TBO -- time between overhauls. This is established by the Army and the engine manufacturer.
Test cell -- building, usually concrete, that contains both a control room and an engine room, used for
testing engines. The test cell is at the manufacturer's; a mobile engine-test unit is used in the
field.
Thermocouple -- device composed of two pieces of metal or wire joined where heat is to be applied and
the free end connected to an electrical measuring instrument.
Thermodynamic cycle -- succession of processes which involve changes in temperature, pressure, and
density in which the substance acts as a means of transformation of energy. See Otto and
Brayton cycles.
Thrust -- pushing or pulling force developed by an aircraft engine.
Torquemeter -- hydromechanical torque-measuring device located in the reduction-gear section of the
inlet housing. The measurement is read as torque oil pressure in psi.
Torquemeter indicating system -- pressure indicator for continuous readings of engine output-shaft
torque.
Transducer -- device actuated by power from one system and supplying power to a second system.
Turbine -- rotary engine actuated by the reaction of a current of fluid (gas in this case) subject to
pressure. The turbine is usually made with a series of curved vanes on a central spindle arranged
to rotate.
Turbine nozzle -- stationary nozzle which discharges a jet of gas against the blades on the periphery of a
turbine wheel.
Turbine rotor -- rotating portion of a turbine engine. It is made of specially alloyed steel because of
severe centrifugal loads, the result of high rotational speeds.
Turbine section -- part of the turbine engine that extracts the kinetic energy of the expanding gases and
transforms it into shaft horsepower.
Turbofan -- compressor section of a turbine engine.
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