Self-excited generators depend upon residual magnetism in the field frame to produce the initial excitation current as soon as the generator begins to turn.
field frame (generator component). The steel housing of a generator in which the field coils are mounted. The field frame provides a low reluctance path for the magnetic flux from the field coils, and it retains enough magnetism, when the generator is not operating, to start the generator producing current. This magnetism is called residual magnetism.
field maintenance (aircraft maintenance). Maintenance performed on an aircraft when it is away from its regular maintenance base or out of the maintenance dock. Field maintenance is limited, as much as possible, to minor replacement operations.
field strength meter (electrical measuring device). An electrical instrument used to measure the strength of the electromagnetic field radiated from a radio transmitting antenna.
filament (electron tube component). The heater in an electron tube. The filament is a small piece of flat resistance wire mounted inside a tube-like cathode.
Electrons flowing through the filament cause it to glow red-hot, and this heats the cathode. The heat speeds up the molecular movement in the cathode enough that electrons are emitted from its surface. Electron tube filaments are heated with low-voltage AC or with low-voltage batteries.
file (metal-cutting tool). A hand-held cutting tool used to remove a small amount of metal by pushing the tool across the metal surface. A file is made of very hard, high-carbon steel, and has rows of teeth cut across its face at an angle to the length of the file.
Files with a single set of teeth are called single-cut files, and a file having a second set of teeth that cross the first set is called a double-cut file. The teeth on a file vary from very fine to coarse. A file with the finest teeth is said to have a dead-smooth cut; next in coarseness is a smooth cut, then a second cut, a bastard cut, and finally a coarse cut.
filed enroute delay (air traffic control). A preplanned delay at points along the route of a flight which requires special flight plan filing and handling techniques.
Filed enroute delays may be terminal area delays, special use airspace delays, or aerial refueling delays.
filiform corrosion. A thread-, or filament-like corrosion which forms on aluminum skins beneath a dense paint film. Filiform corrosion gets its name from the fact that it grows in shape of a thread, or a filament.
filler material (plastic resin component). A material mixed into a plastic resin to give body to the resin. Powdered chalk and microballoons are two commonly used filler materials.
filler neck (fluid reservoir component). A cylindrical tube extending from a fluid reservoir to a location that is convenient to fill the reservoir. Some hydraulic reservoirs and fuel tanks are installed inside an aircraft structure in a location where servicing is difficult. A filler neck is installed on these reservoirs to allow them to be filled from outside the aircraft.
|
