GCAA Ghana AME Exam key terms

A quantity that has both magnitude and direction, such as force, velocity or acceleration. It is drawn as an arrow whose length and orientation show size and direction, and vectors combine by geometric rules rather than simple arithmetic.

The turning effect of a force about a point, found by multiplying the force by the perpendicular distance from that point to the force's line of action. It is measured in newton metres and used in weight-and-balance work.

The relationship stating that the current through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance, written V = I × R for a constant-resistance circuit.

The total opposition a circuit presents to alternating current, combining resistance with capacitive and inductive reactance. It is measured in ohms and, unlike plain resistance, depends on the frequency of the supply.

The ability of two separated conductors to store electric charge when a voltage is applied between them. Measured in farads, it equals charge divided by voltage and is used in filters, tuning circuits and suppression components.

The generation of a voltage in a conductor when it moves through a magnetic field or experiences a changing magnetic field. The principle underlies generators, transformers and many aircraft sensing devices.

A two-terminal device that conducts current readily in one direction and blocks it in the opposite direction. It is used for rectification, circuit protection and transient suppression in aircraft electrical and electronic systems.

A circuit that produces a defined output state, high or low, according to a rule applied to its inputs. Common types include AND, OR, NOT, NAND and NOR, and they are the building blocks of digital systems.

An electronic circuit that samples a continuously varying voltage and turns each sample into a binary number so a digital system can process it. Resolution and sampling rate determine how faithfully the signal is represented.

A shared set of conductors, or a defined digital protocol, over which several avionic units exchange information. Examples include ARINC 429 and ARINC 629, which carry labelled digital words between line-replaceable units.

A metallic material made by combining a base metal with other elements to improve properties such as strength, hardness or corrosion resistance. Aircraft structures commonly use aluminium, titanium and steel alloys.

A process of heating an alloy to a temperature that dissolves its alloying elements into a single solid phase, then cooling it rapidly to trap them. Later natural or artificial ageing raises strength and hardness.

The progressive weakening and eventual cracking of a material subjected to repeated or fluctuating loads, even when each individual load is below the static strength. It usually begins at stress concentrations such as holes and sharp corners.

Corrosion occurring when two dissimilar metals are in electrical contact in the presence of an electrolyte, so that one acts as anode and corrodes preferentially. It is controlled by isolation, sealants and careful material selection.

A calibrated hand tool that applies a controlled turning moment to a fastener and signals when the set value is reached. Correct use prevents under-tightening and over-stressing of threads and joint members.

A safety method in which fine wire is twisted between adjacent fasteners so that neither can rotate loose. The wire is routed so that any tendency to loosen pulls the wire tighter.

A mandatory instruction issued by the State of Design and adopted by the State of Registry, requiring specific inspections or modifications to correct an unsafe condition. Compliance is compulsory and normally carries a calendar or flight-hour deadline.

A certification made by authorised maintenance personnel after completed work, stating that the aircraft or component is airworthy and fit for the intended flight. It is a legal prerequisite for flight following maintenance.

The approval issued for an aircraft, engine or propeller design showing that it meets the applicable airworthiness requirements. Series production and individual certificates of airworthiness are founded on it.

A human factors framework describing how Liveware, the person, interacts with Software, Hardware, Environment and other Liveware. Mismatches at these interfaces are the source of many maintenance errors.

A self-satisfied state in which a person, through familiarity or repetition, stops actively checking work and assumes everything is correct. In maintenance it leads to missed steps, wrong parts and unrecorded tasks.

The roughly 24-hour cycle of physiological and mental alertness governed by the body clock. Disruption by night shifts, long duty periods or time-zone crossing reduces performance and raises the risk of error.

The point at which the entire weight of an aircraft may be considered to act. Keeping it within the certified forward and aft limits is essential for control, stability and structural loading.

The angle between the chord line of an aerofoil and the direction of the relative airflow. Increasing it raises lift up to the critical angle, beyond which the airflow separates and the wing stalls.

A sudden loss of lift occurring when the angle of attack exceeds its critical value and airflow separates from the upper surface. It can happen at any speed, attitude or weight, and recovery requires reducing the angle of attack.

The ratio of a wing's span to its mean chord, equivalent to span squared divided by plan area. High aspect ratio wings produce less induced drag and are typical of gliders and long-range transports.

A statement of energy conservation for steady, incompressible flow: along a streamline, an increase in fluid velocity is accompanied by a fall in static pressure, and vice versa. It explains lift and venturi and pitot effects.

The upward angle of a wing relative to the horizontal when viewed from the front. It contributes lateral stability by producing a restoring rolling moment when the aircraft sideslips.

The ratio of the lift generated to the weight of the aircraft, expressed in g. Manoeuvring and gusts raise it, increasing structural loads and raising the speed at which the aircraft stalls.

A pressure vessel containing hydraulic fluid and a gas charge, used to store energy, damp pressure surges and provide a reserve for emergency operation or peaks in demand.

A valve in the pressure hull of a pressurised aircraft that regulates how quickly cabin air escapes to atmosphere, thereby controlling cabin differential pressure and cabin altitude.

The aircraft pressure-sensing system that supplies total pressure from a pitot probe and static pressure from static ports to the airspeed indicator, altimeter and vertical speed indicator.

A gas turbine condition in which the compressor stalls aerodynamically and airflow through it breaks down or reverses momentarily. It causes loud bangs and temperature rise, and is prevented by bleed valves and variable inlet guide vanes.

Abnormal, uncontrolled and extremely rapid combustion of the fuel-air charge in a piston engine, producing a sharp pressure spike and knocking. Causes include high temperatures, low octane fuel and excessive ignition advance.

Slow permanent deformation of a material under sustained load at elevated temperature. In turbine blades and discs it limits service life and is monitored by measuring blade length and critical dimensions.

The mass or volume of fuel an engine burns per unit of thrust or power produced per unit time. Lower values mean better efficiency and are used to compare engines and cruise conditions.