The function of the compressor section is to pull air into the engine, compress it and then supply it to the combustion and bypass section.

The BR710 engine contains two main rotating assemblies (spools): a single-stage LP compressor (fan) driven by a two-stage LP turbine, and a ten-stage HP compressor, driven by a two-stage HP turbine. In addition, the HP spool provides an external drive for the engine driven accessories mounted on the Accessory Gearbox (AGB).

The compressor section is made up of several modules. Modular Construction has the following advantages:

• Lower overall maintenance costs
• Maximum life achieved from each module
• Reduced turn around time for engine repair
• Reduced spare engine inventory
• Ease of transportation and storage
• Rapid module change with minimum ground running
• Rotating assemblies independently balanced

Air comes into the engine through the inlet cowl and flows along the intake rotating fairing. It then flows into the low pressure (LP) compressor and through the 24 compressor blades. This compresses the air and divides it into two flows, the bypass air and the core air.

The bypass air flows through the LP-compressor outlet guide-vanes (OGVs) and intermediate casing, into the structural bypass duct. It then flows into the exhaust section where it mixes with the core air. The bypass air gives most of the engine thrust.

The core air flows through the LP-compressor engine stator-vanes and the high pressure (HP) compressor-inlet duct. It then flows into the ten-stage HP compressor, through the variable inlet guide-vanes (VIGVs) (one stage). The HP compressor compresses the air more and supplies it to the combustion section. The variable stator vanes (VSVs) are in first three stages of the HP compressor.

The LP compressor module has one stage, wide-chord blades, annulus fillers and a disk. The blades and fillers stay in position with a retaining ring and a sealing plate. The retaining ring, which attaches to the front of the disk, also holds the intake rotating fairing. The sealing plate attaches to the rear of the disk. Bolts (and balance weights) safety the ring and the plate to the disk.

The disk is connected to the LP compressor shaft and the fuel shut-off reference tube. An anti-score plate and a curvic coupling connect the disk to the shaft. A retention shaft is used to safety the disk to the reference tube.

There are 24 wide-chord blades. The blades have dovetail roots to connect them to the disk. A chocking-block attaches to the root of each blade. This prevents too much blade movement at windmill speeds and speeds less than idle.

There are 24 annulus fillers between the blades to give a smooth flow of air along the disk. A rubber seal is bonded to each side of the fillers to prevent leakage of air. Pivot pins on the bottom of the fillers engage lugs on the disk. Bolts and location pins safety the fillers to the retaining ring on the front of the disk.

The LP compressor stator-vanes control the flow of air into the bypass duct and the core of the engine. The LP compressor stator-vanes assembly is divided into two sections, the LP-compressor outlet guide-vanes (OGV) and the LP-compressor engine stator-vanes.

The OGV is a one-piece cast assembly which has 64 vanes between an inner ring and an outer ring. Bolts safety the assembly to the front middle flange of the intermediate casing. The LP-compressor stator-vanes are a welded assembly of 64 forged vanes. There is an annular extension piece at the front of the inner shroud. The LP-compressor stator-vanes attach to the front inner flange of the intermediate module. Bolts, spacers, pins and a retaining ring safety the LP-compressor stator-vanes assembly to the intermediate module.

The compressor has variable inlet guide-vanes (VIGVs) and three stages of variable stator vanes (VSVs). The VIGV actuating mechanism operates the VIGVs and the VSVs of the HP compressor. The VIGVs and VSVs control the airflow through the compressor to prevent surge or stall during engine operation. A fuel-operated actuator controls the movement of the vanes. The engine electronic controller (EEC) controls the actuator.

Each stage of VIGVs and VSVs has a unison ring. A mechanism of levers connects the actuator to four control rods. A power bracket connects each control rod to one of the unison rings. A set of levers for each stage connects the unison rings to the vanes. The levers attach to the top of the vanes. Pins on the levers go into bushings that are in the unison rings.

When the ram of the VSV actuator moves, it pushes or pulls the control rods. The control rods move the unison rings, which then turn all the levers in the same direction. The levers then turn all the vanes together. The vanes move to the correct angle for the speed of the engine.

Each unison ring is divided into two halves. Connectors and bolts connect the halves together. Each ring-half has four centralizer blocks, which keep the ring assembly in its correct position around the case.

The HP compressor provides a pressurized airflow to the combustion chamber for combustion, cooling purposes, pressurized air for the Environmental Control System (ECS), engine nose cowl anti-icing, airframe anti-icing, engine internal cooling and sealing, and for sealing of the accessory gear box.

The HP compressor comprises 10 compressor stages contained on two rotating drum assemblies, which are joined between stages 6 and 7. The rear drum assembly also features the HP compressor shaft, which bolts onto the HP turbine module via a "curvic" coupling; attachment to the intermediate module is also via a curvic coupling.

The front compressor casing, which houses stages 1 to 4 stators, is made in two halves, which bolt together along horizontal flanges. The rear compressor has inner and outer casings. Flanges on the inner case form annular manifolds, which provide bleed air from stages 5 and 8.

Fairing panels are provided to enable smooth airflow around the compressor.

The LP compressor case is around the LP compressor to contain the blades if the compressor fails. It also decreases engine noise and has ice-impact boxes to protect the OGV. Other components are on the external surface of the LP compressor case.

The LP compressor case has an isogrid structure. On the external surface there are three layers of Kevlar, which will contain the compressor blades if the compressor fails. A shield assembly is at the bottom of the LP compressor case to protect it from the starter-motor exhaust gases. The forward liners, fan-track liners, ice-impact boxes and the rear panels attach to the internal surface. The rear of the LP compressor case attaches to the front of the intermediate case.

There are four forward liners and each have a honeycomb panel and a perforated tray. The four forward liners have three honeycomb layers and two forming trays. The inner honeycomb provides a seal at the top of the LP compressor blades. The four rear panels each have a honeycomb layer and a forming tray. Bolts and washers attach the forward liners to the case and the fan-track liners and rear panels are bonded.

Acoustic linings and ice impact boxes are installed around the inner diameter of the LP compressor case. The rear flange of the LP compressor case attaches to the intermediate case with bolts. The four ice-impact boxes are between the fan-track liners and the rear panels. Because of centrifugal force, ice which comes off the LP compressor blades will collect in the boxes.

The composite intake rotating-fairing gives a smooth flow of air into the LP compressor. The intake rotating fairing has a nose cone and a nose cone fairing. The nose cone attaches to the retaining ring of the LP compressor disk. The nose cone fairing is around the cone and also attaches to the LP-compressor disk retaining-ring.