Aviation Maintenance Terms beginning with V
Vapor lock
A condition in which vapors form in the fuel lines and block the flow of fuel to the carburetor.
Vapor pressure
The pressure of the vapor above a liquid needed to prevent the liquid evaporating. Vapor pressure is always specified at a specific temperature.
Variable displacement pump
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.
Varnish (aircraft finishing material)
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.
Varsol
A petroleum product similar to naphtha used as a solvent and cleaning fluid.
Veneer
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.
Vertical axis
An imaginary line, passing vertically through the center of gravity of an airplane.
Vertical fin
The fixed vertical surface in the empennage of an airplane. The vertical fin acts as a weathervane to give the airplane directional stability.
Vibrator-type voltage regulator
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.
Viscosity
The resistance of a fluid to flow. Viscosity refers to the “stiffness” of the fluid, or its internal friction.
Viscosity cup
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.
Vixen file
A metal-cutting hand file that has curved teeth across its faces. Vixen files are used to remove large amounts of soft metal.
Volatile liquid
A liquid that easily changes into a vapor.
Voltmeter multiplier
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.
Vortex (plural vortices)
A whirling motion in a fluid.
Vortex generator
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.
Restrict the list to specific publications by clicking on the menubar at the top of the screen.