Module 06 Materials and Hardware 100 Important Sentences for Revision

1. Basic Material Properties

1. Material science studies properties and behavior of engineering materials.
2. All materials are classified as metals, ceramics, polymers, or composites.
3. Metals are good conductors of heat and electricity.
4. Non-metals are poor conductors of heat and electricity.
5. Density is mass per unit volume.
6. Elasticity is the ability of a material to return to its original shape after deformation.
7. Plasticity is the ability to permanently deform without breaking.
8. Ductility allows a material to be drawn into wires.
9. Malleability allows a material to be hammered into thin sheets.
10. Brittleness means a material breaks easily without deformation.

2. Mechanical Properties

11. Tensile strength is the maximum stress before breaking.
12. Compressive strength resists squeezing forces.
13. Shear strength resists sliding forces.
14. Hardness measures resistance to indentation.
15. Toughness is the ability to absorb energy before fracture.
16. Fatigue is failure caused by repeated stress cycles.
17. Creep is slow deformation under constant stress and temperature.
18. Stress is force per unit area.
19. Strain is the deformation caused by stress.
20. Hooke’s Law states stress is proportional to strain within elastic limit.

3. Ferrous and Non-Ferrous Metals

21. Ferrous metals contain iron.
22. Non-ferrous metals do not contain iron.
23. Steel is an alloy of iron and carbon.
24. Stainless steel contains chromium for corrosion resistance.
25. Cast iron is brittle but strong in compression.
26. Aluminum is lightweight and corrosion resistant.
27. Copper is a good conductor of electricity.
28. Brass is an alloy of copper and zinc.
29. Bronze is an alloy of copper and tin.
30. Titanium is strong, light, and resistant to corrosion — used in aircraft.

4. Heat Treatment

31. Heat treatment changes the physical properties of metals.
32. Annealing softens the metal and relieves stress.
33. Normalizing refines grain structure and improves toughness.
34. Hardening increases hardness by rapid cooling.
35. Quenching is the process of rapid cooling in oil or water.
36. Tempering reduces brittleness after hardening.
37. Case hardening hardens only the surface of steel.
38. Solution heat treatment is used for aluminum alloys.
39. Precipitation hardening increases strength by forming fine particles.
40. Age hardening strengthens certain alloys over time.

5. Corrosion and Protection

41. Corrosion is the deterioration of metal by chemical or electrochemical reaction.
42. Oxidation is a common form of corrosion.
43. Galvanic corrosion occurs when two dissimilar metals contact in moisture.
44. Pitting corrosion causes small, deep holes in metal.
45. Intergranular corrosion occurs along grain boundaries.
46. Filiform corrosion appears as thread-like lines under paint.
47. Stress corrosion cracking occurs under tensile stress and corrosive environment.
48. Erosion corrosion is caused by high-speed fluid flow.
49. Fretting corrosion occurs due to vibration and movement.
50. Protective coatings and paints prevent corrosion.

6. Composite Materials

51. Composite materials are made of two or more different materials.
52. Fiber-reinforced plastics are commonly used in aircraft.
53. Matrix binds the reinforcement together.
54. Reinforcement provides strength and stiffness.
55. Glass fibre is cheap but less strong.
56. Carbon fibre is lightweight and very strong.
57. Kevlar fibre is strong and resistant to impact.
58. Honeycomb structures provide high strength with low weight.
59. Sandwich panels consist of skins and core.
60. Composites are resistant to corrosion and fatigue.

7. Plastics and Rubber

61. Thermoplastics soften when heated and harden when cooled.
62. Thermosetting plastics harden permanently when heated.
63. Nylon, polyethylene, and PVC are thermoplastics.
64. Epoxy and phenolic resins are thermosetting plastics.
65. Rubber is an elastic material used for seals and gaskets.
66. Natural rubber is made from latex of trees.
67. Synthetic rubber is made from petroleum products.
68. O-rings provide tight seals in hydraulic and fuel systems.
69. Plastic components are lightweight but can deform with heat.
70. Plasticizers improve flexibility of plastics.

8. Aircraft Hardware

71. Aircraft hardware includes bolts, nuts, screws, rivets, and washers.
72. AN and MS standards are used for aircraft fasteners.
73. Bolts are used where high strength is required.
74. Screws are used for light loads and soft materials.
75. Self-locking nuts prevent loosening from vibration.
76. Cotter pins secure castle nuts.
77. Washers distribute load and protect surfaces.
78. Rivets are permanent fasteners for joining metal sheets.
79. Solid rivets require access to both sides of the joint.
80. Blind rivets are used where only one side is accessible.

9. Bearings, Pipes, and Control Cables

81. Bearings reduce friction between moving parts.
82. Ball bearings use spherical balls between races.
83. Roller bearings use cylindrical rollers for higher load capacity.
84. Plain bearings rely on lubrication between surfaces.
85. Bushings are sleeve-type plain bearings.
86. Flexible hoses are used for fluid systems.
87. Rigid pipes are made from aluminium or stainless steel.
88. Pipe fittings include flared, flareless, and beaded types.
89. Safety wiring prevents loosening of critical fittings.
90. Aircraft control cables are made of stainless steel.

10. Inspection, Testing, and Safety

91. Visual inspection detects surface defects.
92. Dye penetrant testing reveals surface cracks.
93. Magnetic particle testing detects surface cracks in ferrous metals.
94. Eddy current testing detects cracks without removing paint.
95. Ultrasonic testing detects internal flaws using sound waves.
96. Radiographic testing uses X-rays for internal inspection.
97. Hardness testing determines resistance to indentation.
98. Impact testing measures material toughness.
99. Always wear PPE during material handling and testing.
100. Proper storage prevents corrosion and contamination of materials.

 

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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 04 Electronic 100 Important Sentences for Revision

1. Basics of Electronics

1. Electronics deals with the flow of electrons in vacuum, gas, or semiconductor.
2. Current flow in electronics is controlled using components.
3. Electric current is the movement of free electrons in a circuit.
4. Voltage is the potential difference that drives current.
5. Resistance limits the amount of current in a circuit.
6. Conductors allow easy flow of electrons.
7. Insulators resist the flow of electrons.
8. Semiconductors have conductivity between conductors and insulators.
9. Silicon and germanium are common semiconductor materials.
10. Doping adds impurities to semiconductor to change its properties.

2. Types of Current

11. Direct current (DC) flows in one direction only.
12. Alternating current (AC) changes direction periodically.
13. DC voltage is constant over time.
14. AC voltage varies sinusoidally with time.
15. Frequency is the number of AC cycles per second.
16. Frequency is measured in hertz (Hz).
17. Period is the time taken for one complete AC cycle.
18. The RMS value of AC gives equivalent DC value.
19. Peak value is the maximum value of an AC waveform.
20. Average value of AC equals 0.637 × peak value.

3. Conductors, Resistors, and Materials

21. Ohm’s law states V = I × R.
22. Resistance increases with temperature in most metals.
23. Resistivity depends on material type and temperature.
24. Conductivity is the reciprocal of resistivity.
25. Colour codes identify resistor values.
26. Fixed resistors have constant resistance.
27. Variable resistors allow resistance adjustment.
28. Potentiometers act as voltage dividers.
29. Thermistors change resistance with temperature.
30. LDRs (Light Dependent Resistors) change resistance with light intensity.

4. Capacitors

31. Capacitor stores electrical energy in an electric field.
32. Capacitance is the ability to store charge.
33. Unit of capacitance is the farad (F).
34. Capacitance increases with plate area and decreases with plate distance.
35. Dielectric material increases capacitor’s efficiency.
36. Energy stored in a capacitor = ½ C × V².
37. Capacitor blocks DC and allows AC to pass.
38. Electrolytic capacitors are polarized.
39. Ceramic capacitors are non-polarized.
40. Capacitors are used for filtering, timing, and coupling circuits.

5. Inductors

41. Inductor stores energy in a magnetic field.
42. Inductance opposes change in current flow.
43. Unit of inductance is the henry (H).
44. Inductance increases with more coil turns.
45. Inductance increases with iron or ferrite core.
46. Inductive reactance increases with frequency.
47. Formula for inductive reactance: XL = 2πfL.
48. Inductors are used in filters and tuned circuits.
49. Mutual inductance occurs between two nearby coils.
50. Energy stored in inductor = ½ L × I².

6. AC Circuits

51. In resistive circuit, voltage and current are in phase.
52. In inductive circuit, current lags voltage by 90 degrees.
53. In capacitive circuit, current leads voltage by 90 degrees.
54. Impedance (Z) is total opposition to AC current.
55. Impedance combines resistance and reactance.
56. Formula: Z = √(R² + (XL − XC)²).
57. Power factor = cos φ, where φ is phase angle.
58. True power = V × I × cos φ.
59. Apparent power = V × I.
60. Reactive power = V × I × sin φ.

7. Diodes

61. A diode allows current to flow in one direction only.
62. It has an anode and a cathode terminal.
63. P-N junction forms when p-type and n-type materials join.
64. Forward bias allows current to pass through diode.
65. Reverse bias blocks current flow.
66. Silicon diode forward voltage drop is about 0.7 V.
67. Germanium diode forward voltage drop is about 0.3 V.
68. Zener diode operates in reverse breakdown region for voltage regulation.
69. LED emits light when forward biased.
70. Photodiode generates current when exposed to light.

8. Rectifiers and Power Supplies

71. Rectifiers convert AC voltage into DC voltage.
72. Half-wave rectifier uses one diode.
73. Full-wave rectifier uses two or four diodes.
74. Bridge rectifier uses four diodes in bridge configuration.
75. Filter capacitor smooths pulsating DC output.
76. Ripple voltage is unwanted AC variation in DC output.
77. Voltage regulators maintain constant DC output.
78. Linear regulator dissipates excess voltage as heat.
79. Switching regulator uses high-frequency switching for efficiency.
80. Power supply converts and stabilizes electrical power for circuits.

9. Transistors

81. Transistor is a three-terminal semiconductor device.
82. Terminals are emitter, base, and collector.
83. NPN and PNP are two transistor types.
84. Small base current controls large collector current.
85. Transistor acts as amplifier or switch.
86. Current gain (β) = collector current / base current.
87. In common emitter configuration, output is inverted.
88. Biasing sets correct operating point of transistor.
89. Saturation means transistor fully conducts.
90. Cut-off means transistor completely off.

10. Digital Electronics and Logic Gates

91. Digital signals have two states: ON (1) and OFF (0).
92. Analog signals vary continuously.
93. Logic gates perform basic digital operations.
94. AND gate output is 1 only if all inputs are 1.
95. OR gate output is 1 if any input is 1.
96. NOT gate output is opposite of input.
97. NAND gate output is opposite of AND output.
98. NOR gate output is opposite of OR output.
99. XOR gate output is 1 when inputs are different.
100. Digital electronics form the basis of computer and avionics systems.

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Module 01 Mathematics 100 important sentences for Revision

1. Basic Arithmetic

1. Mathematics is the science of numbers and quantities.
2. Addition combines two or more quantities into one.
3. Subtraction finds the difference between two numbers.
4. Multiplication is repeated addition of the same number.
5. Division splits a number into equal parts.
6. The order of operations follows BODMAS rule.
7. BODMAS means Brackets, Orders, Division, Multiplication, Addition, Subtraction.
8. A fraction shows a part of a whole.
9. The numerator is the number above the fraction line.
10. Below the fraction line the number is called denominator.

2. Fractions and Decimals

11. Like fractions have the same denominator.
12. Unlike fractions have different denominators.
13. To add fractions, make denominators the same.
14. Improper fractions have numerators larger than denominators.
15. Mixed fractions combine whole numbers and fractions.
16. Decimal numbers are fractions with denominators as powers of ten.
17. To convert a fraction to a decimal, divide numerator by denominator.
18. To convert a decimal to percentage, multiply by 100.
19. 0.75 equals ¾ or 75%.
20. 1/5 equals 0.2 or 20%.

3. Ratios and Proportions

21. A ratio compares two quantities by division.
22. A proportion shows two ratios are equal.
23. Ratios can be simplified like fractions.
24. Direct proportion means both quantities increase together.
25. Inverse proportion means one quantity increases, the other decreases.
26. Example: speed and time are inversely proportional.
27. Example: distance and time are directly proportional.
28. Cross multiplication is used to solve proportions.
29. Percentage = (part ÷ whole) × 100.
30. Ratio 2:3 means for every 2 of one, there are 3 of another.

4. Powers and Roots

31. A power or index shows repeated multiplication.
32. .
33. Any number to power zero equals one.
34. A square is a number multiplied by itself.
35. A number multiplied by itself twice is called cube.
36. Square root is the number that produces a given number when multiplied by itself.
37. Cube root gives a number whose cube equals the original number.
38. .
39. .
40. Indices follow rules of addition and subtraction in powers.

5. Algebra Basics

41. Algebra uses symbols to represent unknown quantities.
42. A variable is a letter that represents a number.
43. A term is a combination of numbers and variables.
44. A coefficient is the number multiplied by a variable.
45. Like terms have the same variable and power.
46. Unlike terms have different variables or powers.
47. Equation is a statement showing two expressions are equal.
48. To solve an equation, isolate the variable.
49. Linear equations have variables raised to power one.
50. Simultaneous equations have two or more unknowns solved together.

 6. Algebraic Operations

51. To expand brackets, multiply each term inside by the outside term.
52. To factorize, take out common terms or use identities.
53. .
54. .
55. .
56. Substitution means replacing variables with actual numbers.
57. Formula rearrangement changes the subject of formula.
58. Transposition moves terms across the equal sign by changing signs.
59. Check solutions by substituting values back in the equation.
60. Quadratic equations have variables squared (power of 2).

7. Geometry – Angles and Triangles

61. knowledge of shapes, sizes, and properties of space is geometry.
62. A line is straight with no thickness.
63. An angle is formed when two lines meet.
64. Angles are measured in degrees (°).
65. Right angle equals 90 degrees.
66. Straight line equals 180 degrees.
67. Full circle equals 360 degrees.
68. Acute angle is less than 90 degrees.
69. The Obtuse angle is greater than 90 but less than 180 degrees.
70. Complementary angles add up to 90 degrees.

8. Triangles and Circles

71. The sum of angles in a triangle is always 180 degrees.
72. An equilateral triangle has all sides equal.
73. An isosceles triangle has two sides equal.
74. A scalene triangle has all sides unequal.
75. Pythagoras theorem: .
76. It applies only to right-angled triangles.
77. Hypotenuse is the side opposite the right angle.
78. Circumference of circle = .
79. Area of circle = .
80. Diameter equals twice the radius.

9. Areas and Volumes

81. The Area of rectangle = length × width.
82. The Area of triangle = ½ × base × height.
83. The Area of parallelogram = base × height.
84. Formula of The Area of trapezium = ½ × (sum of parallel sides) × height.
85. The Volume of cube = side³.
86. The Volume of cuboid = length × width × height.
87. The Volume of cylinder = πr²h.
88. The Volume of cone = ⅓πr²h.
89. The Volume of sphere = 4/3πr³.
90. The Surface area of sphere = 4πr².

10. Trigonometry and Statistics

91. Trigonometry relates angles to sides in a triangle.
92. Sine = opposite ÷ hypotenuse.
93. Cosine = adjacent ÷ hypotenuse.
94. Tangent = opposite ÷ adjacent.
95. .
96. The inverse of sine gives angle from ratio.
97. Graphs visually represent data or equations.
98. Formula of Mean = sum of all values ÷ number of values.
99. Median is the middle value in ordered data.
100. Mode is the value that appears most often.

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