CPL Aircraft General Knowledge flashcards

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

Density altitude

Pressure altitude corrected for non-standard temperature; it rises about 120 ft per 1 °C above ISA and reduces engine power, lift and climb performance.

Load factor in turn

In a level coordinated turn, load factor equals one divided by the cosine of the bank angle; at 60° bank it is 2 and stall speed rises by about 41 %.

Ultimate load

The load at which structural failure must not occur; it equals 1.5 times the limit load, the maximum load expected in service.

Semi-monocoque structure

Construction in which the stressed skin and longitudinal stringers carry most loads while frames and bulkheads maintain shape and resist concentrated loads.

Differential ailerons

Ailerons rigged to deflect upward more than downward, reducing adverse yaw by limiting the drag increase on the descending wing.

Control reversal

A condition in which aerodynamic hinge moment twists the wing or tail faster than the surface can deflect, limiting VMO or VNE for irreversible control systems.

Hydraulic accumulator

A pressure vessel that stores hydraulic energy, damps pressure pulses and supplies temporary pressure for emergency operation or peak demand.

Fuel crossfeed

A valve arrangement allowing fuel from any tank to supply either engine, used to correct imbalance or to feed engines after a pump failure.

Pitot heat

Electrical heating of the pitot tube and static ports that prevents ice blockage; loss of heating causes erroneous airspeed and altitude indications.

Manifold pressure

Absolute pressure in the engine intake manifold, used with rpm to set piston engine power; full-throttle value falls about 1 inHg per 1000 ft.

Constant-speed propeller

A propeller whose governor varies blade pitch to hold a selected rpm as power or airspeed changes, improving efficiency over a fixed-pitch design.

Turbine hot start

A start in which EGT rises above limits because of excess fuel or poor air supply; the start must be aborted and the engine inspected.

Altimeter setting QNH

The pressure setting that makes the altimeter indicate elevation above mean sea level when on the ground at the reference station.

Standard rate turn

A turn of 3° per second, requiring a bank angle of roughly 15 % of true airspeed and taking two minutes for a full 360° turn.

V1 decision speed

The speed at which a failure is recognised and the take-off or stop decision is made; it is chosen so accelerate-stop and accelerate-go distances are compatible.

Stall speed formula

Stall speed equals the square root of twice the weight divided by air density, wing area and maximum lift coefficient; it rises with weight and altitude.

Pitot blockage effects

With the pitot blocked and static clear, the airspeed indicator behaves like an altimeter: airspeed increases in a climb and decreases in a descent.

Static blockage effects

With the static source blocked, the airspeed indicator over-reads in a climb, the altimeter freezes and the vertical speed indicator reads zero.

GPWS modes

Ground proximity warnings for excessive descent rate, terrain closure, altitude loss after take-off, unsafe terrain clearance and glideslope deviation; EGPWS adds a terrain database.

Flap effect on lift

Flap extension increases the maximum lift coefficient and drag; take-off settings give lift with little drag penalty, landing settings give maximum lift and steep descent capability.

Flight control rigging

Adjustment of cables, rods and stops so each surface reaches full deflection without overtravel; stops must be checked at the surface, not in the cockpit.

Mass balance

Weights placed ahead of a control surface hinge line to raise the flutter critical speed; balance must be maintained after painting or repair.

Bleed air leak detection

Overheat sensing loops that close the bleed valve and show a fault when duct temperature exceeds limits, protecting the airframe from hot-air damage.

Anti-ice versus de-ice

Anti-ice prevents ice formation using thermal or electric heat; de-ice removes ice already formed, typically with inflatable boots operated cyclically.

Fuel freeze point

The temperature at which wax crystals form in jet fuel; Jet A-1 is about −47 °C and Jet A about −40 °C, and fuel temperature must stay above it.

Carburettor icing

Ice formation in the carburettor at ambient temperatures of roughly 0–20 °C with high humidity; carburettor heat is applied before reducing power.

Turbine N1 and N2

N1 is the low-pressure or fan spool speed and N2 the high-pressure spool speed; both are expressed as percentages and must stay within limits.

Feathering a propeller

Turning the blades to a high angle so they align with the airflow, minimising drag and vibration after an engine failure on a multi-engine aircraft.

TCAS resolution advisory

A traffic alert that commands a specific vertical manoeuvre; the crew must follow the RA promptly and must not manoeuvre opposite to it.

Balanced field length

The longer of the accelerate-stop and accelerate-go distances; V1 is selected so both distances are equal or within the available runway.

VREF approach speed

The landing reference speed, normally 1.3 times the stall speed in the landing configuration, used to compute landing distance and flare.

Fly-by-wire normal law

A control mode in which computers provide stall, overspeed, bank and pitch protection; alternate and direct law reduce or remove these protections after failures.