wrought iron. A commercial grade of iron used for the manufacture of low-strength items. Wrought iron is malleable (it can be shaped by hammering), tough, and relatively soft.
wye connection (electrical connection). A name that is often used for a Y- or star-connected electrical circuit.
 See Y-connection.
X
X-axis. The longitudinal, or roll axis of an aircraft. The vertical axis is the Z-axis, and the lateral axis is the Y-axis. See longitudinal axis.
X-band radar. Radar whose energy is transmitted in a frequency band of between 5.2 and 10.9 gigahertz, and whose wavelength is between about 5.77 and 2.75 centimeters.
xenon. An inert, colorless, odorless, gaseous chemical element. Xenon’s symbol is Xe, its atomic number is 54, and its atomic weight is 131.30. Xenon is extracted from liquified air, and it is used to fill stroboscopic lamps because it gives off a brilliant flash of light when it is ionized and current flows through it.
X-ray inspection. A form of nondestructive inspection in which a piece of photographic film is exposed by X-rays passing through a section of the aircraft structure. The density of the structure determines the amount of energy passed to the film. Because of the different densities of the structure, an image of the structure is formed on the film.