Chapter 8
PRATT AND WHITNEY T73
8.1.
INTRODUCTION
The Pratt and Whitney T73-P-1 and T73-P-700 are the most powerful engines used in Army
aircraft. Two of these engines are used to power the CH-54 flying crane helicopter. The T73 design
differs in two ways from any of the engines covered previously. The airflow is axial through the engine;
it does not make any reversing turns as the airflow of the previous engines did, and the power output
shaft extends from the exhaust end.
Chapter 8 describes and discusses the engine sections and systems. Constant reference to the
illustrations in this chapter will help you understand the discussion.
8.2.
GENERAL DESCRIPTION
The T73-P-1 and the T73-P-700 engines are straight-flow, free-turbine power plants using a
two-stage turbine to drive a nine-stage, axial-flow compressor. The free turbine uses the exhaust gas to
drive a two-stage free turbine rotor. External views of the T73 gas turbine engine are shown in figure
8.1. A cross-sectional view is shown in figure 8.2.
The axial flow compressor consists of a nine-stage rotor and nine stator stages. The gas path
of the compressor is so designed that it forms a convergent duct. The compressor has a moderate
compression ratio.
An automatically-controlled interstage airbleed is used for starting and low power operation of
the engine. The engine's anti-icing system prevents dangerous accumulations of ice on compressor-inlet
surfaces by directing compressor-discharge air into the hollow compressor inlet guide vanes.
To the rear of the compressor is the diffuser section which reduces air velocity and increases
air pressure for entry into the combustion chambers.
The combustion section houses the canannular combustion chambers and the fuel.
manifolds. The eight separate combustion chambers, arranged annularly, are connected by flame tubes.
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