the Aviation Dictionary

tab - A small auxiliary control surface hinged to an
aircraft primary control surface. Tabs can be used to
assist in the movement of a primary control surface or
as a means of trimming an aircraft.
TACAN - An acronym for Tactical Air Navigation
System. An electronic navigation system that provides
an indication of the distance the aircraft is from a
ground station. TACAN operates in the UHF range of
the radio freauencv snectrum.
TACAN-only aircraft - An aircraft, normally military,
possessing TACAN with DME but no VOR
navigational system capability. Clearances must
specify TACAN or VORTAC fixes and approaches.
tachometer - An instrument that measures the rotating
speed of an engine. For reciprocating engines, the
tachometer reads in RPMs. In most turbine engines, the
tachometer reads in percent of the maximum RPM.
tachometer cable -- The flexible cable used to drive a
mechanical tachometer from the engine. It is made of
two layers of steel wire, spiraled in opposite directions
about a central core.
tachometer generator - A small electrical generator
supplying current at frequencies proportional to the
speed of the unit on which it is mounted.
tachometer generator and indicator - The generator
has three-phase AC output of approximately 20V. It is
a gearbox-driven accessory that produces power for a
motor-driven indicator. The indicator provides a RPM
indication in the cockpit.
tack - In composites, stickiness of the adhesive of a prepreg
material.
tack coat - In painting, a very light coat of material
sprayed on a surface and allowed to stay until the
solvents evaporate. It is then covered with the full wet
coat of material.
tack rag - A rag, slightly damp with thinner, used to
wipe a surface after it has been sanded to prepare it for
the application of the next coat of finish.
tack weld - Small temporary welds along a welded
seam made for the purpose of holding the pieces of
metal in position until the weld is completed.
tacking - Hand-sewn temporary stitches removed prior
to machine sewing.
tackle - A pulley in the form of a wheel mounted on a
faced axis and supported by a frame. The wheel, or
disk, is normally grooved to accommodate a rope. The
frame that supports the wheel is called a block. Block
and tackle consists of a pair of blocks. Each block
Aircraft Technical Book Company
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T . tailwheel checkout
contains one or more pulleys and a rope connecting the
pulley(s) of each block.
tacky - A gluey or sticky finish.
tactical air navigation - An ultra-high frequency
electronic rho-theta air navigation aid that provides
suitably equipped aircraft a continuous indication of
bearing and distance to the TACAN station.
tag wire - Thin diameter wire used to tie identification
tags to objects.
tail boom - A spar or outrigger connecting the tail
surfaces to a pod-type fuselage.
tail cone - 1. The conical-shaped portion of a turbine
engine exhaust system used to produce the proper area
increase for the gases as they leave the engine. 2. The
rearmost part of an aircraft fuselage.
tail load - A downward aerodynamic force produced by
the tail of an airplane to maintain dynamic longitudinal
stability.
tail pipe - That portion of the exhaust system of an
aircraft engine through which the gases leave the
aircraft.
tail rotor - In helicopters, a rotor turning in a plane
perpendicular to that of the main rotor and parallel to
the longitudinal axis of the fuselage. It is used to
counteract the torque of the main rotor and to provide
movement about the yaw axis of the helicopter.
tail section - The rear portion, or empennage, of an
airplane.
tail skid - 1. On modem jet aircraft, a portion of the
structure designed to absorb shock in case the tail
strikes the runway during rotation for takeoff. 2. A skid
that supports the tail of an airplane on the ground. Tail
skids were used before the advent of tail wheels.
tail surface - A stabilizing or control surface in the tail
of an aircraft.
tail wheel - A small wheel located at the rear of the
fuselage of an airplane having a conventional landing
gear. It is used as a support for the tail when the
airplane is on the ground.
tail wind - A wind blowing in the same direction the
airplane is flying.
tail-heavy - A condition of balance in an aircraft in
which the center of gravity is behind the aft limit.
tailpipe inserts - Small, sheet metal, wedge-shaped tabs
that are inserted into the tailpipe of some older engines
to reduce the nozzle opening and increase thrust.
Adjustment of thrust is now done at the fuel control.
tailwheel checkout - To act as PIC of a tailwheel
airplane, FAR 6 1.3 1 (g) requires a demonstration of
competency in normal and crosswind takeoffs and