CAA NZ AME Subject 2: Aircraft Engineering Knowledge key terms

The primary longitudinal structural member of a wing or tailplane, designed to carry bending and shear loads from the lifting surfaces to the fuselage.

A transverse structural member that shapes an airfoil section, supports the skin, and transfers loads between the skin and the spar.

A longitudinal stiffener attached to the inside of aircraft skin, running spanwise or lengthwise, which helps carry bending loads and prevents the skin from buckling.

A construction method in which the skin carries part of the load but is reinforced by frames, stringers, and bulkheads, combining the light weight of monocoque with greater strength.

A heavy transverse structural member that carries concentrated loads, closes a fuselage section, and may also form a pressure boundary in pressurized aircraft.

The progressive weakening and eventual cracking of a material caused by repeated cyclic stress, even when each individual stress is below the material's ultimate strength.

The angle between an airfoil's chord line and the relative airflow; increasing it raises lift until the critical angle, beyond which the wing stalls.

An imaginary straight line drawn from the leading edge to the trailing edge of an airfoil, used as the reference for measuring angle of attack and camber.

The curvature of an airfoil's upper and lower surfaces; positive camber means the mean line lies above the chord line and generally produces lift at zero angle of attack.

A loss of lift occurring when the angle of attack exceeds the critical value and airflow separates from the upper wing surface; it can happen at any speed or attitude.

The free-stream Mach number at which airflow somewhere on the aircraft first reaches Mach 1, causing shock waves and a rapid rise in drag.

A dangerous self-excited vibration in which aerodynamic forces and structural elasticity reinforce each other, potentially destroying a control surface or wing within seconds.

A hinged control surface near the wingtip that moves in opposite directions on each wing to produce roll and is used to bank the aircraft.

A hinged control surface on the horizontal tailplane that changes the tail's lift and thereby controls the aircraft's pitch attitude in flight.

A hinged vertical-tail control surface that generates yaw about the vertical axis and is used to coordinate turns and counteract adverse yaw.

A small adjustable surface on a primary control that creates a hinge moment, allowing the pilot to relieve control pressure for a given flight condition.

A flight control system in which pilot inputs are converted to electrical signals and processed by computers that command hydraulic or electromechanical actuators, replacing mechanical cables.

A pressure vessel containing hydraulic fluid and a gas charge or spring that stores energy, damps pressure pulses, and supplies temporary flow when pump output drops.

A valve that opens automatically at a set pressure to protect a hydraulic or pneumatic system from overpressure by returning or venting excess fluid.

Compressed air taken from a turbine engine compressor and used for cabin pressurization, air conditioning, anti-ice, and engine starting.

A valve that lets the crew choose which tank supplies the engine and can shut off fuel; correct selection prevents imbalance and unusable fuel.

An inflatable rubber strip on the leading edge of a wing or tail that periodically expands to break off accumulated ice.

A turbine-driven cooling unit in a pressurized aircraft's environmental system that cools bleed air by expanding it and extracting work.

The reciprocating engine operating sequence of intake, compression, power, and exhaust strokes, completed in two crankshaft revolutions.

A self-contained engine-driven ignition device that generates high voltage for spark plugs without relying on the aircraft's electrical system.

An exhaust-driven turbine coupled to a compressor that increases intake manifold pressure, allowing a reciprocating engine to maintain power at altitude.

A breakdown of airflow through a turbine compressor, causing a loud bang, reverse flow, and possible damage when the compressor cannot accept the delivered pressure.

The temperature of exhaust gases leaving a turbine engine, used to monitor engine power and protect the hot section from over-temperature.

A propeller whose blade pitch is automatically varied by a governor to maintain a selected RPM as engine power and airspeed change.

Rotating a propeller blade to an edge-on position to the airflow, minimizing drag after an engine failure and reducing windmilling.

The electrical connection of aircraft metallic parts to each other and to the airframe to provide a low-resistance path for static electricity and fault currents.

A common electrical conductor that distributes power from a source to multiple circuits and allows them to be switched or protected individually.

A system of probes and lines that supplies total pressure from the pitot tube and static pressure from static ports to airspeed, altimeter, and vertical speed instruments.

Corrosion caused by the electrochemical reaction when two dissimilar metals are in contact in the presence of an electrolyte, with the less noble metal being attacked.

An electrolytic process that thickens the natural oxide layer on aluminium, improving corrosion resistance and providing a base for paint.

A safety method in which twisted wire is threaded through drilled fastener heads to prevent them from loosening under vibration.

A mandatory instruction issued by the aviation authority to correct an unsafe condition in aircraft, engines, or components, requiring compliance within a stated time.

An approved document that allows an aircraft to be dispatched with specified items inoperative, subject to defined conditions and maintenance procedures.

Raising an aircraft on purpose-built lifting devices at designated points to allow landing gear, structural, or systems work, with precautions against tipping.