Glossary

Cabin pressure in terms of equivalent altitude above sea level.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

To lock the gimbals of a gyroscopic instrument so it will not be damaged by abrupt flight maneuvers or rough handling.

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

A measurement of time used by the FAA for inspection and certification purposes. One calendar month from a given day extends from that day until midnight of the last day of that month.

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

The instrument indication compared with a standard value to determine the accuracy of the instrument.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

A hole of specific diameter used to delay the pressure change in the case of a vertical speed indicator.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

The amount of heat required to change the temperature of 1 gram of water by 1 degree Centigrade.

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

An eccentric, or lobe, on a rotating shaft that changes rotary motion into linear motion. A cam is mounted on the magnet shaft in a magneto to push upward on the insulated breaker point to separate, or open, the points when the magnet is in a particular location.

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

A reciprocating engine with axial cylinders arranged around a central shaft. Rollers on the pistons in the cylinders press against a sinusoidal cam mounted on the shaft to produce rotation of the shaft.

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

A reciprocating engine piston that is not round, but is ground so that its diameter parallel to the wrist pin is slightly smaller than its diameter perpendicular to the pin. The mass of metal used in the wrist pin boss, the enlarged area around the wrist pin hole, expands when heated, and when the piston is at its operating temperature, it is perfectly round.

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

The curvature of a wing as viewed by cross section. A wing has upper camber on its top surface and lower camber on its bottom surface. The upper camber is more pronounced; the lower camber is comparatively flat. This causes the velocity of the airflow immediately above the wing to be much higher than that below the wing.

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

A type of combustor used in some large turbojet and turbofan engines. It consists of individual cans into which fuel is sprayed and ignited. These cans mount on an annular duct which collects the hot gases and directs them uniformly into the turbine.

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

A rate gyro whose gimbal axis is tilted so it can sense rotation of the aircraft about its roll axis as well as its yaw axis.

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

A wing designed to carry loads without external struts.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

A wing that is supported by its internal structure and requires no external supports. The wing spars are built in such a way that they carry all the bending and torsional loads.

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

The main top and bottom members of a wing rib. The cap strips give the rib its aerodynamic shape.

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

The property of an electric conductor that characterizes its ability to store an electric charge.

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

The continuation of the spark across the gap in a shielded spark plug after the air/fuel mixture in the cylinder is ignited. Afterfiring is caused by the return of electrical energy stored in the capacitance of the shielded ignition leads. Capacitance afterfiring is eliminated by the use of a resistor in the spark plug.

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

A popular type of electronic fuel quantity indicating system that has no moving parts in the fuel tank. The tank units are cylindrical capacitors, called probes, mounted across the tank, from top to bottom. The dielectric between the plates of the probes is either fuel or the air above the fuel, and the capacitance of the probe varies with the amount of fuel in the tank. The indicator is a servo-type instrument driven by the amplified output of a capacitance bridge.

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

The measure of a capacitor’s opposition to alternating current.

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

An electrical component that stores an electric charge.

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

A soft copper tube with a small inside diameter. The capillary tube used with vapor-pressure thermometer connects the temperature sensing bulb to the Bourdon tube. The capillary tube is protected from physical damage by enclosing it in a braided metal wire jacket.

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

A packet of chemical crystals mounted in the aircraft flight deck or cabin where they are easily visible. The crystals change their color from yellow to green when they are exposed to carbon monoxide.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A type of voltage regulator used with high-output DC generators. Field current is controlled by varying the resistance of a stack of thin carbon discs. This resistance is varied by controlling the amount the stack is compressed by a spring whose force is opposed by the pull of an electromagnet. The electromagnet’s strength is proportional to the generator’s output voltage.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A trail of carbon deposited by an arc across a high-voltage component such as a distributor block. Carbon tracks have a relatively low resistance to the high voltage and can cause misfiring and loss of engine power.

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

An oxyacetylene flame produced by an excess of acetylene. This flame is identified by a feather around the inner cone. A carburizing flame is also called a reducing flame.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

The layers of rubberized fabric that make up the body of an aircraft tire.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A self-contained starter used on some military aircraft. A cartridge similar in size to a shotgun shell is ignited in the starter breech. The expanding gases drive a piston attached to a helical spline that converts the linear movement of the piston into rotary motion to rotate the crankshaft.

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

The cumulative effect that occurs when the output of one series of components serves as the input to the next series.

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

A process in which the surface of a metal is changed chemically by introducing a high carbide or nitride content. Case hardening produces a hard, wear-resistant surface, or case, over a strong, tough core.

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

A low pressure that is maintained inside the case of a hydraulic pump. If a seal becomes damaged, hydraulic fluid will be forced out of the pump rather than allowing air to be drawn into the pump.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A substance used to change the speed, or rate, of a chemical action without being chemically changed itself.

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

A display tube used for oscilloscopes and computer video displays. An electron gun emits a stream of electrons that is attracted to a positively charged inner surface of the face of the tube. Acceleration and focusing grids speed the movement of the electrons and shape the beam into a pinpoint size. Electrostatic or electromagnetic forces caused by deflection plates or coils move the beam over the face of the tube. The inside surface of the face of the tube is treated with a phosphor material that emits light when the beam of electrons strikes it.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

The creation of low pressure in an oil pump when the inlet system is not able to supply all of the oil the pump requires. Prolonged cavitation can damage pump components.

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

A condition that exist in a hydraulic pump when there is not enough pressure in the reservoir to force fluid to the inlet of the pump. The pump picks up air instead of fluid.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

Course deviation indicator.

Aviation Maintenance Technician Handbook — Airframe, p. G-7; Pilot's Handbook of Aeronautical Knowledge, p. G-6

Control display unit.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A twin-engine airplane with both engines mounted in the fuselage. One is installed as a tractor in the front of the cabin. The empennage is mounted on booms.

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

The point about which the nose-heavy and tail-heavy moments are exactly equal in magnitude.

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

The specified forward and aft points within which the CG must be located during flight. These limits are indicated on pertinent airplane specifications.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

The center of gravity range for an aircraft is the limits within which the aircraft must balance. It is identified as a forward-most limit (arm) and an aft-most limit (arm).

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

The location of the chord line of an airfoil at which all the lift forces produced by the airfoil are considered to be concentrated.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

The point on the chord line of an airfoil where all of the aerodynamic forces are considered to be concentrated.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A cam in the nose-gear shock strut that causes the piston to center when the strut fully extends. When the aircraft takes off and the strut extends, the wheel is straightened in its fore-and-aft position so it can be retracted into the wheel well. Charging stand (air conditioning service equipment). A handy and compact arrangement of air conditioning servicing equipment. A charging stand contains a vacuum pump, a manifold gauge set, and a method of measuring and dispensing the refrigerant.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A type of compressor that uses a vaned plate like impeller. Air is taken into the center, or eye, of the impeller and slung outward by centrifugal force into a diffuser where its velocity is decreased and its pressure increased.

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

An impeller-shaped device that receives air at its center and slings the air outward at high velocity into a diffuser for increased pressure. Also referred to as a radial outflow compressor.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

The apparent force occurring in curvilinear motion acting to deflect objects outward from the axis of rotation. For instance, when pulling out of a dive, it is the force pushing the pilot down in their seat.

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

The force in curvilinear motion acting toward the axis of rotation. For instance, when pulling out of a dive, it is the force that the seat exerts on the pilot to offset the centrifugal force. adjacent side

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

The distance in inches aft of the datum of the center of a compartment or a fuel tank for weight and balance purposes.

Aircraft Weight and Balance Handbook, p. G-2

Any of several hard, brittle, heat-resistant, noncorrosive materials made by shaping and then firing a mineral, such as clay, at a high temperature.

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

See center of gravity.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

(GAMA) The arm obtained by adding the airplane’s individual moments and dividing the sum by the total weight.

Aircraft Weight and Balance Handbook, p. G-2

(GAMA) The extreme CG locations within which the aircraft must be operated at a given weight. These limits are indicated on pertinent FAA aircraft type certificate data sheets, specifications, or weight and balance records

Aircraft Weight and Balance Handbook, p. G-2

An enclosed area on a graph of the airplane loaded weight and the CG location. If lines drawn from the weight and CG cross within this envelope, the airplane is properly loaded.

Aircraft Weight and Balance Handbook, p. G-2

An enclosed area on a graph of the airplane loaded weight and loaded moment. If lines drawn from the weight and loaded moment cross within this envelope, the airplane is properly loaded.

Aircraft Weight and Balance Handbook, p. G-2

A point along the route or airway segment between two adjacent navigation facilities or waypoints where changeover in navigation guidance should occur. Chart Supplement U.S. (formerly Airport/Facility Directory). An FAA publication containing information on all airports, communications, and NAVAIDs.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

Reciprocating engine cylinders with hard chromium-plated walls. The surface of this chrome plating forms a spider web of tiny stress cracks. Deplating current enlarges the cracks and forms channels that hold lubricating oil on the cylinder wall.

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

States that all gases expand and contract in direct proportion to the change in the absolute temperature, provided the pressure is held constant.

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

A type of rapid vibration of a hydraulic pump caused by the pump taking in some air along with the hydraulic fluid.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

Longitudinal cracks that extend across a log’s annual rings.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A hydraulic or pneumatic system component that allows full flow of fluid in one direction but blocks all flow in the opposite direction.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A tool that is used as a human factors aid in aviation safety. It is a systematic and sequential list of all operations that must be performed to properly accomplish a task.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

The offset portion of a crankshaft that connects the crankpin to the main bearing journals.

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

Energy released from chemical reactions.

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

An oxygen system used for emergency or backup use. Solid blocks of material that release oxygen when they are burned are carried in special fireproof fixtures. When oxygen is needed, the candles are ignited with an integral igniter, and oxygen flows into the tubing leading to the masks.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A form of one-way seal used in some fluid-power actuators. A chevron seal is made of a resilient material whose cross section is in the shape of the letter V. The pressure being sealed must be applied to the open side of the V.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A component in a lubrication system that attracts and holds ferrous metal chips circulating with the engine oil. Some chip detectors are part of an electrical circuit. When metal particles short across the two contacts in the detector, the circuit is completed, and an annunciator light is turned on to inform the flight crew that metal particles are loose in the lubrication system.

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

A cylinder of a reciprocating engine that is ground so that its diameter at the top of the barrel is slightly smaller than the diameter in the center of the stroke. The large mass of metal in the cylinder head absorbs enough heat to cause the top end of the barrel to expand more than the rest of the barrel. At normal operating temperature, the diameter of a choke-ground cylinder is uniform throughout.

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

A nozzle in a gas turbine engine that limits the speed of gases flowing through it. The gases accelerate until they reach the speed of sound, and a normal shock wave forms that prevents further acceleration.

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

The difference in the bore diameter of a reciprocating engine cylinder in the area of the head and in the center of the barrel.

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

A straight line distance across a wing from leading edge to trailing edge.

Aircraft Weight and Balance Handbook, p. G-2

An imaginary straight line drawn through an airfoil from the leading edge to the trailing edge.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

An imaginary line, passing through a propeller blade, joining the leading and trailing edges.

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

For semirigid rotors, a term used to describe the flapping or teetering axis of the rotor.

Helicopter Flying Handbook, p. G-2

An alloy of nickel and chromium used as the positive element in a thermocouple for measuring exhaust gas temperature.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A commonly used name for a spark plug terminal connector used with a shielded spark plug.

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

A closed plane figure with every point an equal distance from the center. A circle has the greatest area for its circumference of any enclosed shape.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight-in landing from an instrument approach is not possible or is not desirable.

Pilot's Handbook of Aeronautical Knowledge, p. G-6

An electrical component that automatically opens a circuit any time excessive current flows through it. A circuit breaker may be reset to restore the circuit after the fault causing the excessive current has been corrected.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

A method of magnetizing a part for magnetic particle inspection. Current is passed through the part, and the lines of magnetic flux surround it. Circular magnetism makes it possible to detect faults that extend lengthwise through the part.

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

The induction of a magnetic field consisting of concentric circles of force about and within a part, which is achieved by passing electric current through the part.

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

The linear measurement of the distance around a circle. The circumference is calculated by multiplying the diameter of the circle by 3.1416.

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

A coil spring formed into a ring. This type of spring is used to hold segmented ring-type carbon seals tightly against a rotating shaft.

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

The predecessor to the Federal Aviation Regulations.

Aircraft Weight and Balance Handbook, p. G-2

A sheet of aluminum alloy that has a coating of pure aluminum rolled on one or both of its surfaces for corrosion protection.

Aviation Maintenance Technician Handbook — Airframe, p. G-7

An electrical instrument used to measure current without opening the circuit through which it is flowing. The jaws of the ammeter are opened, slipped over the current-carrying wire, and then clamped shut. Current flowing through the wire produces a magnetic field which induces a voltage in the ammeter that is proportional to the amount of current.

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

A dark purplish pink to a dark gray purplish red color.

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

Airspace from 18,000 feet MSL up to and including FL 600, including the airspace overlying the waters within 12 NM of the coast of the 48 contiguous states and Alaska; and designated international airspace beyond 12 NM of the coast of the 48 contiguous states and Alaska within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic procedures are applied.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A fire with solid combustible materials such as wood, paper, and cloth as its fuel.

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

Airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of IFR operations or passenger numbers. The configuration of each Class B airspace is individually tailored and consists of a surface area and two or more layers, and is designed to contain all published instrument procedures once an aircraft enters the airspace. For all aircraft, an ATC clearance is required to operate in the area, and aircraft so cleared receive separation services within the airspace.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A fire that has combustible liquids as its fuel.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

Airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports having an operational control tower, serviced by radar approach control, and having a certain number of IFR operations or passenger numbers. Although the configuration of each Class C airspace area is individually tailored, the airspace usually consists of a 5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends from 1,200 feet to 4,000 feet above the airport elevation.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A fire which involves energized electrical equipment.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

Airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored, and when instrument procedures are published, the airspace is normally designed to contain the procedures.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A fire in which a metal such as magnesium burns.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

Airspace that is not Class A, Class B, Class C, or Class D, and is controlled airspace.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

Airspace that is uncontrolled, except when associated with a temporary control tower, and has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A configuration in which all flight control surfaces have been placed to create minimum drag. In most aircraft this means flaps and gear retracted.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

Glossy, clear, or translucent ice formed by the relatively slow freezing of large, supercooled water droplets.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

ATC permission for an aircraft to proceed under specified traffic conditions within controlled airspace, for the purpose of providing separation between known aircraft.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

Control tower position responsible for transmitting departure clearances to IFR flights.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

The fix, point, or location to which an aircraft is cleared when issued an air traffic clearance.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

An IFR clearance not yet received after filing a flight plan.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

Used by ATC, the time at which the departure clearance is automatically canceled if takeoff has not been made. The pilot must obtain a new clearance or cancel the IFR flight plan if not off by the specified time.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A patented spring-type fastener used to hold metal sheets in position until they can be permanently riveted together.

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

A small hand-held iron with an accurately calibrated thermostat. This iron is used for heat-shrinking polyester fabrics in areas that would be difficult to work with a large iron.

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

An angle formed in sheet metal that has been bent more than 90°.

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

The time elapsing between the assembly of glued joints and the application of pressure.

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

A hydraulic system in which the selector valves are installed in parallel with each other. When no unit is actuated, fluid circulates from the pump back to the reservoir without flowing through any of the selector valves.

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

A type of flow-control valve used to direct pressurized fluid into one side of an actuator, and at the same time, direct the return fluid from the other side of the actuator to the fluid reservoir. Closed-center selector valves are connected in parallel between the pressure manifold and the return manifold.

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

A type of control in which part of the output is fed back to the input. This allows the input to continually compare the command signals with the output to determine the extent to which the commands have been complied with.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

Rotating about the same axis. Coaxial rotors of a helicopter are mounted on concentric shafts in such a way that they turn in opposite directions to cancel torque.

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

A special type of electrical cable that consists of a central conductor held rigidly in the center of a braided outer conductor. Coaxial cable, commonly called coax, is used for attaching radio receivers and transmitters to their antenna.

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

A rotor system utilizing two rotors turning in opposite directions on the same centerline. This system is used to eliminated the need for a tail rotor.

Helicopter Flying Handbook, p. G-2

Established by law to provide for the safe and orderly conduct of flight operations and to prescribe airmen privileges and limitations.

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

A dimensionless number used in the formula for determining induced drag as it relates to the angle of attack.

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

A dimensionless number relating to the angle of attack used in the formula for determining aerodynamic lift.

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

A process of preparing a hole in sheet metal for flush riveting. A coining die is pressed into the rivet hole to form a sharp-edged depression into which the rivet head fits.

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

The solid carbon residue left when all volatile parts of a mineral oil have been evaporated by heat.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A method used for specifying the characteristics of a lubricating oil at low temperature. Oils rated by this test have the letter W (standing for Winter) in their designation. For example, SAE 15W50.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

The boundary between two air masses where cold air is replacing warm air.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

The portion of a gas turbine engine ahead of the combustion section. The cold section includes the inlet, compressor, and diffuser.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A turbine engine lubricating system in which the oil cooler is in the scavenge subsystem.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

The helicopter control that changes the pitch of all of the rotor blades at the same time. Movement of the collective pitch control increases or decreases the lift produced by the entire rotor disc.

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

A ring made of thin corrosion-resistant steel tubing that encircles a radial engine and collects exhaust gases from each cylinder. The ring ends with a connection to the exhaust tail pipe.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

Cellulose nitrate used as a film base for certain aircraft dopes.

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

A type of cabin heater used in some aircraft. Gasoline from the aircraft fuel tanks is burned in the heater.

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

The section of a gas turbine engine in which fuel is injected. This fuel mixes with air from the compressor and burns. The intense heat from the combustion expands the air flowing through the combustor and directs it our through the turbine. Combustors are also called burners.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A mechanical rectifier mounted on the armature shaft of a DC generator or motor. It consists of a cylindrical arrangement of insulated copper bars connected to the armature coils. Carbon brushes ride on the copper bars to carry current into or out of the commutator, providing a unidirectional current from a generator or a reversal of current in the motor coils.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A true course corrected for variation and deviation errors.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A highly refined, water-clear petroleum product similar to kerosene. Compass fluid is used to dampen the oscillations of magnetic compasses.

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

A low-power, low- or medium-frequency (L/MF) radio beacon installed at the site of the outer or middle marker of an ILS.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

A location on an airport where an aircraft can be taken to have its compasses “swung.” Lines are painted on the rose to mark the magnetic directions in 30° increments.

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

A maintenance procedure that minimizes deviation error in a magnetic compass. The aircraft is aligned on a compass rose, and the compensating magnets in the compass case are adjusted so the compass card indicates the direction marked on the rose. After the deviation error is minimized on all headings, a compass correction card is completed and mounted on the instrument panel next to the compass.

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

A vane-type, engine-driven fuel pump that has a diaphragm connected to the pressure regulating valve. The chamber above the diaphragm is vented to the carburetor upper deck where it senses the pressure of the air as it enters the engine. The diaphragm allows the fuel pump to compensate for altitude changes and keeps the carburetor inlet fuel pressure a constant amount higher than the carburetor inlet air pressure.

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

A series winding in a compound-wound DC generator. The compensating windings are embedded in the faces of the field poles and their varying magnetic field works with the fields from the interpoles to effectively cancel the field distortion caused by armature current.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A small hole between a hydraulic brake master cylinder and the reservoir. When the brakes are released, this port is uncovered and the fluid in the master cylinder is vented to the reservoir. When the brake is applied, the master-cylinder piston covers the compensator port and allows pressure in the line to the brake to build up and apply the brakes. When the brake is released, the piston uncovers the compensator port. If any fluid has been lost from the brake, the reservoir will refill the master cylinder. A restricted compensator port will cause the brakes to drag or will cause them to be slow to release.

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

An aircraft with retractable landing gear, flaps, and a controllable-pitch propeller.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

Something made up of different materials combined in such a way that the characteristics of the resulting material are different from those of any of the components.

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

A propeller blade made from several materials such as metal, graphite, glass or aramid fibers, and foam.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A curve formed in more than one plane. The surface of a sphere is a compound curve. Compound gauge (air conditioning servicing equipment). A pressure gauge used to measure the pressure in the low side of an air conditioning system. A compound gauge is calibrated from zero to 30 inches of mercury vacuum, and from zero to about 150-psi positive gauge pressure.

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

The sudden increase in the total drag of an airfoil in transonic flight caused by formation of shock waves on the surface.

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

A type of structural failure in wood caused by the application of too great a compressive load. A compression failure shows up as a faint line running at right angles to the grain of the wood.

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

The ratio of the volume of a cylinder with the piston at the bottom of its stroke to the volume of the cylinder with the piston at the top of its stroke.

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

A heavy structural member, often in the form of a steel tube, used to hold the spars of a Pratt truss airplane wing apart. A compression strut opposes the compressive loads between the spars arising from the tensile loads produced by the drag and antidrug wires.

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

A defect in wood that causes it to have a high specific gravity and the appearance of an excessive growth of summerwood. In most species, there is little difference between the color of the springwood and the summerwood. Any material containing compression wood is unsuited for aircraft structural use and must be rejected.

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

The component in a vapor-cycle cooling system in which the low-pressure refrigerant vapors, after they leave the evaporator, are compressed to increase both their temperature and pressure before they pass into the condenser. Some compressors are driven by electric motors, others by hydraulic motors and, in the case of most light airplanes, are belt driven from the engine.

Aviation Maintenance Technician Handbook — Airframe, p. G-9; Aviation Maintenance Technician Handbook — Powerplant, p. G-7

Air that is tapped off from a turbine engine compressor. Compressor bleed air is used for anti-icing the inlet ducts and for cooling the turbine inlet guide vanes and first stage turbine blades. Bleed air is also used for certain airframe functions. See customer bleed air.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

See compression ratio (turbine engine).

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A condition in a turbine engine axial-flow compressor in which the angle of attack of one or more blades is excessive and the smooth airflow through the compressor is disrupted.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A stall that affects the entire compressor and seriously restricts the airflow through the engine.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

Using a computer in the design of a product.

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

Using a computer in the design and drafting process.

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

Using a computer in the engineering of a product.

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

Using a computer in the manufacturing of a product.

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

Drawing with the use of a computer.

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

A point used to define a navigation track for an airborne computer system such as GPS or FMS.

Pilot's Handbook of Aeronautical Knowledge, p. G-7

The British name for a convergent-divergent duct. See convergent-divergent duct.

Aviation Maintenance Technician Handbook — Powerplant, p. G-7

A surface that is curved inward. The outer edges are higher than the center.

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

Dashed-line circles depicted in the plan view of IAP charts, outside of the reference circle, that show en route and feeder facilities.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

A change of state of water from a gas (water vapor) to a liquid.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

Small particles of solid matter in the air on which water vapor condenses.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The component in a vapor-cycle cooling system in which the heat taken from the aircraft cabin is given up to the ambient air outside the aircraft.

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

The transfer of heat which requires physical contact between an object that has a large amount of heat energy and one that has a smaller amount of heat energy.

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

A material that will carry electric current.

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

A cone-shaped volume of airspace directly above a VOR station where no signal is received, causing the CDI to fluctuate.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

This is a general term, which normally refers to the position of the landing gear and flaps.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

See blade coning.

Helicopter Flying Handbook, p. G-2

The angle formed between the plane of rotation of a helicopter rotor blade when it is producing lift and a line perpendicular to the rotor shaft. The degree of the coning angle is determined by the relationship between the centrifugal force acting on the blades and the aerodynamic lift produced by the blades.

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

A value used in a mathematical computation that is the same every time it is used. For example, the relationship between the length of the circumference of a circle and the length of its diameter is a constant, 3.1416. This constant is called by the Greek name of Pi (π). Constant differential mode (cabin pressurization). The mode of pressurization in which the cabin pressure is maintained a constant amount higher than the outside air pressure. The maximum differential pressure is determined by the structural strength of the aircraft cabin.

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

A fluid pump that moves a specific volume of fluid each time it rotates; the faster the pump turns, the more fluid it moves. Some form of pressure regulator or relief valve must be used with a constant-displacement pump when it is driven by an aircraft engine.

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

The cycle of energy transformation of a gas turbine engine. See Brayton cycle.

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

A special drive system used to connect an alternating current generator to an aircraft engine. The drive holds the generator speed (and thus its frequency) constant as the engine speed varies.

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

A controllable-pitch propeller whose pitch is automatically varied in flight by a governor to maintain a constant rpm in spite of varying air loads.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The cycle of energy transformation of a reciprocating engine. See Otto cycle.

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

A copper-nickel alloy used as the negative lead of a thermocouple for measuring the cylinder head temperature of a reciprocating engine.

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

A remotely actuated, heavy-duty electrical switch. Contactors are used in an aircraft electrical system to connect the battery to the main bus.

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

A troubleshooting tool that consists of a battery, a light bulb, and test leads. The test leads are connected to each end of the conductor under test, and if the bulb lights up, there is continuity. If it does not light up, the conductor is open.

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

An inspection program that is part of a continuous airworthiness maintenance program approved for certain large airplanes (to which 14 CFR Part 125 is not applicable), turbojet multi-engine airplanes, turbopropeller-powered multi-engine airplanes, and turbine-powered rotorcraft.

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

A solenoid-type switch designed to be kept energized by current flowing through its coil for an indefinite period of time. The battery contactor in an aircraft electrical system is a continuous-duty solenoid. Current flows through its coil all the time the battery is connected to the electrical system.

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

A type of oxygen system that allows a metered amount of oxygen to continuously flow into the mask. A rebreather-type mask is used with a continuous-flow system. The simplest form of continuous-flow oxygen system regulates the flow by a calibrated orifice in the outlet to the mask, but most systems use either a manual or automatic regulator to vary the pressure across the orifice proportional to the altitude being flown.

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

A fire-detection system that uses a continuous loop of two conductors separated with a thermistor-type insulation. Under normal temperature conditions, the thermistor material is an insulator; but if it is exposed to a fire, the thermistor changes into a conductor and completes the circuit between the two conductors, initiating a fire warning.

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

A method of magnetic particle inspection in which the part is inspected by flowing a fluid containing particles of iron oxide over the part while the magnetizing current is flowing.

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

Rotating in opposite directions. Turbine rotors are contrarotating when the different stages have a common center, but turn in opposite directions.

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

A method of attitude instrument flying in which one instrument is used for making attitude changes, and the other instruments are used to monitor the progress of the change.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

A display interfaced with the master computer, providing the pilot with a single control point for all navigations systems, thereby reducing the number of required flight deck panels.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The arm on a control surface to which the control cable or push-pull rod attaches to move the surface.

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

The amount of physical exertion on the control column necessary to achieve the desired attitude.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The type of control device used in some airplanes. A vertical stick in the flight deck controls the ailerons by side-to-side movement and the elevators by fore-and-aft movement.

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

The movable column on which an airplane control wheel is mounted. The yoke may be moved in or out to actuate the elevators, and the control wheel may be rotated to actuate the ailerons.

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

The characteristic of an aircraft that allows it to change its flight attitude in response to the pilot’s movement of the flight deck controls.

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

A type of propeller with blades that can be rotated around their long axis to change their pitch. If the pitch can be set to negative values, the reversible propeller can also create reverse thrust for braking or reversing without the need of changing the direction of shaft revolutions.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The process by which heat is transferred by movement of a heated fluid (gas or liquid).

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

Weather advisory concerning convective weather significant to the safety of all aircraft, including thunderstorms, hail, and tornadoes.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

Unstable, rising air found in cumiliform clouds.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

An imaginary flow of electricity that is said to flow from the positive terminal of a power source, through the external circuit to its negative terminal. The arrowheads in semiconductor symbols point in the direction of conventional current flow.

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

Landing gear employing a third rear-mounted wheel. These airplanes are also sometimes referred to as tailwheel airplanes.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

A duct that has a decreasing cross section in the direction of flow (convergent) until a minimum area is reached. After this point, the cross section increases (divergent). Convergent-divergent ducts are called CD ducts or con-di ducts.

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

A duct that has a decreasing cross section in the direction of flow.

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

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

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

A chemical solution used to form an airtight oxide or phosphate film on the surface of aluminum or magnesium parts. The conversion coating prevents air from reaching the metal and keeps it from corroding.

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

A surface that is curved outward. The outer edges are lower than the center.

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

Flight with a minimum disturbance of the forces maintaining equilibrium, established via effective control use.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

See changeover point.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The gas generator portion of a turboshaft, turboprop, or turbofan engine. The core engine consists of the portion of the compressor used to supply air for the engine operation, diffuser, combustors, and turbine(s) used to drive the compressor. The core engine provides the high-velocity gas to drive the fan and/or any free turbines that provide power for propellers, rotors, pumps, or generators.

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

The change in rotor blade velocity to compensate for a change in the distance between the center of mass of the rotor blade and the axis rotation of the blade as the blades flap in flight.

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

The illusion of rotation or movement in an entirely different axis, caused by an abrupt head movement, while in a prolonged constant-rate turn that has ceased to stimulate the brain’s motion sensing system.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

A large shop tool used to make straight bends across a sheet of metal. Cornice brakes are often called leaf brakes.

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

The deterioration of metal by chemical or electrochemical attack.

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

Sheets of metal that have been made more rigid by forming a series of parallel ridges or waves in its surface.

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

A trigonometric function comparing two sides of a right triangle as follows: Cos = hypotenuse

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

A split metal pin used to safety a castellated or slotted nut on a bolt. The pin is passed through the hole in the shank of the bolt and the slots in the nut, and the ends of the pin are spread to prevent it backing out of the hole.

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

A measure of electrical output. One coulomb is 6.24 × 1018 electrons.

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

A tool that cuts a cone-shaped depression around a hole in order to allow a rivet or screw to set flush with the surface of the material.

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

Preparation of a rivet hole for a flush rivet by beveling the edges of the holes with a cutter of the correct angle.

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

Rudder and ailerons are connected with interconnected springs in order to counteract adverse yaw. Can be overridden if it becomes necessary to slip the aircraft.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The intended direction of flight in the horizontal plane measured in degrees from north.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

A small surface-type bimetallic thermometer that calibrates the temperature of an iron used to heat-shrink polyester fabrics.

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

Shutter-like devices arranged around certain air-cooled engine cowlings, which may be opened or closed to regulate the flow of air around the engine.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The removable cover that encloses an aircraft engine.

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

Pointing the nose of an aircraft into the wind to compensate for wind drift.

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

The housing that encloses the crankshaft, camshaft, and many of the accessory drive gears of a reciprocating engine. The cylinders are mounted on the crankcase, and the engine attaches to the airframe by the crankcase.

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

The central component of a reciprocating engine. This high-strength alloy steel shaft has hardened and polished bearing surfaces that ride in bearings in the crankcase. Offset throws, formed on the crankshaft, have ground and polished surfaces on which the connecting rods ride. The connecting rods change the in-and-out motion of the pistons into rotation of the crankshaft.

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

A form of stress-caused damage that occurs in a transparent thermoplastic material. Crazing appears as a series of tiny, hair-like cracks just below the surface of the plastic.

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

The deformation of a metal part that is continually exposed to high centrifugal loads and temperatures.

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

The application of team management concepts in the flight deck environment. It was initially known as cockpit resource management, but as CRM programs evolved to include cabin crews, maintenance personnel, and others, the phrase “crew resource management” was adopted. This includes single pilots, as in most general aviation aircraft. Pilots of small aircraft, as well as crews of larger aircraft, must make effective use of all available resources; human resources, hardware, and information. A current definition includes all groups routinely working with the flight crew who are involved in decisions required to operate a flight safely. These groups include, but are not limited to pilots, dispatchers, cabin crewmembers, maintenance personnel, and air traffic controllers. CRM is one way of addressing the challenge of optimizing the human/machine interface and accompanying interpersonal activities.

Pilot's Handbook of Aeronautical Knowledge, p. G-8

The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight.

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

Areas where disturbances to the ILS localizer and glideslope courses may occur when surface vehicles or aircraft operate near the localizer or glideslope antennas.

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

The flight Mach number at which there is the first indication of supersonic airflow over any part of the aircraft structure.

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

The flight match number at which there is the first indication of air flowing over any part of the structure at a speed of Mach one, the local speed of sound.

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

See crew resource management.

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

The first fundamental skill of instrument flight, also known as “scan,” the continuous and logical observation of instruments for attitude and performance information.

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

A double coat of aircraft finishing material in which the second coat is sprayed at right angles to the first coat, before the solvents have evaporated from the first coat.

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

A valve in a fuel system that allows any of the engines of a multi-engine aircraft to draw fuel from any fuel tank. Cross-feed systems are used to allow a multi-engine aircraft to maintain a balanced fuel condition.

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

An automatic flow-control valve installed between the gear-up and gear-down lines of the landing gear of some large airplanes. When the landing gear is released from its uplocks, its weight causes it to fall faster than the hydraulic system can supply fluid to the gear-down side of the actuation cylinder. The cross-flow valve opens and directs fluid from the gear-up side into the gear-down side. This allows the gear to move down with a smooth motion.

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

Cathode-ray tube.

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

An ATC clearance issued to allow a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. Also authorizes a pilot to proceed to and make an approach at the destination airport.

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

A liquid which boils at a temperature lower than about 110 ºK (-163 ºC) under normal atmospheric pressure.

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

A liquid which boils at temperatures of less than about 110 °F (–163 °C) at normal atmospheric pressures.

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

Constant-speed drive. A component used with either aircraft gas turbine or reciprocating engines to drive AC generators. The speed of the output shaft of the CSD is held constant while the speed of its input shaft varies. The CSD holds the speed of the generator, and the frequency of the AC constant as the engine speed varies through its normal operating range.

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

Centrifugal twisting force. The force acting about the longitudinal axis of a propeller blade, and which tries to rotate the blade to a low-pitch angle. As the propeller rotates, centrifugal force tries to flatten the blade so all of its mass rotates in the same plane.

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

The registered trade name for a particular style of edge-type fluid filter. Cuno filters are made up of a stack of thin metal discs that are separated by thin scraper blades. Contaminants collect on the edge of the discs, and they are periodically scraped out and allowed to collect in the bottom of the filter case for future removal.

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

The flow of electrical charge.

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

An electrical current being induced into, or generated in, any conductor that is crossed by lines of flux from any magnet.

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

An electrical component used to limit the amount of current a generator can produce. Some current limiters are a type of slow-blow fuse in the generator output. Other current limiters reduce the generator output voltage if the generator tries to put out more than its rated current.

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

An operator created and FAA-approved operational loading envelope that is more restrictive than the manufacturer’s CG envelope. It ensures that the aircraft will be operated within limits during all phases of flight Curtailment typically accounts for, but is not limited to, in-flight movement of passengers and crew, service equipment, cargo variation, seating variation, etc.

Aircraft Weight and Balance Handbook, p. G-2

A World War I training airplane powered by a Curtiss OX-5 engine. It was widely available after the war and helped introduce aviation to the general public.

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

A pointed end.

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

Air that is tapped off a turbine engine compressor and used for such airframe functions as the operation of air conditioning and pressurization systems.

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

The mechanical change of the angle of incidence, or pitch, of individual rotor blades, independent of other blades in the system.

Helicopter Flying Handbook, p. G-2

The helicopter control that allows the pilot to change the pitch of the rotor blades individually, at a specific point in their rotation. The cyclic pitch control allows the pilot to tilt the plane of rotation of the rotor disc to change the direction of lift produced by the rotor.

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

The component of a reciprocating engine which houses the piston, valves, and spark plugs and forms the combustion chamber.

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