the Aviation Dictionary

OR gate - A logic device that will have a voltage on its
output any time a voltage appears at any one or more. of
its inputs.
OR gate Otto cycle
O-ring - A sealing device used in a pneumatic or
hydraulic system that has a circular cross section and is
made in the form of a ring.
oral quizzing - The most common means of evaluating ornithopter - An aircraft designed to produce lift by the
a student's knowledge. Proper oral quizzing during a flapping of its wings.
lesson promotes active student participation, identifies
OROCA (off--route obstruction clearance altitude) -
points that need more emphasis, and reveals the
An ofioute altitude that provides obstruction clearance
effectiveness of training procedures.
with a 1,000 foot buffer in nonmountainous terrain
orange peel - A defect in a painted surface that areas i d a 2,000 foot buffer in designated
resembles the skin of an orange. It can be caused by mountainous areas within the United States. This
errors in paint viscosity, air pressure, spray gun altitude may not provide signal coverage from
settings, or an improper distance between the spray gun groundbased navigational aids, air traffic control radar,
and the surface.
or communications coverage.
orbital electron - An electron spinning around the
nucleus of an atom; different from free electrons,
which are able to move from one atom to another.
ordinate - A line parallel to the Y-axis of a graph. A
specified distance from the X-axis, used to fix a point.
orographic - Relating to mountains. In weather, refers
to phenomena caused by mountains, i.e., orographic
clouds.
orographic lifting - The lifting of an airmass when it
encounters a barrier, for example, mountains or a hill.
organic brake linings - Organic material reinforced oronasal oxygen mask - An oxygen mask covering
with brass wool and attached to solid metal backings. only the mouth and the nose of the wearer.
Used for single-disk brakes.
orphaned airplane - Slang, for an aircraft that is
organic - fabric - A woven material made of natural frequently non-airworthy and spends a lot of time in
origin fibers such as cotton or linen. Used in the the-hangar. In the military o; commercial aviation,
manufacturing of aircraft fabric covering materials.
these aircraft are frequently robbed of parts to keep
other aircraft airworthy, thus prolonging the status of
organic fibers - Fibers of natural origin such as cotton
the hangar queen. Also referred to as a hangar queen.
or linen. Used in the manufacture of aircraft fabric
covering materials.
orthographic projection - In mechanical drawing, six
different views of an object are possible through
organic Lining - The friction material used in spot-type,
orthographic projection: front, rear, top, bottom, left
single disk brakes. It is a composition material in
side, and right side. Each view is drawn as if the object
which brass- or copper-wool or particles of brass are
were placed in a box and only one side of the box
embedded to control the coefficient of friction.
opened to reveal one view (either front, rear, top,
organized track system - 1. A movable system of bottom, left side, or right side) of the object.
oceanic tracks that traverses the North Atlantic
oscillate - To swing back and forth with a consistent
between Europe and North America the physical
force or rhythm.
position of which is determined twice daily taking the
best advantage of the winds aloft. 2. A series of fixed oscillator - 1. An electronic device that converts DC
and charted ATS (Air Traffic Services) routes; i.e., into AC. 2. An electronic circuit that produces AC with
CEP, NOPAC; or flexible and described by NOTAM; frequencies determined by the inductance and
i.e., NAT Track Message
capacitance in the circuit.
orientation - In composites, the alignment of the fibers oscillograph - A device for mechanically or
(0°, 45", 90") to the baseline set by the manufacturer for photographically producing a graphical representation
a particular component.
of an electric signal.
orifice - A small hole of a specific size that meters or
controls the flow of a fluid.
orifice check valve - A component in a hydraulic or
pneumatic system that allows unrestricted flow in one
direction and restricted flow in the opposite direction.
original skin - The skin or metal covering originally
used in the manufacturing of an airplane.
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http:llwww.ACTechbooks.com
oscilloscope - An electrical measuring instrument with
which repeating voltage and current changes can be
observed on a cathode-ray tube similar to a small
television tube.
Otto cycle - A constant-volume cycle of events used to
explain the energy transformation that takes place in a
reciprocating engine. In this type of engine, four
strokes are required to complete the required series of
events or opkrating cycle of each cylinder. Two
complete revolutions of the crankshaft (720") are