FAA Aviation Mechanic - General (AMG) key terms

The relationship stating that current in a circuit equals voltage divided by resistance (I = E/R). It is used to calculate any one electrical value when the other two are known.

A circuit in which current has only one path, so the same current flows through every component and total resistance is the sum of individual resistances.

A circuit in which components are connected across the same voltage, so voltage is the same across each branch and total current is the sum of branch currents.

Electric current that periodically reverses direction, typically in a sine wave. In aircraft it is often produced by an alternator and used for certain instruments and systems.

Electric current that flows continuously in one direction. Aircraft batteries and many avionics systems use DC, and it may be produced by a generator or rectifier.

A drawing method that shows an object from multiple views, such as top, front, and side, arranged on a single drawing so each view represents true shape where possible.

A three-dimensional pictorial drawing in which the three axes are spaced 120 degrees apart, used to show an object's overall shape rather than exact dimensions.

The section of an aircraft drawing, usually in a corner, that lists identifying information such as drawing number, title, scale, date, and approval.

An imaginary vertical reference plane from which arm distances are measured for weight and balance calculations. Its location is specified in the aircraft's weight and balance data.

The horizontal distance from the datum to the center of gravity of an item or to a point where a weight is applied, usually measured in inches.

The product of a weight and its arm, expressed in pound-inches. Moments are totaled and divided by total weight to find the aircraft's center of gravity.

The point at which the entire weight of an aircraft is considered concentrated. It must remain within approved limits for safe flight and control.

The weight of an aircraft including its structure, powerplant, fixed equipment, optional equipment, unusable fuel, and full engine oil, but excluding usable fuel, payload, and crew.

The difference between an aircraft's maximum allowable weight and its empty weight. It includes usable fuel, crew, passengers, baggage, and cargo.

A fitting in which the end of a rigid tube is flared to match a cone-shaped fitting body, and a nut pulls the flare against the body to make a seal.

A fitting that seals by compressing a sleeve or ferrule onto the outside of a tube as the nut is tightened, eliminating the need for flaring the tube.

A standardized aircraft hardware fitting made to Air Force-Navy specifications, commonly used for fluid lines and identified by its AN number and size.

A controlled process of heating, holding, and cooling a metal to change its mechanical properties, such as strength, hardness, or ductility, without changing its basic composition.

A heat treatment that softens a metal by heating it to a suitable temperature, holding it, and cooling it slowly, which relieves internal stresses and improves ductility.

The condition of a metal produced by mechanical working or heat treatment, indicating its strength and hardness. Temper designations such as T6 describe the treatment applied.

Securing an aircraft on the ground with ropes or chains to fixed anchors so wind or other forces cannot move or damage it.

The act of fastening an aircraft to ground anchors or weights, usually at designated points, to keep it from moving while parked outdoors.

Raising an aircraft using jacks placed at approved jack points so maintenance such as landing gear or wheel service can be performed safely.

Corrosion caused by contact between two dissimilar metals in the presence of an electrolyte, where one metal acts as an anode and corrodes preferentially.

A form of corrosion that starts along grain boundaries parallel to the surface and lifts or flakes the metal, often appearing as layered swelling on aluminum alloys.

An electrochemical process that forms a protective oxide coating on aluminum, improving corrosion resistance and providing a base for paint or dye.

An equation stating that two ratios are equal, used to solve for an unknown quantity when other values are known, such as fuel consumption or scale conversions.

The measure of a surface in square units, calculated for common shapes using formulas; needed for tasks such as paint coverage or sheet metal repair.

A written record of maintenance, preventive maintenance, or alteration that identifies the work performed, date, and person approving it for return to service.

The form used to document a major repair or major alteration to an aircraft, engine, propeller, or appliance, including the approval for return to service.

A mandatory FAA notice that requires corrective action on a known unsafe condition in an aircraft, engine, propeller, or appliance within a specified time.

A document that lists the approved design, operating limitations, and required equipment for an aircraft, engine, or propeller under its type certificate.

An FAA publication that provides guidance, information, or acceptable methods for complying with regulations; it is not itself a regulation unless incorporated by reference.

A notice from a manufacturer recommending or requiring inspection or modification of a product; it may be mandatory if the FAA adopts it through an airworthiness directive.

Simple or minor preservation work and replacement of small standard parts that a certificated mechanic or pilot may perform, as defined in the regulations.

A repair that significantly affects weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other airworthiness qualities, requiring approved data and documentation.

An alteration that substantially affects weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other airworthiness qualities, requiring approved data and documentation.

The act of certifying that an aircraft or component is airworthy and approved for operation after maintenance, performed by an authorized person with proper records.