GCAA CAR-66 Category A Exam cheat sheet

Pythagoras: in a right triangle, hypotenuse² = sum of squares of the other two sides (a² + b² = c²).

Sine rule: a/sin A = b/sin B = c/sin C for any triangle; cosine rule: a² = b² + c² − 2bc·cos A.

Area of a circle = πr²; circumference = 2πr; volume of a cylinder = πr²h.

Powers of ten: multiply by adding exponents, divide by subtracting exponents; 10⁰ = 1.

Average (mean) = sum of values ÷ number of values; percentage change = (change ÷ original) × 100.

Ratio/proportion: solve by cross-multiplication; if a/b = c/d then ad = bc.

Right-triangle trig ratios: sin = opposite/hypotenuse, cos = adjacent/hypotenuse, tan = opposite/adjacent.

Convert units before calculating: 1 in = 25.4 mm, 1 kg = 2.205 lb, 1 N = 1 kg·m/s².

Newton's second law: F = ma; weight W = mg with g ≈ 9.81 m/s².

Work = force × distance moved in the direction of the force; power = work ÷ time (watts).

Pressure = force ÷ area; in a fluid, pressure increases with depth (p = ρgh).

Density = mass ÷ volume; a body floats when its average density is less than the surrounding fluid.

Kinetic energy = ½mv²; potential energy = mgh; energy is conserved but may change form.

Heat transfer occurs by conduction, convection and radiation; radiation needs no medium.

Speed of sound in air ≈ 340 m/s at sea level; frequency × wavelength = wave speed.

Moment of a force = force × perpendicular distance from the pivot; equilibrium when clockwise moments equal anticlockwise moments.

Ohm's law: V = IR; power P = VI = I²R = V²/R.

Series circuit: resistances add (R = R1 + R2), current is common, voltages add.

Parallel circuit: 1/R = 1/R1 + 1/R2, voltage is common, currents add.

Kirchhoff's laws: sum of currents at a node = 0; sum of voltages around a closed loop = 0.

Capacitance in farads: C = Q/V; capacitors in parallel add, in series use reciprocal rule; energy = ½CV².

Inductance opposes change of current; inductive reactance XL = 2πfL, capacitive reactance XC = 1/(2πfC).

Impedance Z combines resistance and reactance; at resonance XL = XC.

Transformer ratio: Vp/Vs = Np/Ns; power in ≈ power out for an ideal transformer.

Diode conducts from anode to cathode when forward biased; blocks reverse current until breakdown.

A bipolar transistor has base, collector and emitter; small base current controls larger collector current (gain β = Ic/Ib).

A MOSFET is voltage-controlled; gate draws negligible steady current.

Rectifier converts AC to DC: half-wave uses one diode, full-wave bridge uses four.

Zener diode operates in reverse breakdown to provide a regulated reference voltage.

Operational amplifier: very high input impedance; inverting input inverts, non-inverting input does not.

LED emits light when forward biased; a series resistor limits the current.

Silicon junction forward voltage ≈ 0.6–0.7 V; germanium ≈ 0.2–0.3 V.

Binary place values double leftward: 1, 2, 4, 8, 16, 32, 64, 128; hexadecimal uses 0–9 and A–F.

Logic gates: AND outputs 1 only if all inputs are 1; OR if any input is 1; NOT inverts.

NAND and NOR are universal gates; XOR outputs 1 only when inputs differ.

A flip-flop stores one bit and is the basic memory element of sequential logic.

ARINC 429 is a one-way serial bus using two signal lines (A and B); ARINC 629 and Ethernet are bidirectional.

A data bus reduces wiring weight by sharing a common pair of conductors among many units.

ADC converts analog sensor output to digital; DAC converts digital values back to analog.

Electronic displays (CRT/LCD) replace mechanical instruments; redundancy and built-in test are key integrity features.

Aluminium alloys: 2024 has good fatigue resistance but low corrosion resistance; 7075 has high strength; 6061 is weldable.

Aluminium is treated by anodising or cladding (Alclad) to improve corrosion resistance.

Ferrous alloys: carbon content raises hardness and lowers ductility; stainless steel resists corrosion via chromium.

Titanium has high strength-to-weight ratio and good corrosion resistance but is difficult to machine.

Composite fibres (glass, carbon, aramid) carry load; the resin matrix transfers load and protects fibres.

Aircraft bolts are graded by head markings; AN bolts and NAS bolts differ in tolerance and strength.

Rivets: solid rivets for structure, blind rivets where access is one-sided; hole size and grip length must match.

Locking devices: lockwire, self-locking nuts, castellated nuts with split pins, and tab washers prevent loosening.

Torque values are applied with a calibrated wrench; torque = force × lever length.

Safety precautions: disconnect power/battery before electrical work; use lockout/tagging and correct PPE.

Inspection types: scheduled (routine) checks, non-destructive testing (dye penetrant, magnetic particle, eddy current, ultrasonic, radiography).

Dye penetrant reveals surface-breaking defects; magnetic particle only works on ferromagnetic materials.

Corrosion control: remove corrosion, treat with conversion coating/primer, and restore protective finish.

Standard practice: use correct part numbers, record all work in documentation, and observe tool calibration intervals.

Foreign object debris (FOD) control prevents loose items from entering engines or controls.

Fire safety: know extinguisher classes - water (A), foam/CO₂ (B), CO₂/dry powder for electrical (C).

Four forces on an aircraft in flight: lift, weight, thrust and drag; steady level flight has lift = weight and thrust = drag.

Bernoulli's principle: where fluid velocity increases, static pressure decreases.

Angle of attack is the angle between the wing chord line and the relative airflow.

Lift increases with angle of attack up to the critical angle, beyond which the wing stalls.

Induced drag results from lift generation and decreases with increasing speed; parasite drag increases with speed.

Aspect ratio = span² ÷ wing area; higher aspect ratio reduces induced drag.

Centre of pressure moves forward as angle of attack increases on a cambered wing.

Mach number = true airspeed ÷ local speed of sound; compressibility effects appear at high subsonic speeds.

The SHELL model relates Software, Hardware, Environment and Liveware (people); mismatches at interfaces cause error.

The 'dirty dozen' includes fatigue, complacency, distraction, pressure, stress, lack of communication, lack of resources, lack of teamwork, lack of knowledge, lack of assertiveness, norms and lack of awareness.

Hypoxia symptoms include euphoria, impaired judgement and blurred vision; time of useful consciousness falls with altitude.

Circadian rhythm disruption from shift work reduces alertness; fatigue impairs reaction time and decision-making.

Communication errors are reduced by standard phraseology and read-back/confirmation.

Situational awareness is the perception and understanding of the current environment and prediction of its future state.

Vision: cones provide colour and detail in bright light; rods provide low-light and peripheral vision.

Noise and vibration increase stress and error rates; hearing protection and rest breaks reduce risk.

CAR-66 defines aircraft maintenance certifying staff categories (A, B1, B2, B3, C) and their privileges.

A Category A certifying staff may issue certificates of release to service for minor scheduled line maintenance and simple defect rectification within the limits of the authorisation.

Part-145 organisations require approved procedures, trained staff and a quality system.

Maintenance records must be retained and made available to the competent authority for the prescribed period.

Continuing airworthiness is managed through maintenance programmes approved by the authority.

Airworthiness Directives are mandatory; compliance must be recorded.

Certifying staff must not certify work unless properly trained, authorised and current on the relevant type.

The competent authority in the UAE is the GCAA; it issues and oversees licences and approvals.

Wing camber produces lift at zero angle of attack; symmetrical aerofoils need positive angle of attack to lift.

Flaps increase lift and drag by increasing camber and wing area; slats delay stall by re-energising the boundary layer.

Stall speed increases with weight and load factor; Vs(new) = Vs × √(load factor).

Load factor = lift ÷ weight; a level 60° bank gives load factor 2.

Boundary layer separation causes stall; vortex generators and slots delay separation.

Dihedral provides lateral stability; sweepback delays compressibility effects at high speed.

Elevator controls pitch, ailerons control roll, rudder controls yaw.

Adverse yaw occurs in a turn when the downgoing aileron creates more drag; differential ailerons reduce it.

Semi-monocoque structure uses skin, stringers, frames and bulkheads; skin carries shear and some bending.

Primary structure carries flight and ground loads; secondary structure supports systems and fairings.

Hydraulic systems use pumps, reservoirs, accumulators, filters, valves and actuators; pressure is regulated.

Pneumatic systems supply air for pressurisation, anti-ice and engine starting.

Electrical power: AC generators (typically 115 V, 400 Hz) and DC via transformer-rectifier units; batteries provide emergency/APU start power.

Fuel system: tanks, pumps, valves, vents and quantity indication; fuel also cools and lubricates some components.

Landing gear: oleo struts absorb landing loads; brakes may be hydraulic or electric; anti-skid prevents wheel lock.

Pressurisation: cabin altitude and differential pressure are controlled by outflow valves; relief valves prevent overpressure.