Glossary

A fixture that allows a shaft to be centered and rotated to measure any out-of-round condition.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A form of reciprocating engine in which the cylinders are arranged in two banks. The banks are separated by an angle of between 45º and 90º. Pistons in two cylinders, one in each bank, are connected to each throw of the crankshaft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A chart that relates velocity to load factor. It is valid only for a specific weight, configuration and altitude and shows the maximum amount of positive or negative lift the airplane is capable of generating at a given speed. Also shows the safe load factor limits and the load factor that the aircraft can sustain at various speeds.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

The maximum structural cruising speed. Do not exceed this speed except in smooth air. The upper limit of the green arc.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

A design which utilizes two slanted tail surfaces to perform the same functions as the surfaces of a conventional elevator and rudder configuration. The fixed surfaces act as both horizontal and vertical stabilizers.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

See takeoff decision speed.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

See takeoff safety speed.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

See maneuvering speed.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

Electrons in the outer shell, or ring, around the nucleus of an atom. It is the valence electrons that give an atom its electrical characteristics and are the electrons that may be pulled loose from an atom to cause electrical current.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

The portion of the operating cycle of a four-stroke-cycle reciprocating engine during which both the intake and exhaust valves are off of their seats at the same time.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A condition in which vapors form in the fuel lines and block the flow of fuel to the carburetor.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

The portion of atmospheric pressure that is exerted by the moisture in the air (expressed in tenths of an inch of mercury).

Aviation Maintenance Technician Handbook — General, p. G-11

The changing of a liquid into a vapor.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A fluid pump whose output is controlled by the demands of the system. These pumps normally have a built-in system pressure regulator. When the demands of the system are low, the pump moves very little fluid, but when the demands are high, the pump moves a lot of fluid. Most variable displacement pumps used in aircraft hydraulic systems are piston-type pumps.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

The angular difference between true north and magnetic north; indicated on charts by isogonic lines.

Helicopter Flying Handbook, p. G-6

A material used to produce an attractive and protective coating on wood or metal. Varnish is made of a resin dissolved in a solvent and thinned until it has the proper viscosity to spray or brush. The varnish is spread evenly over the surface to be coated, and when the solvents evaporate, a tough film is left.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

A petroleum product similar to naphtha used as a solvent and cleaning fluid.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

See visual approach slope indicator.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

See visual descent point.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

A turbojet or turbofan engine with the fan and/or exhaust nozzles mounted in such a way that they may be rotated in flight to produce forward, vertically upward, or rearward thrust.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

Navigational guidance by assigning headings.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

Calibrated airspeed at which the critical engine of a multi-engine aircraft is assumed to fail.

Pilot's Handbook of Aeronautical Knowledge, p. G-32

A vector quantity that expresses both the speed an object is moving and the direction in which it is moving.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A turbine driven by forces produced by the velocity, rather than the pressure, of gases flowing through the vanes.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

Thin sheets of wood “peeled” from a log. A wide-blade knife held against the surface of the log peels away the veneer as the log is rotated in the cutter. Veneer is used for making plywood. Several sheets of veneer are glued together, with the grain of each sheet placed at 45° or 90° to the grain of the sheets next to it.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

A specially shaped restrictor in a tube designed to speed up the flow of fluid passing through it. According to Bernoulli’s principal, any time the flow of fluid speeds up without losing or gaining any energy from the outside, the pressure of the fluid decreases.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A specially shaped tube attached to the outside of an aircraft to produce suction to allow proper operation of gyro instruments.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

A timing coupling used with base-mounted magnetos. The vernier coupling allows the timing to be adjusted in increments of considerably less than one degree.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

An imaginary line, passing vertically through the center of gravity of an airplane.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

A magnetic compass that consists of an azimuth on a vertical card, resembling a heading indicator with a fixed miniature airplane to accurately present the heading of the aircraft. The design uses eddy current damping to minimize lead and lag during turns.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

The fixed vertical surface in the empennage of an airplane. The vertical fin acts as a weathervane to give the airplane directional stability.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

A rate-of-pressure change instrument that gives an indication of any deviation from a constant pressure level.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

Stability about an aircraft’s vertical axis. Also called yawing or directional stability.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

A tall rectangular instrument that displays the quantity of the parameter being measured by a movable strip of colored tape. The presentation resembles a vertical bar graph.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A vibration in which the movement is up and down, or vertical, as in an out-of-track condition.

Helicopter Flying Handbook, p. G-6

A band of radio frequencies falling between 30 and 300 MHz. Very-high frequency omnidirectional range (VOR). Electronic navigation equipment in which the flight deck instrument identifies the radial or line from the VOR station, measured in degrees clockwise from magnetic north, along which the aircraft is located.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

The central cavity of the bony labyrinth of the ear, or the parts of the membranous labyrinth that it contains.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

The maximum speed with the flaps extended. The upper limit of the white arc.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

ATC authorization for an IFR aircraft to operate in VFR conditions at any appropriate VFR altitude.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

At a scale of 1:250,000, a chart that depicts Class B airspace, which provides for the control or segregation of all the aircraft within the Class B airspace. The chart depicts topographic information and aeronautical information including visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

A loop in a rigid fluid line used to prevent vibration from concentrating stresses that could cause the line to break.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A type of voltage regulator used with a generator or alternator that intermittently places a resistance in the field circuit to control the voltage. A set of vibrating contacts puts the resistor in the circuit and takes it out several times a second.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

Airways based on a centerline that extends from one VOR or VORTAC navigation aid or intersection, to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

Vectoring in forward flight. A method of enhancing the maneuverability of an airplane by vectoring the exhaust gases and/or fan-discharge air to produce thrust components not parallel to the longitudinal axis of the aircraft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

An instrument used to measure the viscosity of a liquid. The time required for a given volume of liquid at a specified temperature to flow through a calibrated orifice is used to indicate the viscosity of the liquid.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

The resistance of a fluid to flow. Viscosity refers to the “stiffness” of the fluid, or its internal friction.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

A specially shaped cup with an accurately sized hole in its bottom. The cup is submerged in the liquid to completely fill it. It is then lifted from the liquid and the time in seconds is measured from the beginning of the flow through the hole until the first break in this flow. The viscosity of the liquid relates to this time.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

A measure of change in viscosity of an oil as it changes temperature. The higher the viscosity index, the less the viscosity changes.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

An additive used to produce a multi-viscosity lubricating oil. The polymer additive expands as temperature increases and contracts as temperature decreases. VI improvers cause viscosity to increase as oil heats and decrease as it cools.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

A visual aid of lights arranged to provide descent guidance information during the approach to the runway. A pilot on the correct glideslope will see red lights over white lights.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

A defined point on the final approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the runway touchdown point may be commenced, provided the runway environment is clearly visible to the pilot.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

Flight rules adopted by the FAA governing aircraft flight using visual references. VFR operations specify the amount of ceiling and the visibility the pilot must have in order to operate according to these rules. When the weather conditions are such that the pilot cannot operate according to VFR, he or she must use instrument flight rules (IFR).

Pilot's Handbook of Aeronautical Knowledge, p. G-33

Meteorological conditions expressed in terms of visibility, distance from cloud, and ceiling meeting or exceeding the minimums specified for VFR.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

A metal-cutting hand file that has curved teeth across its faces. Vixen files are used to remove large amounts of soft metal.

Aviation Maintenance Technician Handbook — Airframe, p. G-38

Landing gear extended speed. The maximum speed at which an airplane can be safely flown with the landing gear extended.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

Landing gear operating speed. The maximum speed for extending or retracting the landing gear if using an airplane equipped with retractable landing gear.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

Minimum control airspeed. This is the minimum flight speed at which a light, twin-engine airplane can be satisfactorily controlled when an engine suddenly becomes inoperative and the remaining engine is at takeoff power.

Pilot's Handbook of Aeronautical Knowledge, p. G-33

Never-exceed speed. The maximum speed the aircraft is allowed to attain in any conditions of flight.

Aviation Maintenance Technician Handbook — Airframe, p. G-39

A liquid that easily changes into a vapor.

Aviation Maintenance Technician Handbook — Airframe, p. G-39

Computer memory that is lost when the power to the computer is turned off.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

The characteristic of a liquid that relates to its ability to vaporize or change into a gas.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

The basic unit of electrical potential or electromotive force. A potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance.

Aviation Maintenance Technician Handbook — General, p. G-11

A current-measuring instrument, designed to indicate voltage by measuring the current flow through a resistance of known value.

Aviation Maintenance Technician Handbook — General, p. G-11

A precision resistor in series with a voltmeter mechanism used to extend the range of the basic meter or to allow a single meter to measure several ranges of voltage.

Aviation Maintenance Technician Handbook — Airframe, p. G-39

The amount of space within a three-dimensional solid.

Aviation Maintenance Technician Handbook — General, p. G-11

The ratio of the volume of the charge of the fuel and air inside the cylinder of a reciprocating engine to the total physical volume of the cylinder.

Aviation Maintenance Technician Handbook — Powerplant, p. G-30

Hans Pabst. The designer and developer of the first turbojet engine to power an airplane. His HeS3b engine was built in Germany by the Heinkel Company and it flew in a Heinkel He178 airplane on August 27, 1939.

Aviation Maintenance Technician Handbook — Powerplant, p. G-31

A ground facility which emits a test signal to check VOR receiver accuracy. Some VOTs are available to the user while airborne, while others are limited to ground use only.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

A whirling motion in a fluid.

Aviation Maintenance Technician Handbook — Airframe, p. G-39

A high-velocity stream of compressor bleed air blown from a nozzle into an area where vortices are likely to form. Vortex dissipaters destroy the vortices that would otherwise suck debris from the ground into engines mounted in pods that are low to the ground.

Aviation Maintenance Technician Handbook — Powerplant, p. G-31

Small, low-aspect-ratio airfoils installed in pairs on the upper surface of a wing, on both sides of the vertical fin just ahead of the rudder, and on the underside of the vertical stabilizers of some airplanes. Their function is to pull high-energy air down to the surface to energize the boundary layer and prevent airflow separation until the surface reaches a higher angle of attack.

Aviation Maintenance Technician Handbook — Airframe, p. G-39

A transient condition of downward flight (descending through air after just previously being accelerated downward by the rotor) during which an appreciable portion of the main rotor system is being forced to operate at angles of attack above maximum. Blade stall starts near the hub and progresses outward as the rate of descent increases.

Helicopter Flying Handbook, p. G-6

See VOR test facility.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

The stalling speed or the minimum steady flight speed in the landing configuration. In small airplanes, this is the power-off stall speed at the maximum landing weight in the landing configuration (gear and flaps down). The lower limit of the white arc.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

The stalling speed or the minimum steady flight speed obtained in a specified configuration. For most airplanes, this is the power-off stall speed at the maximum takeoff weight in the clean configuration (gear up, if retractable, and flaps up). The lower limit of the green arc.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

See vertical speed indicator.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

Best angle-of-climb speed. The airspeed at which an airplane gains the greatest amount of altitude in a given distance. It is used during a short-field takeoff to clear an obstacle.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

Best rate-of-climb speed. This airspeed provides the most altitude gain in a given period of time.

Pilot's Handbook of Aeronautical Knowledge, p. G-34

Best rate-of-climb speed with one engine inoperative. This airspeed provides the most altitude gain in a given period of time in a light, twin-engine airplane following an engine failure.

Pilot's Handbook of Aeronautical Knowledge, p. G-34