时间：2011-03-11 23:11来源：蓝天飞行翻译 作者：admin 点击：次
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The part is soaked in the penetrant. Then, all the penetrant is washed from its surface and the surface is covered with the developer. The developer pulls any penetrant that has seeped into a defect to the surface where it shows up as a visible mark. deviation (magnetic compass error). An error in the indication of a magnetic compass, caused by local magnetic fields within the aircraft. Deviation error, which is different on each heading, is minimized by the technician compensating, or swinging, the compass. A compass must be compensated so the deviation error on any heading is no greater than 10 degrees. dew. Water that condenses out of the air and forms on the ground and on objects that are cooler than the air. Dew usually forms at night when the ground cools as heat leaves it by radiation. Dewar flask. A special container used to store liquid oxygen and liquid nitrogen. A Dewar flask has an inner and an outer container, with the space between them evacuated to form a vacuum. This serves as a thermal insulator and minimizes the amount of heat allowed to enter the container. The two surfaces within the evacuated area are silvered to reflect heat away from the container walls. dewaxed oil. A petroleum oil from which some of the solid hydrocarbons, or waxes, have been removed in the refining process. DEWIZ (distant early warning identification zone). An air defense identification zone (ADIZ) over the coastal waters of Alaska. dew point. The temperature below which air can no longer hold water in its vapor state. At the dew point temperature, the relative humidity is 100% and water vapor condenses out of the air and forms visible water — dew. DF (direction finder) (navigation system component). A radio receiver equipped with a direction-sensing antenna used to take bearings on a radio transmitter. Specialized radio direction finders are used in aircraft as navigation aids. Others are ground-based, primarily to obtain a fix on a pilot requesting orientation assistance or to locate downed aircraft. A location fix is established by the intersection of two or more bearing lines plotted on a navigational chart, using either two separately located direction finders to obtain a fix on an aircraft or by a pilot plotting the bearing indications of his DF on two separately located ground-based transmitters, both of which can be identified on his chart. UDFs receive signals in the ultrahigh frequency radio broadcast band, VDFs in the very high frequency band, and UVDFs in both bands. ATC provides DF service at those air traffic control towers and flight service stations listed in the Airport/Facility Directory and the DOD/FLIP IFR En Route Supplement. DF approach procedure (air traffic control). An emergency approach procedure used under conditions when no other instrument approach procedure can be executed. DF fix. The geographic location of an aircraft obtained by the use of one or more direction finders. DF guidance (air traffic control). Headings provided an aircraft by a ground facility using direction finding equipment. DF headings, if followed, will lead the aircraft to a predetermined location. |
