The first stage gas producer turbine (GPl) and the second
stage gas producer turbine (GP2) are mechanically joined together and
rotate as one assembly (N1). The dual turbine design in later
versions of the T53 permits more lightly loaded turbine blades than
previous single turbine models and has a power output increase of 20%.
As the gases flow from the GP2 they pass on to the first
stage power turbine nozzle (PT1). The gases are again accelerated
and flow across the two N2 power turbines. Both turbine rotors have
tip shrouded blades to prevent air losses and excessive vibrations.
c. Exhaust diffuser. The welded steel diffuser, shown in
figure 4.18, forms a divergent flow path for the exhaust gases. The
diffuser consists of an inner and outer housing separated by four
hollow struts. It is mounted to the aft inner flange of the
combustor housing. Support for the aft section of the diffuser is
provided by a support cone, 20 back in figure 4.1, that is secured by
a "V" band coupling to the aft outer flange of the combustor housing.
Located between the exhaust diffuser and support cone is a stainless
steel fire shield, 19 in figure 4.1. During operation ambient air
flows between the outer and mid cones of the diffuser. This air
passes through a series of holes on the forward area of the outer
cone and into the chamber formed by the diffuser and the fire shield.
Ambient air then lows through the hollow struts to cool the bearing
housing mounted within the diffuser and aft face of the power turbine
(PT2). Mounts for an exhaust gas temperature harness are located on
the diffuser midcone. The aft flange on the diffuser midcone is the
mounting point for an airframe furnished tailpipe. The tailpipe
routes the exhaust gas stream to the atmosphere.
The T53 series engines are designed to operate primarily on
MILJ5624 grade JP4 fuel. The fuel system consists of the
components shown in figure 4.19.
Fuel flow is maintained between components by flexible or
rigid lines. An airframemounted boost pump supplies fuel to the
fuel control inlet port. During the starting sequence fuel flows
through an external line from the hydromechanical fuel control to the
starting fuel solenoid inlet, shown in figure 4.20. The cockpit