ATPL Aircraft General Knowledge flashcards
ATPL Aircraft General Knowledge · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Ultimate load factor
- The load the structure must withstand for three seconds without failure, equal to 1.5 times the limit load expected in service.
- Fail-safe structure
- A design in which a cracked or failed member sheds its load to redundant structure so the aircraft remains safe until the defect is found.
- Open-centre selector valve
- A hydraulic selector that routes pump flow back to the reservoir at neutral, unloading the pump and allowing a fixed-displacement pump without a regulator.
- Hydraulic accumulator precharge
- The nitrogen charge in an accumulator, set with the hydraulic system depressurised, that stores energy for peak demand and damps pressure surges.
- Cabin pressure altitude
- The altitude corresponding to the cabin pressure; controlled by the outflow valve and limited to about 8,000 ft without supplementary oxygen.
- Maximum differential pressure
- The limit on cabin pressure minus ambient pressure, protected by the outflow valve and the positive pressure relief valve to avoid structural overstress.
- Air-cycle cooling machine
- A bootstrap system in which bleed air passes heat exchangers and a compressor, then expands through a turbine that drops its temperature before cabin delivery.
- Diluter-demand oxygen regulator
- A crew regulator that mixes cabin air with oxygen on demand up to about 33,000–40,000 ft, above which 100% oxygen with pressure breathing is needed.
- Pneumatic de-icing boot
- An inflatable rubber strip on the leading edge that cycles to crack and shed accumulated ice; it removes ice rather than preventing its formation.
- Holdover time
- The estimated period a de-icing or anti-icing fluid protects the aircraft against ice accretion, depending on fluid type, precipitation, temperature and wind.
- Type IV anti-icing fluid
- A thickened, high-viscosity fluid giving the longest holdover time of the anti-icing fluids, used when precipitation is expected before takeoff.
- Continuous-loop fire detector
- A sensing wire whose resistance falls with temperature to trigger a fire warning; a shorted or open loop normally produces a fault indication.
- Halon 1301
- Bromotrifluoromethane, the standard extinguishing agent for engine and APU fires, effective at about 5–10% concentration by inhibiting the flame reaction.
- Engine fire handle
- A cockpit control that closes the fuel shut-off valve, bleed and electrical supply to the engine before the extinguishing agent is discharged.
- Transformer-rectifier unit
- A unit that converts 115 V 400 Hz AC into 28 V DC to charge the battery and supply the DC buses when AC power is available.
- Constant-speed drive
- A unit between engine and AC generator that keeps generator speed, and therefore output frequency at 400 Hz, constant despite engine speed changes.
- Battery bus
- A bus fed directly from the battery, supplying essential loads and remaining powered when all generators have failed.
- Nicad thermal runaway
- A condition in nickel-cadmium batteries where overcharging raises temperature, lowering internal resistance and increasing current until the battery overheats.
- Detonation
- Uncontrolled explosive combustion of the fuel-air charge causing high peak cylinder pressures, raised head temperature and possible engine damage.
- Engine pressure ratio
- Turbine discharge pressure divided by compressor inlet pressure, used as a thrust parameter on turbojet and low-bypass turbofan engines.
- Hung start
- A turbine start in which the engine fails to accelerate to idle speed, usually from insufficient starter power or fuel scheduling.
- Wet start
- A start in which fuel is supplied but ignition does not occur, leaving unburnt fuel that must be cleared by motoring before another attempt.
- Propeller blade angle
- The angle between the blade chord line and the plane of rotation; coarse pitch suits high speed, fine pitch suits takeoff and high power at low speed.
- Propeller feathering
- Rotating the blades to align with the relative airflow, minimising drag and stopping windmilling after an engine failure.
- Advance ratio
- Forward speed divided by rotational speed times diameter (V/nD); propeller efficiency peaks at a particular value of this ratio.
- Capacitance fuel gauge
- A gauge measuring the dielectric change of fuel between probe electrodes; because it responds to density it indicates mass only when calibrated.
- Oil pressure relief valve
- A valve that limits lubrication system pressure by bypassing excess oil, protecting seals and lines especially when oil is cold and viscous.
- Exhaust gas temperature
- The temperature of exhaust gases, used to set mixture and monitor engine condition; it peaks near stoichiometric mixture and falls when richer or leaner.
- Differential ailerons
- Ailerons rigged to deflect more upward than downward, reducing adverse yaw by balancing the induced drag of the descending wing.
- Anti-balance tab
- A tab that moves in the same direction as the control surface, increasing control feel and preventing overbalance on stabilators.
- Squat switch
- A weight-on-wheels switch that prevents landing gear retraction on the ground and inhibits systems such as pressurisation and some autopilot functions.
- Oleo strut
- A landing gear shock absorber using compressed nitrogen as the spring and hydraulic oil forced through an orifice as the damper.