曝光台 注意防骗
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training in both IFR and VFR weather conditions below 10,000 feet MSL at airspeeds in excess of 250
knots IAS.
IFR over-the-top. 14 CFR Part 1: “With respect to the operation of aircraft, means the operation of an
aircraft over-the-top on an IFR flight plan when cleared by air traffic control to maintain ‘VFR conditions’
or ‘VFR conditions on top’.”
IFR takeoff minimums and departure procedures (air traffic control). Minimums listed in 14 CFR Part
91, prescribing standard takeoff rules for certain civil users. At some airports, obstructions or other factors
require the establishment of nonstandard takeoff minimums, departure procedures, or both, to assist pilots
in avoiding obstacles during climb to the minimum en route altitude. Those airports are listed in NOS/DOD
Instrument Approach Charts (IAPs) under a section entitled “IFR Takeoff Minimums and Departure
Procedures.” The NOS/DOD IAP chart legend illustrates the symbol used to alert the pilot to nonstandard
takeoff minimums and departure procedures.
When departing IFR from such airports or from any airports where there are no departure
procedures, SIDs or ATC facilities available, pilots should advise ATC of any departure limitations.
Controllers may query a pilot to determine acceptable departure directions, turns, or headings after takeoff.
Pilots should be familiar with the departure procedures and must assure that their aircraft can meet or
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 313
exceed any specified climb gradients.
IGFET (insulated gate field effect transistor). A field-effect transistor whose gate is insulated from the
channel by a layer of silicon oxide.
igniter (gas turbine engine component). A component in a gas turbine engine used to ignite the fuel-air
mixture when the engine is being started. Some igniters resemble spark plugs used in reciprocating engines,
while others are glow plugs heated yellow-hot with electrical current.
ignition (heat engine operation). The procedure by which the temperature of a portion of the fuel-air
mixture in the engine is raised high enough for the hydrocarbon fuel to begin combining with the oxygen in
the air. This heat is normally provided by an electrical spark.
ignition harness (reciprocating engine ignition system component). The complete set of high-tension
cables, terminals, and connectors used to carry high voltage from the magnetos to the various spark plugs in
the engine.
ignition timing (reciprocating engine). The timing of the ignition spark with respect to the piston position
in the cylinder of a reciprocating engine. For the most power to be produced, the fuel-air mixture must be
ignited while the piston is still moving upward on the compression stroke. This allows time for the burning
mixture to produce its maximum push on the piston just as it starts down on the power stroke.
The correct piston position for ignition varies with the speed of the engine, and the ignition timing
on automobile engines is variable; but nearly all aircraft engines have fixed timing. The spark occurs at the
same position of the piston regardless of the engine conditions. Fixed timing is a performance compromise,
but fixed-timing ignition systems are less complicated than variable-timing systems.
ignitron (electrical component). A special high-current rectifier tube. In each cycle of operation of an
ignitron tube, an ignitor dips into a pool of mercury, and as it is withdrawn, it creates an arc which produces
ionized mercury vapor that conducts a large amount of current.
I-head cylinder (reciprocating engine). The cylinder of a reciprocating engine with both the intake and
exhaust valves mounted in the head. I-head cylinders are also called valve-in-head cylinders.
IHP (indicated horsepower). The theoretical horsepower a reciprocating engine is developing. The
horsepower an engine actually delivers to its output shaft is called brake horsepower (BHP). A large
amount of power is used to rotate the engine and compress the air in the cylinders. This power is called
friction horsepower (FHP).
Indicated horsepower is the sum of the brake horsepower and the friction horsepower: IHP = BHP
+ FHP.
illumination. Light energy that falls on a given surface area.
illustrated parts list (service information). An exploded view of an assembly in which all of the
component parts are laid out so each can be identified. Each part is coded with a letter or number, and a
table is included with the drawing, giving the name and correct number for each part and the quantity of the
parts needed for the assembly.
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
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航空术语词典Dictionary of Aeronautical Terms 中(80)
