the Aviation Dictionary

flow indicator - A device in an oxygen system that
provides users with a positive indication that oxygen is
flowing.
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flow meter - An autosyn electrical transmitter that
provides a signal to a cockpit instrument. This indicator
shows pounds per hour of fuel flow being consumed by
an operating engine.
flow reverser - A mechanical device placed in the tail
pipe of a turbojet engine to deflect the exhaust gases
forward. This decreases the aircraft landing roll.
flowchart - A diagram that uses symbols connected by
lines to indicate the sequence of steps that must be
followed in order to achieve a desired end result.
fluctuate - 1. The swing or oscillation of a dial from
low to high. 2. To continually change or vary in an
irregular way.
fluctuating arc - A malfunction in an inert-gas arc
welding system caused by improper grounding.
fluid -- 1. A substance. either gaseous or lisuid, that will
conform to the shape of the-container that hblds it. A
gaseous fluid will expand to fill the entire container,
while a liquid fluid will fill only the lower part of the
container. 2. Any material whose molecules are able to
flow past one another without destroying itself. Gases
and liquids are both fluids.
fluid mechanics - The science and technology of forces
produced by fluids.
flow indicator flux valve wider
and the oil is washed from the surface and the part is
dried. The part is then covered with a developer that
draws the oil out from any crack into which it may
have seeped. The part is inspected under ultraviolet
light, which causes the crack to appear as a vivid green
line.
fluorescent pigment - A paint pigment that can absorb
visible or non-visible electromagnetic radiation and
release it as energy in a wavelength.
fluorine - A gaseous element with the symbol F and an
atomic number of 9.
fluoroscope - An instrument used for observing the
internal structure of an object by means of X rays.
flush - To clean, wash, or empty out with a sudden flow
of solvent or other cleaning agent.
flush patch - A type of sheet metal repair that leaves a
smooth surface maintaining the skin's original contour.
The repair is reinforced on the inside and the damaged
area is filled with a plug patch.
flush repairs - Metal repairs designed to maintain an
aircraft's skin original contour.
flush rivet - A countersunk rivet in which the
manufactured head is flush with the surface of the
metal when it is properly driven.
flush riveting - Riveting using countersunk-head rivets.
Produces a perfectly smooth outside skin.
fluid ounce - A liquid volume equal to '116 liquid pint or
flute - A groove that is cut or formed in a material.
1.8 cu. in. flutes - Spiral-cut grooves in a drill bit that extend from
the point to the shank and allow chips to move from the
fluid power - The transmission of force by the
movement of a fluid. The best examples are hydraulics
and pneumatics.
fluidics - The branch of science that studies the various
shapes of ducts to sense, measure, and control physical
conditions.
fluidity - The ability of a liquid or gas to flow easily and
smoothly.
fluorescent - A substance that will glow or fluoresce
when excited. Some types of dye penetrant material use
fluorescent dyes, which can be observed under
ultraviolet light.
fluorescent finish - A highly light-reflecting aircraft
finish.
fluorescent lamp - A lamp that emits light as the result
of the glowing of a fluorescent coating on the inside
surface-of a &be rather than from the-glowing of an
incandescent filament.
fluorescent penetrant inspection - A form of
nondestructive inspection in which a part is thoroughly
cleaned and immersed in a vat of penetrating oil. When
the part has soaked for a sufficient time, it is removed
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hole being drilled and for lubrication to flow to the
cutting edges.
flutter - The rapid and uncontrolled oscillation of a
flight control resulting from an unbalanced surface.
Flutter normally leads to a catastrophic failure of the
structure.
flux - 1. A material used in soldering, brazing, or
welding - to clean the surface of oxides and prevent
oxides from forming. Helps ensure good adhesion or
fusion of surfaces. 2. Magnetic lines of force.
flux density - The number of lines of magnetic force per
unit area.
flux valve - A special transformer that develops a signal
whose characteristics are determined bv the unit's
position in relation to the Earth's magnetic field. It is
part of an Earth inductor compass system.
flux valve spider - The framework around which the
three pick-up coils of a flux valve are wound. The
spider1; highly permeable material accepts the lines of
flux from the Earth's magnetic field.