GCAA Ghana AME Exam flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Newton's Second Law

Force equals mass multiplied by acceleration (F = ma). A net force on a body produces acceleration proportional to the force and inversely proportional to its mass, in the direction of the force.

Stress and Strain

Stress is force divided by cross-sectional area, measured in pascals. Strain is the change in length divided by original length and is dimensionless. Young's modulus is stress divided by strain in the elastic region.

Moment of a Force

The turning effect of a force about a point, equal to the force multiplied by the perpendicular distance from that point to the line of action. The unit is the newton-metre.

Ohm's Law

Voltage across a conductor equals the current through it multiplied by its resistance (V = IR). It applies to purely resistive DC circuits and links volts, amperes and ohms.

Electrical Power

Power in watts equals voltage multiplied by current (P = VI). In a resistor this also equals current squared times resistance, or voltage squared divided by resistance.

RMS Value of AC

The root-mean-square value of a sine wave equals the peak value divided by the square root of two, about 0.707 times peak. It produces the same heating effect as an equal DC value.

Logic AND Gate

A digital gate whose output is high only when all of its inputs are high. If any input is low the output is low, performing the logical multiplication function.

ARINC 429 Data Bus

A point-to-point avionics bus transmitting 32-bit words at 12.5 or 100 kilobits per second over a twisted shielded pair, using a differential bipolar return-to-zero signal.

Analogue to Digital Conversion

The process of sampling a continuously varying analogue voltage and converting each sample into a binary number, with resolution set by the number of bits in the converter.

Alclad Aluminium Alloy

A wrought aluminium alloy sheet clad on both surfaces with a thin layer of commercially pure aluminium, which corrodes sacrificially to protect the stronger alloy core beneath.

Galvanic Corrosion

Corrosion caused when two dissimilar metals are in electrical contact in the presence of an electrolyte. The more anodic metal corrodes while the more cathodic metal is protected.

Carbon Fibre Composite

A material of carbon fibres embedded in a polymer resin matrix, giving a high strength-to-weight ratio and stiffness but brittle failure and sensitivity to impact damage and moisture.

Dye Penetrant Inspection

A non-destructive test in which a coloured or fluorescent penetrant is applied to a cleaned surface, drawn into surface-breaking defects, then developed so the defects become visible.

Eddy Current Inspection

A non-destructive test using alternating current in a coil to induce eddy currents in a conductive test piece. Changes in coil impedance reveal cracks, corrosion or conductivity variations.

Lockwire Safetying

A method of securing fasteners against vibration using twisted stainless steel wire passed through drilled holes so that any loosening tendency tightens the adjacent fastener.

Critical Angle of Attack

The angle of attack at which an aerofoil reaches its maximum lift coefficient. Exceeding it causes airflow separation and the wing stalls regardless of speed or attitude.

Induced Drag

Drag produced as a by-product of lift, caused by spanwise flow and wingtip vortices. It increases with the square of the lift coefficient and decreases as airspeed rises.

Mach Number

The ratio of an object's true airspeed to the local speed of sound in the surrounding air, used to classify flight as subsonic, transonic, supersonic or hypersonic.

SHELL Model

A human factors framework describing the interaction of Software, Hardware, Environment and Liveware, with the central Liveware representing the person and the surrounding blocks the interfaces around them.

Hypoxia

A deficiency of oxygen reaching body tissues. Symptoms include impaired judgement, light-headedness and euphoria, and onset is insidious so an affected person may not recognise it.

Circadian Rhythm

The roughly 24-hour internal biological cycle governing sleepiness, body temperature and alertness. Disruption by shift work or time-zone crossing causes fatigue and degraded performance.

ICAO Annex 1

The International Civil Aviation Organization annex containing Standards and Recommended Practices for the licensing of flight crew, air traffic controllers and aircraft maintenance personnel.

Part-66 Licence

A maintenance personnel licensing standard defining categories A, B1, B2 and C, with the knowledge, experience and examination requirements for certifying staff.

Certificate of Airworthiness

A document issued by the state of registry confirming that an aircraft conforms to its approved type design and is safe to operate under specified conditions.

Hydraulic System Pressure

Typical transport aircraft hydraulic systems operate at about 3000 psi (207 bar), while many light aircraft use 1000 to 1500 psi for landing gear and brake actuation.

Outflow Valve Function

A pressurisation system valve that modulates the rate at which air leaves the cabin, controlling cabin altitude and the rate of climb or descent to protect the structure.

Semi-Monocoque Structure

An aircraft structural concept in which the skin carries part of the load, stiffened by longitudinal stringers and transverse frames, with the remainder carried by the internal framework.

Dihedral Effect

The tendency of a wing with upward dihedral angle to generate a rolling moment away from a sideslip, providing lateral static stability about the longitudinal axis.

Brayton Cycle

The thermodynamic cycle of a gas turbine comprising intake, compression, constant-pressure combustion and exhaust expansion. Thermal efficiency rises with compressor pressure ratio.

Bypass Ratio

The ratio of the mass of air flowing through the fan bypass duct to the mass flowing through the engine core in a turbofan engine.

Compressor Surge

A severe unstable condition in a gas turbine compressor where airflow reverses momentarily, causing loud bangs, high exhaust gas temperature and possible flame-out or damage.

Four-Stroke Piston Cycle

A reciprocating engine cycle with induction, compression, power and exhaust strokes. The crankshaft turns twice per complete cycle in a conventional four-stroke aircraft engine.