the Aviation Dictionary

is wrapped around the structure and attached by sewing
or cementing it in place to either the trailing edge of a
wing or to the longerons of a fuselage.
blanking - The process of forcing stock material
through a cutout in a die plate with a die that is slightly
smaller, and the same shape, as the cutout in the die
plate. Creates a shaped piece (blank) of the same shape
as the punch.
blast fence - A sturdy structure used to prevent jet blast
damage to equipment and personnel located behind
operating aircraft.
bleed -- In composites, an escape passage at the parting
line of a mold (like a vent, but deeper), which allows
material to escape, or bleed out.
bleed air - Compressed air tapped from the compressor
stages of a turbine engine by use of ducts and tubing.
Bleed air can be used for deice, anti-ice, cabin
pressurization, heating, and cooling systems.
bleed orifice - A calibrated orifice used to bleed down
or adjust the pressure in a system.
blanking blister
bleedout - In composites, excess resin that flows out
during the curing process, usually into a bleeder cloth.
Sometimes appears during the filament winding
process if the fiber has been through a resin bath.
blemish - A defect or injury mark that damages an
object or diminishes its value.
blending - A metal filing and stoning procedure used to
recontour damaged compressor and turbine blades to
an aerodynamic shape. A fine stone is used to blend
(smooth) the reworked area into the original surface of
the blade.
blimp - A non-rigid airship.
blind flight - An early aviation term for instrument
flying.
. -
blind rivet - A rivet designed to
be used in sheet metal structure
where it is not possible to use a
bucking bar for riveting.
blind speed - The rate of
departure or closing of a target
bleed valve - In a turbine engine, a flapper valve, a relative to the radar antenna at
popoff valve, or a bleed band designed to bleed off a which cancellation of the
portion of the compressor air to the atmosphere. Used primary radar target by moving target indicator (MTI)
to maintain blade angle of attack and provide stall-free circuits in the radar equipment causes a reduction or
engine acceleration and deceleration.
complete loss of signal. See also blind velocity.
bleeder - In composites, a layer of material used during blind spot -An area that is not visible.
the manufacture or repair of a part to allow entrapped
blind spot - 1. An area from which radio transmissions
air and resin to escape. It is removed after curing. lt
and/or radar echoes cannot be received. 2. Portion of
also serves as a vacuum valve contact with the part.
the airport not visible from the control tower.
bleeder current - A current drawn from a source
blind transmission -A transmission from one station to
through a bleeder resistor to ground. Used to stabilize
other stations in circumstances where two-way
the output voltage.
communication cannot be established, but where it is
bleeder resistance - A permanently connected resistor
connected across the output of a power supply and
believed that the called stations may be able to receive
the transmission.
designed to "bleed off' a small portion of the current.
bleeder resistor - The resistor of a voltage divider
through which the smallest amount of current flows.
This resistor is generally selected so that the current
through it is about 10% of the total circuit current. Also
used in power supplies to stabilize the output voltage or
to bleed the voltage from capacitors after a component
is turned off.
bleeding - 1. The act of removing air from a system. 2.
A maintenance procedure for purging the fuel system
of air locks and to aid in flushing any traces of
preservative oil from a pressure carburetor. 3. A
maintenance procedure in which air is removed from
the hydraulic fluid in the brake system of an aircraft. If
there is any air in the fluid in hydraulic brakes, the air
will compress when the brakes are applied, the brakes
will feel "spongy," and their effectiveness will be
reduced.
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blind velocity [ICAO] - The radial velocity of a
moving target such that the target is not seen on
primary radars fitted with certain forms of fixed echo
suppression.
blind zone - See blind spot.
blink Zyglo - A method of Zyglo inspection wherein a
part is cleaned and soaked with a fluorescent penetrant
for an appropriate length of time. The part is rinsed and
all of the penetrant is cleaned from its surface. The part
is vibrated while it is being examined under a black
light. If the vibration opens up a crack that has
accepted some of the penetrant, the crack will show up
as a blinking light.
blinker - Oxygen-flow indicator acting as a moveable
shutter, opening and closing with each breath.
blister - 1. An enclosed raised spot on the surface of a
finish on a metal. It may be filled with vapor or with