CPL AGK / Systems flashcards

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

Fail-safe structure

A design approach where redundant load paths, crack stoppers and multiple members ensure a single crack or failure cannot cause catastrophic structural failure before it is detected in inspection.

Semi-monocoque fuselage

A structure in which the skin and stringers carry tension and shear loads while frames and bulkheads maintain shape and carry concentrated loads such as wing and landing gear attachments.

Flutter prevention

Control surfaces are mass balanced so their centre of gravity lies ahead of the hinge line, preventing aerodynamic energy from feeding uncontrolled oscillation of the surface and structure.

Asymmetric flap protection

A system that detects unequal flap extension, stops flap motion and displays a warning, because asymmetry produces a strong rolling moment that may exceed available control authority.

Hydraulic accumulator

A gas-charged pressure vessel that stores hydraulic energy for peak demands, emergency operation and damping of pressure pulsations; precharge is checked with the system depressurised.

Constant-delivery pump

A hydraulic pump that delivers a fixed volume per revolution; a pressure regulator and relief valve return excess flow to the reservoir and limit system pressure.

Sequence valve

A hydraulic valve that permits flow to a second actuator only after a first actuator has completed its movement, such as opening gear doors before extending the landing gear.

Hydraulic priority valve

A valve that reduces or cuts flow to non-essential consumers when system pressure falls, preserving pressure for essential services such as flight controls and brakes.

Bleed air sources

Pressurised air taken from engine compressor stages, the APU load compressor or a ground cart, used for anti-icing, air conditioning, pressurisation, engine starting and hydraulic reservoir pressurisation.

Outflow valve

A valve that modulates the rate at which cabin air leaves the aircraft, thereby controlling cabin altitude and the pressure differential between cabin and outside atmosphere.

Air cycle machine

A compressor-turbine unit in an air-conditioning pack that cools bleed air by expanding it through a turbine; heat exchangers and a water separator complete the pack.

Cabin altitude warning

A warning that activates when cabin pressure altitude exceeds about 10,000 feet, alerting the crew to a pressurisation failure before passenger oxygen is required.

Transformer-rectifier unit

A unit that converts AC electrical power into 28 volt DC for aircraft DC buses, often replacing or supplementing engine-driven DC generators on transport aircraft.

Integrated drive generator

An AC generator combined with a constant-speed drive that holds generator frequency constant at 400 Hz regardless of engine speed, with the generator control unit providing protection.

Generator control unit

An electronic unit that regulates generator voltage, controls connection to the bus and trips the generator offline for overvoltage, undervoltage, overfrequency or feeder faults.

Nickel-cadmium battery

An aircraft battery type requiring electrolyte level checks that can suffer thermal runaway if overheated or overcharged, so overheat detection and correct charging are important.

Capacitance fuel gauging

A fuel quantity system using probes whose capacitance changes with fuel level; a compensator corrects for fuel density so the indicated mass remains accurate.

Fuel tank venting

Vents keep tank pressure close to ambient during refuelling, feeding and climb or descent, preventing structural overpressure and avoiding vacuum that could stop fuel flow.

Fuel crossfeed valve

A valve connecting left and right fuel manifolds so that either tank can feed either or both engines, used for balancing fuel and for feeding during a boost pump failure.

Fuel jettison system

A system that dumps fuel from outer tanks to reduce aircraft weight to landing limits, interlocked so fuel needed by the engines is not dumped.

Propeller feathering

Rotating the propeller blades to a high pitch angle that minimises drag after an engine failure, reducing asymmetric drag and allowing the engine to be secured.

Propeller beta range

The ground operating range of propeller blade angle below flight idle, used for taxi and reverse thrust, where blade angle is controlled directly rather than by the governor.

Air-turbine starter

A starter driven by bleed air that rotates the engine compressor up to self-sustaining speed, after which ignition and fuel are established and the starter cuts out.

Oil chip detector

A magnetic plug in the engine oil system that collects ferrous metal particles, indicating internal wear or damage when inspected or when it triggers a warning.

Pitot heater failure

Loss of pitot heat can allow ice to block the pitot tube, causing airspeed indications to behave like a blocked pitot and making airspeed unreliable.

Carburettor icing conditions

Ice can form in the carburettor at outside air temperatures between about minus five and plus fifteen degrees Celsius with high humidity, and is cleared by applying carburettor heat.

Windscreen anti-ice and rain removal

Electrical heating prevents ice and fog on the windscreen, while wipers or a rain-repellent coating remove rain; uncontrolled heat can crack the glass.

Antiskid system

A braking system that uses wheel speed sensors to detect an impending locked wheel and modulates brake pressure to maintain optimum slip and retain steering control.

Landing gear downlock

A mechanical lock that holds the landing gear in the extended position, confirmed by green indicator lights and required before landing.

Fusible plug

A plug in the wheel assembly with a low melting point that releases tyre pressure if brake heat raises wheel temperature, preventing a tyre burst.

Blocked static port

A blocked static source causes the altimeter to freeze at the trapped pressure and the airspeed indicator to over-read in climb and under-read in descent.

Master caution and warning

Central alerting that draws attention to a system fault: master warning (red) for urgent conditions and master caution (amber) for conditions needing attention.

AHRS

An attitude and heading reference system using solid-state sensors to compute attitude and heading for the displays, replacing mechanical gyroscopes.

Engine fire loop

A continuous sensing element around an engine that responds to overheat or fire and triggers a fire warning, with dual loops providing fault tolerance.

Passenger oxygen deployment

Passenger oxygen masks drop automatically when cabin altitude reaches about 14,000 feet, supplied by chemical generators or a manifold from the crew oxygen system.

Emergency locator transmitter

A device that transmits a distress signal on 121.5 and 406 MHz after activation by impact or manually, aiding search and rescue after an accident.

Autopilot disengagement

The autopilot disconnects when the pilot overrides it, when a fault or sensor failure occurs, or when required data is lost, giving an aural and visual warning.

Flight director

A system that computes and displays guidance cues on the attitude indicator for the pilot to follow, using the same commands the autopilot would apply.

ARINC 429 data bus

A widely used avionics digital data bus that transmits labelled parameters one way between line-replaceable units, allowing modular avionics architecture.

TCAS resolution advisory

A traffic alert and collision avoidance command that instructs the crew to climb or descend to increase separation, and may command the autopilot to follow it.