Aeronautical Terms beginning with F
Feathering Propeller (Feathered)
A controllable pitch propeller with a pitch range sufficient to allow the blades to be turned parallel to the line of flight to reduce drag and prevent further damage to an engine that has been shut down after a malfunction.
Fire resistant
(1) With respect to sheet or structural members, the capacity to withstand the heat associated with fire at least as well as aluminum alloy in dimensions appropriate for the purpose for which they are used; and
(2) With respect to fluid-carrying lines, fluid system parts, wiring, air ducts, fittings, and powerplant controls, the capacity to perform the intended functions under the heat and other conditions likely to occur when there is a fire at the place concerned.
Fireproof
(1) With respect to materials and parts used to confine fire in a designated fire zone, the capacity to withstand at least as well as steel in dimensions appropriate for the purpose for which they are used, the heat produced when there is a severe fire of extended duration in that zone; and
(2) With respect to other materials and parts, the capacity to withstand the heat associated with fire at least as well as steel in dimensions appropriate for the purpose for which they are used.
Fixed-Pitch Propellers
Propellers with fixed blade angles. Fixed-pitch propellers are designed as climb propellers, cruise propellers, or standard propellers.
Flame resistant
Not susceptible to combustion to the point of propagating a flame, beyond safe limits, after the ignition source is removed.
Flap extended speed
The highest speed permissible with wing flaps in a prescribed extended position.
Flaps
Hinged portion of the trailing edge between the ailerons and fuselage. In some aircraft, ailerons and flaps are interconnected to produce full-span “flaperons.” In either case, flaps change the lift and drag on the wing.
Flash resistant
Not susceptible to burning violently when ignited.
Flat Pitch
A propeller configuration when the blade chord is aligned with the direction of rotation.
Flight Idle
Engine speed, usually in the 70-80 percent range, for minimum flight thrust.
Force (F)
The energy applied to an object that attempts to cause the object to change its direction, speed, or motion. In aerodynamics, it is expressed as F, T (thrust), L (lift), W (weight), or D (drag), usually in pounds.
Form Drag
The part of parasite drag on a body resulting from the integrated effect of the static pressure acting normal to its surface resolved in the drag direction.
Forward wing
A forward lifting surface of a canard configuration or tandem-wing configuration airplane. The surface may be a fixed, movable, or variable geometry surface, with or without control surfaces.
Friction Drag
The part of parasitic drag on a body resulting from viscous shearing stresses over its wetted surface.
Frise-Type Aileron
Aileron having the nose portion projecting ahead of the hinge line. When the trailing edge of the aileron moves up, the nose projects below the wing’s lower surface and produces some parasite drag, decreasing the amount of adverse yaw.
Fuel Control Unit
The fuel-metering device used on a turbine engine that meters the proper quantity of fuel to be fed into the burners of the engine. It integrates the parameters of inlet air temperature, compressor speed, compressor discharge pressure, and exhaust gas temperature with the position of the cockpit power control lever.
Fuel Efficiency
Defined as the amount of fuel used to produce a specific thrust or horsepower divided by the total potential power contained in the same amount of fuel.
Fuel Heaters
A radiator-like device which has fuel passing through the core. A heat exchange occurs to keep the fuel temperature above the freezing point of water so that entrained water does not form ice crystals, which could block fuel flow.
Fuel Injection
A fuel metering system used on some aircraft reciprocating engines in which a constant flow of fuel is fed to injection nozzles in the heads of all cylinders just outside of the intake valve. It differs from sequential fuel injection in which a timed charge of high-pressure fuel is sprayed directly into the combustion chamber of the cylinder.
Fuel Load
The expendable part of the load of the airplane. It includes only usable fuel, not fuel required to fill the lines or that which remains trapped in the tank sumps.
Fuel Tank Sump
A sampling port in the lowest part of the fuel tank that the pilot can utilize to check for contaminants in the fuel.
Fulcrum
The point about which a lever balances.
Fuselage
The section of the airplane that consists of the cabin and/or cockpit, containing seats for the occupants and the controls for the airplane.
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