the Aviation Dictionary

ground resonance - guttered surface
unit is connected to the aircraft when needed. Similar
to an aircraft installed auxiliary -. power unit.
ground resonance - On rotorcraft, an aerodynamic
phenomenon associated with fully-articulated rotor
systems. Ground resonance develops when the rotor
blades move out of phase with each other and cause the
rotor disc to become unbalanced. This condition only
occurs when the rotorcraft is in contact with the ground
and can cause the craft to self-destruct in a matter of
seconds. At high RPM, immediate lift-off will stop the
resonance. At low RPM, immediate closing of the
throttle and lowering of the collective will stop the
resonance.
ground return electrical circuit - An electrical circuit
that uses the structure of the aircraft as one of the
conductors in the circuit.
ground speed - The speed of an aircraft relative to the
surface of the earth.
ground support equipment (GSE) - Equipment
separate from the aircraft but used in direct support to
facilitate maintenance. GSE can include such items as
engine hoist, auxiliary power units, testing equipment,
compressed air units, etc.
ground visibility - Prevailing horizontal visibility near
the earth's surface as reported by the United States
National Weather service-or an accredited observer.
ground wave - The portion of a radio wave that travels
to the receiver along - the surface of the Earth.
ground-adjustable propeller - A propeller with a pitch
that can be adjusted and locked on the ground when the
engine is not operating but cannot be changed during
flight.
primary of a transformer and the armature forms the
secondary. Shorts show ur, since they cause vibration
in a thin piece of metal, sich as a hacksaw blade, held
over the armature.
guarded switch - A switch protected against accidental
movement by having a guard or shroud located directly
over the switch. The guard must be raised before the
switch can be actuated.
gudgeon pin - British for wrist pin. See wrist pin.
guide vanes - In a turbine engine, stationary airfoil
sections positioned radially around the inside of the
engine. The airfoils direct the flow of air or gases from
one major part to another.
guided discussion - An educational presentation where
the topic to be covered by a group is introduced and the
instructor participates only as necessary to keep the
group focused on the subject.
guided discussion method - An educational
presentation typically used in the classroom where the
topic to be covered by a group is introduced and the
instructor participates only as necessary to keep the
group focused on the subject.
guncotton - Nitrocellulose. A nitrated cotton fiber used
in nitrate dope.
G-unit - The unit of acceleration as a measure of the
force of gravity. One G-unit is the attraction of gravity
for a body.
Gunk - A chemical degreaser used for loosening grease
and soft carbon from the surface of metal parts.
gusset - A small reinforcing member used to support the
comers of a structure.
ground-boost engine - An engine that, because of gust - A sudden brief increase in wind; according to
supercharging (including turbocharging), can develop U.S. weather observing practices, gusts are reported
more power at sea level than it could without the when the variation in wind speed between peaks and
supercharging. lulls is at least 1 l) knots.
ground-controlled landing approach - A directed
approach to landing through instructions provided by a
ground controller The controller watches the aircraft on
a radar scope showing the relative position of the
aircraft to the glide slope and its horizontal position.
The controller gives the pilot instructions necessary for
keeping the aircraft on its intended path until it lands.
grounded - To declare an aircraft or airman unfit for
flight.
groundspeed - Speed of the aircraft in relation to the
ground.
group task - Part of cooperative, or group learning.
Each activity your students engage in is known as a
group task.
growler - Test equipment used to check generator and
starter armatures for shorts. The growler forms the
Aircraft Technical Book Company
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gust front - The sharp boundary found on the edge of a
pool of cold air that is fed by the downdrafts and
spreads out below the thunderstorm. A gust front is the
key to the long life of a multicell thunderstorm.
gust lock - Locks used to prevent controls from being
damaged by wind gusts while an airplane is parked on
the ground. External locks are positioned between the
movable surfaces and the fixed aircraft structure. They
are usually painted red and will have a warning
streamer to indicate their installation. Internal control
surface locks are set in the cockpit.
gustnadoes - A tomado-like vortex that sometimes
occurs near gust fronts and the edge of a downburst.
guttered - surface - Severe erosion confined to narrow
areas in the direction of the gas flow. One cause is
improper valve seating that allows escape of