DOC AIRBUS | AMM A320FOIL - GENERAL - DESCRIPTION AND OPERATION
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** ON A/C NOT FOR ALL
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** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. Description
Engine Oil Flow Schematic DiagramA. Because parts turn against each other, oil is necessary to lubricate them.
(1) Oil between mating metal parts keeps the surfaces apart, and the result is less friction and wear.
(2) Because parts operate in hot areas, it is also necessary to keep parts as cool as possible. Oil that flows across hot surfaces removes heat from those surfaces, and in an oil-oil heat exchanger, cool oil removes heat from the hot oil.
B. To prevent too much heat from the oil system, a thermal management system is necessary.
(1) This system uses heat exchangers which use available flows of air, fuel or oil to remove heat from the oil that comes out of the engine.
2. Oil System Control
A. The flow of oil into the bearing compartments and in and out of the heat exchangers is controlled by a central Oil Control Module (OCM).
(1) This OCM is attached to the left side of the main gearbox.
(2) Oil flows into and through this module through external oil tubes and internal gearbox and OCM housing openings.
(3) Attached to the OCM are the Main Oil Temperature (MOT) sensor, Low Oil Pressure (LOP) switch, and Main Oil Pressure (MOP) sensor which measure oil pressures and temperatures. Also attached are the Active Oil Damper Valve (AODV) and Fuel/Oil Cooler (FOC) bypass valve which, when necessary, are controlled by signals from the Full Authority Digital Engine Control (FADEC).
(4) Attached to the Variable Oil Reduction Valve (VORV) manifold is a Journal Oil Shuttle Valve (JOSV) to control oil to the Fan Drive Gear System (FDGS) journal bearings and a VORV which schedules oil flow to the FDGS gear teeth and the No. 1, No. 1.5 and No. 2 bearings. The VORV manifold also contains the Auxiliary Oil Pressure (AOP) sensor and lube trim check valve.
3. Bearing Lubrication
A. The PW1100-JM engine rotors have friction less (ball and roller) bearings.
(1) These bearings must have oil to lubricate them and to keep them cool.
(2) The FDGS uses journal bearings in which cylindrical bearing surfaces, isolated by a constant film of oil, turn against each other without balls or rollers.
(3) It is necessary to keep oil in these journal bearings at all times as a protection from friction and heat.
(4) A special pump system is used to keep sufficient oil pressure in these journal bearings during windmill and negative G conditions.
4. FDGS Journal Bearing Auxiliary Oil Supply
A. To keep sufficient oil flow to the FDGS journal bearings during windmill rotation, or negative G conditions, an auxiliary oil supply is used.
(1) An auxiliary oil tank is part of the No. 1 bearing support, at the right side of the support structure.
(2) A gear on the rear of the FDGS gearbox shaft engages a two stage auxiliary pump. One stage supplies oil from the sump and the other stage supplies oil from the auxiliary oil tank.
(3) This pump supplies oil from either the auxiliary oil tank or the No. 1 and 1.5 bearing compartment sump, through the JOSV, back to the oil tank during engine operation.
B. During windmill rotation, the JOSV supplies the windmill pump oil to the FDGS journal bearings to keep these bearings lubricated.
(1) If the engine and aircraft are on the ground and wind conditions cause the fan and LPC rotor to turn (windmill), the JOSV lets bearing compartment sump oil go to the windmill pump stage to the FDGS bearings through the JOSV.
(2) If the engine and aircraft are in flight in a zero or negative G condition, oil from the auxiliary oil tank goes to the auxiliary pump stage and from there to the JOSV and to the FDGS journal bearings.
(3) During engine operation, oil used by the FDGS flows out by centrifugal force to collect in an oil channel ("gutter").
(4) This collected oil then flows to the auxiliary oil tank in the No. 1 support where it is available when necessary.
(5) The auxiliary oil tank oil drains down into the compartment sump at engine shutdown.
5. JOSV
A. The JOSV directs the oil flow to the journal bearings.
6. Bearing Oil Damping
A. The No. 1, No. 2, No. 3, No. 4 and No. 6 bearings in the engine are oil-damped.
(1) With these bearings, a layer of pressurized oil between the bearing outer race and its support absorbs rotor vibration and keeps engine vibration to minimum.
(2) The No. 3 bearing damping pressure is controlled by the AODV which is attached to the OCM. The AODV is FADEC controlled.
7. Oil Breather
A. Oil pressurization of the bearing compartments causes the air pressure in these compartments to increase.
(1) In the Compressor Intermediate Case (CIC) section, oil pressurization of the No. 3 bearing compartment and Angle Gearbox (AGB) causes an increase in the air pressure which it is necessary to release. This released air pressure is called breather.
(2) External tubes supply No. 3 and No. 5/6 bearing breather air (air mixed with oil vapor) to a deoiler unit in the main gearbox. The No. 5/6 bearing breather tubes contain a siphon break used for anti-coking features.
(3) Added to this bearing compartment breather air is the breather from the main gearbox and from the oil tank (released through the tank pressure valve back to the deoiler in the gearbox).
(4) The deoiler removes the oil droplets from the air, and the air then goes overboard.
8. Oil Filtration
A. To keep oil as clean as possible, oil is put through a main oil filter to remove contamination and unwanted material.
NOTE: The engine main oil filter has two stages, a 30-micron inner primary stage and a 150-micron outer secondary stage. Flow through the filter is reverse-type in which the oil flows from the inner (primary) element to the outer (secondary) element. If there is blockage of the primary stage, an oil filter bypass valve opens and supplies pressurized oil directly to the secondary filter. A differential (delta) pressure sensor is installed on the oil pump supplies a signal to the FADEC for maintenance action.
9. Oil Tank
A. To have a unit for oil storage and supply to the engine, an oil tank is installed on the left side of the engine on the fan case.
(1) The approximately 10.00 gallon (37.85 liter) oil tank supplies oil to the pressurization system and receives oil from the oil scavenge system.
(2) A deaerator in the tank removes air bubbles from oil before the oil goes into the tank.
(3) A pressure valve in the tank releases air/oil pressure to the deoiler in the gearbox when necessary.
10. Oil Pressurization
A. A lubrication and scavenge pump is installed on the left side in front of the main gearbox and it is connected to the gearbox gear train.
(1) This pump has eight pump stages on two rotors. It uses six of these stages to remove scavenge oil from the bearing compartments and the gearboxes and two of them to supply pressurized oil to the oil control manifold.
(2) The six scavenge pump stages pull scavenge oil from the No. 1, No. 1.5, No. 2 bearings, FDGS compartment, No. 3 bearing compartment, AGB, main gearbox, the No. 4 compartment and the No. 5/6 bearing compartment.
(3) There are internal chip collectors in each scavenge compartment to catch metallic particles. Only the No. 4 bearing chip collector is installed in the oil return lines.
11. Thermal Management
A. Hot scavenge oil is supplied to the oil tank by the six scavenge chambers of the lubrication and scavenge oil pump.
(1) From the tank the oil goes to the pressure chamber of the pump and from there to the OCM.
(2) Pressurized oil is supplied to a sequence of heat exchangers.
B. A fuel/oil heat exchanger uses fuel to make the oil cooler and an air/oil heat exchanger uses fan air to remove more heat from the oil.
NOTE: A fuel/oil heat exchanger bypass modulating valve controls oil flow between the fuel/oil heat exchanger and the air/oil heat exchanger. Operation of this bypass valve is controlled by the FADEC (fuel and oil temperature data is supplied to the FADEC by the oil temperature sensor and the fuel temperature sensor).
(1) The fuel/oil heat exchanger has an internal bypass valve which is mechanically operated and lets oil flow around the cooler elements during cold starts (when it is possible that oil can be thicker) or if there is blockage of the heat exchanger.
C. An air/oil heat exchanger is installed downstream of the fan discharge and uses this fan air to remove heat from the oil.
(1) The air/oil heat exchanger also has an internal bypass valve which is mechanically operated and lets oil flow around the cooler elements during cold starts (when it is possible that oil can be thicker) or if there is blockage of the heat exchanger.
D. An oil/oil heat exchanger is installed downstream of the air/oil heat exchanger and fuel/oil heat exchanger. It uses engine oil to cool the Integrated Drive Generator (IDG) oil. In some conditions, such as hot day ground idle, heat is transferred from the oil/oil heat exchanger to the engine oil.
(1) The oil/oil heat exchanger has a bypass valve which is mechanically operated.