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

Eddy current inspection. An inspection method where eddy currents are induced into the material to be tested. In aircraft manufacturing plants, eddy current is used to inspect castings, stampings, machine parts, forgings, and extrusions.

Electrical energy. Electrical energy is converted to heat energy when an electric current flows through any form of resistance such as an electric iron, electric light, or an electric blanket.

Electromotive force (EMF). The pressure or force that causes electrons to flow in an electrical circuit.

Electrostatic field. A field of force that exists around a charged body.

Empennage. The section of the airplane that consists of the vertical stabilizer, the horizontal stabilizer, and the associated control surfaces.

Empty-weight center of gravity range. The distance between the allowable forward and aft empty-weight CG limits.

Empty-weight center of gravity. The center of gravity of an aircraft when it contains only the items specified in the aircraft empty weight.

Empty weight. See standard empty weight.

Energy. The capacity of a physical system to perform work. There are two types of energy, kinetic and potential.

Exploded view drawing. A pictorial drawing of two or more parts that fit together as an assembly. The view shows the individual parts and their relative position to the other parts before they are assembled.

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

Extension lines. Used to extend the line showing the side or edge of a figure for the purpose of placing a dimension to that side or edge.

FAA Form 337. This form must be completed when a major repair or alteration is accomplished.

Ferrous metals. Metals having iron as their principal constituent.

Force. The intensity of an impetus, or the intensity of an input.

Foreign object damage (FOD). Any damage caused by any loose object to aircraft, personnel, or equipment. These loose objects can be anything from broken runway concrete to shop towels and safety wire.

Fraction. A number written in the form N⁄D in which N is the numerator and D is the denominator. For example, 5⁄16 is a fraction.