the Aviation Dictionary

lee wave region a lift fan
lee wave region - The upper layer of a two-layer leewave
system where smooth wave flow dominates and
microscale turbulence occasionally occurs.
lee wave system - A system marked by two distinct
layers. The upper layer is the lee wave region, which
begins just above mountain to level, and the lower
layer is the lower turbulent zone.
left brain - A concept that each hemisphere of the brain
processes information differently. People with leftbrain
dominance are more verbal, analytical, and
objective.
left-hand rule - 1. The left-hand generator rule: The
fingers of the left hand are arranged in such a way that
the thumb, first finger, and second finger point 90" to
each other. If the thumb points in the direction of
movement of the conductor. the first finger - will ~oint
in the direction of the lines of flux (north to south), and
the second finger will point in the direction of the
induced voltage (back- voltage, from positive to
negative). 2. The direction of magnetic flux: If the
fingers of the left hand encircle a conductor in the
direction of the lines of magnetic flux, the thumb will
point in the direction of electron flow. 3. The polarity
of an electromagnet: If the coil of an electromagnet is
grasped in such a way that the fingers encircle the coil
in the same way the electrons are flowing, the thumb
will point to the north pole of the electromagnet that is
formed by the coil.
left-hand thread - A thread that winds in a
counterclockwise direction. All left-hand threads are
designated LH.
leg - 1. One side of a formed angle. 2. One portion of a
trip made with dead reckoning navigation (the distance
between turn points.) 3. The portion of a trip between
stops.
legs of a right triangle - The sides of a right triangle
joined by the right angle (90').
LEMAC - The leading edge of the mean aerodynamic
chord. Often used as a reference location for
aerodynamic measurements in aircraft operations and
designs.
instructor in that it tells what to do, in what order to do
it, and what procedure to use in teaching the material of
a lesson.
letter of authorization (LOA)- A letter from the FAA
authorizing use of a Minimum Equipment List (MEL)
for a specific airplane. The letter and the MEL together
are considered a supplemental type certificate.
level - 1. The horizontal condition of a body: A flat
horizontal surface of an object is level when no part of
the object is higher than another. 2. A spirit or bubble
level: An indicating device that has a curved glass tube
filled with a slightly colored liquid, except fir a small
air bubble. The tube is mounted in a housing so when it
is place in a parallel position to the ground the bubble
will move to the center of the tube indicating a level
condition.
leveling lugs - The points on an aircraft on which a
level can be placed for leveling - the aircraft.
leveling means - A method of checking an aircraft for
level flight attitude as specified by the aircraft
manufacturer. This can be longitudinal, lateral, andlor
both.
leveling scale - A scale built into the aircraft for
checking the leveling of the aircraft in conjunction with
a plumb bob.
lever - 1. A device such as a bar used for prying. 2. A
flat bar ~ivoting - on a fulcrum.
Leyden jar -- A primitive capacitor. In effect, an
apparatus for storing an electric charge on the inside
foil lining of a glass jar.
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lenticular cloud - A cloud shaped like a lens that forms
on the downwind side of a mountain. It usually
indicates severe air turbulence and should be avoided.
They can extend the entire length - of the mountain
range producing the wave and are called wave clouds
or lennies by glider pilots.
Lenz's law - The law of induced current that says the
current induced in a conductor will produce a magnetic
field that opposes the field producing the original
current.
lesson plan - An organized outline for a single
instructional period. It is a necessary guide for the
Aircraft Technical Book Company
P.O. Box 270
Tabernash, CO 80478
http:llw.ACTechbooks.com
L-filter - An inductor-input filter consisting of an
inductor and a capacitor used to smooth the ripple from
the output of a rectifier.
licensed empty weight - The empty weight that consists
of the airframe, engine(s), unusable fuel, and
undrainable oil. . vlus . standard and ovtional equivment - *
as specified in the equipment list.
life-limited part - A part with a specified number of
operating hours or operating cycles before it must be
removed for overhaul.
life-support systems - The oxygen and pressurization
systems in an aircraft that make it possible for the
occupants to function at high altitudes.
lift - One of the four main forces acting on an aircraft.
On a fixed-wing aircraft, an upward force created by
the effect of airflow as it passes over and under thk
wing.
lift fan - A turbofan engine with an exhaust duct that
can be pointed down to provide upward thrust for
vertical or short takebff. used in VSTOL
(VerticalIShort Takeoff and Land) aircraft.