Chapter 7
ALLISON T63
7.1.
INTRODUCTION
The T63 series turboshaft engine is manufactured by the Allison Division of General Motors
Corporation. The T63-A-5A is used to power the OH-6A, and the T63-A-700 is in the OH-58A light
observation helicopter.
Although the engine dash numbers are not the same for each of these, the engines are
basically the same. As shown in figure 7.1, the engine consists of four major components: the
compressor, accessory gearbox, combustor, and turbine sections. This chapter explains the major
sections and related systems.
7.2.
OPERATIONAL DESCRIPTION
The T63 turboshaft engine, being an internal combustion engine, requires intake,
compression, combustion, and exhaust, as does a reciprocating engine.
Figure 7.2 is a cutaway view of the T63 engine. By looking at the letters in the arrows in
figure 7.2, you will be able to follow the air's path through the engine.
Air is routed to the compressor assembly by intake ducts on the aircraft. The (A)
compressor assembly "squeezes" incoming air to high pressures. This compressed air is discharged
through twin air-transfer tubes (B) into the combustion chamber (C) and mixed with fuel which is then
burned. The exhaust gases expand through the compressor turbine (D) which extracts energy from
these hot gases to drive the compressor (A). The power turbine (E) takes the remaining energy to drive
the power-output shaft (F). The gases are then released through exhaust ducts (G).
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