Aviation Maintenance Terms beginning with W
Wake
The high-velocity stream of turbulent air behind an operating aircraft engine.
Wankel engine
See rotating combustion (RC) engine.
Warning
The level or category of alert for conditions that require immediate flight crew awareness and immediate flight crew response.
Warp
Threads in a fabric that run the length of the woven material as it comes from the mill.
Warp clock
An alignment indicator included in a structural repair manual to show the orientation of the piles of a composite material. The ply direction is shown in relation to a reference direction.
Warp threads
Threads that run the length of the roll of fabric, parallel to the selvage edge. Warp threads are often stronger than fill threads.
Warp tracers
Threads of a different color from the warp threads that are woven into a material to identify the direction of the warp threads.
Wash in
A twist in an airplane wing that increases its angle of incidence near the tip.
Wash out
A twist in an airplane wing that decreases its angle of incidence near the tip.
Waste gate
A controllable butterfly valve in the exhaust pipe of a reciprocating engine equipped with an exhaust-driven turbocharger. When the waste gate is open, exhaust gases leave the engine through the exhaust pipe, and when it is closed, they leave through the turbine.
Waterline (WL)
A horizontal reference plane used to locate vertical positions on an aircraft. Positions are usually given in inches above or below the waterline.
Watt
A unit of power equal to one joule per second.
Watt
The basic unit of electrical power. One watt is equal to 1⁄746 horsepower.
Watt
The unit of power; equal to a joule per second.
Watt
The basic unit of power in the metric system. One watt is the amount of power needed to do one joule (0.7376 foot- pound of work) in one second. One watt is 1⁄746 horsepower.
Wattmeter
An instrument for measuring electrical power.
Waveguide
A hollow, typically rectangular, metallic tube designed to carry electromagnetic energy at extremely high frequencies.
Wavy-grained wood
Wood in which the fibers collectively take the form of waves or undulations.
Way point
A phantom location created in certain electronic navigation systems by measuring direction and distance from a VORTAC station or by latitude and longitude coordinates from Loran or GPS.
Web of a spar
The part of a spar between the caps.
Weft threads
See fill threads.
Weighing points
Locations on an aircraft that the manufacturer designates for the placement of scales when weighing aircraft.
Weight
A measure of the pull of gravity acting on the mass of an object.
Weight-shift-control aircraft
A powered aircraft with a framed pivoting wing and a fuselage controllable only in pitch and roll by the pilot’s ability to change the aircraft’s center of gravity with respect to the wing. Flight control of the aircraft depends on the wing’s ability to flexibly deform rather than the use of control surfaces.
Welding
A materials-joining process used in making welds.
Welding rod
A form of welding filler metal, normally packaged in straight lengths.
Welding torch
The device used in gas welding.
Wet-sump engine
An engine that carries its lubricating oil supply in a reservoir that is part of the engine itself.
Wet-sump lubrication system
A lubrication system in which the oil supply is carried within the engine itself. Return oil drains into the oil reservoir by gravity.
Wet-type vacuum pump
An engine-driven air pump that uses steel vanes. These pumps are lubricated by engine oil drawn in through holes in the pump base. The oil passes through the pump and is exhausted with the air. Wet-type pumps must have oil separators in their discharge line to trap the oil and return it to the engine crankcase.
Whittle, Sir Frank
The British Royal Air Force flying officer who in 1929 filed a patent application for a turbojet engine. Whittle’s engine first flew in a Gloster E.28 on May 15, 1941. The first jet flight in America was made on October 2, 1942, in a Bell XP-59A that was powered by two Whittle-type General Electric I-A engines.
Whole numbers
The numbers: 0, 1, 2, 3, 4, 5, and so on.
Wide Area Augmentation System (WAAS)
The U.S. implementation of SBAS.
Windmilling propeller
A propeller that is rotated by air flowing over the blades rather than powered by the engine.
Wing fences
Vertical vanes that extend chordwise across the upper surface of an airplane wing to prevent spanwise airflow.
Wing heavy
An out-of-trim flight condition in which an airplane flies hands off, with one wing low.
Winglet or tip fin
An out-of-plane surface extending from a lifting surface. The surface may or may not have control surfaces.
Wire bundle
A compact group of electrical wires held together with special wrapping devices or with waxed string. These bundles are secured to the aircraft structure with special clamps.
Wiring diagrams
A diagram that shows the electrical wiring and circuitry, coded for identification, of all the electrical appliances and devices used on aircraft.
Wood decay
Disintegration of wood substance through the action of wood-destroying fungi.
Wood decay - incipient
The early stage of decay in which the disintegration has not proceeded far enough to soften or otherwise perceptibly impair the hardness of the wood.
Wood decay - typical or advanced
The stage of decay in which the disintegration is readily recognized because the wood has become punky, soft and spongy, stringy, pitted, or crumbly.
Woof threads
See fill threads.
Work
The amount of energy transferred by a force
Work
The product of force times distance.
Work
The product of a force times the distance the force is moved.
Worm gear
A helical gear mounted on a shaft. The worm meshes with a spur gear whose teeth are cut at an angle to its face. A worm gear is an irreversible mechanism. The rotation of the shaft, on which the worm gear locks the spur gear so its shaft cannot be rotated.
Wrist pin
The hardened steel pin that attaches a piston to the small end of a connecting rod.
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