the Aviation Dictionary

sheet metal layout - The pattern of a sheet metal part
before forming, cutting, or drilling. Patterns allow a
great degree oiaccuracy in laying out the finished part.
Sheet metal layout consists of flat layout, duplication
of patterns, or projection through a set of points.
shelf cloud - A cloud that indicates the rising air over
the gust front. Associated with the updraft of a
multicell thunderstorm it is 'located just above the gust
front at low levels.
shelf life - The period of time a material can be stored
and remain suitable for use. In composites, the time
span that a product will remain useful. This should be
listed on the label. Temperature during storage will
affect the shelf life.
shell - The outer structure of an atom formed by the
rotating electrons around the nucleus.
shell-type transformer - A transformer encased in steel
containing the magnetic lines of flux.
shielded cable - An electrical conductor encased inside
a braided metal shielding. The shielding intercepts
radiated electrical energy-and conducts it to
rather than allowing it to cause radio interference.
shielded ignition cable - An electrical cable enclosed in
a metal braid. Used to carry high voltage from the
distributor of the magneto to the spark plug. Its purpose
is to prevent radio interference caused by
electromagnetic radiation.
shielded spark plug - A spark plug completely encased
in a steel shell. The radiated energy from the spark is
conducted to ground through the shielding and helps
prevent radio interference.
shielded-arc welding - A method of gas welding in
which an inert gas such as argon, helium, or carbondioxide
is used as a covering shield around the arc.
Preventing the atmosphere from contaminating the
weld results in a stronger, more ductile, and more
corrosion resistant weld.
shielding - Metal covers placed around electric and
electronic devices to prevent the intrusion of external
electrostatic and electromagnetic fields.
sheet metal layout short takeoff and landing aircraft
shock loading - Stress loading for an extremely short
duration.
shock mounted - Any device attached to the airframe
with shock mounts to minimize the transmission of
vibration or shock from one unit into another.
shock mounts - A shock absorbing attachment used to
mount an engine or instrument panel to an airframe to
minimize vibration.
shock stall - Turbulent airflow on an airfoil that occurs
when the speed of sound is reached. The shock wave
distorts aerodynamic airflow causing loss of lift and
stall.
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shock strut - An aircraft landing gear shock strut that
absorbs the initial landing impact by the transfer of oil
from one chamber to another through a restricting
orifice. Taxi shocks are absorbed with comvressed air
or by a spring.
shock wave - A compression wave formed when a body
moves through the air at a speed greater than the speed
of sound.
shop head - The upset head of an aircraft rivet.
shop head rivet - The head formed on a rivet when it is
driven.
Shore scleroscope - A hardness tester used for metal,
plastic, and rubber.
short circuit - A path for electrons to flow from one
electrical potential to another without completing a
usefbl circuit.
short range clearance - A clearance issued to a
departing IFR flight that authorizes IFR flight to a
specific fix short of the destination while air traffic
control facilities are coordinating and obtaining the
com~lete clearance.
short stack - An exhaust system for aircraft
reciprocating engines consisting of a short exhaust pipe
attached to the exhaust port of the cylinder. Short
stacks use no collector system.
short take off and vertical landing (STOVL)- A
fixed-wing aircraft capable landing vertically and of
shim - A thin piece of metal used to fill in a space clearing a 15-meter (50-foot) obstacle within 450
between two objects in order to adjust a preload or the
clearance between bearing parts.
shimmy - A rapid and violent oscillation of a nose
wheel or tail wheel of an airplane often caused by
excessive wear in the support bearings.
shimmy damper - A hydraulic snubbing cylinder
installed between the nose wheel fork and the landing
gear structure. It is used to minimize shimmying of thk
nose wheel during takeoffs and landings.
shock absorber - A device built into the landing gear of
an aircraft to absorb the energy of the landing impact.
Aircraft Technical Book Company
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meters (1 500 feet) of commencing takeoff run.
short takeoff and landing (STOL)- The ability of an
aircraft to take off and land in a distance of 1,000 feet
(sometimes 1,500 ft.) or less while clearing 50-foot
obstacles. These obstacles are located just after takeoff
or just prior to landing.
short takeoff and landing aircraft - An aircraft that, at
some weight within its-approved operating weight, is
capable of operating from a STOL runway in
compliance with the applicable STOL characteristics,
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