BIOS stands for Basic Input Output System.
55. Input devices include keyboard, mouse, and scanner.
56. Output devices include monitor and printer.
57. Storage devices include hard drive, SSD, and USB.
58. Data bus carries data between components.
59. Address bus carries memory addresses.
60. Control bus manages operation timing and control signals.

7. Digital Data Transmission

61. Data transmission can be serial or parallel.
62. In serial transmission, bits are sent one after another.
63. In parallel transmission, multiple bits are sent simultaneously.
64. Synchronous transmission uses a clock signal.
65. Asynchronous transmission uses start and stop bits.
66. Baud rate defines number of signal changes per second.
67. Modulation converts digital data to analog signals.
68. Demodulation converts analog signal back to digital.
69. Multiplexing allows multiple signals on one channel.
70. Demultiplexing separates combined signals.

8. Aircraft Digital Systems

71. Modern aircraft use digital avionics for precision and reliability.
72. ADC converts analog signals to digital form.
73. DAC converts digital signals to analog form.
74. ARINC 429 is a common digital data bus in aircraft.
75. ARINC 429 uses one-way transmission and two wires.
76. ARINC 629 allows multiple transmitters on one bus.
77. MIL-STD-1553 is used in military aircraft.
78. Digital data buses reduce wiring complexity.
79. Redundancy ensures system reliability in avionics.
80. EFIS displays flight data on LCD or CRT screens.

9. Instrument Systems

81. Digital instruments replace traditional mechanical gauges.
82. ADCs are used in digital flight data systems.
83. Flight Data Recorder (FDR) stores aircraft data continuously.
84. Cockpit Voice Recorder (CVR) stores crew communications.
85. Digital Air Data Computer (ADC) calculates altitude and airspeed.
86. Attitude and Heading Reference System (AHRS) provides aircraft attitude.
87. Inertial Reference System (IRS) uses accelerometers and gyros.
88. Gyros sense angular rotation.
89. Accelerometers sense linear acceleration.
90. Glass cockpit integrates multiple displays into one system.

10. Safety, Maintenance, and Testing

91. Static electricity can damage electronic circuits.
92. Always use anti-static wrist straps when handling components.
93. Grounding prevents electrostatic discharge (ESD) damage.
94. Continuity testing checks complete electrical paths.
95. Insulation testing ensures isolation between circuits.
96. Logic probes test digital high or low states.
97. Oscilloscopes display voltage over time.
98. Multi meters measure voltage, current, and resistance.
99. Built-in Test Equipment (BITE) detects faults automatically.
100. Regular calibration ensures accurate electronic readings.

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Module 03 Electrical 100 important sentences for Revision

1. Basic Electrical Terms

1. Electricity is the flow of electrons through a conductor.

2. Electric current is the rate of flow of charge.

3. The unit of current is the ampere (A).

4. Voltage is the electrical pressure that causes current flow.

5. The unit of voltage is the volt (V).

6. Resistance opposes the flow of electric current.

7. The unit of resistance is the ohm (Ω).

8. Power is the rate of doing electrical work.

9. The unit of electrical power is the watt (W).

10. Energy equals power multiplied by time.

2. Electric Charge and Current

11. Electric charge is measured in coulombs (C).

12. One coulomb equal one ampere-second.

13. Electrons have negative charge and move in conductors.

14. Conventional current flows from positive to negative.

15. Electron flow direction is opposite to conventional current.

16. Static electricity is charge at rest.

17. Conductors allow free movement of electrons.

18. Insulators resist electron movement.

19. Semiconductors conduct under certain conditions only.

20. Electric current requires a complete circuit to flow.

3. Ohm’s Law and Circuits

21. Ohm’s law: V = I × R.

22. If voltage increases, current increases proportionally.

23. Current decreases when resistance increases.

24. Series circuit current is same in all components.

25. Parallel circuit voltage is same across all branches.

26. Total resistance in series equals sum of all resistors.

27. Total resistance in parallel is always less than smallest resistor.

28. Kirchhoff’s voltage law states sum of voltages in a loop equals zero.

29. Kirchhoff’s current law states sum of currents entering a junction equals sum leaving.

30. Power formula: P = V × I.

4. Electrical Power and Energy

31. Electrical energy measured in watt-hours or kilowatt-hours.

32. One kilowatt-hour equals 3.6 million joules.

33. Efficiency equals output power divided by input power.

34. Power loss in resistor equals I² × R.

35. Electric fuse protects circuit by melting under overcurrent.

36. Circuit breaker opens automatically when current exceeds limit.

37. Switch controls current flow manually.

38. Ammeter connected in series measures current.

39. Voltmeter connected in parallel measures voltage.

40. Ohmmeter measures resistance of circuit components.

5. Magnetism and Electromagnetism

41. Magnetic materials attract iron, nickel, and cobalt.

42. Magnetic field lines travel from north to south outside magnet.

43. Magnetic flux is total number of magnetic field lines.

44. Unit of magnetic flux is the weber (Wb).

45. Magnetic flux density equals flux divided by area.

46. Unit of flux density is the tesla (T).

47. Right-hand rule shows direction of magnetic field around conductor.

48. Electromagnetism is magnetic effect produced by current.

49. Solenoid converts electrical energy into magnetic field.

50. Relays and contactors operate using electromagnetic coils.

6. Electromagnetic Induction

51. Electromagnetic induction produces voltage by changing magnetic field.

52. Faraday’s law states induced emf proportional to rate of flux change.

53. Lenz’s law states induced emf opposes cause producing it.

54. Self-induction occurs when current change induces emf in same coil.

55. Mutual induction occurs between two coils placed close together.

56. Inductance is ability to oppose change in current.

57. Unit of inductance is henry (H).

58. Energy stored in inductor equals ½ L × I².

59. Induced voltage polarity always opposes current change.

60. Alternators generate AC voltage using electromagnetic induction.

7. Capacitance

61. Capacitor stores electric charge and energy in electric field.

62. Capacitance equals charge divided by voltage (C = Q/V).

63. Unit of capacitance is farad (F).

64. Dielectric material increases capacitor’s storage ability.

65. Series capacitance total is less than smallest capacitor.

66. Parallel capacitance total equals sum of all capacitances.

67. Energy stored in capacitor equals ½ C × V².

68. Capacitor blocks DC but passes AC signals.

69. Electrolytic capacitors are polarized and used in DC circuits.

70. Ceramic capacitors are non-polar and used in AC circuits.

8. Alternating Current (AC)

71. Alternating current changes direction periodically.

72. AC waveform is usually sinusoidal.

73. Frequency is number of cycles per second in hertz (Hz).

74. Period is time taken for one complete cycle.

75. Amplitude is maximum value of AC voltage or current.

76. RMS value equals 0.707 × peak value for sine wave.

77. Average value equals 0.637 × peak value.

78. Phase angle is difference in phase between two AC waveforms.

79. In pure resistance, current and voltage are in phase.

80. In inductive circuit, current lags voltage by 90 degrees.

9. Inductive and Capacitive Reactance

81. Inductive reactance (XL) = 2πfL.

82. Capacitive reactance (XC) = 1 / (2πfC).

83. Reactance opposes change in AC current flow.

84. Impedance (Z) is total opposition to AC, combining resistance and reactance.

85. Impedance formula: Z = √(R² + (XL − XC)²).

86. Power factor = cosine of phase angle between current and voltage.

87. Power factor = true power divided by apparent power.

88. Lagging power factor indicates inductive load.

89. Leading power factor indicates capacitive load.

90. Correction capacitors improve lagging power factor.

10. Transformers and Power Systems

91. Transformer transfers electrical energy between circuits by magnetic induction.

92. Primary winding receives input voltage.

93. Secondary winding delivers output voltage.

94. Turns ratio determines voltage transformation ratio.

95. Step-up transformer increases voltage and reduces current.

96. Step-down transformer decreases voltage and increases current.

97. Transformer efficiency equals output power divided by input power.

98. Core losses include hysteresis and eddy current losses.

99. Isolation transformer separates two circuits for safety.

100. Autotransformer uses common winding for both primary and secondary.

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Module 2 Physics 100 Important Sentences for Revision

1. Basic Concepts

1. Physics is the study of matter, energy, and motion.

2. Matter has mass and occupies space.

3. Mass is the quantity of matter in a body.

4. Weight is the force of gravity acting on mass.

5. Density equals mass divided by volume.

6. Specific gravity is the ratio of substance density to water.

7. Force equals mass multiplied by acceleration.

8. The unit of force is the Newton (N).

9. One Newton equals one kilogram-meter per second squared.

10. Pressure equals force divided by area.

2. Motion and Laws

11. Displacement is the shortest distance between two points.

12. Speed is the rate of change of distance.

13. Velocity is speed in a given direction.

14. Acceleration is the rate of change of velocity.

15. Deceleration is negative acceleration or slowing down.

16. Newton’s first law states a body remains at rest or constant motion unless acted by force.

17. Newton’s second law defines force equals mass times acceleration.

18. Newton’s third law states every action has equal and opposite reaction.

19. Momentum equals mass times velocity.

20. Impulse equals force multiplied by time.

3. Work, Energy, and Power

21. Work is done when a force moves an object.

22. Work equals force multiplied by distance moved.

23. Unit of work is joule (J).

24. Energy is the capacity to do work.

25. Kinetic energy equals half mass times velocity squared.

26. Potential energy equals mass times gravity times height.

27. Mechanical energy equals potential plus kinetic energy.

28. Power equals work done divided by time.

29. Unit of power is watt (W).

30. One horsepower equals 746 watts approximately.

4. Machines and Efficiency

31. Simple machines change magnitude or direction of force.

32. Levers have three classes depending on fulcrum, effort, and load.

33. Mechanical advantage equals load divided by effort.

34. Velocity ratio equals distance moved by effort to load.

35. Efficiency equals mechanical advantage divided by velocity ratio.

36. Pulley systems provide mechanical advantage by rope arrangements.

37. Inclined plane reduces effort needed to lift weight.

38. Gear trains transfer motion and torque between shafts.

39. Screw jack converts rotary motion into linear motion.

40. No machine is 100% efficient due to friction losses.

5. Properties of Matter

41. Elasticity is the ability of material to return to original shape.

42. Hooke’s law states stress is proportional to strain within elastic limit.

43. Stress equals force divided by cross-sectional area.

44. Strain equals change in length divided by original length.

45. Modulus of elasticity equals stress divided by strain.

46. Plastic deformation is permanent change beyond elastic limit.

47. Ductility allows a material to be drawn into wire.

48. Malleability allows a material to be hammered into sheets.

49. Brittleness is property of breaking without deformation.

50. Toughness is resistance to fracture when energy is absorbed.

6. Fluids – Statics

51. Fluid includes both liquids and gases.

52. Pascal’s law states pressure applied to fluid is transmitted equally.

53. Hydrostatic pressure equals density times gravity times height.

54. Archimedes’ principle states a body immersed in fluid experiences buoyant force equal to weight of displaced fluid.

55. Buoyant force acts upward against gravity.

56. Specific weight equals weight per unit volume.

57. Gauge pressure is measured above atmospheric pressure.

58. Absolute pressure equals gauge pressure plus atmospheric pressure.

59. Manometer is used to measure fluid pressure difference.

60. Barometer measures atmospheric pressure using mercury column.

7. Fluids – Dynamics

61. Bernoulli’s principle states increase in fluid speed decreases pressure.

62. Continuity equation states area times velocity remains constant in streamline flow.

63. Laminar flow has smooth parallel layers with no mixing.

64. Turbulent flow contains irregular eddies and mixing motion.

65. Viscosity is internal friction between fluid layers.

66. Reynolds number determines type of fluid flow.

67. Cavitation occurs when vapor bubbles form and collapse in liquid.

68. Flow rate equals volume of fluid per unit time.

69. Venturi tube measures fluid velocity using pressure difference.

70. Pitot tube measures total and static pressures in airflow.

8. Heat and Temperature

71. Heat is energy transferred due to temperature difference.

72. Temperature measures average kinetic energy of particles.

73. Celsius scale has freezing point 0°C and boiling point 100°C.

74. Kelvin scale absolute zero equals −273°C.

75. Heat flows from hot to cold bodies.

76. Specific heat capacity is heat required to raise unit mass by one degree.

77. Latent heat is energy absorbed or released during phase change.

78. Conduction transfers heat through solids by particle vibration.

79. Convection transfers heat through fluids by movement of molecules.

80. Radiation transfers heat without any medium.

9. Gas Laws

81. Boyle’s law: pressure inversely proportional to volume at constant temperature.

82. Charles’s law: volume directly proportional to temperature at constant pressure.

83. Gay-Lussac’s law: pressure directly proportional to temperature at constant volume.

84. Combined gas law relates pressure, volume, and temperature.

85. Ideal gas law: PV = nRT.

86. Absolute zero is temperature where molecular motion stops.

87. Isothermal process occurs at constant temperature.

88. Adiabatic process occurs without heat transfer.

89. Gas expands when heated and contracts when cooled.

90. Standard atmospheric pressure equals 1013.25 hPa or 14.7 psi.

10. Sound and Light

91. Sound requires a medium for transmission.

92. Frequency is number of vibrations per second measured in hertz.

93. Speed of sound increases with temperature.

94. Ultrasound has frequency above 20,000 hertz.

95. Reflection occurs when sound or light bounces from surface.

96. Refraction is bending of light when passing between mediums.

97. Diffraction is spreading of waves around obstacles.

98. Interference occurs when two waves overlap each other.

99. Light travels in straight lines in uniform medium.

100. White light is a mixture of seven visible colors.

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