Glossary

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-22

Primary lead. The wire that connects the primary winding of a magneto to the ignition switch. The magneto is turned off by grounding its P-lead.

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

See precipitation static.

Pilot's Handbook of Aeronautical Knowledge, p. G-22

A covering applied to an object or structure to protect it and improve its appearance. Paint consists of a pigment suspended in a vehicle such as oil or water. When the vehicle dries by evaporation or curing, the pigment is left as a film on the surface.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

See precision approach path indicator.

Pilot's Handbook of Aeronautical Knowledge, p. G-22

A reflector whose surface is made in the form of a parabola.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

A circuit in which two or more electrical resistances or loads are connected across the same voltage source.

Aviation Maintenance Technician Handbook — General, p. G-8

A circuit in a multi-engine aircraft electrical system that controls a flow of control current which is used to keep the generators or alternators sharing the electrical load equally. The relay opens automatically to shut off the flow of paralleling current any time the output of either alternator or generator drops to zero.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

A relay in multi-engine aircraft electrical system that controls a flow of control current which is used to keep the generators or alternators sharing the electrical load equally. The relay opens automatically to shut off the flow of paralleling current any time the output of either alternator or generator drops to zero.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

Lines of latitude.

Pilot's Handbook of Aeronautical Knowledge, p. G-22

A form of aerodynamic drag caused by friction between the air and the surface over which it is flowing.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

The metal being welded. This term is used to distinguish between the metal being welded and the welding rod.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

The percentage of the total pressure of a mixture of gases produced by each of the individual gases in the mixture.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

A layer of thin plastic material placed between a composite lay-up and the heating blanket. It prevents the blanket from sticking to the fabric.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

The unit of pressure produced when one newton of force acts uniformly over an area of one square meter. One pascal is equal to 14.503 ∙ 10-5 (0.00014503) psi. The kilopascal (kPa) is easier to manipulate. 1 kPa = 1,000 Pa = 0.14503 psi.

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

The law that states that pressure applied anywhere to a body of fluid causes a force to be transmitted equally in all directions; the force acts at right angles to any surface in contact with the fluid.

Aviation Maintenance Technician Handbook — General, p. G-8

The abbreviation of passengers.

Aircraft Weight and Balance Handbook, p. G-4

(GAMA) The weight of occupants, cargo, and baggage.

Aircraft Weight and Balance Handbook, p. G-4

Plenum chamber burning. A method of thrust augmentation used on engines with vectored nozzles. Fuel injected into the fan-discharge air is burned to increase thrust.

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

The voltage of AC electricity that is measured from zero voltage to the peak of either alternation.

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

The lateral or longitudinal oscillation of the fuselage due to its suspension from the rotor system.

Helicopter Flying Handbook, p. G-4

The length of time a part is left in the penetrant when preparing it for inspection by the fluorescent or dye penetrant method. The hotter the part and the longer the penetrant dwell time, the smaller the fault that will be detected.

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

The distance in inches of the CG from LEMAC divided by the MAC. It is a good standard for CG location in airplanes because it permits a standard weight and balance program for different types of airplanes.

Aircraft Weight and Balance Handbook, p. G-4

Used to express a number as a fraction of 100. Using the percentage sign, %, 90 percent is expressed as 90%.

Aviation Maintenance Technician Handbook — General, p. G-8

The anti-detonation rating of a fuel that has a higher critical pressure and temperature than iso-octane (a rating of 100). Iso-octane that has been treated with varying amounts of tetraethyl lead is used as the reference fuel.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

A weight permanently installed in an aircraft to bring its CG into allowable limits. Permanent ballast is part of the aircraft empty weight.

Aircraft Weight and Balance Handbook, p. G-2

A piece of hardened steel that has been exposed to a strong magnetizing force which has aligned the spin axes of the electrons surrounding its atoms. The high retentivity of the material causes the electrons to retain their magnetic orientation.

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

A casting made in a reusable metal mold. The walls of permanent-mold castings can be made thinner than similar walls made by sand casting.

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

Used to refer to the ease with which a magnetic flux can be established in a given magnetic circuit.

Aviation Maintenance Technician Handbook — General, p. G-8

The embodiment of personal traits and characteristics of an individual that are set at a very early age and extremely resistant to change.

Pilot's Handbook of Aeronautical Knowledge, p. G-22

A drawing that shows a three-dimensional object (portraying height, width, and depth) as it appears to an observer. It most closely resembles the way an object would look in a photograph.

Aviation Maintenance Technician Handbook — General, p. G-8

A special abrasive compound used inside an aluminum wire terminal being swaged onto a piece of aluminum electrical wire. When the terminal is compressed, the zinc dust abrades the oxides from the wire, and the petrolatum prevents oxygen reaching the wire so no more oxides can form.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

The various components of a hydrocarbon fuel that are separated by boiling them off at different temperatures in the process of fractional distillation.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

See primary flight display.

Pilot's Handbook of Aeronautical Knowledge, p. G-22

Composed of one long and two short evenly spaced dashes, indicates an alternate position of parts of the object or the relative position of a missing part.

Aviation Maintenance Technician Handbook — General, p. G-8

The sequence with which the output phases of a three-phase generator are connected to the load. Reversing the phase sequence of a generator from A-B-C to A-C-B prevents the generator from being synchronized with the others on the bus.

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

A complex antenna which consists of a number of elements. A beam of energy is formed by the superimposition of the signals radiating from the elements. The direction of the beam can be changed by varying the relative phase of the signals applied to each of the elements.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

A plastic material made of a thermosetting phenol-formaldehyde resin, reinforced with cloth or paper. Phenolic plastic materials are used for electrical insulators and for chemical-resistant table tops.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

Long-period oscillations of an aircraft around its lateral axis. It is a slow change in pitch accompanied by equally slow changes in airspeed. Angle of attack remains constant, and the pilot often corrects for phugoid oscillations without even being aware of them.

Pilot's Handbook of Aeronautical Knowledge, p. G-22

An electronic filter used to prevent radio frequency energy produced in the ignition exciter from feeding back into the aircraft electrical system. The filter is made of an inductor with a capacitor on its input and output. The name is derived from the resemblance of the three components on a schematic diagram to the Greek letter pi (π).

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

See pilot in command.

Pilot's Handbook of Aeronautical Knowledge, p. G-22

A drawing that is similar to a photograph. It shows an object as it appears to the eye, but it is not satisfactory for showing complex forms and shapes.

Aviation Maintenance Technician Handbook — General, p. G-8

A small hole punched or drilled in a piece of sheet metal to locate a rivet hole.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

Report of meteorological phenomena encountered by aircraft. Pilot’s Operating Handbook/Airplane Flight Manual (POH/AFM). FAA-approved documents published by the airframe manufacturer that list the operating conditions for a particular model of aircraft.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

An FAA-approved document published by the airframe manufacturer that lists the operating conditions for a particular model of aircraft and its engine(s).

Aircraft Weight and Balance Handbook, p. G-4

A group of knots, all having a diameter of less than approximately 1⁄16 inch.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

A small gear that meshes with a larger gear, a sector of a gear, or a toothed rack.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

Cloth tape whose edges have small V-shaped notches cut along their length. The pinked edges prevent the tape from raveling.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

Shears used to cut aircraft fabric with a series of small notches along the cut edge.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

See pilot report.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A sliding plug in an actuating cylinder used to convert pressure into force and then into work.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

See wrist pin.

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

Rotation of an aircraft about its lateral axis.

Aviation Maintenance Technician Handbook — General, p. G-8; Aviation Maintenance Technician Handbook — Airframe, p. G-25

The angle between the chord line of a rotor blade and the reference plane of the main rotor hub, or the plane of rotation of the rotor.

Aviation Maintenance Technician Handbook — General, p. G-8

The lateral axis of an aircraft that extends from wing tip to wing tip and passes through the center of gravity. This is the axis about which the aircraft pitches.

Aviation Maintenance Technician Handbook — General, p. G-8

The gradual twist in the propeller blade from shank to tip.

Aviation Maintenance Technician Handbook — General, p. G-8

Pockets of pitch that appear in the growth rings of a piece of wood.

Aviation Maintenance Technician Handbook — Airframe, p. G-25

Ram air pressure used to measure airspeed. The pitot tube faces directly into the air flowing around the aircraft. It stops the air and measures its pressure.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A combination pickup used to sample pitot pressure and static air pressure.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

Fabric in which each warp thread passes over one fill thread and under the next. Plain-weave fabric typically has the same strength in both warp and fill directions.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A type of radar scope that shows both the direction and distance of the target from the radar antenna. Some radar antenna rotate and their PPI scopes are circular. Other antenna oscillate and their PPI scopes are fan shaped.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

The overhead view of an approach procedure on an instrument approach chart. The plan view depicts the routes that guide the pilot from the en route segments to the IAF.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

The plane in which a propeller blade rotates. The plane of rotation is perpendicular to the propeller shaft.

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

A woodworking power tool used to smooth the surfaces of a piece of wood.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A type of large-ratio reduction gearing. A series of small planetary gears are mounted on a spider attached to the output shaft. The planetary gears rotate between a fixed sun gear and a driven ring gear.

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

The shape or form of a wing as viewed from above. It may be long and tapered, short and rectangular, or various other shapes.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A method of removing paint from an aircraft surface by dry-blasting it with tiny plastic beads.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A constituent in dope or lacquer that gives its film flexibility and resilience.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

The generic name for any of the organic materials produced by polymerization. Plastics can be shaped by molding or drawing.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

An enclosed chamber in which air can be held at a pressure higher than that of the surrounding air.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

An enclosed chamber in which air can be held at a pressure slightly higher than that of the surrounding air. Plenum chambers are used to stabilize the pressure of the air before it enters a double entry centrifugal compressor.

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

A heavy metal object, cylinder- or coneshaped, with a sharp point at one end that is suspended by a string to produce a vertical reference line useful in aircraft measurements.

Aviation Maintenance Technician Handbook — General, p. G-8

The rating of an aircraft tire that indicates its relative strength. The ply rating does not indicate the actual number of plies of fabric in the tire; it indicates the number of piles of cotton fabric needed to produce the same strength as the actual piles.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A wood product made by gluing several pieces of thin wood veneer together. The grain of the wood in each layer runs at 90° or 45° to the grain of the layer next to it.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

Operation by the use of compressed air.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

The system of fluid power which transmits force by the use of a compressible fluid.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A bipolar transistor made of a thin base of N-type silicon or germanium sandwiched between a collector and an emitter, both of which are made of P-type material.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

Pilot’s Operating Handbook. A document published by the airframe manufacturer and approved by the FAA that lists the operating conditions for a particular model of aircraft. Engine operating parameters are included in the POH.

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

See Pilot’s Operating Handbook/Airplane Flight Manual.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A type of helicopter instrument approach procedure to a missed approach point more than 2,600 feet from an associated helicopter landing area.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

Inward extensions from the field frame of a generator around which the field coils are wound.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

A synthetic fiber made by the polymerization process in which tiny molecules are united to form a long chain of molecules. Polyester fibers are woven into fabrics that are known by their trade names of Dacron, Fortrel, and Kodel. Polyester film and sheet are known as Mylar and Celenar.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A thermosetting resin used as a matrix for much of the fiberglass used in composite construction.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A hard, chemically resistant finish used on aircraft. Polyurethane enamel is resistant to damage from all types of hydraulic fluid.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A thermoplastic resin used in the manufacture of transparent tubing for electrical insulation and fluid lines which are subject to low pressures.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A series of mistakes that may lead to an accident or incident. Two basic principles generally associated with the creation of a poor judgment chain are: (1) one bad decision often leads to another; and (2) as a string of bad decisions grows, it reduces the number of subsequent alternatives for continued safe flight. ADM is intended to break the poor judgment chain before it can cause an accident or incident.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A T-shaped valve with a circular head. Poppet valves are used to cover the intake and exhaust openings in the cylinder head of a reciprocating engine. The valves are held closed by one or more coil springs and are opened by a cam lobe or a rocker arm pushing on the end of the valve stem.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

A hard, white, translucent ceramic material that was used as the insulator in some of the early aircraft spark plugs.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

The error in pitot-static instruments caused by the static ports not sensing true static air pressure. Position error changes with airspeed and is usually greatest at low airspeeds.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A report over a known location as transmitted by an aircraft to ATC.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A fluid pump that moves a specific volume of fluid each time it rotates. Spur-gear pumps, gerotor pumps, and vane pumps are all positive-displacement pumps.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

A number that is greater than zero.

Aviation Maintenance Technician Handbook — General, p. G-8

The initial tendency to return to a state of equilibrium when disturbed from that state.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

The length of time a resin will remain workable after the catalyst has been added. If a catalyzed material is not used within its usable pot life, it must be discarded and a new batch mixed up.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

The water carried in an aircraft for the purpose of drinking.

Aircraft Weight and Balance Handbook, p. G-4

A difference in electrical pressure.

Aviation Maintenance Technician Handbook — General, p. G-8

Energy that is stored.

Aviation Maintenance Technician Handbook — General, p. G-8

A variable tapped resistor that can be used as a voltage divider.

Aviation Maintenance Technician Handbook — General, p. G-8

A shorthand method of indicating how many times a number, called the base, is multiplied by itself. For example, in the number 43, 3 is the power, or exponent, and 4 is the base. That is, 43 is equal to 4 × 4 × 4 = 64.

Aviation Maintenance Technician Handbook — General, p. G-8

A test run made of a gas turbine engine to determine how its performance compares with its precious performance as new or freshly overhauled.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

Aircraft brakes that use the main hydraulic system to supply fluid for the brake actuation. Aircraft that require a large amount of fluid for their brake actuation normally use power brakes, and the volume of fluid sent to the brakes is increased by the use of deboosters.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

A hand-operated hydraulic pump unloading valve. When the valve is open, fluid flows from the pump to the reservoir with little opposition. To actuate a unit, turn the selector valve, and manually close the power control valve. Pressurized fluid flows to the unit, and when it is completely actuated, the power control valve automatically opens.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

The complete installation of an aircraft engine, propeller, and all accessories needed for its proper function.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

Also called scientific notation. It is a shorthand method of depicting very large or very small numbers.

Aviation Maintenance Technician Handbook — General, p. G-8

Ignition of the air/fuel mixture inside the cylinder of an engine before the time for normal ignition. Pre-ignition is often caused by incandescent objects inside the cylinder.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

The characteristic of a gyroscope that causes a force to be felt, not at the point of application, but at a point 90° in the direction of rotation from that point.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

Any or all forms of water particles (rain, sleet, hail, or snow) that fall from the atmosphere and reach the surface.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A method of increasing the strength of heat-treated aluminum alloy. After the aluminum alloy has been solution-heat-treated by heating and quenching, it is returned to the oven and heated to a temperature lower than that used for the initial heat treatment. It is held at this temperature for a specified period of time, and then removed from the oven and allowed to cool slowly.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A form of radio interference caused by rain, snow, or dust particles hitting the antenna and inducing a small radio-frequency voltage into it.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A standard instrument approach procedure in which both vertical and horizontal guidance is provided.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A system of lights similar to the VASI, but consisting of one row of lights in two- or four-light systems. A pilot on the correct glideslope will see two white lights and two red lights. See VASI.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A type of radar used at an airport to guide an aircraft through the final stages of landing, providing horizontal and vertical guidance. The radar operator directs the pilot to change heading or adjust the descent rate to keep the aircraft on a path that allows it to touch down at the correct spot on the runway.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

System allows simultaneous, independent instrument flight rules (IFR) approaches at airports with closely spaced parallel runways.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

Routes established in the major terminal and en route environments to increase system efficiency and capacity. IFR clearances are issued based on these routes, listed in the Chart Supplement U.S. except when severe weather avoidance procedures or other factors dictate otherwise.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A required inspection to determine the condition of the aircraft for the flight to be conducted. It is conducted by the pilot-in-command.

Aviation Maintenance Technician Handbook — Airframe, p. G-26

Ignition occurring in the cylinder before the time of normal ignition. Preignition is often caused by a local hot spot in the combustion chamber igniting the fuel-air mixture.

Pilot's Handbook of Aeronautical Knowledge, p. G-23

A type of composite material in which the reinforcing fibers are encapsulated in an uncured resin. Prepreg materials must be kept refrigerated to prevent them from curing before they are used.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

An indicator light fixture whose lens can be pressed in to complete a circuit that tests the filament of the light bulb.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

The amount of force acting on a specific amount of surface area, typically measured in pounds per square inch or psi.

Aviation Maintenance Technician Handbook — General, p. G-8

The altitude in standard air at which the pressure is the same as that of the existing air. Pressure altitude is read on an altimeter when the barometric scale is set to the standard sea level pressure of 29.92 inches of mercury.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A carburetor installed on some aircraft reciprocating engines that uses the pressure difference between air inside the venture and ram air entering the carburetor to produce a fuel-metering force. Pressure carburetors have generally been replaced with continuous-flow fuel injection systems.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

A method of air cooling a reciprocating engine in which the cylinders are enclosed in tight-fitting shrouds. The cowling is divided into two compartments by baffles and seals, with half of each cylinder in each compartment. Ram air is directed into one compartment, and the pressure in the other is decreased by air flowing over a flared exit or adjustable cowl flaps. The pressure difference across the cylinders causes cooling air to be drawn through the fins to remove the unwanted heat.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

A type of oxygen system used by aircraft that fly at very high altitude. This system functions as a diluter-demand system until, at about 40,000 feet, the output to the mask is pressurized enough to force the needed oxygen into the lungs, rather than depending on the low pressure produced when the wearer of the mask inhales to pull in the oxygen. (See diluter-demand oxygen system.)

Aviation Maintenance Technician Handbook — Airframe, p. G-27

The method of fueling used by almost all transport aircraft. The fuel is put into the aircraft through a single underwing fueling port. The fuel tanks are filled to the desired quantity and in the sequence selected by the person conducting the fueling operation. Pressure fueling saves servicing time by using a single point to fuel the entire aircraft, and it reduces the chances for fuel contamination.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A multibarrel pressure carburetor used on large radial and V-engines. Fuel is metered on the basis of air mass flowing into the engine and is sprayed under pressure into the eye, or center, of the internal supercharger impeller.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

The portion of a fluid power system from which the selector valves receive their pressurized fluid.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A strong, heavy plate used in a multiple-disc brake. The pressure plate receives the force from the brake cylinders and transmits this force to the discs. Pressure reducing valve (oxygen system component). A valve used in an oxygen system to change high cylinder pressure to low system pressure.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A valve in an oxygen system that relieves the pressure if the pressure reducing valve should fail.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

The strengthened portion of an aircraft structure that is sealed and pressurized in flight.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

The torque required to turn a threaded fastener before it contacts the surface it is intended to hold.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

The greatest horizontal visibility equaled or exceeded throughout at least half the horizon circle (which is not necessarily continuous).

Pilot's Handbook of Aeronautical Knowledge, p. G-24

A method of attitude instrument flying using the instrument that provides the most direct indication of attitude and performance.

Pilot's Handbook of Aeronautical Knowledge, p. G-24

A display that provides increased situational awareness to the pilot by replacing the traditional six instruments used for instrument flight with an easy-to-scan display that provides the horizon, airspeed, altitude, vertical speed, trend, trim, and rate of turn among other key relevant indications.

Pilot's Handbook of Aeronautical Knowledge, p. G-24

The winding in a magneto or ignition coil that is between the source of voltage and the breaker points. The primary winding is normally made of comparatively large diameter wire, and has a small number of turns, typically about 200.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

A component in a finishing system that provides a good bond between the surface and the material used for the topcoats.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

See precision runway monitor.

Pilot's Handbook of Aeronautical Knowledge, p. G-24

A maneuver prescribed when it is necessary to reverse direction to establish an aircraft on the intermediate approach segment or final approach course.

Pilot's Handbook of Aeronautical Knowledge, p. G-24

The result of multiplication.

Aviation Maintenance Technician Handbook — General, p. G-8

Aerodynamic drag produced by skin friction. Profile drag is a form of parasite drag.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

The tip of an axial-flow compressor bladed whose thickness is reduced to give it a higher resonant frequency so it will not be subject to the vibrations that would affect a blade with a squared tip. The profile tip also provides a more aerodynamically efficient shape for the high velocity air that is moved by the blade. Profile tips often touch the housing and make a squealing noise as the engine is shut down. For this reason profile tips are often called squealer tips.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

Side view of an IAP chart illustrating the vertical approach path altitudes, headings, distances, and fixes.

Pilot's Handbook of Aeronautical Knowledge, p. G-24

A precision measuring instrument used to measure the depth of the hone marks in the surface of a cylinder wall.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

Breaking down the large task of conducting a major inspection into smaller tasks which can be accomplished periodically without taking the aircraft out of service for an extended period of time.

Aviation Maintenance Technician Handbook — General, p. G-8

An instrument used to measure the amount of horsepower an engine is delivering to its output shaft. The engine is operated at a specific rpm, and a brake is applied to its output shaft. The amount of torque applied to the brake is measured, and this, with the rpm, is converted into brake horsepower.

Aviation Maintenance Technician Handbook — Powerplant, p. G-21

The end of a reciprocating engine to which the propeller is attached.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

Certain propeller rpm settings or helicopter rotor speeds can cause the VOR course deviation indicator (CDI) to fluctuate as much as ±6°. Slight changes to the rpm setting will normally smooth out this roughness.

Pilot's Handbook of Aeronautical Knowledge, p. G-24

The registered trade name by Hamilton Standard of an ultra-high-bypass turbine engine. See UHB engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

A proportion is a statement of equality between two or more ratios. The example of A is to B as C is to D can be represented A:B = C:D or A/B = C/D.

Aviation Maintenance Technician Handbook — General, p. G-8

A measure of the effectiveness with which an aircraft engine converts the fuel it burns into useful thrust. It is the ratio of the thrust horsepower produced by a propeller to the torque horsepower of the shaft turning the propeller. The nearer the speed of the aircraft is to the speed of the exhaust jet or propeller wake, the less kinetic energy is lost in the jet or wake, and the higher the propulsive efficiency.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

Power recovery turbine. A turbine driven by exhaust gases from several cylinders of a reciprocating engine. Energy extracted from exhaust gases by the turbine is coupled, through a fluid clutch, to the engine crankshaft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

Direct current whose voltage periodically changes, but whose electrons flow in the same direction all of the time.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

A type of air-breathing reaction engine used during World War II to power jet-propelled missiles. Fuel is sprayed into the combustion chamber and ignited. As the heated air expands, it closes the one-way shutter valve in the front of the engine and exits the engine through the nozzle at the rear. As soon as the pressure inside the combustion chamber decreases, air enters through the shutter valve and more fuel is ignited. The thrust is produced in a series of pulses.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

A control valve in a hydraulic system that allows the pilot to manually direct the output of the hydraulic pump back to the reservoir when no unit is being actuated.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A registered trade name for clad aluminum alloy.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

To remove all of the moisture and air from a cooling system by flushing the system with a dry gaseous refrigerant.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A fit between pieces in a mechanical assembly that is close enough to require the parts to be pushed together. A push fit is looser than a press fit, but closer than a free fit.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

An engine installed with the propeller facing the rear of the aircraft. Thrust produced by the propeller mounted on a pusher engine pushes rather than pulls the aircraft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

A powerplant whose propeller is mounted at the rear of the airplane and pushes, rather than pulls, the airplane through the air.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

A propeller installed on an aircraft engine so that it faces the rear of the aircraft. Thrust from the propeller pushes rather than pulls the aircraft.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

A diagram showing the relationship between the volume of a cylinder and the pressure during a cycle of engine operation.

Aviation Maintenance Technician Handbook — Powerplant, p. G-22

A thermoplastic resin used to make transparent tubing for insulating electrical wires.

Aviation Maintenance Technician Handbook — Airframe, p. G-27

An equation used to find the length of a third side of any right triangle when the lengths of two sides are known. The Pythagorean Theorem states that a2 + b2 = c2. The square of the hypotenuse (side opposite the right angle) is equal to the sum of the squares of the other two sides (a and b).

Aviation Maintenance Technician Handbook — General, p. G-8