GCAA Ghana AME Exam cheat sheet

Newton's second law: F = m·a. A net force produces acceleration proportional to the force and inversely proportional to the mass.

Work = force × distance moved in the direction of the force; Power = work ÷ time; Kinetic energy = ½mv²; Potential energy = mgh.

Pressure = force ÷ area. 1 bar = 100 kPa = 14.5 psi; 1 atmosphere = 101.325 kPa = 29.92 inHg.

Density ρ = mass ÷ volume. Relative density (specific gravity) compares a substance's density with that of pure water (1000 kg/m³).

Moment of a force = force × perpendicular distance from the pivot. A body in equilibrium has zero resultant force and zero resultant moment about any point.

Direct stress σ = F/A; direct strain ε = ΔL/L (dimensionless); Young's modulus E = σ/ε applies only in the elastic region, below the proportional limit.

Trigonometry for right triangles: sin θ = opposite/hypotenuse, cos θ = adjacent/hypotenuse, tan θ = opposite/adjacent; Pythagoras c² = a² + b².

Temperature conversion: K = °C + 273.15; °F = (°C × 9/5) + 32. Standard gravity g = 9.81 m/s²; 1 kgf = 9.81 N.

Useful conversions: 1 inch = 25.4 mm; 1 lb = 0.4536 kg; 1 nautical mile = 1852 m; 1 knot = 0.5144 m/s.

Ohm's law: V = I·R. Power: P = V·I = I²R = V²/R.

Series resistances add directly: R_T = R1 + R2 + R3. Parallel resistances: 1/R_T = 1/R1 + 1/R2 + 1/R3.

Kirchhoff's current law: the sum of currents entering a junction equals the sum leaving. Voltage law: the sum of EMFs around a closed loop equals the sum of potential drops.

Capacitance C = Q/V in farads. Capacitors in parallel add (C_T = ΣC); in series 1/C_T = Σ(1/C). Energy stored = ½CV².

Reactance: X_C = 1/(2πfC) falls with frequency; X_L = 2πfL rises with frequency. Impedance Z = √(R² + (X_L − X_C)²).

AC relationships: f = 1/T; RMS value = peak ÷ √2 ≈ 0.707 × peak; average value of a sine wave = 0.637 × peak.

Transformer ratio: V1/V2 = N1/N2 = I2/I1. Power in equals power out for an ideal transformer.

Typical aircraft supplies: 115 V AC at 400 Hz for large transport aircraft and 28 V DC (14 V on many light aircraft).

Three-phase systems: line voltage = √3 × phase voltage in a star connection; 400 Hz is used because smaller, lighter transformers and motors result.

A diode conducts when the anode is positive with respect to the cathode (forward bias, about 0.7 V drop for silicon); it blocks in reverse bias up to its peak inverse voltage.

Binary is base 2. One hexadecimal digit represents 4 bits; 8 bits = 1 byte; convert decimal to binary by repeated division by 2, recording remainders in reverse order.

Gate rules: AND is high only when all inputs are high; OR is high when any input is high; NOT inverts; NAND and NOR are inverted AND and OR; XOR is high only when inputs differ.

De Morgan's theorems: NOT(A·B) = NOT A + NOT B, and NOT(A+B) = NOT A · NOT B.

ARINC 429: 32-bit word, unidirectional point-to-point, transmitted at 12.5 kbps (low speed) or 100 kbps (high speed) over a twisted shielded pair.

MIL-STD-1553B: 1 Mbps command/response multiplex data bus with dual redundant channels and a bus controller.

ADC resolution = full-scale voltage ÷ 2ⁿ where n is the number of bits; a DAC performs the reverse conversion for displays and actuators.

Fibre-optic data buses are immune to electromagnetic interference and produce no crosstalk, but are limited by minimum bend radius and connector cleanliness.

Electronic instrument systems present data on CRT, LCD or LED displays; EICAS/ECAM concentrate engine and system warnings, replacing discrete gauges.

2024 aluminium alloy: copper-bearing, high strength with good fatigue resistance but poor corrosion resistance; usually supplied Alclad and used for fuselage skins and lower wing surfaces.

7075 aluminium alloy: zinc-bearing, the highest strength of the common aircraft alloys but low corrosion resistance; used for wing spars, fittings and highly loaded components.

6061 aluminium alloy: medium strength, good corrosion resistance and weldability; used for structures and fittings not requiring maximum strength.

Heat treatment terms: annealing softens; solution treatment followed by precipitation hardening (ageing) strengthens; over-ageing reduces strength.

Alclad sheet has a thin cladding of commercially pure aluminium that corrodes sacrificially to protect the alloy core; cladding thickness limits are stated in the manual.

Galvanic series (anodic to cathodic): magnesium, zinc, aluminium, steel, stainless steel, titanium, graphite. The anodic member of a coupled pair corrodes.

Common corrosion forms: uniform surface, galvanic, pitting, intergranular, exfoliation, stress-corrosion and fretting.

Titanium is chosen for high strength-to-weight ratio and heat resistance, but is difficult to machine and its swarf is a fire hazard.

Hardware standards: AN (Air Force–Navy), MS (Military Standard) and NAS. Bolt grip length must equal the total thickness of the parts being joined.

Torque is applied with a calibrated wrench to the nut (not the bolt head) unless specified; the wrench must be within its calibration interval and re-verified after settling.

Lockwire: 6–8 twists per inch, a pigtail of 0.5–1.0 inch, and routed so any tendency to loosen pulls the wire in the tightening direction.

Self-locking nuts are not reused when the locking feature is free-running; fibre-insert nuts are limited in temperature and reuse.

Non-destructive testing selection: dye penetrant for surface defects in non-porous materials; magnetic particle for surface/near-surface defects in ferromagnetic parts; eddy current for conductive surfaces; ultrasonic and radiography for internal defects.

ATA 100 chapter awareness: 05 time limits, 12 servicing, 20 standard practices, 32 landing gear, 71 power plant, 79 oil system.

The MEL permits dispatch with specified defects under defined conditions; it may never be less restrictive than the MMEL and must be approved by the authority.

A maintenance release (certificate of release to service) certifies that the work has been completed and the aircraft is fit for flight; records are retained for the period required by regulation.

Jacking: use the specified jack points, one jack at a time, fit safety locks and maintain the aircraft in the level attitude at the stated reference points.

Foreign object damage prevention relies on tool control, shadow boards, accountability checks and inspection of intakes and control surfaces after work.

Four forces in flight: lift, weight, thrust and drag. In steady, unaccelerated level flight, lift = weight and thrust = drag.

Lift L = C_L × ½ρV²S; drag D = C_D × ½ρV²S, where S is wing area and ρ is air density.

C_L rises with angle of attack up to the critical angle, beyond which the airflow separates and the wing stalls; stall can occur at any speed or attitude.

Parasite drag increases with the square of speed, while induced drag decreases as speed rises at constant weight; total drag is least at the speed for maximum L/D.

Aspect ratio = span² ÷ area. Higher aspect ratio reduces induced drag but increases structural bending loads.

Mach number = true airspeed ÷ local speed of sound. Speed of sound a = √(γRT) depends only on temperature; at ISA sea level it is about 340 m/s.

Reynolds number Re = ρVc/μ describes the ratio of inertia to viscous forces; a high value indicates a turbulent boundary layer with greater skin-friction drag but delayed separation.

The centre of pressure moves forward as angle of attack increases, up to the stall.

Bernoulli's equation for steady incompressible flow along a streamline: p + ½ρV² = constant, so higher velocity gives lower static pressure.

SHELL model: Software, Hardware, Environment and Liveware (others) surround the central Liveware (the person); mismatches at the interfaces produce error.

Swiss cheese model: latent organisational failures and active failures line up to breach successive defences and produce an accident.

The Dirty Dozen: complacency, distraction, lack of communication, lack of teamwork, fatigue, lack of resources, pressure, lack of assertiveness, stress, lack of awareness, lack of knowledge and norms.

Hypoxia signs include impaired judgement, euphoria, light-headedness, headache and cyanosis; onset is insidious so self-detection is unreliable.

Dark adaptation takes about 30 minutes; bright white light destroys it, so red or dim lighting is used at night and off-centre viewing detects dim objects.

Prolonged exposure to noise above about 85 dB(A) risks hearing damage; hearing loss first affects high frequencies and is irreversible.

Short-term memory holds roughly 7 items for about 20 seconds; chunking and written procedures reduce memory lapses.

Yerkes–Dodson law: performance improves with arousal up to a moderate optimum, then deteriorates as stress increases further.

Circadian low points occur roughly 0300–0500 and 1500–1700, when alertness is naturally reduced and error rates are higher.

The Convention on International Civil Aviation (Chicago Convention, 1944) established ICAO; Ghana is a contracting state and the GCAA is its national civil aviation authority.

ICAO Annexes of note: Annex 1 Personnel Licensing, Annex 6 Operation of Aircraft, Annex 8 Airworthiness of Aircraft, Annex 19 Safety Management.

The Ghana Civil Aviation Act 2004 (Act 678) established the Ghana Civil Aviation Authority and gives it power to make and enforce safety regulations.

EASA Part-66 licence categories: A (limited line maintenance certification), B1 (mechanical), B2 (avionics) and C (base maintenance management).

Part-145 sets the requirements for approved maintenance organisations, including facilities, personnel, records and quality systems.

Continuing airworthiness is managed under Part-M/Part-CAMO, covering maintenance programmes, airworthiness directives and defect control.

An aircraft requires a Certificate of Registration and a valid Certificate of Airworthiness confirming conformity with the approved type design.

The Type Certificate is issued by the state of design; modifications require approval through a Supplemental Type Certificate or equivalent.

A certificate of release to service / maintenance release must be issued before flight after maintenance, and occurrences must be reported to the authority.

Primary controls: ailerons (roll), elevator (pitch) and rudder (yaw). Secondary controls: flaps, slats, spoilers and trim; flaps raise C_L and drag, and a Fowler flap also increases wing area.

Spoilers destroy lift and increase drag; they assist roll control and are used as ground lift dumpers after touchdown.

Typical transport hydraulic systems operate at about 3000 psi (207 bar); main components are reservoir, pump, accumulator, filter, selector valve and actuator.

Pneumatic power comes from engine bleed air and supplies anti-icing, pressurisation and air conditioning through an air-cycle machine.

Electrical power: 115 V AC 400 Hz and 28 V DC, with generators or IDGs, transformer-rectifier units and batteries for emergency supply.

Pressurisation limits cabin altitude to about 8000 ft; the outflow valve controls cabin pressure and the rate of change, and relief valves limit differential pressure.

Fuel grades: Jet A-1 kerosene for turbine engines, AVGAS 100LL for piston engines; water in fuel is detected by sump drains before flight.

Landing gear: air-oil oleo strut absorbs landing loads, torque links maintain alignment, a shimmy damper prevents nosewheel oscillation, and anti-skid modulates braking.

Semi-monocoque construction uses skin, longitudinal stringers and transverse frames; the wing is built around spars, ribs and stringers, and bulkheads carry concentrated loads in the fuselage.

Gas turbine operation follows the Brayton cycle: intake, compression, constant-pressure combustion and expansion through the turbine and nozzle.

Thermal efficiency increases with compressor pressure ratio and turbine inlet temperature; specific fuel consumption falls as bypass ratio rises in turbofans.

Bypass ratio = mass airflow through the bypass duct ÷ mass airflow through the engine core; high-bypass turbofans are quieter and more fuel-efficient.

Key engine parameters: N1 (LP spool speed %), N2 (HP spool speed %), EGT, EPR and fuel flow. EGT limits are critical because they govern turbine life.

Compressor surge is an unstable reversal of airflow causing loud bangs, high EGT and possible flame-out; it may follow throttle mishandling, blade damage or distorted intake flow.

Approximate thrust = mass flow × (jet velocity − aircraft velocity); propeller thrust rises with blade angle and rpm but falls as forward speed increases.

Piston engines run the four-stroke Otto cycle: induction, compression, power and exhaust, with two crankshaft revolutions per cycle.

Mixture control: rich settings cool the engine and are used for take-off and climb; lean settings improve economy at cruise. Detonation and pre-ignition are distinct abnormal combustion events.

Magnetos are self-contained ignition sources independent of the aircraft battery; dual magnetos provide redundancy and slight timing advance for efficiency.

A propeller governor controls blade angle to hold a selected rpm; feathering aligns blades to the airflow to minimise drag after engine failure.