hand-off (air traffic control). An action taken to transfer the radar identification of an aircraft from one controller to another if the aircraft will enter the receiving controller’s airspace and radio communications with the aircraft will be transferred.
hand-operated bending tool (tubing bending tool). A tool used to bend thin-wall tubing without it collapsing.
The tubing is bent around a deep-grooved radius block, using a sliding bar with a matching groove.
hand pump (hydraulic system component). A device used in a hydraulic system to move fluid.
Most hand pumps are of the piston type, in which movement of the pump lever, or handle, moves a piston inside the pump.
Some hand pumps are single-acting, which means that they move fluid only during one stroke of the handle. No fluid is moved during the return stroke. Other hand pumps are double-acting, which means that they move fluid during both strokes of the handle.
Most aircraft hydraulic systems that use an engine-driven or electric motor-driven hydraulic pump have a hand pump as a backup in case the power pump fails.
hand tools. A general name for all of the hand-held tools a technician uses when performing aircraft maintenance.
hangar. A building used to house aircraft.
hangar rash. Scrapes, bends, and dents in an aircraft structure that are caused by careless handling, usually when the aircraft is being moved inside the hangar.
hard (physical condition of a material). Compact, solid, and difficult to bend or deform.
hardboard. A composition material made by bonding sawdust and chips of wood with an adhesive under heat and pressure.
hard bronze. A high-strength copper alloy made of 88% copper, 7% tin, 3% zinc, and 2% lead.
hard-drawn copper wire. Copper wire that has not been annealed after it was formed by pulling it through dies. Pulling the wire through dies reduces its diameter to the desired size. It also work hardens the wire and increases its tensile strength.
hardenability (metals). The ability of a metal to be hardened by either heat treatment or cold-working.
hardened steel. Steel that has been heated red-hot and then quenched in brine, water, or oil. Hardened steel is strong but brittle.
hardener (plastic resin component). A material used with a plastic resin to improve its hardening.
hardening (metal heat treatment). A step in the heat treatment of metal in which the metal is made hard but brittle. Most ferrous metals (metals containing iron) are hardened by heating them to a specified temperature and then quenching them in oil, water, or brine. Other metals can be hardened only by cold-working them: by rolling them between steel rollers or by bending or hammering them.