the Aviation Dictionary

lead - lee wave
The total opposition to the flow of current in an LCR
circuit is the vector sum of resistance and the
difference between inductive and capacitive reactances.
lead - A heavy, pliant, silvery metallic element with a
symbol of Pb and an atomic weight of 82.
lead and lag - In rotorcraft, the fore (lead) and aft (lag)
movement of the rotor blade in the plane of rotation.
lead of screw thread - The distance a nut will move
forward on a screw if it is turned one revolution.
lead-acid battery - A commonly used secondary cell
having lead as its negative plate and lead peroxide as
its positive plate. Sulfuric acid and water serve as the
electrolyte.
leading current - An AC electrical circuit in which the
current that flows in the circuit has more capacitive
reactance than it has inductive reactance.
leading edge - The foremost edge of an airfoil section.
leading edge flap - A portion of the leading edge of an
airplane wing that folds downward to increase the
camber, lift, and drag of the wing. The leading-edge
flaps are extended for takeoffs and landings to increase
the amount of aerodynamic lift that is produced at any
given airspeed.
leading edge mean aerodynamic chord (LEMAC) -
The leading edge of the mean aerodynamic chord often
used as a location or reference for many aerodynamic
measurements in aircraft operations and designs.
lead-lag hinge - A hinge at the root of a helicopter rotor
blade with its axis perpendicular to the plane of
rotation. Also referred to as the alpha, drag, or hunting
hinge.
lead-off question - A question used by an instructor to
open up an area for discussion. The purpose is to get
the discussion started.
leaf brake - A bending
u
tool used to form
straight bends in sheet
metal. The material is
clamped in the tool, and
a heavy leaf folds the
metal back over a radius
block to form the
desired bend. Also
referred to as a cornice brake.
leaf spring assembly - A series of flat springs hinged at
one end and arched in the center. When a load is
applied to the center of the arch it is absorbed as the
spring alternately straightens out and returns to its
arched shape.
leakage - 1. The breakdown of the dielectric strength of
an insulator that allows current to pass through it. 2. An
amount of a liquid or gas that leaks into or out of
something.
leakage current - The amount of current that flows
from the battery terminals to the battery case through
any moisture or contamination on top of the battery.
leakage flux - The magnetic flux that does not follow a
direct path between the poles of a magnet and which
does not provide any useful work.
lean blow out - A condition in jet engine fuel
combustion during which the fuel supply is decreased
to maintain or reduce engine speed. During this
condition the burning can be so slow that the flame is
carried out of the combustion chamber and
extinguished.
lean flame out - A condition of turbine engine
operation in which the fire goes out in the engine
because the fuel-air mixture is too lean to support
combustion.
lean mixture - A fuel-air mixture in which there is an
excess amount of air in the mixture.
learning - A change in behavior as a result of
experience.
learning plateau - A learning phenomenon where
progress appears to cease or slow down for a time
before once again increasing.
learning style - The concept that how a person learns is
dependent on that person's background and
personality, as well as the instructional methods used.
least significant bit - A bit in a binary number that has
the lowest value. It is the bit on the far right of a binary
number.
least significant digit - A digit in a decimal number that
is the least meaningful for accuracy. It is the digit on
the far right of a decimal number.
Leclanche cell battery - A name for a common
carbon-zinc cell flashlight battery.
lecture method - An educational presentation usually
delivered by an instructor to a group of students with
the use of instructional aids and training devices.
Lectures are useful for the presentation of new
material, summarizing ideas, and showing relationships
between theory and practice.
lee side - The downwind side of a mountain range,
building, island, etc.
lee wave - Any stationary wave disturbance caused by a
barrier in a fluid flow. In the atmosphere when
sufficient moisture is present, this wave will be
evidenced by lenticular clouds to the lee of mountain
barriers. Also referred to as a mountain wave or
standing wave.
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