Glossary

A measure of efficiency of an airfoil. It is the ratio of the lift to the total drag at a specified angle of attack.

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

See low or medium frequency.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

See local area augmentation system.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

A type of air and/or seal used around the main –shaft bearings in a gas turbine engine. The seal consists of a series of rotating blades that almost contact the seal land. A small amount of air flows between the seal and the land to prevent oil flowing past the seal. Land (piston) The portion of a piston between the ring grooves.

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

A finishing material made of a film base, solvents, plasticizers, and thinners. The film base forms a tough film over the surface when it dries. The solvents dissolve the film base so it can be applied as a liquid. The plasticizers give the film base the needed resilience, and the thinners dilute the lacquer so it can be applied with a spray gun. Lacquer is sprayed on the surface as a liquid, and when the solvents and thinners evaporate, the film base remains as a tough decorative and protective coating.

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

The delay that occurs before an instrument needle attains a stable indication.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

Airflow in which the air passes over the surface in smooth layers with a minimum of turbulence.

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

A type of wood made by gluing several pieces of thin wood together. The grain of all pieces runs in the same direction.

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

The portion of a splined shaft between the grooves.

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

Land without delay at the nearest suitable area, such as an open field, at which a safe approach and landing is assured.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

The landing site and duration of flight are at the discretion of the pilot. Extended flight beyond the nearest approved landing area is not recommended.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

A coastal breeze flowing from land to sea caused by temperature differences when the sea surface is warmer than the adjacent land. The land breeze usually occurs at night and alternates with the sea breeze that blows in the opposite direction by day.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

The urgency of the landing is paramount. The primary consideration is to ensure the survival of the occupants. Landing in trees, water, or other unsafe areas should be considered only as a last resort.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

A system of lights used to indicate the condition of the landing gear. A red light illuminates when any of the gears are in an unsafe condition; a green light shows when all of the gears are down and locked, and no light is lit when the gears are all up and locked. An aural warning system is installed that sounds a horn if any of the landing gears are not down and locked when the throttles are retarded for landing.

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

The takeoff weight of an aircraft minus the fuel burned and/or dumped en route.

Aircraft Weight and Balance Handbook, p. G-3

A highly accurate tachometer that shines a laser beam on a rotating element that has reflective tape or a contrasting mark. The reflected laser beam is converted into electrical pulses which are counted and displayed on a monitoring instrument.

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

A small filter installed in the oil line to the bearing jet in a gas turbine engine. This filter traps any contaminants that have passed the main filter and holds them until the engine is disassembled for overhaul.

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

Heat that is added to a material that causes a change in its state without changing its temperature.

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

An imaginary line, passing through the center of gravity of an airplane, and extending across it from wing tip to wing tip.

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

The balance around the roll, or longitudinal, axis.

Aircraft Weight and Balance Handbook, p. G-3

The moment, in pound inches, of a force that tends to rotate a helicopter about its longitudinal axis. The lateral offset moment is the product of the weight of the object and its distance from butt line zero. Lateral offset moments that tend to rotate the aircraft clockwise are positive, and those that tend to rotate it counterclockwise are negative.

Aircraft Weight and Balance Handbook, p. G-3

The stability about the longitudinal axis of an aircraft; the rolling stability, or the ability of an airplane to return to level flight due to a disturbance that causes one of the wings to drop.

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

A vibration in which the movement is in a lateral direction, such as imbalance of the main rotor.

Helicopter Flying Handbook, p. G-4

Measurement north or south of the equator in degrees, minutes, and seconds. Lines of latitude are also referred to as parallels.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

The placement of the various layers of resin-impregnated fabric in the mold for a piece of laminated composite material.

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

Liquid crystal display. A digital display that consists of two sheets of glass separated by a sealed-in, normally transparent liquid crystal material. The outer surface of each glass sheet has a transparent conductive coating with the viewing side etched into character-forming segments with leads going to the edges of the display. A voltage applied between the front and back coatings disrupts the orderly arrangement of molecules and causes the liquid to darken so that light cannot pass through it. The segment to which the voltage is applied appears as black against a reflected background.

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

The maximum ratio between total lift (L) and total drag (D). This point provides the best glide speed. Any deviation from the best glide speed increases drag and reduces the distance you can glide.

Helicopter Flying Handbook, p. G-4

The fore (lead) and aft (lag) movement of the rotor blade in the plane of rotation.

Helicopter Flying Handbook, p. G-4

The radial at which the turn from the DME arc to the inbound course is started.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

The thick edge at the front of a propeller blade.

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

High lift devices which are found on the leading edge of the airfoil. The most common types are fixed slots, movable slats, and leading edge flaps.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

A portion of the leading edge of an airplane wing that folds downward to increase the camber, lift, and drag of the wing. The leading-edge flaps are extended for takeoffs and landings to increase the amount of aerodynamic lift that is produced at any given airspeed.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

A condition in which the fire in a gas turbine engine goes out because the air/fuel mixture ratio is too lean to sustain combustion.

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

A air/fuel mixture that contains more than 15 parts of air to 1 part of fuel, by weight.

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

A physical sensation caused by an abrupt correction of a banked attitude entered too slowly to stimulate the motion sensing system in the inner ear. The abrupt correction can create the illusion of banking in the opposite direction.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

The course-deviation indicator used with a VOR navigation system.

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

Leading edge of the mean aerodynamic chord. A reference point for measurements, and specified in inches from the datum to allow computations to relate percent MAC to the datum.

Aircraft Weight and Balance Handbook, p. G-3

The simplest machine. There are three basic parts in all levers: the fulcrum “F,” a force or effort “E,” and a resistance “R.”

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

Basic empty weight not including full engine oil, just undrainable oil.

Helicopter Flying Handbook, p. G-4

One of the four main forces acting on a helicopter. It acts perpendicular to the relative wind.

Helicopter Flying Handbook, p. G-4

A hole cut in a piece of structural material to get rid of weight without losing any strength. A hole several inches in diameter may be cut in a piece of metal at a point where the metal is not needed for strength, and the edges of the hole are flanged to give it rigidity. A piece of metal with properly flanged lightening holes is more rigid than the metal before the holes were cut.

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

Amount of stress, or load factor, that an aircraft can withstand before structural damage or failure occurs.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

A method of assuring concentricity of bored holes. A boring bar extends through all of the holes and cuts the inside diameters so they all have the same center.

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

A fluid power actuator that uses a piston moving inside a cylinder to change pressure into linear, or straight-line, motion.

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

A change in which the output is directly proportional to the input.

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

Invisible lines of magnetic force passing between the poles of a magnet.

Pilot's Handbook of Aeronautical Knowledge, p. G-17

The rod in a radial engine that connects one of the piston wrist pins to a knuckle pin on the master rod. Also called articulating rods.

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

The removal of unwanted heat from an aircraft engine by transferring the heat into a liquid and then passing the heated liquid through a liquid-to-air heat exchanger (radiator) to transfer the heat into the ambient air.

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

A component in an electronic weighing system that is placed between the jack and the jack pad on the aircraft. The load cell contains strain gauges whose resistance changes with the weight on the cell.

Aviation Maintenance Technician Handbook — General, p. G-6; Aircraft Weight and Balance Handbook, p. G-3

A graph of load weight and load moment indexes. Diagonal lines for each item relate the weight to the moment index, eliminating the need for calculations.

Aircraft Weight and Balance Handbook, p. G-3

A method of calculating and documenting aircraft weight and balance prior to taxiing to ensure the aircraft will remain within all required weight and balance limitations throughout the flight

Aircraft Weight and Balance Handbook, p. G-3

A current meter used in some aircraft electrical systems to show the amount of current the generator or alternator is producing. Loadmeters are calibrated in percent of the generator rated output.

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

A differential global positioning system (DGPS) that improves the accuracy of the system by determining position error from the GPS satellites, then transmitting the error, or corrective factors, to the airborne GPS receiver.

Pilot's Handbook of Aeronautical Knowledge, p. G-18

The portion of an ILS (Instrument Landing System) that directs the pilot along the center line of the instrument runway.

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

A NAVAID used for nonprecision instrument approaches with utility and accuracy comparable to a localizer but which is not a part of a complete ILS and is not aligned with the runway. Some LDAs are equipped with a glideslope.

Pilot's Handbook of Aeronautical Knowledge, p. G-18

Nondirectional radio beacon (NDB) compass locator, collocated with a middle marker (MM).

Pilot's Handbook of Aeronautical Knowledge, p. G-18

NDB compass locator, collocated with an outer marker (OM).

Pilot's Handbook of Aeronautical Knowledge, p. G-18

A magnetized piece of natural iron oxide.

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

A type of graphic chart that can be made up for a specific process or procedure to help follow the process through all of its logical steps.

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

Measurement east or west of the Prime Meridian in degrees, minutes, and seconds. The Prime Meridian is 0° longitude and runs through Greenwich, England. Lines of longitude are also referred to as meridians.

Pilot's Handbook of Aeronautical Knowledge, p. G-18

An imaginary line, passing through the center of gravity of an airplane, and extending lengthwise through it from nose to tail.

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

The balance around the pitch, or lateral, axis.

Aircraft Weight and Balance Handbook, p. G-3

A method of magnetizing through a solenoid, or coil, that encircles the part so the lines of magnetic flux pass lengthwise through the part. Longitudinal magnetism makes it possible to detect faults that extend across the part.

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

The magnetic field is produced in a direction parallel to the long axis of the part. This is accomplished by placing the part in a solenoid excited by electric current.

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

The tendency for an aircraft nose to pitch up or pitch down, rotating around the lateral axis (wingtip to wingtip).

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

Long Range Aid to Navigation. A hyperbolic navigation system that operates with frequencies of 1,950 kHz, 1,850 kHz, and 1,900 kHz.

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

The LORAN system used in aircraft. It operates on a frequency of 100 kHz.

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

A turbofan engine whose bypass ratio is less than 2:1.

Aviation Maintenance Technician Handbook — Powerplant, p. G-17

A frequency range between 190 and 535 kHz with the medium frequency above 300 kHz. Generally associated with nondirectional beacons transmitting a continuous carrier with either a 400 or 1,020 Hz modulation.

Pilot's Handbook of Aeronautical Knowledge, p. G-18

The first-stage compressor in a dual-spool gas turbine engine. The low-pressure compressor is called the N1 compressor and its speed is not governed. It seeks its own best speed as the atmospheric conditions change so it can furnish a relatively constant mass of air to the inlet of the second-stage compressor.

Aviation Maintenance Technician Handbook — Powerplant, p. G-17

Pressure in a Teledyne- Continental fuel injector pump that is adjusted by the relief valve.

Aviation Maintenance Technician Handbook — Powerplant, p. G-17

Line replaceable unit.

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

A reference on a magnetic compass and directional gyro that represents the nose of the aircraft. The heading of the aircraft is shown on the compass card opposite the lubber line.

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