The turbine section comprises the high pressure turbine (HPT) section and the low pressure turbine (LPT) section. The turbine section attaches to the exhaust section with the exit guide vane (EVG). The hot gases from the combustion section move to the HPT section. The HPT gives the mechanical energy to operate the high-pressure compressor and accessory gearbox. From the HPT section, the gases pass through the LPT. The LTP gives mechanical energy to operate the fan rotor.

The turbine sections of the engine use the hot air from the combustor and increase the speed of this airflow necessary for engine thrust. The HP turbine is a two-stage turbine and it is installed in the combustion turbine section of the engine. The LP turbine section has a three-stage turbine and is attached to the EGV assembly. The LP turbine section is installed after the HP turbine.

The high-pressure (HP) turbine is a two-stage turbine with forward and aft coupler assemblies, rotor assembly, stator, and nozzles. The HP turbine is attached to the aft mounting flange of the combustor case.

A HP turbine/combustor support provides support for the combustor and axial clamping loads between the HP turbine stage 1 nozzle and the combustor outer liner wall. It keeps the concentricity of the HP turbine shroud support to the HP turbine rotor. The air passes through the HP turbine/combustor support to cool the air to the HP turbine.

The HP turbine has four airfoils. Each of the four airfoils continuously receive cool air. The HP disks connect with cover plates that let the blade receive cooling air. The disks also give the positive axial hold for the blades. A tangential onboard injector (TOBI) of the HP turbine supplies high-pressure air to cool the first-stage HP turbine blades. The HP turbine shrouds have a layer of thermal barrier coating (TBC) material on the gas path side to decrease the shroud temperatures. The damper seals in each stage of the HP turbine help decrease the hot gas to a minimum into the blade attachment area.

There are 16 air blast fuel nozzles which are designed to remove most of the welds. The tip of the fuel nozzle has a low oxidation rate and long life.

Two ignitor plugs are installed at the 4 and 8 o’clock positions into a boss found on the combustor case. They give the sparking gap necessary to light the engine under all start conditions.

The removal of the igniter plugs provides access for the borescope (or 'boroscope')inspection of the combustion liner, fuel nozzle tips, and the HP turbine. There is a dedicated borescope port for the HP turbine interstage access. The removal of the fuel nozzles allows greater access for borescope inspection.

The hot air from the HP turbine moves to the LP turbine. The LP turbine uses this air to move the fan.

The LP turbine is a three-stage rotor assembly attached directly to the fan rotor assembly through the LP shaft. A single LP turbine drive arm connects the LP rotors to the stub shaft, which is connected to the LP shaft. There is a LP turbine drive hub which lets the removal of the LP turbine module without the complete removal of the LP shaft. The LP turbine shaft gives the rear support for the LP rotor assembly and connects to the fan assembly at its forward end. It also supports the HP spool through the No. 4 bearing spring cage. All three LP turbine rotors are connected with bolted flanges and attached to the drive hub with no performance loss.

In the LP turbine, there is a N1 broken shaft detector. This detector is attached to the No. 5 bearing housing with the plunger near the LP turbine shaft.

The LP turbine is made for minimum parts count to increase reliability. All blade stages of the LP turbine have tip shrouds. These tip shrouds help decrease the vibration and accept light rubs of the blade tip, but do not decrease blade performance.

The LP turbine shrouds are made with honeycomb material. They reduce gas leakage around the tips of the LP turbine blades which increases the airflow and efficiency of the LP turbine. There are three borescope plugs at the LP turbine section which give access for the borescope inspection.

The exit guide vane (EGV) is installed between the LP turbine housing and the exhaust mixer nozzle. It supplies a path for cooling air, oil, and vent services for the aft sump. The EGV decreases the swirl of turbine gas flow from the LPT3 rotor before it goes into the exhaust duct. It also keeps the same amount of airflow as the hot gases exit the engine core. The EGV has a mount for the aft side of engine, exhaust gas thermocouple rakes, and the exhaust mixer nozzle and centerbody. The engine gas temperature (EGT) probe is installed in the EGV. This protects the EGT probe.

The HP turbine has first- and second-stage nozzles with a two-vane segment for easy replacement. The HP turbine has an access for the borescope for on-condition maintenance. It also has the honeycomb seals that can be replaced. The HP turbine is assembled and disassembled vertically or horizontally.

Hot air from the combustor goes through the HP turbine to move the rotor. The LP turbine then takes a quantity of the energy remaining in the airstream to move the fan to supply the engine thrust. The speed of the core engine discharge air increases through the core exhaust nozzle to produce the remaining thrust.

The turbine section interfaces with the following systems/components:

• Exhaust Mixer Nozzle

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