DOC AIRBUS | AMM A320FDISTRIBUTION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL
The lubrication functions are provided by the lubrication unit.
The lubrication unit provides oil under the required pressure for lubrication of the engine bearings and gears, for scavenge of the oil after lubrication and return to the oil tank.
But, before return to the oil tank, the scavenged oil from the engine sumps circulates, successively, through:
** ON A/C NOT FOR ALL Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL The lubrication unit provides oil under the required pressure for lubrication of the engine bearings and gears, for scavenge of the oil after lubrication and return to the oil tank.
But, before return to the oil tank, the scavenged oil from the engine sumps circulates, successively, through:
- The 4 scavenge screens (in the lubrication unit housing) which provide a first and coarse filtration of the oil scavenged from the AGB, the engine forward bearing sump, the TGB and the engine aft bearing sump.
- The master magnetic chip detector (on the lubrication unit) through which circulates the total scavenged oil flow.
- The servo fuel heater (on the fuel pump housing) (see note below).
NOTE: Though it has its oil circuit connected hydraulically in series with that of the main oil/fuel heat exchanger, the servo fuel heater (Ref. AMM D/O 73-10-00-00) is not (functionally) a part of the oil distribution system. However, the "piggyback" and scavenge oil circulation arrangement of the servo fuel heater (also a heat exchanger) and main oil/fuel heat exchanger is such that the scavege oil undergoes two levels of cooling before return to tank: the first one takes place in the servo fuel heater; the second, through the main oil/fuel heat exchanger.
The lubrication unit is installed on the right-hand side of the AGB front face. 2. Description
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL
The lubrication unit has a single housing containing the following items :
** ON A/C NOT FOR ALL Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL - Five positive displacement pumps (one oil supply and 4 scavenge pumps).
- Six filters (one 15-micron main oil supply filter, 4 coarse scavenge screens and one 44-micron back-up filter).
- One relief valve (on oil supply pump discharge side).
- One oil temperature sensor
- One clogging indicator transmitter (oil filter differential pressure switch) to provide the cockpit with a warning of the main oil filter clogging, should this occur during engine operation.
- One bypass valve for the main oil supply filter.
- One master magnetic chip detector (MCD) to detect the contamination of the engine oil system by magnetic chips/particles and connected to a master chip detector indicator.
3. Supply
A. General
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL
Oil from the oil tank is routed to the lubrication unit which is protected downstream by a supply filter. The oil pressure is between 2.50 bar and 2.70 bar (36.26 psid - 39.16 psid).
The oil then is routed through a line.
Tappings are provided on this line to distribute the oil to the various items to be lubricated (forward sump (bearings 1, 2, 3), aft sump (bearings 4, 5), TGB, AGB).
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL The oil then is routed through a line.
Tappings are provided on this line to distribute the oil to the various items to be lubricated (forward sump (bearings 1, 2, 3), aft sump (bearings 4, 5), TGB, AGB).
B. Description
(1) Supply pump
(a) The 5 gerotor-type-positive-displacement pumps are powered by a single drive shaft driven by the accessory gearbox (AGB).
(b) The external tooth gear has one lobe more than internal tooth gear it meshes with. The gears rotate in the same direction but with different angular speeds. The volume corresponding to the missing tooth is therefore displaced from the inlet to the outlet.
(c) Since the 2 gear rotational axes are mutually offset, the space between the two tooth profiles progressively increases until maximum volume is reached - i.e when rotated by approximately 180 degrees.
During the initial half-cycle, the volume increases and moves past the suction inlet creating a partial vacuum which sucks in the oil.
During the next half-cycle, the volume progressively decreases, discharging the oil through the outlet.
During the initial half-cycle, the volume increases and moves past the suction inlet creating a partial vacuum which sucks in the oil.
During the next half-cycle, the volume progressively decreases, discharging the oil through the outlet.
(d) The supply element provides a flow rate of 2495 l.h (659 USgal.h) at take off and a normal pressure of 60 psid (4.14 bar)
(2) Supply circuit
The supply circuit main flow-through components are the supply pump, the supply filter and the back-up filter. At engine start-up the supply pump draws oil from the tank and pressurizes it. The pressure relief valve bypasses any excess flow to the suction side of one of the scavenge pumps.
The supply circuit main flow-through components are the supply pump, the supply filter and the back-up filter. At engine start-up the supply pump draws oil from the tank and pressurizes it. The pressure relief valve bypasses any excess flow to the suction side of one of the scavenge pumps.
(3) Lubrication unit main oil supply filter
Oil under pressure from the supply pump is filtered through a 15 micron filter element which protects the lubrication supply nozzle from contamination.
The inlet filtered oil is thus supplied to critical components:
Downstream of the supply pump, the oil flows through the supply filter assembly. The filter has the following components.
Oil under pressure from the supply pump is filtered through a 15 micron filter element which protects the lubrication supply nozzle from contamination.
The inlet filtered oil is thus supplied to critical components:
Downstream of the supply pump, the oil flows through the supply filter assembly. The filter has the following components.
(a) One filter (15 microns)
(b) One clogging indicator transmitter (oil filter differential pressure switch) subjected to the upstream and downstream pressures of the supply filter.
(c) One bypass valve which opens if the supply filter clogs.
(d) One 44-micron back-up filter operating if the supply filter clogs.
(e) One capped provision for a pressure gage upstream of the filter.
(f) An oil temperature sensor.
(4) Engine lubrication
Downstream of supply filter, the oil flows through the three lubrication unit outlets to the forward sump, aft sump and the AGB where it is bypassed externally to the transfer gearbox (TGB).
The following oil quantities flow at take off :
Downstream of supply filter, the oil flows through the three lubrication unit outlets to the forward sump, aft sump and the AGB where it is bypassed externally to the transfer gearbox (TGB).
The following oil quantities flow at take off :
- Total = 2495 l.h (659 USgal.h)
- Forward engine sump = 1195 l.h (315.68 USgal.h)
- Aft engine sump = 475 l.h (125.48 Usgal.h)
- AGB = 535 l.h (141.33 USgal.h)
- TGB = 260 l.h (68.68 USgal.h)
- Anti siphon = 30 l.h (7.92 USgal.h).
(5) Anti siphon System
The supply line from the oil tank to the pump supply has an antisiphon device to prevent the drainage of the tank into the gearboxes and sumps when the engine is shut down for extended periods.
The supply line from the oil tank to the pump supply has an antisiphon device to prevent the drainage of the tank into the gearboxes and sumps when the engine is shut down for extended periods.
(a) Oil filter differential pressure
(b) Oil temperature
C. Internal Lubrication of Lubrication Unit
The internal lubrication of the lubrication unit is provided by oil bled from the supply pump discharge circuit via a passage machined in the housing. This oil enters the central conduit of the drive shaft. From there, it flows radially through holes in the shaft to lubricate the split bushing and then flows on toward the other end of shaft to lubricate the shaft external splines via 2 calibrated orifices.
The internal lubrication of the lubrication unit is provided by oil bled from the supply pump discharge circuit via a passage machined in the housing. This oil enters the central conduit of the drive shaft. From there, it flows radially through holes in the shaft to lubricate the split bushing and then flows on toward the other end of shaft to lubricate the shaft external splines via 2 calibrated orifices.
4. Scavenge
A. General
The oil which has lubricated the engine bearings, accessory gearbox and TGB is scavenged by 4 pumps, each protected upstream by a coarse filtration screen (1000 microns).
This oil is then collected in a single line/circuit comprising, downstream and in this order:
The oil which has lubricated the engine bearings, accessory gearbox and TGB is scavenged by 4 pumps, each protected upstream by a coarse filtration screen (1000 microns).
This oil is then collected in a single line/circuit comprising, downstream and in this order:
- a master magnetic chip detector connected to the master chip detector indicator.
- the servo-fuel heater
- the main oil/fuel heat exchanger
B. Description
The scavenge circuit main flow-through components are a follows :
The scavenge circuit main flow-through components are a follows :
- Four scavenge plugs, each with an integral screen (1000 microns) and a provision for installation of an optional magnetic rod in the plug assembly.
- Four scavenge pumps
- One master magnetic chip detector(MCD) connected to the master chip detector indicator
- One servo-fuel heater
- One main oil/fuel heat exchanger
(1) Screening upstream of the 4 scavenge pumps
The air/oil mixtures returning from the AGB, forward sump, TGB and aft sump, first flow through the scavenge screens, and then to the specific scavenge pump. The forward sump scavenge pump also receives the flow internally bypassed from the supply pump through the relief valve.
The air/oil mixtures returning from the AGB, forward sump, TGB and aft sump, first flow through the scavenge screens, and then to the specific scavenge pump. The forward sump scavenge pump also receives the flow internally bypassed from the supply pump through the relief valve.
(2) Scavenge pump
After lubrication, the 4 scavenge pumps scavenge the air/oil mixture from the 2 engine sumps and gearboxes through 4 tubes external to the lubrication unit.
The 4 scavenge elements of the 5-gerotor-type-positive displacement pumps are powered by the same AGB-driven single drive shaft as the supply element (pump).
They have the same technology and principle of operation as those described for the supply pump.
After lubrication, the 4 scavenge pumps scavenge the air/oil mixture from the 2 engine sumps and gearboxes through 4 tubes external to the lubrication unit.
The 4 scavenge elements of the 5-gerotor-type-positive displacement pumps are powered by the same AGB-driven single drive shaft as the supply element (pump).
They have the same technology and principle of operation as those described for the supply pump.
(3) Master Magnetic Chip Detector.
The flows from the 4 scavenge pumps are mixed together at the master chip detector inlet. This detector consists of the following :
The flows from the 4 scavenge pumps are mixed together at the master chip detector inlet. This detector consists of the following :
(a) One cross shaped hydraulic housing with 2 square flanges:
- One for attachment to the lubrication unit housing (oil inlet flange)
- One for attachment to a tube which connects with the servo-fuel heather (oil outlet flange).
(b) A check valve, part of the hydraulic housing, to prevent oil spills when the electrical chip detector is removed.
(c) A hand-removable chip detector probe, locked on the hydraulic housing by a bayonet attachment system.
From its outer end to tip, the probe is equipped with:
From its outer end to tip, the probe is equipped with:
- One back-up seal for safety purposes
- One o-ring seal
- Two magnets, separated by a gap. These identical magnets function as normally-open electrical contacts. When metal particles contaminate the scavenged oil, they bridge the magnetic gap and close the contacts formed by the 2 magnets.
(d) A two-wire, shielded electrical cable and its 28 VDC interface connector. The master magnetic chip detector is connected to a master chip detector indicator. A pop out information, in the fan case compartment at the master chip detector indicator, is given after chip detection.
(4) Main Oil/fuel heat exchanger
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL
From the discharge side of the master magnetic chip detector housing, the scavenged oil flows through a pipe, outside of the lubrication unit, to the servo-fuel heater, then to the main oil/fuel heat exchanger, and then back to the oil tank.
Location of the Lubrication Unit, Main Oil/Fuel Heat Exchanger and Master Magnetic Chip Detector ** ON A/C NOT FOR ALL (a) General
The main oil/fuel heat exchanger cools the oil by using fuel as a cooling medium.
The main oil/fuel heat exchanger is installed on the fuel pump housing, between the AGB aft face and piggiback on the servo-fuel heater at the 7:30 o'clock position, approximately, aft looking forward.
The main oil/fuel heat exchanger cools the oil by using fuel as a cooling medium.
The main oil/fuel heat exchanger is installed on the fuel pump housing, between the AGB aft face and piggiback on the servo-fuel heater at the 7:30 o'clock position, approximately, aft looking forward.
(b) Description
The oil/fuel heat exchanger is of tubular type. It consists of a removable core, housing and cover.
The oil/fuel heat exchanger is of tubular type. It consists of a removable core, housing and cover.
1 The core consists of a cylinder, end plates, and fuel tubes.
The fuel tubes are attached to the end plates. Two inner baffles lengthen the oil circulation path around the fuel inlet tubes.
The fuel tubes are attached to the end plates. Two inner baffles lengthen the oil circulation path around the fuel inlet tubes.
2 The housing contains the core of the oil/fuel heat exchanger. The following items are located on the outside of the oil/fuel heat exchanger housing :
- One oil pressure relief valve and one fuel pressure relief valve.
- One drain port which collects possible fuel leaks from core end inter-seal cavities and prevents fuel from leaking into the oil cavity and contaminating the oil system.
- One port for a fuel-out temperature probe (optional).
- One attaching flange for the servo fuel heater.
- One flange for attachment to the fuel pump.
- One port on fuel-in for fuel returned from HMU after circulating through the IDG oil cooler.
3 The cover provides access to the oil/fuel heat exchanger for core installation.
(c) Operation
The oil to fuel heat transfer is achieved through conduction and convection within the exchanger where both fluids are circulated.
Fuel from the fuel pump and from HMU enters the inlet. It flows in one direction through one half of the core tubes to the end cover. At the end cover, the fuel flows around the baffle and back through the other half of the core tubes to the fuel outlet. While passing through the exchanger, the fuel gets heated. The fuel portion of the exchanger is equipped with a pressure relief valve which bypasses fuel around the exchanger if core clogging impedes fuel flow.
Oil from the scavenge system enters the oil inlet. The oil flows around the fuel tubes, as routed by interior baffles, and exits at the oil outlet after being cooled. The oil portion of the exchanger is equipped with a pressure relief valve which bypasses oil through the exchanger if core clogging impedes oil flow.
The oil to fuel heat transfer is achieved through conduction and convection within the exchanger where both fluids are circulated.
Fuel from the fuel pump and from HMU enters the inlet. It flows in one direction through one half of the core tubes to the end cover. At the end cover, the fuel flows around the baffle and back through the other half of the core tubes to the fuel outlet. While passing through the exchanger, the fuel gets heated. The fuel portion of the exchanger is equipped with a pressure relief valve which bypasses fuel around the exchanger if core clogging impedes fuel flow.
Oil from the scavenge system enters the oil inlet. The oil flows around the fuel tubes, as routed by interior baffles, and exits at the oil outlet after being cooled. The oil portion of the exchanger is equipped with a pressure relief valve which bypasses oil through the exchanger if core clogging impedes oil flow.
C. Indicating
The filter clogging system indicates that the filter is clogged, when the scavenge filter pressure differential reaches 25.5 PSID.
The filter clogging system indicates that the filter is clogged, when the scavenge filter pressure differential reaches 25.5 PSID.
5. Breather/Vent System
A. General
To ensure satisfactory lubrication throughout the flight envelope, the oil pressure is maintained within the engine oil supply system.
This results in :
To ensure satisfactory lubrication throughout the flight envelope, the oil pressure is maintained within the engine oil supply system.
This results in :
- Some air being entrapped in the main oil flow (scavenge subsystem)
- Some oil droplets escaping with the air of the pressurization sub system. For safety and oil consumption reasons, the air kept in the scavenged oil is separated by the tank deaerator and is then directed to the venting subsystem through the TGB. The oil contained in the pressurized air is collected by a deaerator incorporated in the low pressure turbine shaft and is returned to the engine oil system.
B. Oil Seal Pressurization Subsystem
The oil seal pressurization subsystem consits of the following :
Labyrinth seals, composed of a stationary member (rub strip) and a rotating member (multi-toothed), provide a positive, dependable, long life system. Pressurization air is extracted from the fan booster discharge.
This air is distributed internally through the engine to each sump pressurization cavity and oil seal. The passage between the core rotor air duct and the low pressure shaft is utilized to conduct pressurization air to the aft sump, therefore no external piping is needed for the sump pressurization air. The pressurization air completely surrounds the sumps for improved wall cooling and sealing.
The oil seal pressurization subsystem consits of the following :
- Pressurizing air from the fan booster discharge
- Pressurizing air distribution passages
- Sump cavity seals
- Sump pressure cavity and piping.
Labyrinth seals, composed of a stationary member (rub strip) and a rotating member (multi-toothed), provide a positive, dependable, long life system. Pressurization air is extracted from the fan booster discharge.
This air is distributed internally through the engine to each sump pressurization cavity and oil seal. The passage between the core rotor air duct and the low pressure shaft is utilized to conduct pressurization air to the aft sump, therefore no external piping is needed for the sump pressurization air. The pressurization air completely surrounds the sumps for improved wall cooling and sealing.
C. Sump Vent Subsystem
The sump vent subsystem consists of the following components :
External engine piping is minimized by venting the sumps through the exhaust nozzle.
The tank is vented to the forward sump through the transfer gearbox and radial drive shaft housing. Thus, oil tank pressure is adequate to provide pressurization of the supply pump inlet.
The sump vent subsystem consists of the following components :
- Air/oil separators incorporated in the low pressure shaft
- Center vent piping.
External engine piping is minimized by venting the sumps through the exhaust nozzle.
The tank is vented to the forward sump through the transfer gearbox and radial drive shaft housing. Thus, oil tank pressure is adequate to provide pressurization of the supply pump inlet.