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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detent. A spring-loaded pin or tab that enters a hole or groove when the device to which it is attached is in a certain position. Detents are used on fuel selector valves to provide a positive means of identifying the position in which the valve is fully on and fully off. detergent. A synthetic cleaning material. A detergent is similar to soap in its ability to emulsify oil and hold dirt and other solid or semi-solid contaminants. Unlike soap, a detergent is composed of man-made chemicals, rather than organic matter such as animal or vegetable fat. detergent oil. A type of mineral oil to which metallic-ash-forming detergents have been added. Detergent oil is not generally used in aircraft engines because of its tendency to loosen carbon deposits from the engine parts. These loosened deposits can plug oil passages inside the engine. detonation (reciprocating engine condition). An explosion or uncontrolled burning inside the cylinder of a reciprocating engine. Detonation occurs when the pressure and temperature inside the cylinder become higher than the critical pressure and temperature of the fuel, and may be caused by using fuel that has a lower octane rating or performance number than is specified for the engine. The pressure rise inside the cylinder caused by the fast-moving flame front can heat and compress the unburned fuel-air mixture enough for it to explode, or release its energy faster than the engine can accept it. This causes a rapid rise in cylinder pressure, excessive cylinder head temperature, and a decrease in engine power. Detonation is often confused with preignition but is not the same. See preignition. DETRESFA (distress phase) (ICAO). The code word used to designate an emergency phase wherein there is reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger or require immediate assistance. deuterium. An isotope of hydrogen which has one proton and one neutron in the nucleus. A normal atom of hydrogen has one proton, but no neutrons in its nucleus. Deutsch rivet. A type of hollow-shank, high-strength blind rivet. The rivet is put into the hole in the structure, and a tapered pin is driven into the hollow shank. The pin expands the rivet so serrations on the outside of the shank press into the sides of the hole and hold the rivet firmly in place. developed width of a part (sheet metal layout). The width of the sheet metal cut to form a part. If an angle, with legs of one inch and two inches, is to be formed of sheet metal, the developed width of the metal will be less than three inches. This is because the metal does not go to the mold lines of the angle, but goes around the corner in the bend radius. The developed width of the metal is the sum of the flats plus the bend allowance. This is less than the sum of the mold line lengths (MLL). developer (dye penetrant inspection). A powder used to pull a penetrating dye out of a defect in a part being inspected by the dye-penetrant inspection method. |
