Brunei DCA CPL AGK - Airframe, Systems & Power Plant flashcards

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

Semi-monocoque fuselage

Construction in which the stressed skin carries most shear and tension loads, while frames and stringers stiffen the skin against buckling and carry concentrated loads.

Wing spar cap load

The upper spar cap carries compression and the lower cap carries tension when the wing bends upward in flight; the spar web resists shear between them.

Differential aileron travel

The up-going aileron deflects through a larger angle than the down-going one, equalising drag on both wings and reducing adverse yaw during roll.

Servo tab function

A small tab that moves in the opposite direction to the control surface, generating an aerodynamic force that drives the surface and reduces the pilot's control effort.

Accumulator precharge check

With the hydraulic system unpressurised, the nitrogen precharge is checked against the maintenance figure; low precharge reduces emergency braking and surge damping.

Hydraulic relief valve

A valve that opens at a set pressure to return fluid to the reservoir, protecting the system and seals from overpressure if the regulator fails.

Hydraulic pressure regulator

An unloading valve that senses system pressure and diverts pump output back to the reservoir once the set pressure is reached, holding pressure constant.

Air-cycle machine cooling

Bleed air is cooled in a heat exchanger, compressed, cooled again, then expanded through a turbine that drops its temperature and drives the compressor.

Cabin differential pressure

The difference between cabin pressure and outside ambient pressure; it is limited by a relief valve so the fuselage structure is never overstressed.

Outflow valve role

A valve that controls the rate at which cabin air leaves the aircraft, thereby setting cabin altitude and rate of change during climb and descent.

Reverse-current relay

A relay that opens the circuit when current flows from the battery back into the generator, preventing the generator from running as a motor and draining the battery.

Constant-speed drive

A unit between the engine and an AC generator that keeps generator speed, and therefore output frequency, constant as engine speed varies.

Circuit breaker reset rule

A tripped circuit breaker may only be reset once the cause has been identified and cleared; repeated resetting risks fire from a persistent short circuit.

Oleo shock strut

An air-and-oil strut in which compressed nitrogen supports static load and oil forced through an orifice absorbs the energy of landing impact.

Anti-skid system

Wheel speed sensors and a control valve modulate brake pressure to keep wheel slip near the optimum, preventing locked wheels and preserving steering control.

Tyre fuse plug

A heat-sensitive plug in the wheel that melts at high brake temperature, releasing tyre pressure gradually instead of allowing an explosive blow-out.

Capacitance fuel gauging

Fuel quantity is derived from the change in capacitance between probes as fuel, with a different dielectric constant from air, fills the tank.

Boost pump purpose

An electric pump in the tank that supplies positive fuel pressure to the engine pump, preventing vapour lock and maintaining flow at high altitude.

Crossfeed valve

A valve connecting the left and right fuel supply lines so either engine can be fed from either tank, allowing imbalance to be corrected in flight.

Carburettor icing range

Ice can form in the carburettor at outside temperatures roughly between minus 10 and plus 20 degrees Celsius when humidity is high, causing power loss.

Fire loop detector

A continuous sensing element around the engine that changes resistance when heated, triggering an overheat or fire warning in the cockpit.

Chemical oxygen generator

A sodium chlorate candle that produces oxygen when ignited, used for passenger masks; once started it cannot be switched off.

Magneto function

A self-contained engine-driven generator that produces the high-tension voltage for the spark plugs, independent of the aircraft electrical system.

Carburettor venturi

A narrowed throat in the induction passage where airflow speeds up and pressure falls, drawing fuel through the main jet into the airstream.

Dry-sump lubrication

Oil is stored in a separate tank, a pressure pump feeds the engine and a scavenge pump returns oil to the tank, allowing inverted flight and better cooling.

Geometric pitch

The theoretical distance a propeller would advance in one revolution if it screwed through the air without slip; effective pitch is always less.

Propeller governor

A flyweight-controlled valve that ports oil to or from the propeller hub to change blade angle and hold the RPM selected by the pilot.

Feathering

Rotating the propeller blades to approximately edge-on to the relative airflow so that drag is minimised after an engine failure.

Compressor surge

A breakdown of airflow through the compressor, with flow reversal and loud bangs, caused by excessive blade angle of attack or disturbed inlet air.

Turbine gas temperature

The temperature of the gas entering or leaving the turbine; it is the main limiting parameter because excessive temperature damages turbine blades.

Afterburner

A thrust augmentation system that adds fuel downstream of the turbine and burns it in the exhaust, giving a large short-term increase in thrust.

Hot start

A turbine start in which fuel is introduced before sufficient airflow exists, causing excessively high turbine temperature; it must be aborted immediately.