TORQUE SENSOR—
See TORQUE METER.

TORQUE—1.Aresistance to turning
or twisting. 2. Forces that produce a
twisting or rotating motion. 3. In an
airplane, the tendency of the aircraft
to turn (roll) in the opposite direction
of rotation of the engine and propeller.

TOTAL DRAG—The sum of the
parasite and induced drag.

TOUCHDOWN ZONE LIGHTS—
Two rows of transverse light bars
disposed symmetrically about the
runway centerline in the runway
touchdown zone.

TRACK—The actual path made over
the ground in flight.

TRAILING EDGE—The portion of
the airfoil where the airflow over the
upper surface rejoins the lower
surface airflow.

TRANSITION LINER—
The portion of the combustor that
directs the gases into the turbine
plenum.

TRANSONIC—At the speed of
sound.

TRANSPONDER—The airborne
portion of the secondary surveillance
radar system. The transponder emits a
reply when queried by a radar facility.

TRICYCLE GEAR—Landing gear
employing a third wheel located on
the nose of the aircraft.

TRIM TAB—A small auxiliary
hinged portion of a movable control
surface that can be adjusted during
flight to a position resulting in a
balance of control forces.

TRIPLE SPOOL ENGINE—
Usually a turbofan engine design
where the fan is the N1 compressor,
followed by the N2 intermediate
compressor, and the N3 high pressure
compressor, all of which rotate on
separate shafts at different speeds.

TROPOPAUSE—The boundary
layer between the troposphere and the
mesosphere which acts as a lid to
confine most of the water vapor, and
the associated weather, to the
troposphere.

TROPOSPHERE—The layer of the
atmosphere extending from the
surface to a height of 20,000 to 60,000
feet depending on latitude.

TRUE AIRSPEED (TAS)—
Calibrated airspeed corrected for altitude
and nonstandard temperature.
Because air density decreases with an
increase in altitude, an airplane has to
be flown faster at higher altitudes to
cause the same pressure difference
between pitot impact pressure and
static pressure. Therefore, for a given
calibrated airspeed, true airspeed
increases as altitude increases; or for a
given true airspeed, calibrated airspeed
decreases as altitude increases.

TRUE ALTITUDE—The vertical
distance of the airplane above sea
level—the actual altitude. It is often
expressed as feet above mean sea
level (MSL). Airport, terrain, and
obstacle elevations on aeronautical
charts are true altitudes.

T-TAIL—An aircraft with the
horizontal stabilizer mounted on the
top of the vertical stabilizer, forming
a T.

TURBINE BLADES—The portion
of the turbine assembly that absorbs
the energy of the expanding gases and
converts it into rotational energy.

TURBINE OUTLET
TEMPERATURE (TOT)—
The temperature of the gases as they
exit the turbine section.

TURBINE PLENUM—The portion
of the combustor where the gases are
collected to be evenly distributed to
the turbine blades.

TURBINE ROTORS—The portion
of the turbine assembly that mounts to
the shaft and holds the turbine blades
in place.

TURBINE SECTION—The section
of the engine that converts high
pressure high temperature gas into
rotational energy.

TURBOCHARGER—
An air compressor driven by exhaust
gases, which increases the pressure of
the air going into the engine through
the carburetor or fuel injection
system.

TURBOFAN ENGINE—A turbojet
engine in which additional propulsive
thrust is gained by extending a portion
of the compressor or turbine blades
outside the inner engine case. The
extended blades propel bypass air
along the engine axis but between the
inner and outer casing. The air is not
combusted but does provide additional
thrust.

TURBOJET ENGINE—A jet
engine incorporating a turbine-driven
air compressor to take in and compress
air for the combustion of fuel,
the gases of combustion being used
both to rotate the turbine and create a
thrust producing jet.

TURBOPROP ENGINE—A turbine
engine that drives a propeller through
a reduction gearing arrangement.
Most of the energy in the exhaust
gases is converted into torque, rather
than its acceleration being used to
propel the aircraft.

TURBULENCE—An occurrence in
which a flow of fluid is unsteady.

TURN COORDINATOR—A rate
gyro that senses both roll and yaw due
to the gimbal being canted. Has
largely replaced the turn-and-slip
indicator in modern aircraft.

TURN-AND-SLIP INDICATOR—
A flight instrument consisting of a rate
gyro to indicate the rate of yaw and a
curved glass inclinometer to indicate
the relationship between gravity and
centrifugal force. The turn-and-slip
indicator indicates the relationship
between angle of bank and rate of
yaw. Also called a turn-and-bank
indicator.