Glossary

See decision altitude.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

The registered trade name for a cloth woven from polyester fibers.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

States that a mixture of several gases which do not react chemically exerts a pressure equal to the sum of the pressures which the several gases would exert separately if each were allowed to occupy the entire space alone at the given temperature.

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

Oscillation whose amplitude decreases with time.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

Physical and chemical adjustments of the eye that make vision possible in relative darkness.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

The input for computer processing in the form of numerical information that represents characters or analog quantities.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

A wire or group of wires that are used to move data within a computer system.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

A body of information that is available on any particular subject.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

The performance specifications of a turbine engine observed and recorded by the engine manufacturer or overhauler and recorded on the engine dataplate. This data includes the engine speed at which a specified EPR is attained. When trimming the engine, the technician uses this data as the goal.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

Specification of each gas turbine engine determined in the manufacturer’s test cell when the engine was calibrated. This data includes the engine serial number with the EPR that produced a specific RPM. The technician refers to this information when trimming the engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

An imaginary vertical plane or line from which all measurements of arm are taken. The datum is established by the manufacturer. Once the datum has been selected, all moment arms and the location of CG range are measured from this point.

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

Direct current. Electrical current in which the electrons always flow in the same direction.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

Navigation of an airplane solely by means of computations based on airspeed, course, heading, wind direction and speed, groundspeed, and elapsed time.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

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

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

Separation of the bond between the skin laminates and the core of a composite structure.

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

A valve in a power brake system between the power brake control valve and the wheel cylinder. This valve lowers the pressure of the fluid going to the brake and increases its volume. A debooster valve increases the smoothness of brake application and aids in rapid release of the brakes.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

The breakdown of the structure of wood fibers. Wood that shows any indication of decay must be rejected for use in aircraft structure.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

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

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

A magnetic compass error that occurs when the aircraft decelerates while flying on an easterly or westerly heading, causing the compass card to rotate toward South.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

The unit for measuring sound intensity. One decibel is the smallest change in sound intensity the human ear can detect.

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

A type of tree that sheds its foliage at the end of the growing season. Hardwoods come from deciduous trees.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

The number system, also called the base-ten system, based on the number 10. Consisting of ten symbols, or digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9), the main principle is that 10 is considered as a new unit from which point counting starts again.

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

The breakdown of the structure of wood fibers. Wood that shows any indication of decay must be rejected for use in aircraft structure.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

A small digital computer, often built into an instrument or control device that contains a built-in program that causes it to perform a specific function.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

A vacuum pump capable of removing almost all of the air from a refrigeration system. A deep-vacuum pump can reduce the pressure inside the system to a few microns of pressure.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

A cap for a tire, strut, or accumulator air valve that, when screwed onto the valve, depresses the valve stem and allows the air to escape safely through a hole in the side of the cap.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

The alteration of material properties (e.g., strength, modulus, coefficient of expansion) which may result from deviations in manufacturing or from repeated loading and/or environmental exposure.

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

Any flight environment of reduced visibility in which situational awareness of the aircrew or control of the aircraft may be severely diminished, completely lost, or may not be maintained as comprehensively as they are during flight operations within clear or undiminished visibility. DVE conditions are further categorized into eleven different types: smoke, smog, clouds, rain, fog, snow, whiteout, night, flat light, sand, and brownout.

Helicopter Flying Handbook, p. G-2

An English designed observation airplane built in large quantities in the united States during World War I. After the war, surplus DH-4s were used for carrying the U.S. Mail.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

The act of removing ice accumulation from an aircraft structure.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

A system that removes ice after it has formed on an aircraft.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

The removal of ice that has formed on a surface.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

Separation of the bond between the individual plies of a laminated composite structure.

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

An isolation valve at the discharge side of the air turbine that prevents the loss of pressurization through a disengaged cabin air compressor.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

The Greek symbol “Δ” means a change in something. ΔCG means a change in the center of gravity location.

Aircraft Weight and Balance Handbook, p. G-2

An airplane with a triangular-shaped wing. This wing has an extreme amount of sweepback on its leading edge, and a trailing edge that is almost perpendicular to the longitudinal axis of the airplane.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

A method of connecting three electrical coils into a ring or, as they are drawn on a schematic diagram as a triangle, a delta (D).

Aviation Maintenance Technician Handbook — Airframe, p. G-11

A flapping hinge with an axis skewed so that the flapping motion introduces a component of feathering that would result in a restoring force in the flap-wise direction.

Helicopter Flying Handbook, p. G-3

A measure of the fineness of the yarns in a fabric.

Aviation Maintenance Technician Handbook — Airframe, p. G-11

The lower part of a fraction (represented by the letter D in N⁄D), the quantity by which the numerator is divided.

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

The weight of a substance per unit volume.

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

The altitude in standard air at which the density is the same as that of the existing air.

Aviation Maintenance Technician Handbook — Airframe, p. G-11; Aviation Maintenance Technician Handbook — Powerplant, p. G-9

The ratio of the density of the air at a given altitude to the density of the air at sea level under standard conditions.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

Preplanned IFR ATC departure, published for pilot use, in textual and graphic format.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

The direct transformation of a gas to a solid state, in which the liquid state is bypassed. Some sources use sublimation to describe this process instead of deposition.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

Reduction in the rated voltage or current of an electrical component. Derating is done to extend the life or reliability of the device.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A drying agent used in an air conditioning system to remove water from the refrigerant. A desiccant is made of silica-gel or some similar material.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A description of a single part, given in such a manner as to describe bylines, notes, and symbols the specifications for size, shape, material, and methods of manufacture to be used in making the part.

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

A thorough examination of an item including disassembly. The overhaul of a component is considered to be a detailed inspection.

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

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 a fuel valve to provide a positive means of identifying the fully on and fully off position of the valve.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A type of mineral oil with metallic-ash-forming additives that protects the inside of an engine from sludge and varnish buildup. Used in automotive engines, it has proven unsuitable for use in aircraft engines.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

Uncontrolled burning of fuel in the cylinder of a reciprocating engine. Detonation causes explosive burning of the fuel which creates an increased cylinder pressure, excessive cylinder head temperature, and decreased engine performance.

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

A compass error caused by magnetic disturbances from the electrical and metal components in the aircraft. The correction for this error is displayed on a compass correction card placed near the magnetic compass of the aircraft.

Helicopter Flying Handbook, p. G-3

An error in a magnetic compass caused by localized magnetic fields in the aircraft. Deviation error, which is different on each heading, is compensated by the technician “swinging” the compass. A compass must be compensated so the deviation error on any heading is no greater than 10 degrees.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

Moisture that has condensed from water vapor. Usually found on cooler objects near the ground, such as grass, as the near-surface layer of air cools faster than the layers of air above it.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

The temperature to which humid air must be cooled at constant pressure to become saturated.

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

A vessel designed to hold liquefied gases. It has double walls with the space between being evacuated to prevent the transfer of heat. The surfaces in the vacuum area are made heat-reflective.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

The temperature at which air reaches a state where it can hold no more water.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

Differential global positioning system.

Pilot's Handbook of Aeronautical Knowledge, p. G-9

Measures variations in a surface by using an accurately machined probe mechanically linked to a circular hand whose movement indicates thousandths of an inch, or is displayed on a liquid crystal display (LCD) screen.

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

The length of a line passing directly through the center of a circle. Twice the radius of the circle.

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

Used for cutting external threads on round stock.

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

The answer to a subtraction problem.

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

Aileron movement in which the upward-moving aileron deflects a greater distance than the one moving downward. The up aileron produces parasite drag to counteract the induced drag caused by the down aileron. Differential aileron travel is used to counteract adverse yaw.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

Control surface rigged such that the aileron moving up moves a greater distance than the aileron moving down. The up aileron produces extra parasite drag to compensate for the additional induced drag caused by the down aileron. This balancing of the drag forces helps minimize adverse yaw.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

A system that improves the accuracy of Global Navigation Satellite Systems (GNSS) by measuring changes in variables to provide satellite positioning corrections.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

The difference between two pressures. An airspeed indicator is a differential-pressure gauge. It measures the difference between static air pressure and pitot air pressure.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A type of reverse-current cutout switch used with heavy-duty electrical systems. This switch connects the generator to the electrical bus when the generator voltage is a specific amount higher than the battery voltage.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A component in a gas turbine engine that decreases the velocity of air flowing through it and increases its pressure.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

An electrical test instrument that can be used to measure voltage, current, and resistance. The indication is in the form of a liquid crystal display in discrete numbers.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A modified image picked up by the miniature TV camera in the end of a fiber-optic probe. This image is converted into a digital electronic signal that eliminates unwanted portions of the viewed area and allows the desired image to be enhanced for a clearer view of the inside of a turbine engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

The positive angle formed between the lateral axis of an airplane and a line that passes through the center of the wing or horizontal stabilizer. Dihedral increases the lateral stability of an airplane.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A popular type of oxygen system in which the oxygen is metered to the mask, where it is diluted with cabin air by an airflow-metering aneroid assembly which regulates the amount of air allowed to dilute the oxygen on the basis of cabin altitude. The mixture of oxygen and air flows only when the wearer of the mask inhales. The percentage of oxygen in the air delivered to the mask is regulated, on the basis of altitude, by the regulator. A diluter-demand regulator has an emergency position which allows 100 percent oxygen to flow to the mask, by-passing the regulating mechanism.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A half wavelength, center-fed radio antenna. The length of each of the two arms is approximately one fourth of the wavelength of the center frequency for which the antenna is designed.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A gage, in the form of a thin metal rod, used to measure the level of liquid in a reservoir. The dipstick is pushed into the reservoir until it contacts a built-in stop; then it is removed and visually inspected. The level of liquid in the reservoir is indicated by the amount of the dipstick wet by the liquid.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

The ability to maneuver a helicopter by tilting the rotor disk and changing the pitch of the rotor blades.

Helicopter Flying Handbook, p. G-3

Electricity that flows in one direction at all times.

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

The true and instantaneous reflection of aircraft pitch-and-bank attitude by the miniature aircraft, relative to the horizon bar of the attitude indicator.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

A single-shaft turbine engine in which the compressor and power section are mounted on a common driveshaft.

Helicopter Flying Handbook, p. G-3

A system that provides current FAA weather and flight plan filing services to certified civil pilots, via personal computer, modem, or telephone access to the system. Pilots can request specific types of weather briefings and other pertinent data for planned flights.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

Stability about the vertical axis of an aircraft, whereby an aircraft tends to return, on its own, to flight aligned with the relative wind when disturbed from the equilibrium state.

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

A large, cigar-shaped, rigid, lighter-than-air flying machine. Dirigibles are made of a rigid truss structure covered with fabric. Gas bags inside the structure contain the lifting gas, which is either helium or hydrogen.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

The total area swept by the blades of a helicopter main rotor.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

An interruption in the normal physical structure or configuration of a part, such as a crack, forging lap, seam, inclusion, porosity, and the like. A discontinuity may or may not affect the usefulness of a part.

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

The area swept by the blades of the rotor. It is a circle with its center at the hub and has a radius of one blade length.

Helicopter Flying Handbook, p. G-3

The total helicopter weight divided by the rotor disk area.

Helicopter Flying Handbook, p. G-3

Caused by contact between dissimilar metal parts in the presence of a conductor.

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

The unequal lift across the rotor disk resulting from the difference in the velocity of air over the advancing blade half and the velocity of air over the retreating blade half of the rotor disk area.

Helicopter Flying Handbook, p. G-3

See reference circle.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

A pulse-type electronic navigation system that shows the pilot, by an instrument-panel indication, the number of nautical miles between the aircraft and a ground station or waypoint.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

Alternator stator windings wound in a series of slots in the stator frame. A distributed pole stator is distinguished from a salient pole stator whose coils are wound around separate pole shoes that project inward from the field frame toward the rotor.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

A high-voltage selector switch that is gear-driven from the shaft of the rotating magnet in a magneto. The distributor rotor picks up the high voltage from the secondary winding of the coil and directs it to high-voltage terminals. From here, it is carried by high-tension ignition leads to the spark plugs.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

A duct that has an increased cross-sectional area in the direction of flow.

Aviation Maintenance Technician Handbook — Powerplant, p. G-9

Oscillation whose amplitude increases with time.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A duct, or passage, whose cross-sectional area increases in the direction of fluid flow.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

In a division problem, the number to be divided by the divisor. In 6 ÷ 2 = 3, the dividend is 6.

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

The process of finding how many times one number (the divisor) is contained in another number (the dividend).

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

In a division problem, the number by which dividend is to be divided. In 6 ÷ 2 = 3, the divisor is 2.

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

A flight track that is a constant distance from the station or waypoint.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

Department of Defense.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

A turn-and-slip indicator dial mark in the shape of a doghouse. Domestic Reduced Vertical Separation Minimum (DRVSM). Additional flight levels between FL 290 and FL 410 to provide operational, traffic, and airspace efficiency.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

The treatment of a structure to be covered with fabric to keep the solvents in the dope from softening the protective coating on the structure.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

A condition of aircraft dope brushed onto a surface in such a way that it forms a stringy, uneven surface rather than flowing out smoothly. Double-acting actuator (hydraulic system component). A linear actuator moved in both directions by fluid power. Double-acting hand pump (hydraulic system component). A hand-operated fluid pump that moves fluid during both strokes of the pump handle.

Aviation Maintenance Technician Handbook — Airframe, p. G-12

The process by which small amounts of additives called impurities are added to the semiconductor material to increase their current flow by adding a few electrons or a few holes.

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

A type of mount used for the gyro in an attitude instrument. The axes of the two gimbals are at right angles to the spin axis of the gyro, allowing free motion in two planes around the gyro.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

A piece of sheet metal used to strengthen and stiffen a repair in a sheet metal structure.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

A carburetor that mounts on the top of a reciprocating engine. Air entering the engine flows downward through the carburetor. ∆P (delta P). Differential pressure.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

Any time during which an aircraft is out of commission and unable to be operated.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

Air forced down by aerodynamic action below and behind the wing of an airplane or the rotor of a helicopter. Aerodynamic lift is produced when the air is deflected downward. The upward force on the aircraft is the same as the downward force on the air.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

See departure procedure.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

Fore-and-aft movement of the tip of a helicopter rotor blade in its plane of rotation.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

The curve created when plotting induced drag and parasite drag.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

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

Aviation Maintenance Technician Handbook — Airframe, p. G-13

Brakes that do not fully release when the brake pedal is released. The brakes are partially applied all the time, which causes excessive lining wear and heat.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

Angle between heading and track.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

An electric or pneumatic motor that drives a chuck that holds a twist drill. The best drill motors produce high torque, and their speed can be controlled.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

A fuel quantity indicator used to measure the fuel level in the tank when the aircraft is on the ground. The drip stick is pulled down from the bottom of the tank until fuel drips from its opened end. This indicates that the top of the gauge inside the tank is at the level of the fuel. Note the number of inches read on the outside of the gauge at the point it contacts the bottom of the tank, and use a drip stick table to convert this measurement into gallons of fuel in the tank.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

A progressive decrease in RPOM with load in a gas turbine engine whose speed is governed with a fly-weight-type governor in the fuel control. As the load increases, the pilot valve drops down to meter more fuel. The lower position of the valve decreases the compression of the speeder spring and allows the flyweights to assume an on-speed position at a lower rpm.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

See Domestic Reduced Vertical Separation Minimum.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

An engine-driven air pump which used carbon vanes. Dry pumps do not use any lubrication, and the vanes are extremely susceptible to damage from the solid airborne particles. These pumps must be operated with filters in their inlet so they will take in only filtered air.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

Solidified carbon dioxide. Dry ice sublimates, or changes from a solid directly into a gas, at a temperature of –110 °F (–78.5 °C).

Aviation Maintenance Technician Handbook — Airframe, p. G-13

Decomposition of wood fibers caused by fungi. Dry rot destroys all strength in the wood.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

An engine that carries its lubricating oil supply in a tank external to the engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

An ignition system of an aircraft reciprocating engine that has two of every critical unit, including two spark plugs in each cylinder. Dual ignition provides safety in the event of one system malfunctioning, but more important, igniting the air/fuel mixture inside the cylinder at two locations provides more efficient combustion of the air/fuel mixture in the cylinder.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

A rotor system utilizing two main rotors.

Helicopter Flying Handbook, p. G-3

An axial-flow turbine engine that has two compressors, each driven by its own stage or stages of turbines.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

See direct user access terminal system.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

A thrust augmentation system, similar to an afterburner, where fuel is added to the fan-discharge air and burned.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

A decrease in pressure of the air flowing into a gas turbine engine caused by friction.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

The property of a material that allows it to be drawn into a thin section without breaking.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

A noninductive, high-power, 50-ohm resistor that can be connected to a transmission line in place of the antenna. The transmitter can be operated into the dummy load without transmitting any signal.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

Transmitting on one frequency and receiving on a separate frequency.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

A measure of engine life. Durability is usually measured in TBO hours.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

The name for the original alloy of aluminum, magnesium, manganese, and copper. Duralumin is the same as the modern 2017 aluminum alloy.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

An undesirable, low-amplitude coupled oscillation about both the yaw and roll axes that affects many swept wing airplanes. Dutch roll is minimized by the use of a yaw damper.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

A common name for compound-action sheet metal shears.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

A schedule that allows a device to operate for a given period of time, followed by a cooling down period before the device can be operated again.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

A chamber in a turbine engine into which the scavenged oil is returned. Entrained air separates from the oil in the dwell chamber before it is picked up by the pressure pump.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

A condition that exists when landing on a surface with standing water deeper than the tread depth of the tires. When the brakes are applied, there is a possibility that the brake will lock up and the tire will ride on the surface of the water, much like a water ski. When the tires are hydroplaning, directional control and braking action are virtually impossible. An effective anti-skid system can minimize the effects of hydroplaning.

Pilot's Handbook of Aeronautical Knowledge, p. G-10

The actual weight of the aircraft multiplied by the load factor, or the increase in weight caused by acceleration.

Aircraft Weight and Balance Handbook, p. G-2

The pressure a moving fluid would have if it were stopped. Dynamic pressure is measured in pounds per square foot.

Aviation Maintenance Technician Handbook — Airframe, p. G-13

The tendency of a helicopter to continue rolling when the critical angle is exceeded, if one gear is on the ground, and the helicopter is pivoting around that point.

Helicopter Flying Handbook, p. G-3

The property of an aircraft that causes it, when disturbed from straight-and level flight, to develop forces or moments that restore the original condition of straight and level.

Aviation Maintenance Technician Handbook — General, p. G-4; Pilot's Handbook of Aeronautical Knowledge, p. G-11

A device used to measure the amount of torque being produced by an engine. The drive shaft of the engine is loaded with either an electric generator or a fluid pump, and the output of the generator or pump is measured and converted into units of torque. Torque at a specific rpm can be converted into brake horsepower.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10

The unit of force that imparts an acceleration of one centimeter per second, per second to a mass of one gram. One dyne is equal to 2.248 ∙ 10-6 pounds.

Aviation Maintenance Technician Handbook — Powerplant, p. G-10