DOC AIRBUS | AMM A320FCOMPRESSOR SECTION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The compressor section consists of three modules:
** ON A/C NOT FOR ALL The compressor section consists of three modules:
- LP compressor (fan) module assembly,
- LP compressor/intermediate case module,
- HP compressor.
- a large portion is delivered to the exhaust nozzle,
- the remainder is compressed in the booster before being again compressed by the HP compressor.
2. LP Compressor (Fan) Module Assembly
A. General
The LP compressor (fan) module is a rotor assembly which includes twenty two titanium blades and a titanium disk. Rotation of the rotor causes air to be ingested into the front of the engine and compressed. A larger proportion of the compressed air is delivered through the fan discharge duct to the exhaust nozzle to provide the majority of engine thrust. The remainder of the compressed air passes into the booster section for further compression by the booster.
The LP compressor (fan) module is a rotor assembly which includes twenty two titanium blades and a titanium disk. Rotation of the rotor causes air to be ingested into the front of the engine and compressed. A larger proportion of the compressed air is delivered through the fan discharge duct to the exhaust nozzle to provide the majority of engine thrust. The remainder of the compressed air passes into the booster section for further compression by the booster.
B. Description
(1) Fan blades
The blades are wide-chord unshrouded. They are retained radially in the disk by a dovetail at the root. Axial retention is achieved by front and rear blade retaining rings. Both blade and disk dovetails are coated with dry film lubricant to reduce fretting.
The blades are wide-chord unshrouded. They are retained radially in the disk by a dovetail at the root. Axial retention is achieved by front and rear blade retaining rings. Both blade and disk dovetails are coated with dry film lubricant to reduce fretting.
(2) Annulus fillers
The blades do not have integral platforms to form the gas-path inner annulus boundary. This function is fulfilled by annulus fillers which are located between neighbouring pairs of blades. The material of the fillers is aluminium. Each annulus filler has a hooked trunnion at the rear and a dowel pin and a chamfered trunnion pin at the front. The rear trunnion is inserted in a hole in the rear blade retaining ring. The front pins are inserted in holes in the front blade retaining ring. The fillers are radially located by the front and rear blade retaining rings. Each filler is secured to the front blade retaining ring by a bolt.
In order to minimize the leakage of air between the fillers and the aerofoils, there is a rubber seal bonded to each side of each filler.
The blades do not have integral platforms to form the gas-path inner annulus boundary. This function is fulfilled by annulus fillers which are located between neighbouring pairs of blades. The material of the fillers is aluminium. Each annulus filler has a hooked trunnion at the rear and a dowel pin and a chamfered trunnion pin at the front. The rear trunnion is inserted in a hole in the rear blade retaining ring. The front pins are inserted in holes in the front blade retaining ring. The fillers are radially located by the front and rear blade retaining rings. Each filler is secured to the front blade retaining ring by a bolt.
In order to minimize the leakage of air between the fillers and the aerofoils, there is a rubber seal bonded to each side of each filler.
(3) Inlet cone
The inlet cone is bolted to the LP compressor retaining ring to form the gas-path inner wall in front of the blades. The inlet cone is fabricated of glass-reinforced composite material with a polyurethane coating. There is a small rubber tip at the apex of the inlet cone.
If ice begins to form on the rubber tip, it is thrown slightly out of balance and begins to vibrate. This vibration results in the shedding of the first formations of ice on the inlet cone. The combination of the low friction polyurethane coating and the 57 degree cone angle provides the optimum conditions for minimizing ice accretion on the non-heated cone.
The inlet cone is single plane balanced during manufacture. This is achieved by the attachment of a strip of steel filled putty to the cone inner surface
detail (3).
The inlet cone is bolted to the LP compressor retaining ring to form the gas-path inner wall in front of the blades. The inlet cone is fabricated of glass-reinforced composite material with a polyurethane coating. There is a small rubber tip at the apex of the inlet cone.
If ice begins to form on the rubber tip, it is thrown slightly out of balance and begins to vibrate. This vibration results in the shedding of the first formations of ice on the inlet cone. The combination of the low friction polyurethane coating and the 57 degree cone angle provides the optimum conditions for minimizing ice accretion on the non-heated cone.
The inlet cone is single plane balanced during manufacture. This is achieved by the attachment of a strip of steel filled putty to the cone inner surface
detail (3).
(4) Fan disk
The fan disk is driven through a curvic coupling which attaches it to the LP stub shaft. The curvic coupling radially locates and drives the fan disk.
During manufacture of the fan disk, it is dynamically balanced by removal of metal from a land on the disk
detail (2).
The fan disk is driven through a curvic coupling which attaches it to the LP stub shaft. The curvic coupling radially locates and drives the fan disk.
During manufacture of the fan disk, it is dynamically balanced by removal of metal from a land on the disk
detail (2).
(5) Balancing and trim balance
When the LP compressor module is built, the blades are distributed in an array determined by a computer program utilizing the three dimensional moment weights marked on each blade.
The annulus fillers are distributed in an array determined by the weight of each filler.
The LP compressor module without the inlet cone is dynamically balanced in two planes by the attachment of balance weights to the front and rear blade retaining rings
detail (1).
Trim balancing of the LP system can be achieved by the attachment of weights to the front blade retaining ring and to the inlet cone flange.
The weights attached to front retaining ring are relatively heavy and selected for initial estimation. The weights attached to the inlet cone flange are relatively light and selected for precise trim balance adjustment
When the LP compressor module is built, the blades are distributed in an array determined by a computer program utilizing the three dimensional moment weights marked on each blade.
The annulus fillers are distributed in an array determined by the weight of each filler.
The LP compressor module without the inlet cone is dynamically balanced in two planes by the attachment of balance weights to the front and rear blade retaining rings
detail (1).
Trim balancing of the LP system can be achieved by the attachment of weights to the front blade retaining ring and to the inlet cone flange.
The weights attached to front retaining ring are relatively heavy and selected for initial estimation. The weights attached to the inlet cone flange are relatively light and selected for precise trim balance adjustment
3. LP Compressor/Intermediate Case Module
A. General
The LP compressor intermediate case module consists of booster section, a fan case section and an internal gearbox and drive section.
The LP compressor intermediate case module consists of booster section, a fan case section and an internal gearbox and drive section.
B. Description
(a) General
The internal gearbox and drive section of LP compressor/intermediate case module include:
The internal gearbox and drive section of LP compressor/intermediate case module include:
- Intermediate structure,
- Power Take Off (PTO) drive shaft bearing and support,
- No. 3 bearing, internal gearbox and support assembly,
- Front Bearing Compartment rear air seal,
- No. 1 bearing support assembly,
- LP shaft, No. 1 and No. 2 bearing assembly,
- No. 1 bearing seal support and tubes,
- PTO shaft seal tube,
- PTO shaft,
- Intermediate structure oil & air transfer tubes.
(b) Description
1 Intermediate structure
The intermediate structure is a welded titanium structure wich includes 10 outer struts and 10 inner starts separated by an annular torsion box.
The intermediate structure provides structural support for the following:
Other struts contain the air tubes and the remaining oil tubes.
Pressure tubes and thermocouples are brazed to the leading edges of three struts to measure the following parameters which are used solely in the optional condition monitoring system:
The intermediate structure is a welded titanium structure wich includes 10 outer struts and 10 inner starts separated by an annular torsion box.
The intermediate structure provides structural support for the following:
- HP compressor front case,
- Fan case,
- Booster section,
- Master and slave actuators of the LP compressor air flow control system,
- PTO drive shaft bearing and support,
- No. 3 bearing, internal gearbox and support assembly,
- F.B.C rear air seal,
- No. 1 bearing support assembly,
- PTO shaft seal tube,
- Intermediate structure oil & air transfer tubes,
- Forward engine mount.
Other struts contain the air tubes and the remaining oil tubes.
Pressure tubes and thermocouples are brazed to the leading edges of three struts to measure the following parameters which are used solely in the optional condition monitoring system:
- Fan discharge air pressure at No. 1 strut,
- HP compressor inlet air pressure at No. 6 strut,
- HP compressor inlet air temperature at No. 5 strut.
2 PTO drive shaft bearing and support
A roller bearing supports the PTO shaft at mid span.
A roller bearing supports the PTO shaft at mid span.
3 No. 3 bearing, internal gearbox and support assembly
This assembly includes:
This assembly includes a driven gear (steel), a ball bearing, two roller bearings and a housing. The driven gear is located radially and axially by the three bearings.
The housing is bolted to the No. 2 bearing support.
The driven gear is splined to the PTO shaft and engages the internal gearbox driving gear.
The rear flange of the No. 3 bearing rotor center is attached to the HP compressor rotor by a curvic coupling. The No. 3 supports the internal gearbox driving gear.
The No. 3 bearing provides axial and radial location for the HP compressor rotor.
The No. 3 bearing is a split inner race ball bearing. The outer race is secured to the No. 3 bearing housing by a bolted flange on the race. The housing is centered by rods in a cage configuration which act as springs. A hydraulic damper for the bearing is formed by an annulus between the housing and the support.
This assembly includes:
- Internal gearbox driven gear assembly,
- No. 2 bearing support,
- Hydraulic seal assembly,
- No. 3 bearing rotor center and support assembly.
- Internal gearbox driven gear assembly.
This assembly includes a driven gear (steel), a ball bearing, two roller bearings and a housing. The driven gear is located radially and axially by the three bearings.
The housing is bolted to the No. 2 bearing support.
The driven gear is splined to the PTO shaft and engages the internal gearbox driving gear.
- No.2 bearing support
- No. 2 bearing,
- internal gearbox driven gear assembly (described previously),
- LP speed probes trim balance and LP speed/trim balance probe harness,
- hydraulic seal assembly.
- No. 3 bearing rotor center and support assembly
This assembly includes: - No. 3 bearing rotor center (titanium),
- Internal gearbox driving gear (steel),
- No.3 bearing,
- No. 3 bearing housing.
The rear flange of the No. 3 bearing rotor center is attached to the HP compressor rotor by a curvic coupling. The No. 3 supports the internal gearbox driving gear.
The No. 3 bearing provides axial and radial location for the HP compressor rotor.
The No. 3 bearing is a split inner race ball bearing. The outer race is secured to the No. 3 bearing housing by a bolted flange on the race. The housing is centered by rods in a cage configuration which act as springs. A hydraulic damper for the bearing is formed by an annulus between the housing and the support.
4 FBC rear air seal
The function of the rear air seal is described in paragraph (11).
The function of the rear air seal is described in paragraph (11).
5 No. 1 bearing support assembly
The No. 1 bearing support provides structural support for the No. 1 bearing, oil supply tube and No. 1 bearing seal support.
This assembly includes:
a) No. 1 bearing support (steel)
b) Oil jet and oil supply tube
The No. 1 bearing support provides structural support for the No. 1 bearing, oil supply tube and No. 1 bearing seal support.
This assembly includes:
a) No. 1 bearing support (steel)
b) Oil jet and oil supply tube
6 LP shaft No. 1 and No. 2 bearing assembly.
This assembly includes:
The outer flange of the No. 1 bearing center shaft is bolted to the booster rotor.
The rear end of the LP stub shaft is splined to the LP turbine shaft.
Both No. 1 bearing and the No. 2 bearing support the No. 1 bearing rotor center shaft and the LP stub shaft.
Both shafts perform the following functions:
The inner races have an interference fit onto the No. 1 bearing rotor center shaft.
The No. 2 bearing is a cylindrical roller bearing with a shouldered outer race.
The outer race incorporates a squeeze film damper to avoid unacceptable rotor vibration.
Lugs on the outer race prevent rotation. The inner race has an interference fit onto the LP stub shaft.
The phonic wheel of the LP rotational speed indicating system is installed onto the LP stub shaft.
The phonic wheel is secured to the LP stub shaft by the LP turbine shaft lock nut.
This assembly includes:
- LP stub shaft (steel),
- No. 1 bearing rotor center shaft (titanium),
- No. 1 bearing (steel),
- No. 2 bearing (steel).
The outer flange of the No. 1 bearing center shaft is bolted to the booster rotor.
The rear end of the LP stub shaft is splined to the LP turbine shaft.
Both No. 1 bearing and the No. 2 bearing support the No. 1 bearing rotor center shaft and the LP stub shaft.
Both shafts perform the following functions:
- To provide axial and radial location for the LP compressor (fan) module and the booster rotor stages 1.5, 2, 2.3 & 2.5 assembly,
- To provide axial location for the LP turbine,
- To tranfer drive from the LP turbine to the LP compressor module and the booster stage 1.5, 2, 2.3 & 2.5 assembly.
The inner races have an interference fit onto the No. 1 bearing rotor center shaft.
The No. 2 bearing is a cylindrical roller bearing with a shouldered outer race.
The outer race incorporates a squeeze film damper to avoid unacceptable rotor vibration.
Lugs on the outer race prevent rotation. The inner race has an interference fit onto the LP stub shaft.
The phonic wheel of the LP rotational speed indicating system is installed onto the LP stub shaft.
The phonic wheel is secured to the LP stub shaft by the LP turbine shaft lock nut.
7 No. 1 bearing seal support, front air seal and tubes.
This assembly includes:
This assembly includes:
- No. 1 bearing seal support,
- No. 1 bearing compartment scavenge oil tube.
- Front bearing compartment front oil seal (carbon seal),
- No. 1 bearing compartment scavenge oil tube.
8 PTO shaft seal tube
The PTO shaft seal tube houses the PTO shaft and allows oil to drain from the front bearing compartment to the accessory gearbox.
The PTO shaft seal tube houses the PTO shaft and allows oil to drain from the front bearing compartment to the accessory gearbox.
9 PTO shaft
PTO shaft (steel) is splined to the accessory gearbox driving gear.
PTO shaft (steel) is splined to the accessory gearbox driving gear.
10 Intermediate structure oil and air transfer tubes
The transfer tubes include:
No. 1, 2, 3 bearing scavenge tube
Hot vent tube
The scavenge tube is located in the No. 6 strut.
The hot vent tube is located in the No. 3 strut.
The function of each tube is described in the following paragraph.
The transfer tubes include:
No. 1, 2, 3 bearing scavenge tube
Hot vent tube
The scavenge tube is located in the No. 6 strut.
The hot vent tube is located in the No. 3 strut.
The function of each tube is described in the following paragraph.
11 Sealing parts
Oil Feed to No. 1 Bearing and Front Oil Seal Oil Feed to No. 3 Bearing Rear Oil Seal and Driven Gear Bearings ** ON A/C NOT FOR ALL
The Nos. 1, 2, and 3 bearings, the internal gearbox driven gear assembly and the internal gearbox drive gear are contained within the front bearing compartment and require oil lubrication.
Sealing of the compartment is performed by the following components:
No. 1 bearing front carbon oil seal.
Hydraulic seal assembly for center seal.
Bearing compartment rear brush air seal and No. 3 bearing rear carbon oil seal.
The oil feed is divided. The oil flow to the No. 3 bearing damper is maintained at the full oil feed pressure whilst the rest of the flow passes through a restrictor to drop the pressure. This allows larger jet diameters to facilitate flow tolerance control.
Some of the oil is taken forward to the oil jet and oil supply tube which directs a jet of oil under an oil catcher formed in the LP rotor center. Oil is directed from the catcher through radial holes to the split line of the No. 1 bearing inner race. Passages machined in the inner race split line abutment faces carry the oil to the rolling elements of the No. 1 bearing.
A second oil jet black, situated between the No. 2 and No. 3 bearings, is used to lubricate:
The rear of the No. 2 bearing
The hydraulic seal
The internal gearbox driven gear assembly
A third oil jet block is used to direct oil to the bevel gear mesh and to the oil catcher for the No. 3 bearing. Oil caught in a groove on the front of the internal gearbox driving gear is centrifuged through a leak-free path to enter the bearing through radial holes.
Oil Feed to No. 1 Bearing and Front Oil Seal Oil Feed to No. 3 Bearing Rear Oil Seal and Driven Gear Bearings ** ON A/C NOT FOR ALL Sealing of the compartment is performed by the following components:
No. 1 bearing front carbon oil seal.
Hydraulic seal assembly for center seal.
Bearing compartment rear brush air seal and No. 3 bearing rear carbon oil seal.
The oil feed is divided. The oil flow to the No. 3 bearing damper is maintained at the full oil feed pressure whilst the rest of the flow passes through a restrictor to drop the pressure. This allows larger jet diameters to facilitate flow tolerance control.
Some of the oil is taken forward to the oil jet and oil supply tube which directs a jet of oil under an oil catcher formed in the LP rotor center. Oil is directed from the catcher through radial holes to the split line of the No. 1 bearing inner race. Passages machined in the inner race split line abutment faces carry the oil to the rolling elements of the No. 1 bearing.
A second oil jet black, situated between the No. 2 and No. 3 bearings, is used to lubricate:
The rear of the No. 2 bearing
The hydraulic seal
The internal gearbox driven gear assembly
A third oil jet block is used to direct oil to the bevel gear mesh and to the oil catcher for the No. 3 bearing. Oil caught in a groove on the front of the internal gearbox driving gear is centrifuged through a leak-free path to enter the bearing through radial holes.
12 Balancing of shafts
The LP stub shaft is dynamically balanced during manufacture by the removal of a suitable mass of material from lands at its front and rear.
The No. 1 bearing rotor center shaft is single plane balanced during manufacture by the removal of a suitable mass of material.
When the LP stub shaft and the No. 1 bearing rotor center shaft are assembled, the assembly is dynamically balanced with a dummy LP compressor rotor and a dummy booster rotor. Balance is achieved by the removal of a suitable mass of material from lands on the No.1 bearing rotor center shaft and on the LP stub shaft.
The PTO shaft is dynamically balanced during manufacture by the removal of a suitable mass of material from lands near each end.
The LP stub shaft is dynamically balanced during manufacture by the removal of a suitable mass of material from lands at its front and rear.
The No. 1 bearing rotor center shaft is single plane balanced during manufacture by the removal of a suitable mass of material.
When the LP stub shaft and the No. 1 bearing rotor center shaft are assembled, the assembly is dynamically balanced with a dummy LP compressor rotor and a dummy booster rotor. Balance is achieved by the removal of a suitable mass of material from lands on the No.1 bearing rotor center shaft and on the LP stub shaft.
The PTO shaft is dynamically balanced during manufacture by the removal of a suitable mass of material from lands near each end.
(2) Booster section
(a) General
The booster section of LP compressor/intermediate case module includes:
Fan outlet inner vane assembly
Booster stage 1.5, 2, 2.3 & 2.5 assembly
Booster stage bleed valve and actuator and actuating mechanism.
The fan outlet inner vane assembly, compressor stage 1.5, 2, 2.3 & 2.5 assembly and compressor stage 2.5 vanes compress the air which is received from the fan module and delivers it at a suitable pressure level to the HP compressor.
An LPC bleed valve and actuating mechanism is incorporated to bleed the air from the exit of the LP compressor stage 2.5 vanes. The bleed valve and actuating mechanism is actuated and controlled by the LP compressor air flow control system. When the bleed valves are opened, air is bled into the fan duct through the bleed valve outlet case.
The modulated bleed ensures that the booster has adequate surge margin under all operating conditions.
The booster section of LP compressor/intermediate case module includes:
Fan outlet inner vane assembly
Booster stage 1.5, 2, 2.3 & 2.5 assembly
Booster stage bleed valve and actuator and actuating mechanism.
The fan outlet inner vane assembly, compressor stage 1.5, 2, 2.3 & 2.5 assembly and compressor stage 2.5 vanes compress the air which is received from the fan module and delivers it at a suitable pressure level to the HP compressor.
An LPC bleed valve and actuating mechanism is incorporated to bleed the air from the exit of the LP compressor stage 2.5 vanes. The bleed valve and actuating mechanism is actuated and controlled by the LP compressor air flow control system. When the bleed valves are opened, air is bled into the fan duct through the bleed valve outlet case.
The modulated bleed ensures that the booster has adequate surge margin under all operating conditions.
(b) Description
1 Fan outlet inner vane assembly, booster stage 1.5, 2, 2.3 & 2.5 assembly and booster stage 2.5 vanes.
The LPC stage 1.5, 2, 2.3 & 2.5 assembly includes:
Stages 1.5, 2, 2.3 & 2.5 blades are made of titanium and are located into the dovetail slots of their respective disks. The blades are axially retained in the disk by retaining and locking plates which are inserted into the grooves of the blades and the disks.
Recirculation of the compressed air is also prevented by the retaining plates.
Dovetails of the stage 1.5, 2, 2.3 & 2.5 blades are coated with dry film lubricant to reduce fretting and possible cracking.
The entire rotor assembly consisting of the fan module, LP compressor stage 1.5, 2, 2.3 & 2.5 rotor and the LP stub shaft and rotor centre, is located and supported by the No.1 bearing (ball) and No.2 bearing (roller).
The LPC stage 1.5, 2, 2.3 & 2.5 disk is dynamically balanced during its manufacture.
Balance is achieved by removing an appropriate quantity of metal from a balancing land on the disk. When the disk and blades are assembled, the blades are distributed in an array determined by a computer program utilising their radial moment weights.
The assembly is dynamically balanced in two planes using balance weights rivetted to the front and rear disk flanges.
Each vane of the fan outlet inner vane assembly is bolted to the LPC front case flange and the splitter fairing flange. All vanes are bonded to an inner ring by rubber filler
The stages 1.5, 2, and 2.3 vanes are bonded to inner rings in the same way to damp vane vibration
Stage 2.5 vanes are each secured to an inner ring by a bolt. The vane are also bonded to an outer ring by rubber filler
The inner ring of the stage 2.5 vanes is supported by the intermediate structure. The outer ring of the stage 2.5 vanes supports the LPC front and rear cases and the bleed valve and actuating mechanism
Materials are as follows:
The following components incorporate an abradable rubber coating to form the blade rotor paths and inter stage seal linings.
The LPC stage 1.5, 2, 2.3 & 2.5 assembly includes:
- Stage 1.5, 2, 2.3 & 2.5 disk (LPC disk)
- Stages 1.5, 2, 2.3 & 2.5 blades
- LPC front case and LPC rear case
- Stages 1.5, 2 and 2.3 vanes
Stages 1.5, 2, 2.3 & 2.5 blades are made of titanium and are located into the dovetail slots of their respective disks. The blades are axially retained in the disk by retaining and locking plates which are inserted into the grooves of the blades and the disks.
Recirculation of the compressed air is also prevented by the retaining plates.
Dovetails of the stage 1.5, 2, 2.3 & 2.5 blades are coated with dry film lubricant to reduce fretting and possible cracking.
The entire rotor assembly consisting of the fan module, LP compressor stage 1.5, 2, 2.3 & 2.5 rotor and the LP stub shaft and rotor centre, is located and supported by the No.1 bearing (ball) and No.2 bearing (roller).
The LPC stage 1.5, 2, 2.3 & 2.5 disk is dynamically balanced during its manufacture.
Balance is achieved by removing an appropriate quantity of metal from a balancing land on the disk. When the disk and blades are assembled, the blades are distributed in an array determined by a computer program utilising their radial moment weights.
The assembly is dynamically balanced in two planes using balance weights rivetted to the front and rear disk flanges.
Each vane of the fan outlet inner vane assembly is bolted to the LPC front case flange and the splitter fairing flange. All vanes are bonded to an inner ring by rubber filler
The stages 1.5, 2, and 2.3 vanes are bonded to inner rings in the same way to damp vane vibration
Stage 2.5 vanes are each secured to an inner ring by a bolt. The vane are also bonded to an outer ring by rubber filler
The inner ring of the stage 2.5 vanes is supported by the intermediate structure. The outer ring of the stage 2.5 vanes supports the LPC front and rear cases and the bleed valve and actuating mechanism
Materials are as follows:
| Fan outlet inner vane assembly Titanium |
| Stage 1.5, 2 and 2.3 vanes Titanium |
| Stage 2.5 vanes Aluminium |
| Inner and outer rings Aluminium |
| Intermediate structure front fairing Aluminium |
| LPC front and rear cases Aluminium |
The following components incorporate an abradable rubber coating to form the blade rotor paths and inter stage seal linings.
- LPC front and rear cases.
- Inner rings of the fan outlet inner vanes, stage 1.5, 2 and 2.3 vanes.
- Outer rings of the stage 2.5 vanes.
The abradable rubber enables hight control of stage 1.5, 2, 2.3 & 2.5 blade tip and interstage seal clearances and yet avoids damage to the blades and disks from rubbing.
2 Booster stage bleed valve (BSBV) and actuating mechanism
The bleed valve mechanism is supported by the intermediate structure and the outer ring of the stage 2.5 vanes.
Two actuating rods which are each motivated by actuators impart a circumferential and axial motion to the valve ring via 2 power arms. 8 arms are synchronized by valve ring itself and set axial position of valve ring uniformly.
The bleed valve mechanism is supported by the intermediate structure and the outer ring of the stage 2.5 vanes.
Two actuating rods which are each motivated by actuators impart a circumferential and axial motion to the valve ring via 2 power arms. 8 arms are synchronized by valve ring itself and set axial position of valve ring uniformly.
(3) Fan case section
(a) General
The fan case section of LP Compressor/intermediate case module consists of the following items:
Fan case
LP compressor outlet guide vanes
Fan case rear panels
Bifurcation panel.
The fan case section of LP Compressor/intermediate case module consists of the following items:
Fan case
LP compressor outlet guide vanes
Fan case rear panels
Bifurcation panel.
1 Fan case
The fan case provides a titanium shroud around the fan rotor and forms the outer annulus of the cold stream duct.
The front of the fan case is of reduced section to provide a locally flexible ring foreward of the containment case. A flange at the front of the fancase provides attachment for the intake cowl. The flexible ring provides attachment integrity for the intake cowl in the event of fan blade loss and subsequent vibration.
The front acoustic lining is attached to the inner wall of the flexible ring. This lining is made of 1/2" cell size aluminium honeycomb covered by a titanium perforated skin. The combination of the unfilled honeycomb and the perforated skin provides acoustic attenuation.
At the rear of the front acoustic lining, the containment case features an annular hook which is embedded and concealed by the acoustic lining at the front and the rotor path lining at the rear. This hook is provided to prevent a fan blade exiting the engine from the front in the event of blade failure.
Fan blade tip sealing is provided by an attrition lining attached to the inner wall of the containment case. The lining consists of two honeycomb layers separated by a Glass Reinforced Composite (GRC) skin. A filled 1/8" honeycomb Nomex layer forms a smooth annulus surface around the fan blades. The sub-layer is 1/4" unfilled aluminium honeycomb.
An ice impact panel is attached to the fan case behind the attrition lining to protect the casing from ice impact damage. To achieve the required strength, this panel consists of filled 3/4" aluminium honeycomb, the surface of which is covered by a GRC skin. The panel forms a continuous smooth annulus surface rearward of the containment case.
Behind the ice impact panel is the rear acoustic lining. This lining is made of 1/2" cell size aluminium honeycomb which is covered by a titanium perforated skin forming an annulus.
The combination of the unfilled honeycomb and the perforated skin provides acoustic attenuation.
At the rear of the fan case a V-groove provides forward outer location for the thrust reverser.
The fan case features a number of flanges, the purpose of which is to support the accessory gearbox and other external engine components.
The fan case provides a titanium shroud around the fan rotor and forms the outer annulus of the cold stream duct.
The front of the fan case is of reduced section to provide a locally flexible ring foreward of the containment case. A flange at the front of the fancase provides attachment for the intake cowl. The flexible ring provides attachment integrity for the intake cowl in the event of fan blade loss and subsequent vibration.
The front acoustic lining is attached to the inner wall of the flexible ring. This lining is made of 1/2" cell size aluminium honeycomb covered by a titanium perforated skin. The combination of the unfilled honeycomb and the perforated skin provides acoustic attenuation.
At the rear of the front acoustic lining, the containment case features an annular hook which is embedded and concealed by the acoustic lining at the front and the rotor path lining at the rear. This hook is provided to prevent a fan blade exiting the engine from the front in the event of blade failure.
Fan blade tip sealing is provided by an attrition lining attached to the inner wall of the containment case. The lining consists of two honeycomb layers separated by a Glass Reinforced Composite (GRC) skin. A filled 1/8" honeycomb Nomex layer forms a smooth annulus surface around the fan blades. The sub-layer is 1/4" unfilled aluminium honeycomb.
An ice impact panel is attached to the fan case behind the attrition lining to protect the casing from ice impact damage. To achieve the required strength, this panel consists of filled 3/4" aluminium honeycomb, the surface of which is covered by a GRC skin. The panel forms a continuous smooth annulus surface rearward of the containment case.
Behind the ice impact panel is the rear acoustic lining. This lining is made of 1/2" cell size aluminium honeycomb which is covered by a titanium perforated skin forming an annulus.
The combination of the unfilled honeycomb and the perforated skin provides acoustic attenuation.
At the rear of the fan case a V-groove provides forward outer location for the thrust reverser.
The fan case features a number of flanges, the purpose of which is to support the accessory gearbox and other external engine components.
2 Fan case front panel fairing
There is a single front panel fairing each of which is an aluminium-skinned honeycomb sandwich. The honeycomb is unfilled 1/2" cell size aluminium. The air washed skin is perforated to provide acoustic attenuation. The fairing is attached by screws and held off the fan case at the front by a rubber cushion bonded to the skin of the panel to prevent fretting.
There is a single front panel fairing each of which is an aluminium-skinned honeycomb sandwich. The honeycomb is unfilled 1/2" cell size aluminium. The air washed skin is perforated to provide acoustic attenuation. The fairing is attached by screws and held off the fan case at the front by a rubber cushion bonded to the skin of the panel to prevent fretting.
3 LP compressor outlet guide vanes
Aerodynamic control air flow within the cold air steam duct is achieved by 60 vanes manufactured in aluminium. The vanes consist of 20 segments, each containing 3 vanes. Both sides of the vanes are attached to the outer and inner platforms.
The outer platform is bolted to the fan case and the inner platform is pinned to the outer shroud ring of the LP compressor stage 2.5 stator assembly.
Aerodynamic control air flow within the cold air steam duct is achieved by 60 vanes manufactured in aluminium. The vanes consist of 20 segments, each containing 3 vanes. Both sides of the vanes are attached to the outer and inner platforms.
The outer platform is bolted to the fan case and the inner platform is pinned to the outer shroud ring of the LP compressor stage 2.5 stator assembly.
4 Fan case rear panels
Fan case rear panels are installed between 10 intermediate structures which are located in the rear section of the fan case.
The purpose of these panels is to form an aerodynamic annulus surface between the 10 vanes.
Fan case rear panels are installed between 10 intermediate structures which are located in the rear section of the fan case.
The purpose of these panels is to form an aerodynamic annulus surface between the 10 vanes.
5 Bifurcation panel
This panel is made of titanium sheet and is bolted to intermediate structure.
The purpose of the panel is to provide proof-wall between both fire zones.
This panel is made of titanium sheet and is bolted to intermediate structure.
The purpose of the panel is to provide proof-wall between both fire zones.
4. HP Compressor Module
A. General
The HP compressor is a 10 stage axial flow module. It comprises the HP compressor rotor, blades, the front casing and variable vanes, the rear casing which contains the fixed stators and forms the bleed manifolds. Mounted on the front casing is the linkage system associated with the variable inlet guide vanes and stators. Attached to the rear of the compressor rotor is the rear thrust balance seal rotating member. Power to drive the HP compressor is provided through the rear shaft from the HP turbine system.
The function of the HP compressor is to accept air from the LP compressor and booster system, further compress it, and direct the air to the diffuser/combustion system where fuel is added.
Air is also bled off to either pressurize/cool various locations of the core engine or for starting and aircraft supply purposes.
The stages that are bled and the specific reasons for the offtakes are as follows.
Stage 7:
The HP compressor is a 10 stage axial flow module. It comprises the HP compressor rotor, blades, the front casing and variable vanes, the rear casing which contains the fixed stators and forms the bleed manifolds. Mounted on the front casing is the linkage system associated with the variable inlet guide vanes and stators. Attached to the rear of the compressor rotor is the rear thrust balance seal rotating member. Power to drive the HP compressor is provided through the rear shaft from the HP turbine system.
The function of the HP compressor is to accept air from the LP compressor and booster system, further compress it, and direct the air to the diffuser/combustion system where fuel is added.
Air is also bled off to either pressurize/cool various locations of the core engine or for starting and aircraft supply purposes.
The stages that are bled and the specific reasons for the offtakes are as follows.
Stage 7:
- Air is supplied at high power setting for aircraft needs (using anti-icing, cabin pressurization and heating).
Air is also bled off to aid starting and handling by maintening compressor surge margin.
At all power settings the nose cowl is supplied with anti-icing air from this stage.
- Air is bled internally and is used to seal the LP turbine compartment. The air cools the rear of the stage 2 HP turbine disc and the LP turbine drum internally. It is also used to pressurize the number 5 bearing compartment.
- Air is supplied when power settings are low for aircraft needs (using anti-icing, cabin pressurization and heating).
Air is also bled off to aid starting and handling by maintaining compressor surge margin.
HP turbine cooling air is supplied at all power settings. A further controlled supply is taken to the stage 2 HP turbine front face.
- Air is tapped via tubes to an air cooled air cooler and is fed to the centre air supply (stage 12) bearing buffer cooling zone of the number 4 bearing.
B. Description
(a) The 10 stage HP compressor rotor consists of 2 drums bolted together at the stage 8-9 split line. A vortex reducer is incorporated at this split line to remove residual swirl from the stage 8 internal bleed air.
Attached to the rear of stage 12 is an Inconel mini disc and HP turbine shaft. The rotating member of the thrust balance seal is bolted to the turbine shaft.
Attached to the rear of stage 12 is an Inconel mini disc and HP turbine shaft. The rotating member of the thrust balance seal is bolted to the turbine shaft.
(b) Blades of the stage 3, 4 and 5 are fitted to axial, dovetail slots with flatplate lockplates providing axial retention and root sealing. Stages 6 to 12 blades are fitted in circumferential dovetail grooves and fixed by a locking and anti-rotation feature.
Stage 6 to 8 have circumferential sealing wires to reduce root leakage.
Sealing of stages 9 to 12 roots is achieved by close tolerances.
Stage 3 blades incorporate aerofoil snubbers to reduce vibration.
The blading of each stage is as follows:
Stage 6 to 8 have circumferential sealing wires to reduce root leakage.
Sealing of stages 9 to 12 roots is achieved by close tolerances.
Stage 3 blades incorporate aerofoil snubbers to reduce vibration.
The blading of each stage is as follows:
| STAGE QUANTITY MATERIAL |
| 3 31 Titanium |
| 4 38 Titanium |
| 5 64 Titanium |
| 6 79 Titanium |
| 7 93 Titanium |
| 8 84 Titanium |
| 9 89 Inconel |
| 10 85 Inconel |
| 11 78 Inconel |
| 12 71 Inconel |
(c) The rotor is balanced to minimize engine vibration. Primary balancing of individual rotor shaft components is obtained by metal removal from balance lands at the front and rear of each drum. The rotor is then assembled ensuring minimal eccentricity of each component to the other. The blades are used to reduce any remaining imbalance by repositioning light/heavy blades around the disc circumference. Final balance is achieved by inserting pins in stage 3 blade dovetail holes and by the addition of balance weights at the rear thrust balance seal location flange.
(d) The rotor is located at the front through a curvic coupling by the bearing rotor centre and number 3 bearing which is a thrust bearing. At the rear it is supported by the number 4 bearing.
(e) The HP turbine is splined to the rear shaft and retained by a clamping nut assembly.
(f) Interstage sealing of the stator vanes on stages 3, 4 and 5 is by knife edge seals and minimal clearances on stages 6 to 11. An abrasive coating on the rotor drum prevents metal to metal contact between the stator vanes and the rotor on stages 6 to 11.
(2) Rear case and vanes assembly
The rear casing is made of steel and is bolted at the front to the HPC split casing and to the diffuser casing at the rear and forms part of the engine structure. It has been designed to minimize engine carcase distortion and eccentricity and features internal flanges onto which the inner cases are mounted. The assembly of the inner and outer cases forms the 7th and 10th stage bleed manifolds. The case has four bleed houses from the 7th stage from the 10th stage there are 8 air system off take bosses.
The rear inner case assembly is a series of flanged rings and spacers mounted off a shallow cone at the front and located at the rear on crosskeys. The stage 10 flanged ring also carries a seal separating the stages 7 and 10 manifolds. The inner bores of the flanged rings are coated with an abradable lining that forms the rotor blade tip path. The cantilevered stators are clamped into position by the flanged rings, the spacers ensuring correct clamping is achieved. Cut-outs in the outer feet of the stator vanes on stages 7 and 10 align with corresponding apertures in the spacers allowing passage of air from these stages into the bleed manifolds.
The quality and material of each stator vane stage is as follows:
The rear casing is made of steel and is bolted at the front to the HPC split casing and to the diffuser casing at the rear and forms part of the engine structure. It has been designed to minimize engine carcase distortion and eccentricity and features internal flanges onto which the inner cases are mounted. The assembly of the inner and outer cases forms the 7th and 10th stage bleed manifolds. The case has four bleed houses from the 7th stage from the 10th stage there are 8 air system off take bosses.
The rear inner case assembly is a series of flanged rings and spacers mounted off a shallow cone at the front and located at the rear on crosskeys. The stage 10 flanged ring also carries a seal separating the stages 7 and 10 manifolds. The inner bores of the flanged rings are coated with an abradable lining that forms the rotor blade tip path. The cantilevered stators are clamped into position by the flanged rings, the spacers ensuring correct clamping is achieved. Cut-outs in the outer feet of the stator vanes on stages 7 and 10 align with corresponding apertures in the spacers allowing passage of air from these stages into the bleed manifolds.
The quality and material of each stator vane stage is as follows:
| STAGE QUANTITY MATERIAL |
| 7 88 Steel |
| 8 92 Steel |
| 9 104 Steel |
| 10 100 Steel |
| 11 108 Nickel Alloy |
(3) Front case and variable stator vane assembly
The front case is a horizontally split single wall titanium component which forms part of the engine structure. It houses 4 rows of variable stator vanes and one fixed row of stator vanes. In addition it carries the variable stator vane actuating mechanism.
Steel liners, coated with an abradable material, are fitted to form stages 4 to 6 rotor paths. The stage 3 abradable coating is sprayed directly onto the front compressor casing. The steel liners of stages 4 to 6 are designed to absorb any heat generated should excessive tip rubbing occur.
The Inlet Guide Vanes (IGV) and Variable Stator Vanes (VSV) are spindled at the inner and outer ends, to accomodate the variable geometry required to maintain the compressor surge margin. The spindles run in bushes fitted to the front case housing and inner shroud assemblies. The inner shroud of the IGV is an aluminium assembly split circumferentially and is sealed to the intermediate case at the front by an O-ring. The inner shrouds of stages three and four VSVs are similar to the IGV but have steel rings carrying abradable linings for the knife edge interstage seals bolted onto the assemblies.
The stage 5 inner shroud is of steel material and combines the interstage seal land and abradable lining.
The variable stator actuating mechanism consists of the following elements:
One Fuel powered actuator ram
One Actuator ram/crakshaft draglinks
One Crankshaft
One Crankshaft unison ring draglinks
One Unison rings
One Spindle levers
Control of the mechanism is by the EEC using power from the fuel system.
The movement of the ram is transmitted to the crankshaft lever by draglinks. The unison rings are formed from hollow square section titanium tubing in circular arcs. The unison ring movement is transmitted to the vane spindle levers by riveted titanium pins. The levers are designed to accommodate the small inherent geometrical imperfections between the lever pins and unison ring movements.
The quantity and material of each variable stator vane stage is as follows:
The variable stator vane system is described in ATA 75-30-00.
The front case is a horizontally split single wall titanium component which forms part of the engine structure. It houses 4 rows of variable stator vanes and one fixed row of stator vanes. In addition it carries the variable stator vane actuating mechanism.
Steel liners, coated with an abradable material, are fitted to form stages 4 to 6 rotor paths. The stage 3 abradable coating is sprayed directly onto the front compressor casing. The steel liners of stages 4 to 6 are designed to absorb any heat generated should excessive tip rubbing occur.
The Inlet Guide Vanes (IGV) and Variable Stator Vanes (VSV) are spindled at the inner and outer ends, to accomodate the variable geometry required to maintain the compressor surge margin. The spindles run in bushes fitted to the front case housing and inner shroud assemblies. The inner shroud of the IGV is an aluminium assembly split circumferentially and is sealed to the intermediate case at the front by an O-ring. The inner shrouds of stages three and four VSVs are similar to the IGV but have steel rings carrying abradable linings for the knife edge interstage seals bolted onto the assemblies.
The stage 5 inner shroud is of steel material and combines the interstage seal land and abradable lining.
The variable stator actuating mechanism consists of the following elements:
One Fuel powered actuator ram
One Actuator ram/crakshaft draglinks
One Crankshaft
One Crankshaft unison ring draglinks
One Unison rings
One Spindle levers
Control of the mechanism is by the EEC using power from the fuel system.
The movement of the ram is transmitted to the crankshaft lever by draglinks. The unison rings are formed from hollow square section titanium tubing in circular arcs. The unison ring movement is transmitted to the vane spindle levers by riveted titanium pins. The levers are designed to accommodate the small inherent geometrical imperfections between the lever pins and unison ring movements.
The quantity and material of each variable stator vane stage is as follows:
| STAGE QUANTITY MATERIAL |
| IGV 40 Titanium |
| 3 32 Nickel alloy |
| 4 50 Nickel alloy |
| 5 64 Nickel alloy |
The variable stator vane system is described in ATA 75-30-00.