Brunei DCA CPL AGK - Airframe, Systems & Power Plant key terms

A fuselage or wing construction in which the load is carried mainly by the stressed skin, with frames and stringers stiffening it against buckling rather than forming a heavy load-bearing frame.

A longitudinal stiffening member riveted to the skin of a semi-monocoque structure that carries bending loads and prevents the thin skin from buckling under compression or shear.

A heavy transverse structural member in the fuselage that carries concentrated loads, closes a pressure bulkhead boundary, or provides a hard attachment point for wings, engines or landing gear.

The main longitudinal beam of a wing that carries bending and shear loads from the lift distribution and provides the primary attachment to the fuselage centre section.

A chordwise structural member of a wing or tailplane that maintains the aerofoil shape, supports the skin and stringers, and transfers loads between them and the spar.

A primary flight control hinged near the trailing edge of the outer wing that moves differentially to produce roll, one rising as the other falls.

A primary flight control on the trailing edge of the horizontal stabiliser that changes pitch attitude by increasing or decreasing the tail downforce.

A primary flight control hinged to the vertical stabiliser that produces yaw about the normal axis and is used to balance turns and counter adverse yaw.

A small secondary control surface hinged to the trailing edge of a primary control that relieves steady stick or pedal forces by holding the main surface in a deflected position.

A secondary lift-augmenting surface on the wing trailing edge that increases camber and often wing area, allowing lower approach speeds and steeper descent angles without exceeding limits.

A leading-edge lift device that extends forward to form a slot, energising the boundary layer over the wing upper surface so that higher angles of attack are usable before stall.

A tank that stores system fluid, allows for thermal expansion and contraction, accommodates pump flow demand, and provides a head of pressure at the pump inlet to prevent cavitation.

A device that converts mechanical drive from an engine or electric motor into fluid flow and pressure, commonly of the gear, vane, piston or variable-displacement type with a pressure compensator.

A pressure vessel containing a gas charge separated from the hydraulic fluid by a bladder, diaphragm or piston, used to store energy, damp pressure surges and supply flow during peak demand.

A valve that opens at a preset pressure to return fluid to the reservoir, protecting the system and its components from overpressure if a pump or control malfunctions.

A directional control valve that routes hydraulic pressure to one side of an actuator and connects the other side to return, determining the direction and often the speed of component movement.

A hydraulic cylinder or motor that converts fluid pressure and flow into linear or rotary mechanical movement to operate landing gear, flaps, flight controls or doors.

Compressed air tapped from a gas turbine compressor stage and used for cabin pressurisation, air conditioning, engine anti-ice and, on some types, engine starting or hydraulic reservoir pressurisation.

A motorised valve in the pressure hull that regulates the rate at which cabin air escapes to atmosphere, thereby controlling cabin altitude and the rate of climb or descent of cabin pressure.

The difference between cabin pressure and ambient static pressure, limited by structural design and normally kept below the maximum by pressure controllers and safety relief valves.

A cooling pack in which hot bleed air passes through a primary heat exchanger, compressor and secondary heat exchanger, is expanded through a turbine, and emerges cold for cabin supply.

An AC generator whose output is rectified to DC in light aircraft, or which supplies AC directly on larger aircraft, driven by the engine through a belt or gearbox.

Electronic equipment that regulates generator or alternator output voltage, controls field excitation, monitors for faults such as overvoltage or open phase, and trips the generator offline when required.

A conductive distribution point that receives power from generators, batteries or external supplies and feeds it through circuit breakers to the individual electrical loads of the aircraft.

A resettable protective device that opens the circuit automatically on overload, protecting wiring and components from overheating, and may be of the thermal or magnetic type.

A one-shot protective device containing a metal element that melts and permanently opens the circuit when current exceeds its rating, protecting wiring from overheating and fire.

A rechargeable battery with high current capability used for engine starting and emergency power, requiring careful charging because of thermal runaway and cell imbalance risks.

A hydraulic or friction device fitted to a nose landing gear that resists rapid castoring oscillation of the wheel about its vertical axis during taxi, take-off and landing.

A folding scissor linkage on a landing gear leg that allows the shock strut to extend and compress while preventing rotation of the lower leg about the oleo axis.

A system using wheel speed sensors and control valves to modulate brake pressure and prevent wheel lock and skidding, preserving steering control and minimising stopping distance on slippery runways.

A motive-flow pump with no moving parts that uses high-pressure fuel from an engine-driven pump to entrain and transfer fuel from a tank, often used to keep collector tanks full.

A small tank inside a main fuel tank that is kept full by transfer pumps so that engine feed outlets remain submerged during uncoordinated flight, low fuel states or negative-g manoeuvres.

The system, commonly using capacitance probes or float sensors, that measures and displays the fuel mass or volume in each tank and drives low-level warnings and imbalance indications.

An inflatable rubber strip on a wing or tailplane leading edge that cycles between inflated and deflated states to break off and shed accumulated ice in flight.

A system that pumps glycol-based fluid through porous panels or laser-drilled holes in the leading edges to prevent ice formation and to help remove existing ice.

Electrical heating of the pitot tube and static ports that prevents ice blockage, which would otherwise cause erroneous airspeed, altitude and climb indications.

A continuous sensing element routed around an engine or compartment that changes resistance or capacitance with temperature rise and triggers a warning in the cockpit.

A pressurised container of extinguishing agent discharged through a squib or valve into a designated fire zone, often with two bottles and a choice of one or both.

A crew mask regulator that supplies oxygen only on inhalation and mixes cabin air with oxygen according to altitude, so that the delivered concentration suits the cabin altitude.

Ice formation in the venturi and throttle region caused by fuel vaporisation and pressure drop, which leans the mixture and reduces power even at ambient temperatures well above freezing.

A pilot-controlled valve that admits heated air from around the exhaust to the carburettor inlet, melting ice but also enriching the mixture and slightly reducing maximum power.

The cockpit control that sets the fuel-to-air ratio delivered by the carburettor or fuel injection system, leaned for altitude and economy and enriched for high power settings.

A system that meters fuel directly into the intake ports or cylinders rather than through a venturi, giving more even mixture distribution and immunity to carburettor icing.

A self-contained engine-driven ignition unit that generates its own high-tension supply and fires one spark plug per cylinder, with two magnetos providing independent redundancy.

The screened high-tension leads and connectors that carry the magneto output to the spark plugs, with shielding to prevent radio interference and secure terminals to avoid flashover.

A propeller governor that senses engine rpm and adjusts oil pressure to the propeller hub to change blade angle, holding a selected rpm as power or airspeed varies.

Rotating propeller blades to a coarse angle near the flight direction so that an inoperative engine produces minimum drag and the windmilling propeller stops.

A system that matches the rpm of two or more propellers on the same aircraft so that their blade passing frequencies coincide, reducing beat noise and vibration.

Ice accretion on blades and spinner that disturbs balance and efficiency and can cause severe vibration, usually countered by heated blade elements or fluid anti-ice.

A gas turbine compressor stage arrangement in which air flows parallel to the shaft through alternating rotor and stator rows, each row raising pressure by a modest amount.

A breakdown of smooth airflow through the compressor, causing violent pressure fluctuations, bang noises, high exhaust gas temperature and possible flameout if not corrected by reducing power.

The section where fuel is sprayed into compressed air and burned continuously, raising gas temperature and energy before the flow enters the turbine nozzle guide vanes.

The temperature of gas leaving the turbine, a key engine limit used to set take-off power and to monitor combustion, cooling and turbine condition in service.

A means of increasing thrust beyond dry rating, such as afterburning in a jet pipe or water-methanol injection, used for short periods at take-off or in combat.