时间：2011-03-11 23:13来源：蓝天飞行翻译 作者：admin 点击：次
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lost communications. Loss of the ability to communicate by radio. Aircraft in this condition are sometimes referred to as NORDO (no radio). Standard pilot procedures for lost communications are specified in 14 CFR Part 91. lost-wax casting. A method of casting such components as turbine blades. A highly polished internal cavity is made in the die, having the exact inverse shape of the finished part, and a special molten wax is injected into it to completely fill the cavity. When the wax solidifies, it is removed from the die. Several of the wax patterns are assembled on a wax gating tree, which is then dipped into a liquid ceramic slurry a number of times until a ceramic coat about a quarter of an inch thick builds up. The resulting ceramic mold is fired at a temperature of about 1,000°C, which melts the wax out and prepares the mold for the next steps. The extremely hot mold is filled with the blade alloy which has been melted in an induction furnace. After the metal has cooled, the mold is removed and the blades are cleaned and inspected. louver. A slotted opening in a structure, used for the passage of cooling air. Louvers are often fitted with vanes to control the amount of air flowing through them. low (meteorology). An area of low barometric pressure, with its attendant system of winds. A low is also called a barometric depression or cyclone. low altitude airway structure. The network of airways serving aircraft operations, up to, but not including, 18,000 feet MSL. low-altitude alert system. See LAAS. low approach. An approach over an airport or runway following an instrument approach or a VFR approach, including the go-around maneuver in which the pilot intentionally does not make contact with the runway. low-bypass engine. A turbofan engine whose bypass ratio is less than 2:1. See bypass ratio. low-frequency radio waves. Electromagnetic waves with frequencies between 30 and 300 kilohertz. Low-frequency radio waves have wavelengths between 10,000 and 1,000 meters. low-lead 100-octane aviation gasoline. A type of aviation gasoline having an octane rating of 100, but containing a maximum of two milliliters of tetraethyl lead per gallon. Normal, or high-lead, 100-octane aviation gasoline is allowed to have as much as 4.6 milliliters of lead per gallon, and this additional lead fouls the spark plugs of engines designed to use fuel with a lower lead content. Low-lead 100-octane aviation gasoline is dyed blue to distinguish it from normal 100-octane aviation gasoline which is dyed green. low-oxygen concentration cell corrosion. Corrosion that forms between the lap joints of metal and under labeling tape, tabs or placards that trap and hold moisture. Moisture on the surface of the metal absorbs oxygen from the air, and the extra oxygen causes the water to attract electrons from the metal to form negative hydroxide ions. Moisture trapped in the lap joints does not have any extra oxygen and therefore does not form any negative ions. |
