Module 02
Intermediate Pressure (IP) Compressor

This module comprises three casings bolted together, and the compressor rotor.

First is the front bearing housing (FBH) which locates the roller bearings for both LP & IP compressors and a row each of fixed and variable vanes to control the airflow into the compressor. Next is the variable stator vane (VSV) casing containing a further two stages of variable vanes. The third casing is an assembly of bolted rings carrying six stages of fixed stator vanes.

The compressor rotor is a welded drum assembly with eight stages of blades. A stub-shaft at the front of the drum locates in the IP roller bearing, and a curvic coupling extends from the stage 6 disc to connect to the IP shaft.

Module 03
Intermediate Case

The intermediate case is a fabricated, spoked structure housing the thrust bearings for all shafts, and forming the air path between the IP and HP compressors. Externally it carries the A-frame support arms which brace the fan case (Module 7), and its internal hollow struts provide access for services such as oil tubes, cooling air, and the radial drive-shaft to the accessory gearbox.

Module 04
High Pressure (HP) System

The outer casing of this module links the intermediate case module and the IP turbine module. It contains the inner casing, HP compressor, combustion system and turbine, and also provides locations for fuel spray nozzles and igniter plugs. The compressor casing is made up of six flanged rings which, when bolted together, form slots into which the stator vanes are fitted during the bolting sequence.

Two welded disc assemblies, bolted together, form the drum of the six-stage compressor into which the rotor blades are fitted. The first stage disc incorporates a curvic coupling to connect to the thrust bearing in the intermediate casing and the sixth disc extends into a drive cone and mini-disc which bolts to the turbine shaft. Within the inner case are the HP compressor outlet guide vanes,the annular combustion liner,and the air-cooled nozzle guide vane (NGV) assembly which directs the hot expanding gases into the turbine blades. The turbine is a single-stage unit. The hollow air-cooled blades are attached to the disc by fir-tree roots. A forward extension of the disc connects the turbine to the compressor mini-disc, and a stub-shaft for the turbine bearing is bolted to a rearward extension.

Module 05
Intermediate Pressure (IP) Turbine

Following the HP module is the IP turbine module. This assembly comprises turbine casing, blades and vanes, the turbine disc and shaft, and roller bearings for the HP and IP shafts.

In the casing are mounted the IP NGVs and the first-stage LP NGVs. Both sets of NGVs are hollow, the IP vanes enclosing service tubes and struts for supporting the bearing housing, and the LP1 vanes containing thermo-couples for measurement of gas temperature.

The IP vanes are air cooled. Fir-tree roots locate the IP blades in the disc of the single-stage turbine. Bolted to the turbine disc is the turbine shaft which has helical splines at its forward end. These connect to the IP compressor stub-shaft via the thrust bearings in the intermediate case.

Module 06
High-Speed (HS) Gearbox

The gearbox is mounted on the lower part of the LP compressor case. It is driven by a radial and angled drive shaft system from the intermediate case module and provides the drive for the accessories mounted on its front and rear faces.

These accessories include oil, fuel and hydraulic pumps, electrical generators and the starter motor. During the starting sequence the air-driven starter motor drives back through the gearbox and drive shaft to provide initial rotation of the HP system.

Module 07
Low Pressure (LP) Compressor Case

Largest of the modules, this is an assembly of forward and rear cylindrical casings and the fan outlet guide vane (OGV) ring. It is often referred to as the fan-case.

The forward casing has to be able to contain a fan blade should it become detached during engine running.To meet this eventuality the specially-machined lightweight aluminium casing structure is wrapped with energy-absorbing Kevlar fabric. Internally, the casing contains acoustic panels, ice impact panels and the fan track lining.

The titanium rear casing carries the fancase-mounted accessories and also contains acoustic linings.

At their inner ends, the fan OGVs are secured to the torsion ring which locates the IP compressor module,whilst the outer ends are bolted to the front mounting ring.This assembly is welded to the titanium rear casing and bolted to the front casing.

Module 08
Low Pressure (LP) Turbine

Rearmost of the core engine modules is that of the LP turbine containing blades, vanes, discs, and the shaft and its roller bearing.

The casing is made up of the turbine case and the turbine rear bearing support assembly.The latter also incorporates location bosses for the rear engine mount. Five bolted discs form the turbine rotor, with all blades located in fir-tree slots.

The turbine shaft is bolted to the rotor via a curvic coupling and connects to the LP compressor shaft through helical splines at its forward end. The shaft extends rearwards into the roller bearing.

Service tubes, electrical harnesses, and pressure sensing for the engine pressure ratio system are routed through the hollow vanes of the turbine bearing support assembly.