Glossary

See initial approach fix.

Pilot's Handbook of Aeronautical Knowledge, p. G-15

See instrument approach procedures.

Pilot's Handbook of Aeronautical Knowledge, p. G-15

A spark plug failure that occurs when starting a reciprocating engine in extremely cold weather. When a cylinder fires, the air/fuel mixture is converted into carbon dioxide and water vapor. The water vapor condenses on the spark plug electrodes and forms ice that bridges the electrode gap and prevents the plug firing until the ice is melted. This normally requires removing the spark plugs from the engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A solid rivet made of 2017 or 2024 aluminum alloy. These rivets are too hard to drive in the condition they are received from the factory, and must be heat-treated to soften them. They are heated in a furnace and then quenched in cold water. Immediately after quenching they are soft, but within a few hours at room temperature they become quite hard. The hardening can be delayed for several days by storing them in a subfreezing icebox and holding them at this low temperature until they are to be used.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

Air Traffic Control request for a pilot to push the button on the transponder to identify return on the controller’s scope.

Pilot's Handbook of Aeronautical Knowledge, p. G-15

Integrated drive generator. An AC generator installed on turbine engines. An IDG incorporates a brushless, three-phase AC generator and a constant-speed drive in a single component.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

The component in a turbine-engine ignition system that provides a high-energy spark for igniting the air/fuel mixture in the combustion chamber for starting.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

Indicated horsepower. The theoretical horse-power a reciprocating engine develops.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

Categories of instrument approach procedures allowed at airports equipped with the following types of instrument landing systems: ILS Category I: Provides for approach to a height above touchdown of not less than 200 feet, and with runway visual range of not less than 1,800 feet. ILS Category II: Provides for approach to a height above touchdown of not less than 100 feet and with runway visual range of not less than 1,200 feet. ILS Category IIIA: Provides for approach without a decision height minimum and with runway visual range of not less than 700 feet. ILS Category IIIB: Provides for approach without a decision height minimum and with runway visual range of not less than 150 feet. ILS Category IIIC: Provides for approach without a decision height minimum and without runway visual range minimum.

Pilot's Handbook of Aeronautical Knowledge, p. G-15

See instrument meteorological conditions.

Pilot's Handbook of Aeronautical Knowledge, p. G-15

Indicated mean effective pressure. The average pressure existing inside the cylinder of a reciprocating engine during its power stroke.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A fraction with the numerator equal to or greater than the denominator.

Aviation Maintenance Technician Handbook — General, p. G-5

A spring-loaded coupling between a magneto shaft and the drive gear inside the engine. When the engine is rotated for starting, the impulse coupling locks the magnet so it cannot turn. The spring in the coupling winds up as the crankshaft continues to turn, and when the piston is near top center, the coupling releases and spins the magnet, producing a hot and retarded spark.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

Hovering close to the surface (usually less than one rotor diameter distance above the surface) under the influence of ground effect.

Helicopter Flying Handbook, p. G-4

Glowing because of intense heat.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A measure of work accomplished when a force of 1 pound moves an object a distance of 1 inch.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

An instrument consisting of a curved glass tube, housing a glass ball, and damped with a fluid similar to kerosene. It may be used to indicate inclination, as a level, or, as used in the turn indicators, to show the relationship between gravity and centrifugal force in a turn.

Pilot's Handbook of Aeronautical Knowledge, p. G-15

The registered trade name for an alloy of chromium, iron, and nickel. Inconel is similar to stainless steel, but cannot be hardened by heat treatment.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A location specified by the aircraft manufacturer from which arms used in weight and balance computations are measured. Arms measured from the index point are called index arms.

Aircraft Weight and Balance Handbook, p. G-3

The altitude read directly from the altimeter (uncorrected) when it is set to the current altimeter setting.

Pilot's Handbook of Aeronautical Knowledge, p. G-15

A reflection of aircraft pitch-and-bank attitude by instruments other than the attitude indicator.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

Electrical current produced in a conductor when it is moved through or crossed by a magnetic field.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

Aerodynamic drag produced by an airfoil when it is producing lift. Induced drag is affected by the same factors that affect induced lift.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

The component of air flowing vertically through the rotor system resulting from the production of lift.

Helicopter Flying Handbook, p. G-4

The ability of a coil or conductor to oppose a change in current flow.

Aviation Maintenance Technician Handbook — General, p. G-6

A type of ice in the induction system that reduces the amount of air available for combustion. The most commonly found induction icing is carburetor icing.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

The time allowed an epoxy or polyurethane material between its initial mixing and its application. This time allows the materials to begin their cure.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

The opposition to the flow of current which inductances put in a circuit.

Aviation Maintenance Technician Handbook — General, p. G-6

A coil of wire that produces inductance in an electrical circuit.

Aviation Maintenance Technician Handbook — General, p. G-6

The tendency of a body to resist acceleration. A body at rest will remain at rest or a body in motion will stay in motion in a straight line unless acted on by an outside force.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A starter for a large reciprocating engine that uses energy stored in a rapidly spinning flywheel to turn the crankshaft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A computer-based navigation system that tracks the movement of an aircraft via signals produced by onboard accelerometers. The initial location of the aircraft is entered into the computer, and all subsequent movement of the aircraft is sensed and used to keep the position updated. An INS does not require any inputs from outside signals.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

Electromagnetic radiation whose wavelengths are longer than those of visible light.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

A large block of metal that was molded as it was poured from the furnace. Ingots are further processed into sheets, bars, tubes, or structural beams.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

The fix depicted on IAP charts where the instrument approach procedure (IAP) begins unless otherwise authorized by ATC.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

A set of stator vanes in front of the first stage of compression in a gas turbine engine. The inlet guide vanes deflect the air entering the compressor in the correct direction for optimum operation. Inlet guide vanes may be fixed, or their angle may be controlled hydraulically by fuel from the fuel control.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A reciprocating engine with all of the cylinders arranged in a straight line.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

Higher minimums are prescribed when the specified visual aids are not functioning; this information is listed in the Inoperative Components Table found in the United States Terminal Procedures Publications.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

Inertial Navigation System.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

Calipers with outward curved legs for measuring inside diameters, such as diameters of holes.

Aviation Maintenance Technician Handbook — General, p. G-5

An authorization that may be issued to an experienced aviation maintenance technician who holds both an Airframe and Powerplant rating. It allows the holder to conduct annual inspections and to approve an aircraft or aircraft engine for return to service after a major repair or major alteration.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

A drawing that includes all necessary information for a part or an assembly in the final installed position in the aircraft.

Aviation Maintenance Technician Handbook — General, p. G-5

Assists in interpretation by instantaneously indicating the rate of climb or descent at a given moment with little or no lag as displayed in a vertical speed indicator (VSI).

Pilot's Handbook of Aeronautical Knowledge, p. G-16

A series of predetermined maneuvers for the orderly transfer of an aircraft under IFR from the beginning of the initial approach to a landing or to a point from which a landing may be made visually.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

Rules and regulations established by the Federal Aviation Administration to govern flight under conditions in which flight by outside visual reference is not safe. IFR flight depends upon flying by reference to instruments in the flight deck, and navigation is accomplished by reference to electronic signals.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

An electronic system that provides both horizontal and vertical guidance to a specific runway, used to execute a precision instrument approach procedure. Instrument meteorological conditions (IMC). Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than the minimums specified for visual meteorological conditions, requiring operations to be conducted under IFR.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

Using the instruments rather than outside visual cues to maintain runway heading and execute a safe takeoff.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

A material that does not conduct electrical current very well or not at all. Examples are glass, ceramic, and plastic.

Aviation Maintenance Technician Handbook — General, p. G-6

A fuel tank which is formed by sealing off part of the aircraft structure and using it as a fuel tank. An integral wing tank is called a “wet wing.” Integral tanks are used because of their large weight saving. The only way of repairing an integral fuel tank is by replacing damaged sealant and making riveted repairs, as is done with any other part of the aircraft structure.

Aviation Maintenance Technician Handbook — Airframe, p. G-19

An air-to-air heat exchanger installed between a turbosupercharger and the carburetor. Intercoolers decrease the temperature of compressed air to prevent detonation.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

The difference between the valve seat and the valve face angles. Normally, the valve seats are ground with between 0.5º and 1º greater angle than the valve face. This allows the face to touch the seat with a line contact that provides the best sealing.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

Parasite drag caused by air flowing over one portion of the airframe interfering with the smooth flow of air over another portion.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

A type of fit used when assembling certain mechanical devices. The hole is made smaller than the part that fits into it. The material containing the hole is heated to expand the hole, and the part that fits into the hole is chilled to shrink it. The parts are assembled, and when they reach the same temperature their fit is so tight they will not loosen in service.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

An attack along the grain boundaries of an alloy that commonly results from a lack of uniformity in the alloy structure.

Aviation Maintenance Technician Handbook — General, p. G-5

A solenoid-type switch whose coil is designed for current to flow through it for only a short period of time. The coil will overheat if current flows through it too long.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

A form of heat engine in which the fuel and air mixture is burned inside the engine to heat and expand the air so it can perform useful work.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

The adjustment of the breaker points of a magneto so they will begin to open at the time the magnet is in its E-gap position.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

The United Nations agency for developing the principles and techniques of international air navigation, and fostering planning and development of international civil air transport.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

A model of standard variation of pressure and temperature.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

Determine a value in a range between two known values.

Aircraft Weight and Balance Handbook, p. G-3

The estimation of an intermediate value of a quantity that falls between marked values in a series. Example: In a measurement of length, with a rule that is marked in eighths of an inch, the value falls between 3/8 inch and 1/2 inch. The estimated (interpolated) value might then be said to be 7/16 inch.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

A field pole in a compound-wound DC generator used to minimize armature reaction. Interpoles are located between each of the regular field poles, and their coils are in series with the armature winding so all of the armature current flows through them. The magnetic field produced by the interpole coils cancels the distortion caused by the armature field and allows the brushed to remain in the neutral plane where there is no potential difference between the commutator segments. Keeping the brushes in the neutral plane minimizes sparking.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

An increase in temperature with altitude.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

The feeling that the aircraft is tumbling backwards, caused by an abrupt change from climb to straight-and-level flight while in situations lacking visual reference.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

An inline or V-engine in which the cylinders are mounted below the crankshaft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-15

A solid-state electronic device that converts D.C. into A.C. current of the proper voltage and frequency to operate A.C. gyro instruments.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

An atom or group of atoms in which the number of electrons is different from the number of protons. It is a positive ion if the number of electrons is less than the number of protons, and a negative ion if the number of electrons is greater than the number of protons.

Aviation Maintenance Technician Handbook — General, p. G-6

A very hard, brittle, highly corrosion-resistant, whitish-yellow, metallic chemical element. Iridium is used for the fine-wire electrodes in spark plugs that must operate in engines using fuel with an exceptionally high lead content.

Aviation Maintenance Technician Handbook — Powerplant, p. G-16

Inertial Reference System.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

Inertial Reference Unit.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

A hydrocarbon, C8H18, which has very high critical pressure and temperature. Iso-octane is used as the high reference for measuring the antidetonation characteristics of a fuel.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

The mode of pressurization in which the cabin pressure is maintained at a constant value regardless of the outside air pressure.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

Lines which connect points of equal barometric pressure.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

A line drawn on an aeronautical chart along which the angular difference between the magnetic and geographic north poles is the same.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

Lines drawn across aeronautical charts to connect points having the same magnetic variation.

Pilot's Handbook of Aeronautical Knowledge, p. G-16

A drawing that uses a combination of the views of an orthographic projection and tilts the object forward so that portions of all three views can be seen in one view.

Aviation Maintenance Technician Handbook — General, p. G-6

A colorless liquid used in the manufacture of acetone and its derivatives and as a solvent and anti-icing agent.

Aviation Maintenance Technician Handbook — Airframe, p. G-20

A physical change that takes place within a material in which heat energy is added to or taken from the material as needed to keep its temperature constant.

Aviation Maintenance Technician Handbook — Powerplant, p. G-16

See instantaneous vertical speed indicator.

Pilot's Handbook of Aeronautical Knowledge, p. G-16