Glossary

A takeoff that is terminated prematurely when it is determined that some condition exists that makes takeoff or further flight dangerous.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

A strip of material in the compressor housing of some axial-flow gas turbine engines. The tip of the compressor blade touches the abradable strip, and wears, or abrades a groove in it. This groove ensures the minimum tip clearance.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

The tip of some axial-flow compressor blades constructed so that it will abrade, or wear away, upon contact with the compressor housing, which ensures the minimum tip clearance between the blade and the housing.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

The ability to determine present position in space independently, and is most often used by pilots.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

The actual distance an object is above the ground.

Helicopter Flying Handbook, p. G-1

The actual amount of the water vapor in a mixture of air and water.

Aviation Maintenance Technician Handbook — General, p. G-1

Equal to gauge pressure plus atmospheric pressure. Also known as psia.

Aviation Maintenance Technician Handbook — General, p. G-1

A valve used in a pneumatic system at the pump inlet to regulate the compressor inlet air pressure to prevent excessive speed variation and/or overspeeding of the compressor.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

Temperature measured relative to absolute zero. Absolute temperature scales include Kelvin and Rankine.

Aviation Maintenance Technician Handbook — General, p. G-1

The point at which all molecular motion ceases. Absolute zero is –460 °F and –273 °C.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

Alternating current. Electrical current in which the electrons continually change their rate of flow and periodically reverse their direction.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

Active clearance control. A system for controlling the clearance between tips of the compressor and turbine blades and the case of high-performance turbofan engines. When the engine is operating at maximum power, the blade tip clearance should be minimum, and the ACC system sprays cool fan discharge air over the outside of the engine case. This causes the case to shrink enough to decrease the tip clearance. For flight conditions that do not require such close clearance, the cooling air is turned off, and the case expands to its normal dimensions. The control of the ACC system is done by the FADEC, or full-authority digital electronic control.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

The distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1, and continue the takeoff on the remaining engine(s). The runway required includes the distance required to climb to 35 feet by which time V2 speed must be attained.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

The distance required to accelerate to V1 with all engines at takeoff power, experience an engine failure at V1, and abort the takeoff and bring the airplane to a stop using braking action only (use of thrust reversing is not considered).

Pilot's Handbook of Aeronautical Knowledge, p. G-1

The amount the velocity of an object is increased by a force during each second it is acted upon by that force. Acceleration is usually measured and expressed in terms of feet per second, per second (fps²).

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

The acceleration of an object caused by gravity. On earth, it is measured as 32.2 feet per second per second (32.2 fps/s).

Aviation Maintenance Technician Handbook — General, p. G-1

A magnetic compass error apparent when the aircraft accelerates while flying on an easterly or westerly heading, causing the compass card to rotate toward North.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

A part of an inertial navigation system (INS) that accurately measures the force of acceleration in one direction.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

The end of a reciprocating engine on which many of the accessories are mounted. Also, called the anti-propeller end.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

A hydraulic component that consists of two compartments separated by a movable component, such as a piston, diaphragm, or bladder. One compartment is filled with compressed air or nitrogen, and the other is filled with hydraulic fluid and is connected into the system pressure manifold. An accumulator allows an incompressible fluid to be stored under pressure by the force produced by a compressible fluid. Its primary purposes are to act as a shock absorber in the system, and to provide a source of additional hydraulic power when heavy demands are placed on the system.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

A fluid power device that changes fluid pressure into mechanical motion.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

A mineral-based lubricating oil used in reciprocating engines. This oil does not contain any metallic ash-forming additives, but has additives that disperse the contaminants and hold them in suspension until they can be removed by filters.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

Air data computer.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

The process in which the value of one number is added to the value of another.

Aviation Maintenance Technician Handbook — General, p. G-1

Automatic direction finder.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

Attitude director indicator.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

A system used with some large reciprocating engines in which a mixture of water and alcohol is sprayed into the engine with the fuel when operating at extremely high power. The air/fuel mixture is leaned to allow the engine to develop its maximum power, and the ADI fluid absorbs excessive heat when it vaporizes.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

A physical change that takes place within a material in which heat energy is neither added to the material, nor taken away. If a container of gas is compressed, with no heat energy added to or taken from it, the gas will become hotter; its temperature will rise.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

A process of cooling the air through expansion. For example, as air moves up slope it expands with the reduction of atmospheric pressure and cools as it expands.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

A process of heating dry air through compression. For example, as air moves down a slope it is compressed, which results in an increase in temperature.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

A propeller with blades whose pitch can be adjusted on the ground with the engine not running, but which cannot be adjusted in flight. Also referred to as a ground adjustable propeller. Sometimes also used to refer to constant-speed propellers that are adjustable in flight.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

A stabilizer that can be adjusted in flight to trim the airplane, thereby allowing the airplane to fly hands-off at any given airspeed.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

See aeronautical decision-making.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

See automatic dependent surveillance-broadcast.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

The blade on a helicopter rotor whose tip is moving in the same direction the helicopter is moving.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

Fog resulting from the movement of warm, humid air over a cold surface.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

A weight and balance check to determine that no condition of legal loading of an aircraft can move the CG outside of its allowable limits.

Aircraft Weight and Balance Handbook, p. G-1

A condition of flight at the beginning of a turn in which the nose of an airplane momentarily yaws in the opposite direction from the direction in which the turn is to be made.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

Issued to inform the aviation public in a systematic way of nonregulatory material. An AC is issued to provide guidance and information in a designated subject area or to show a method acceptable to the Administrator for complying with a related 14 CFR part.

Aviation Maintenance Technician Handbook — General, p. G-1

The total resistance to the movement of an object through the air. Aerodynamic drag is composed of both induced drag and parasite drag. See induced drag and parasite drag.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

The force produced by air moving over a specially shaped surface called an airfoil. Aerodynamic lift acts in a direction perpendicular to the direction the air is moving.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

The science of the action of air on an object, and with the motion of air on other gases. Aerodynamics deals with the production of lift by the aircraft, the relative wind, and the atmosphere.

Pilot's Handbook of Aeronautical Knowledge, p. G-1

A patented variable-pitch propeller that has flyweights around the blade shanks and the blades angled back from the hub to increase the effects of aerodynamic and centrifugal twisting forces. This propeller automatically maintains a relatively constant rpm for any throttle setting.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

A map used in air navigation containing all or part of the following: topographic features, hazards and obstructions, navigation aids, navigation routes, designated airspace, and airports.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

A systematic approach to the mental process used by pilots to consistently determine the best course of action in response to a given set of circumstances.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

A corporation whose principal stockholders are the airlines. Its function is to operate certain communication links between airliners in flight and the airline ground facilities. ARINC also sets standards for communication equipment used by the airlines.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

A turbofan engine with the fan mounted behind the compressor section. The blades of an aft-fan are normally extensions of the free turbine blades.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

A component in the exhaust system of a turbojet or turbofan engine used to increase the thrust for takeoff and for special flight conditions. Since much of the air passing through a gas turbine engine is used only for cooling, it still contains a great deal of oxygen. Fuel is sprayed into the hot, oxygen-rich exhaust in the afterburner, where it is ignited and burned to produce additional thrust.

Aviation Maintenance Technician Handbook — Powerplant, p. G-1

A change in the characteristics of a material with time. Certain aluminum alloys do not have their full strength when they are first removed from the quench bath after they have been heat-treated, but they gain this strength after a few days by the natural process of aging.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

A line drawn on an aeronautical chart along which there is no angular difference between the magnetic and geographic north poles.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

Primary flight control surfaces mounted on the trailing edge of an airplane wing, near the tip. Ailerons control roll about the longitudinal axis.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

A small hole in the fuel passage between the float bowl and the discharge nozzle of a float carburetor. Air drawn into the liquid fuel through the air bleed breaks the fuel up into an emulsion, making it easy to atomize and vaporize.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

The removal of unwanted heat from an aircraft engine by transferring the heat directly into the air flowing over the engine components.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A system for cooling the air in the cabin of a turbojet-powered aircraft. Compressor bleed air passes through two heat exchangers where it gives up some of its heat; then, it drives an expansion turbine where it loses still more of its heat energy as the turbine drives a compressor. When the air leaves the turbine, it expands and its pressure and temperature are both low. Aircraft communication addressing and reporting system (ACARS). A two-way communication link between an airliner in flight and the airline’s main ground facilities. Data is collected in the aircraft by digital sensors and is transmitted to the ground facilities. Replies from the ground may be printed out so the appropriate flight crewmember can have a hard copy of the response.

Aviation Maintenance Technician Handbook — Airframe, p. G-1

An aircraft computer that receives and processes pitot pressure, static pressure, and temperature to calculate very precise altitude, indicated airspeed, true airspeed, and air temperature.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

The density of the air in terms of mass per unit volume. Dense air has more molecules per unit volume than less dense air. The density of air decreases with altitude above the surface of the earth and with increasing temperature.

Helicopter Flying Handbook, p. G-1

The ratio of the weight of the air to that of the fuel in the mixture fed into the cylinders of an engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A turbine engine starter that basically consists of a nozzle that blows a stream of compressed air against the turbine blades to rotate the compressor for starting the engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

An extensive body of air having fairly uniform properties of temperature and moisture.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

A component in a turbine engine lubrication system that removes the air from the scavenged oil before it is returned to the oil tank.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

Air route traffic control center (ARTCC) radar used primarily to detect and display an aircraft’s position while en route between terminal areas.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

Provides ATC service to aircraft operating on IFR flight plans within controlled airspace and principally during the en route phase of flight.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

The actual height above sea level at which the aircraft is flying.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

A performance grouping of aircraft based on a speed of 1.3 times the stall speed in the landing configuration at maximum gross landing weight.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

The movement of the aircraft about its lateral, or pitch, axis. Movement of the cyclic forward or aft causes the nose of the helicopter to pitch up or down.

Helicopter Flying Handbook, p. G-1

The movement of the aircraft about its longitudinal axis. Movement of the cyclic right or left causes the helicopter to tilt in that direction.

Helicopter Flying Handbook, p. G-1

FAA recordkeeping documents issued for both type-certificated and non-typecertificated products which have been found eligible for U.S. airworthiness certification.

Aviation Maintenance Technician Handbook — General, p. G-1

Any device that creates a force, or lift, based on Bernoulli’s principles or Newton’s laws, when air is caused to flow over the surface of the device.

Aviation Maintenance Technician Handbook — General, p. G-1

Inflight weather advisory issued as an amendment to the area forecast, concerning weather phenomena of operational interest to all aircraft and that is potentially hazardous to aircraft with limited capability due to lack of equipment, instrumentation, or pilot qualifications.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

An FAA-approved document, prepared by the holder of a type certificate for an aircraft, that specifies the operating limitations and contains the required markings and placards and other information applicable to the regulations under which the aircraft was certificated

Aircraft Weight and Balance Handbook, p. G-1

A document developed by the airplane manufacturer containing general information about the make and model of an airplane. The airplane owner’s manual is not FAA approved and is not specific to a particular serial numbered airplane. This manual is not kept current, and therefore cannot be substituted for the AFM/POH.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

The section of an instrument approach procedure chart that shows a detailed diagram of the airport. This diagram includes surface features and airport configuration information.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

See Chart Supplement U.S.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

Radar equipment specifically designed to detect all principal features and traffic on the surface of an airport, presenting the entire image on the control tower console; used to augment visual observation by tower personnel of aircraft and/or vehicular movements on runways and taxiways.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

Approach control radar used to detect and display an aircraft’s position in the terminal area.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

An instrument approach in which ATC issues instructions for pilot compliance based on aircraft position in relation to the final approach course and the distance from the end of the runway as displayed on the controller’s radar scope.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

Rate of the aircraft’s progress through the air.

Pilot's Handbook of Aeronautical Knowledge, p. G-2

A flight instrument that measures the pressure differential between the pitot, or ram, air pressure, and the static pressure of the air surrounding the aircraft. This differential pressure is shown in units of miles per hour, knots, or kilometers per hour.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An airway is based on a centerline that extends from one navigation aid or intersection to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route procedures between terminal areas.

Pilot's Handbook of Aeronautical Knowledge, p. G-3

A document required to be onboard an aircraft that indicates the aircraft conforms to type design and is in condition for safe operation.

Aviation Maintenance Technician Handbook — General, p. G-1

Issued by the FAA in response to deficiencies and/or unsafe conditions found in aircraft, engines, propellers, or other aircraft parts. Compliance with an AD is mandatory.

Aviation Maintenance Technician Handbook — General, p. G-1

A registered trade name for clad aluminum alloy.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

Used to designate sheets that consist of an aluminum alloy core coated with a layer of pure aluminum to a depth of approximately 51⁄2 percent on each side.

Aviation Maintenance Technician Handbook — General, p. G-1

The branch of mathematics that uses letters or symbols to represent numbers in formulas and equations.

Aviation Maintenance Technician Handbook — General, p. G-1

A shielded spark plug designed for high altitude operation. The ceramic insulator is recessed into the shell to allow a resilient grommet on the ignition harness to provide a watertight seal. All weather spark plugs, also called high-altitude spark plugs, are identified by their 3/4- 20 shielding threads.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

The difference of the upper and lower variation of a part.

Aviation Maintenance Technician Handbook — General, p. G-1

Information the global positioning system (GPS) receiver can obtain from one satellite which describes the approximate orbital positioning of all satellites in the constellation. This information is necessary for the GPS receiver to know what satellites to look for in the sky at a given time.

Pilot's Handbook of Aeronautical Knowledge, p. G-3

The registered trade name for a popular conversion coating chemical used to produce a hard, airtight, oxide film on aluminum alloy for corrosion protection.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

A simple chemical treatment for all aluminum alloys to increase their corrosion resistance and to improve their paint bonding qualities.

Aviation Maintenance Technician Handbook — General, p. G-1

The flight operating mode from takeoff through landing for a turbo-prop engine. Alpha mode includes operations from 95% to 100% of the engine’s rated rpm.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

Symbols made up of all of the letters in our alphabet, numerals, punctuation marks, and certain other special symbols.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

A change or modification to an aircraft from its previous state Alternating current. An electric current that reverses direction in a circuit at regular intervals.

Aviation Maintenance Technician Handbook — General, p. G-1

A valve in the instrument static air system that supplies reference air pressure to the altimeter, airspeed indicator, and vertical speed indicator if the normal static pickup should become clogged or iced over.

Pilot's Handbook of Aeronautical Knowledge, p. G-3

An electrical generator that produces alternating current. The popular DC alternator used on light aircraft produces three-phase AC in its stator windings. This AC is changed into DC by a six-diode, solid-state rectifier before it leaves the alternator.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An instrument that indicates flight altitude by sensing pressure changes and displaying altitude in feet or meters.

Helicopter Flying Handbook, p. G-1

The barometric pressure at a given location corrected to mean (average) sea level.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An alloy of nickel, aluminum, manganese, and silicon that is the negative element in a thermocouple used to measure exhaust gas temperature.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

Aircraft built by individuals as a hobby rather than by factories as commercial products. Amateur-built or home-built aircraft do not fall under the stringent requirements imposed by the FAA on commercially built aircraft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

The pressure of the air that surrounds an object.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

The pressure of the air surrounding a person or an object.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

The temperature of the air surrounding a person or an object.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

See aviation medical examiner.

Pilot's Handbook of Aeronautical Knowledge, p. G-3

The circulation date and revision number of an instrument approach procedure, printed above the procedure identification.

Pilot's Handbook of Aeronautical Knowledge, p. G-3

The system of measurement of wire size used in aircraft electrical systems.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An instrument for measuring electric current in amperes.

Aviation Maintenance Technician Handbook — General, p. G-1

A unit of measure of the rate of electron flow or current in an electrical conductor. One ampere of current represents one coulomb of electrical charge (6.24 × 1018 charge carriers) moving past a specific point in one second.

Aviation Maintenance Technician Handbook — General, p. G-1

An airplane with landing gear that allows it to operate from both water and land surfaces.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An electronic circuit in which a small change in voltage or current controls a much larger change in voltage or current.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

Electronics in which values change in a linear fashion. Output values vary in direct relationship to changes of input values.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An indicator that shows the value of the parameter being measured by a number marked on a graduated dial aligned with a movable pointer.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

An electrical meter that indicates values by the amount a pointer moves across a graduated numerical scale.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

The sensitive component in an altimeter or barometer that measures the absolute pressure of the air. The aneroid is a sealed, flat capsule made of thin corrugated discs of metal soldered together and evacuated by pumping all of the air out of it. Evacuating the aneroid allows it to expand or collapse as the air pressure on the outside changes.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An instrument that measures the absolute pressure of the atmosphere by balancing the weight of the air above it against the spring action of the aneroid.

Pilot's Handbook of Aeronautical Knowledge, p. G-3

The acute angle formed between the chord line of an airfoil and the direction of the air that strikes the airfoil.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

An instrument that measures the angle between the local airflow around the direction detector and the fuselage reference plane.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

The acute angle formed between the chord line of an airfoil and the longitudinal axis of the aircraft on which it is mounted.

Aviation Maintenance Technician Handbook — Airframe, p. G-2; Pilot's Handbook of Aeronautical Knowledge, p. G-4

A downward slant from root to tip of an aircraft’s wing or horizontal tail surface.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

The process of heating a metal to a prescribed temperature, holding it there for a specified length of time, and then cooling the metal back to room temperature.

Aviation Maintenance Technician Handbook — General, p. G-1

An inspection required by the FAA once every 12 calendar months if other suitable inspections do not occur within that timeframe. An A&P technician with inspection authorization must perform this inspection.

Aviation Maintenance Technician Handbook — General, p. G-1

The rings that appear in the end of a log cut from a tree. The number of annual rings per inch gives an indication of the strength of the wood. The more rings there are and the closer they are together, the stronger the wood. The pattern of alternating light and dark rings is caused by the seasonal variations in the growth rate of the tree. A tree grows quickly in the spring and produces the light-colored, less dense rings. The slower growth during the summer, or latter part of the growing season, produces the dark-colored, denser rings.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

A duct, or passage, that surrounds an object. The annular fan-discharge duct surrounds the core engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A ring-shaped orifice, normally one that surrounds another orifice.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A ring or groove around the outside of a circular body or shaft, or around the inside of a cylindrical hole.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A panel of warning lights in plain sight of the pilot. These lights are identified by the name of the system they represent and are usually covered with colored lenses to show the meaning of the condition they announce.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

The most common surface treatment of nonclad aluminum alloy surfaces. The aluminum alloy sheet or casting is the positive pole in an electrolytic bath in which chromic acid or other oxidizing agent produces an aluminum oxide film on the metal surface. Aluminum oxide is naturally protective, and anodizing merely increases the thickness and density of the natural oxide film.

Aviation Maintenance Technician Handbook — General, p. G-1

Aspecial device used with electronic communication and navigation systems to radiate and receive electromagnetic energy.

Aviation Maintenance Technician Handbook — Airframe, p. G-2

Preventing the accumulation of ice on an aircraft structure via a system designed for that purpose.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A system that prevents the formation of ice on an aircraft structure.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

Prevention of the formation of ice on a surface.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A chemical added to the turbine-engine fuel used in some aircraft. This additive mixes with water that condenses from the fuel and lowers its freezing temperature so it will not freeze and block the fuel filters. It also acts as a biocidal agent and prevents the formation of microbial contamination in the tanks.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

The end of a reciprocating engine that does not attach to the propeller. Also called the accessory end.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A structural wire inside a Pratt truss airplane wing between the spars. Antidrag wires run from the rear spar inboard, to the front spar at the next bay outboard. Antidrag wires oppose the forces that try to pull the wing forward.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

A tab installed on the trailing edge of a stabilator to make it less sensitive. The tab automatically moves in the same direction as the stabilator to produce an aerodynamic force that tries to bring the surface back to a streamline position. This tab is also called an antibalance tab.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

An electrohydraulic system in an airplane’s power brake system that senses the deceleration rate of every main landing gear wheel. If any wheel decelerates too rapidly, indicating an impending skid, pressure to that brake is released and the wheel stops decelerating. Pressure is then reapplied at a slightly lower value.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

Strips of aircraft fabric laid under the reinforcing tape before the fabric is stitched to an aircraft wing.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

The pedal used to control the pitch of the tail rotor or air diffuser in a NOTAR® system.

Helicopter Flying Handbook, p. G-1

See tail rotor.

Helicopter Flying Handbook, p. G-1

Absolute pressure controller.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

That power apparently available for use in an AC circuit containing a reactive component. It is the product of effective voltage times the effective current, expressed in volt-amperes.

Aviation Maintenance Technician Handbook — General, p. G-1

Provides lights that will penetrate the atmosphere far enough from touchdown to give directional, distance, and glidepath information for safe transition from instrument to visual flight.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A certificate of approval issued by the FAA for the design of an aircraft, engine, or propeller.

Aircraft Weight and Balance Handbook, p. G-1

Fiber made from an organic compound of carbon, hydrogen, oxygen, and nitrogen. It has high strength and low density. It is flexible under load and is able to withstand impact, shock, and vibration. Kevlar is a well-known aramid fiber.

Aviation Maintenance Technician Handbook — Powerplant, p. G-2

A press with either a mechanically or hydraulically operated ram used in a maintenance shop for a variety of pressing functions.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

The buoyant force that a fluid exerts upon a submerged body is equal to the weight of the fluid the body displaces.

Aviation Maintenance Technician Handbook — General, p. G-1

Sparking between a commutator and brush or between switch contacts that is caused by induced current when a circuit is broken.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

A measurement of the amount of surface inside a two-dimensional object.

Aviation Maintenance Technician Handbook — General, p. G-2

Part of the low-altitude en route chart series, this chart furnishes terminal data at a larger scale for congested areas.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A report that gives a picture of clouds, general weather conditions, and visual meteorological conditions (VMC) expected over a large area encompassing several states.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

The horizontal distance that a part of the aircraft or a piece of equipment is located from the datum.

Aviation Maintenance Technician Handbook — General, p. G-2

The rotating part of an electric generator or motor.

Aviation Maintenance Technician Handbook — General, p. G-2

A chemical compound such as toluene, xylene, and benzene that is blended with gasoline to improve its anti-detonation characteristics.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

See air route surveillance radar.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

See air route traffic control center.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A rotor system in which each of the blades is connected to the rotor hub in such a way that it is free to change its pitch angle, and move up and down and fore and aft in its plane of rotation.

Helicopter Flying Handbook, p. G-1

See link rod.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

See airport surface detection equipment.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

See Automated Surface Observing System.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

The relationship of the length (wingtip to wingtip), or span, of an airfoil to its width, or chord.

Aviation Maintenance Technician Handbook — General, p. G-2

A description of an object made up of two or more parts.

Aviation Maintenance Technician Handbook — General, p. G-2

Also known as P-factor. A tendency for an aircraft to yaw to the left due to the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal axis is in a climbing attitude in relation to the relative wind. The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

An airfoil section that is not the same on both sides of the chord line.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

A condition of uneven lift produced by the rotor when a helicopter is in forward flight. Asymmetrical lift is caused by the difference between the airspeed of the advancing blade and that of the retreating blade.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

The loading of a propeller disc that causes one side to produce more thrust than the other side.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

See air traffic control radar beacon system.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

Aerodynamic twisting force. The aerodynamic force that acts on a rotating propeller blade to increase its blade angle. The axis of rotation of a blade is near the center of its chordline, and the center of pressure is between the axis and the leading edge. Aerodynamic lift acting through the center of pressure tries to rotate the blade to a higher pitch angle.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

See automatic terminal information service.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A bending of the electromagnetic (EM) wave from the satellite that creates an error in the GPS system.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

The smallest particle composed of a nucleus that contains protons, neutrons, and electrons, which revolve around the nucleus.

Aviation Maintenance Technician Handbook — General, p. G-2

The process of breaking a liquid down into tiny droplets or a fine spray. Atomized liquids vaporize easily.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

To weaken, or lessen the intensity of, an activity.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

A personal motivational predisposition to respond to persons, situations, or events in a given manner that can, nevertheless, be changed or modified through training as sort of a mental shortcut to decision-making.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A system composed of three-axis sensors that provide heading, attitude, and yaw information for aircraft. AHRS are designed to replace traditional mechanical gyroscopic flight instruments and provide superior reliability and accuracy.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

An aircraft attitude indicator that incorporates flight command bars to provide pitch and roll commands.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A gyroscopic flight instrument that gives the pilot an indication of the attitude of the aircraft relative to its pitch and roll axes. The attitude indicator in an autopilot is in the sensing system that detects deviation from a level-flight attitude.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

Controlling the aircraft by reference to the instruments rather than by outside visual cues.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

The ability to recognize hazardous attitudes in oneself and the willingness to modify them as necessary through the application of an appropriate antidote thought.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

A long, stainless steel tube around the discharge of the exhaust pipes of a reciprocating engine. Exhaust gases flow through the augmenter tube and produce a low pressure that pulls additional cooling air through the engine compartment. Heat may be taken from the augmenter tubes and directed through the leading edges of the wings for thermal anti-icing.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

A long, specially shaped stainless steel tube mounted around the exhaust tail pipe of a reciprocating engine. As exhaust gases flow through the augmentor tube, they produce a low pressure in the engine compartment that draws in cooling air through the cylinder fins.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

A pressure vessel inside of which air can be heated to a high temperature and pressure raised to a high value. Autoclaves are used in the composite manufacturing industry to apply heat and pressure for curing resins.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

A heavier-than-air rotor-wing aircraft sustained in the air by rotors turned by aerodynamic forces rather than by engine power. When the name Autogyro is spelled with a capital A, it refers to a specific series of machines built by Juan de la Cierva or his successors.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

A system on a turbine engine that automatically energizes the igniters to provide a relight if the engine should flame out.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

Nighttime visual illusion that a stationary light is moving, which becomes apparent after several seconds of staring at the light.

Pilot's Handbook of Aeronautical Knowledge, p. G-4

Weather reporting system which provides surface observations every minute via digitized voice broadcasts and printed reports. Automated Weather Observing System (AWOS). Automated weather reporting system consisting of various sensors, a processor, a computer-generated voice subsystem, and a transmitter to broadcast weather data. Automatic dependent surveillance—broadcast (ADS–B). A function on an aircraft or vehicle that periodically broadcasts its state vector (i.e., horizontal and vertical position, horizontal and vertical velocity) and other information.

Pilot's Handbook of Aeronautical Knowledge, p. G-5

A subsystem in an aircraft disc brake that compensates for disc or lining wear. Each time the brakes are applied, the automatic adjuster is reset for zero clearance, and when the brakes are released, the clearance between the discs or the disc and lining is returned to a preset value. A malfunctioning automatic adjuster in a multiple-disc brake can cause sluggish and jerky operation.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

Electronic navigation equipment that operates in the low- and medium-frequency bands. Used in conjunction with the ground-based nondirectional beacon (NDB), the instrument displays the number of degrees clockwise from the nose of the aircraft to the station being received.

Pilot's Handbook of Aeronautical Knowledge, p. G-5

The full system of automatic flight control that includes the autopilot, flight director, horizontal situation indicator, air data sensors, and other avionics inputs.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

An intake valve opened by low pressure created inside the cylinder as the piston moves down. There is no mechanical means of opening it.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

The device in a fuel metering system, such as a carburetor or fuel injection system, that keeps the air/fuel mixture ratio constant as the density of air changes with altitude.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

An automatic flight control device that controls an aircraft about one or more of its three axes. The primary purpose of an autopilot is to relieve the pilot of the control of the aircraft during long periods of flight.

Aviation Maintenance Technician Handbook — Airframe, p. G-3

The continuous broadcast of recorded non-control information in selected terminal areas. Its purpose is to improve controller effectiveness and relieve frequency congestion by automating repetitive transmission of essential but routine information.

Pilot's Handbook of Aeronautical Knowledge, p. G-5

Those units and components that furnish a means of automatically controlling the aircraft.

Helicopter Flying Handbook, p. G-1

A synchro system used in remote indicating instruments. The rotors in an Autosyn system are two-pole electromagnets, and the stators are delta-connected, three-phase, distributed-pole windings in the stator housings. The rotors in the transmitters and indicators are connected in parallel and are excited with 26-volt, 400-Hz AC. The rotor in the indicator follows the movement of the rotor in the transmitter. Auxiliary power unit (APU).A small turbine or reciprocating engine that drives a generator, hydraulic pump, and air pump. The APU is installed in the aircraft and is used to supply electrical power, compressed air, and hydraulic pressure when the main engines are not running.

Aviation Maintenance Technician Handbook — Airframe, p. G-4

A physician with training in aviation medicine designated by the Civil Aerospace Medical Institute (CAMI).

Pilot's Handbook of Aeronautical Knowledge, p. G-5

Observation of current surface weather reported in a standard international format.

Pilot's Handbook of Aeronautical Knowledge, p. G-5

Compound-action hand shears used for cutting sheet metal. Aviation snips come in sets of three. One pair cuts to the left, one pair cuts to the right, and the third pair of snips cuts straight.

Aviation Maintenance Technician Handbook — Airframe, p. G-4

Oxygen that has had almost all of the water and water vapor removed from it.

Aviation Maintenance Technician Handbook — Airframe, p. G-4

The branch of technology that deals with the design, production, installation, use, and servicing of electronic equipment mounted in aircraft.

Aviation Maintenance Technician Handbook — Airframe, p. G-4

See Automated Weather Observing System.

Pilot's Handbook of Aeronautical Knowledge, p. G-5

Three imaginary lines that pass through an aircraft’s center of gravity. The axes can be considered as imaginary axles around which the aircraft rotates. The three axes pass through the center of gravity at 90° angles to each other. The axis from nose to tail is the longitudinal axis (pitch), the axis that passes from wingtip to wingtip is the lateral axis (roll), and the axis that passes vertically through the center of gravity is the vertical axis (yaw).

Pilot's Handbook of Aeronautical Knowledge, p. G-5

The load on a bearing parallel to the shaft on which the bearing is mounted. Thrust produces an axial load on a bearing.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

A type of compressor used in gas turbine engines. Air passes through the compressor in essentially a straight line, parallel to the axis of the compressor. The compressor is made of a number of stages of rotating compressor blades between stages of stationary stator vanes.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

A turbine that is turned by a fluid flowing through it in a direction that is approximately parallel to the shaft on which the turbine wheel is mounted.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

The center line about which a propeller rotates.

Aviation Maintenance Technician Handbook — Powerplant, p. G-3

A horizontal angular distance, measured clockwise from a fixed reference direction to an object.

Aviation Maintenance Technician Handbook — Airframe, p. G-4

A card that may be set, gyroscopically controlled, or driven by a remote compass.

Pilot's Handbook of Aeronautical Knowledge, p. G-5