DOC AIRBUS | AMM A320FHYDRAULIC RESERVOIR PRESSURIZING SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The aircraft has a pressurization system for the hydraulic reservoirs . Each reservoir gets pressurized air to 50 psi (3.5 bar) (usual operation), which prevents cavitation of the pumps. The system also remains airtight in the event of failure of the pressurization system or after an engine shutdown.
Air for the reservoir pressurization system comes from:
** ON A/C NOT FOR ALL The aircraft has a pressurization system for the hydraulic reservoirs . Each reservoir gets pressurized air to 50 psi (3.5 bar) (usual operation), which prevents cavitation of the pumps. The system also remains airtight in the event of failure of the pressurization system or after an engine shutdown.
Air for the reservoir pressurization system comes from:
- the left engine high pressure (HP) compressor (HP air) (usual operation),
- the low pressure (LP) air bleed of both the left and right engines and the APU (LP air) (if failure of the left engine occurs),
- the ground supply.
2. Component Location
Component Location (Sheet 1) ** ON A/C NOT FOR ALL
Component Location (Sheet 1) ** ON A/C NOT FOR ALL
Component Location (Sheet 1) ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL Component Location (Sheet 1) ** ON A/C NOT FOR ALL Component Location (Sheet 1) ** ON A/C NOT FOR ALL Component Location (Sheet 1) ** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 1005GM | RELIEF-V.-G.SYS. | 148 | 29-14-17 | ||
| 1087GM | G.RSVR DEPRESS.VALVE | 197CB | 197 | 29-14-16 | |
| ** ON A/C NOT FOR ALL | |||||
| 1392GM | BLEED AIR RESTICTOR | 476CR | 400 | 29-14-13 | |
| ** ON A/C ALL | |||||
| 1360GM | RSVR PRESS UNIT | 195 | 29-14-41 | ||
| 1383GM | GAUGE PRESSURE AIR | 147 | 29-14-15 | ||
| 1388GM | CHECK VALVE G | 147 | 29-14-18 | ||
| 2005GM | RELIEF-V.-B.SYS. | 197EB | 197 | 29-14-17 | |
| 2087GM | B RSVR DEPRESS.VALVE | 197EB | 197 | 29-14-16 | |
| 2383GM | GAUGE PRESSURE AIR | 197FB | 197 | 29-14-15 | |
| 2388GM | CHECK VALVE B | 197FB | 197 | 29-14-18 | |
| 3005GM | RELIEF-V.-Y.SYS. | 196BB | 196 | 29-14-17 | |
| 3087GM | Y RSVR DEPRESS.VALVE | 198CB | 198 | 29-14-16 | |
| 3383GM | GAUGE PRESSURE AIR | 196BB | 196 | 29-14-15 | |
| 3388GM | CHECK VALVE Y | 196BB | 196 | 29-14-18 | |
3. System Description
The reservoir pressurization system gets:
The system has a reservoir pressurization unit which controls the pressure of the air supplied to the reservoirs. This is necessary because the pressure of the HP air from the engine can be as much as 26 bar (377 psi) and the system operates at 4.5 bar absolute. The pressure of the LP bleed air is 3.5 bar relative. Thus it is not necessary to decrease the pressure of this air supply.
A water separator is installed on the reservoir pressurization unit. The water separator is located upstream of the pressure reducing valve . The water separator makes sure that the air is clear of water. A reservoir pressurization ground connector is also installed on the unit. It makes it possible to pressurize the system from a ground service cart. A filter assembly is also installed on the unit.
An air pressure gage is installed in each system, adjacent to the related reservoir. Each reservoir has a pressure relief valve to prevent overpressurization of the reservoir.
Each reservoir has a reservoir depressurization valve to let the pressure out of the reservoir. The valve is installed in the related ground service panel.
** ON A/C NOT FOR ALL The reservoir pressurization system gets:
- HP air (usual operation)
- LP air (if failure of left engine occurs)
- ground supply air.
The system has a reservoir pressurization unit which controls the pressure of the air supplied to the reservoirs. This is necessary because the pressure of the HP air from the engine can be as much as 26 bar (377 psi) and the system operates at 4.5 bar absolute. The pressure of the LP bleed air is 3.5 bar relative. Thus it is not necessary to decrease the pressure of this air supply.
A water separator is installed on the reservoir pressurization unit. The water separator is located upstream of the pressure reducing valve . The water separator makes sure that the air is clear of water. A reservoir pressurization ground connector is also installed on the unit. It makes it possible to pressurize the system from a ground service cart. A filter assembly is also installed on the unit.
An air pressure gage is installed in each system, adjacent to the related reservoir. Each reservoir has a pressure relief valve to prevent overpressurization of the reservoir.
Each reservoir has a reservoir depressurization valve to let the pressure out of the reservoir. The valve is installed in the related ground service panel.
4. Component Description
A. Pressure Relief Valve FIN: 1005-GM FIN: 2005-GM FIN: 3005-GM
A pressure relief valve is installed on each reservoir. In the event of a system overpressurization, the valve operates to relieve the pressure to the atmosphere.
If the system pressure gets higher than 5.3 bar (76.85 psi) relative, the piston moves against the pressure of the spring. The valve opens to relieve the high pressure. When the system pressure decreases, the valve closes under pressure of the spring. The valve can let out up to 20 l/min (122 cu.in/min) at 6.3 bar (91.35 psi) relative.
A pressure relief valve is installed on each reservoir. In the event of a system overpressurization, the valve operates to relieve the pressure to the atmosphere.
If the system pressure gets higher than 5.3 bar (76.85 psi) relative, the piston moves against the pressure of the spring. The valve opens to relieve the high pressure. When the system pressure decreases, the valve closes under pressure of the spring. The valve can let out up to 20 l/min (122 cu.in/min) at 6.3 bar (91.35 psi) relative.
(1) Water Separator
The water separator is installed on the reservoir pressurization unit. It receives supply air from the reservoir pressurization unit and then moves the air through the element. The element is a non-cleanable element which separates the water from the air. A large quantity of water can collect in the container. When the temperature is below the freezing point the water will freeze. Thus an automatic drain valve drains the water regulary after each engine or APU shutdown. A manual self-sealing drain valve is also installed on the container of the water separator.
The connection of the inlet and outlet to the water separator is through the interface.
The water separator is installed on the reservoir pressurization unit. It receives supply air from the reservoir pressurization unit and then moves the air through the element. The element is a non-cleanable element which separates the water from the air. A large quantity of water can collect in the container. When the temperature is below the freezing point the water will freeze. Thus an automatic drain valve drains the water regulary after each engine or APU shutdown. A manual self-sealing drain valve is also installed on the container of the water separator.
The connection of the inlet and outlet to the water separator is through the interface.
C. Reservoir Depressurization Valve (1087GM, 2087GM and 3087GM)
The reservoir depressurization valve is a 2/2-way valve. It is a manually- operated valve. The valve is installed in the ground service panel of the related system. It is connected to the applicable hydraulic reservoir with pipes. You can depressurize each hydraulic reservoir independently.
The valve is usually closed under pressure of the spring. When the ground depressurization coupling is connected or when the cap assembly is operated, the piston moves against the spring. The valve is then open. A standard hydraulic unit connects the valve to the system installation.
The reservoir depressurization valve is a 2/2-way valve. It is a manually- operated valve. The valve is installed in the ground service panel of the related system. It is connected to the applicable hydraulic reservoir with pipes. You can depressurize each hydraulic reservoir independently.
The valve is usually closed under pressure of the spring. When the ground depressurization coupling is connected or when the cap assembly is operated, the piston moves against the spring. The valve is then open. A standard hydraulic unit connects the valve to the system installation.
(1) Reservoir Pressurization Unit
The reservoir pressurization unit has three inlet ports, one from each supply source (HP air, LP air and the ground connection). Outlet of the airflow is through the water separator which is fitted to the reservoir pressurization unit. Also fitted to the unit is the pressure reducing valve.
Two filters are installed in the reservoir pressurization unit. One is located in the filter bowl. It is a non-cleanable filter element. It cleans the inlet air. An indicator is installed in front of the reservoir pressurization unit to show when the filter is clogged.
The other filter is located in the water separator. It is a non-cleanable filter element. It separates water from the inlet air. An indicator is installed on top of the reservoir pressurization unit to show when the filter is clogged.
The connections to the manifold are standard hydraulic connections.
The reservoir pressurization unit has three inlet ports, one from each supply source (HP air, LP air and the ground connection). Outlet of the airflow is through the water separator which is fitted to the reservoir pressurization unit. Also fitted to the unit is the pressure reducing valve.
Two filters are installed in the reservoir pressurization unit. One is located in the filter bowl. It is a non-cleanable filter element. It cleans the inlet air. An indicator is installed in front of the reservoir pressurization unit to show when the filter is clogged.
The other filter is located in the water separator. It is a non-cleanable filter element. It separates water from the inlet air. An indicator is installed on top of the reservoir pressurization unit to show when the filter is clogged.
The connections to the manifold are standard hydraulic connections.
E. Pressure Reducing Valve
The pressure reducing valve is installed on the reservoir pressurization unit in the air supply line. The valve contains two bellows, each works together with a spring to control the air flow. Inlet pressure causes the upper bellows (in which there is a vacuum) to become smaller. The valve assembly then moves in the direction of the closed position, and the outlet pressure decreases. The outlet pressure also goes into the balance bellows. This reduces the rate of movement of the valve assembly to control the effect of irregular inlet pressures.
The pressure reducing valve is installed on the reservoir pressurization unit in the air supply line. The valve contains two bellows, each works together with a spring to control the air flow. Inlet pressure causes the upper bellows (in which there is a vacuum) to become smaller. The valve assembly then moves in the direction of the closed position, and the outlet pressure decreases. The outlet pressure also goes into the balance bellows. This reduces the rate of movement of the valve assembly to control the effect of irregular inlet pressures.
F. Check Valve (1382GM, 1388GM, 2388GM and 3388GM)
All the check valves installed in the reservoir pressurization system are the same. They are of the flapper type.
All the check valves installed in the reservoir pressurization system are the same. They are of the flapper type.
G. Air Pressure Gage
An air pressure gage is installed in the air supply line to each reservoir. The gage gets input of the system pressure which is constantly displayed. The gage has an analog display with a range of 0-75 psi.
An air pressure gage is installed in the air supply line to each reservoir. The gage gets input of the system pressure which is constantly displayed. The gage has an analog display with a range of 0-75 psi.
H. Reservoir Pressurization Ground Connector
The ground connector is installed on the reservoir pressurization unit. The connector is a plunger-type valve. It is opened and closed manually. Rotation of the nut moves the plunger in or out to open or close the valve. A cap fitted to the connector prevents external contamination.
The ground connector is installed on the reservoir pressurization unit. The connector is a plunger-type valve. It is opened and closed manually. Rotation of the nut moves the plunger in or out to open or close the valve. A cap fitted to the connector prevents external contamination.
I. Restrictor Valve (1392GM)
A restrictor valve is installed in the HP air supply line from the left engine. It has a calibrated orifice which restricts the volume of air which can flow through it. It also has a filter element to prevent contamination of the valve.
A restrictor valve is installed in the HP air supply line from the left engine. It has a calibrated orifice which restricts the volume of air which can flow through it. It also has a filter element to prevent contamination of the valve.
5. Operation
In flight, two sources of air supply are available to the reservoir pressurization unit (HP air from the left engine and LP air from both engines and the APU). The air supply from the left engine goes through the restrictor (1392GM) (located in the pylon) and then into the unit (1360GM) through the check valve. On the ground the air supply by means of a ground supply cart goes directly into the unit. In the unit the HP air supply, or ground air supply goes through the filter and the water separator and the pressure reducing valve to the check valve. The LP air supply from the bleed air system goes directly into the unit via the LP relief valve through the filter and the water separator and the pressure reducing valve to the check valve. The air supply of the higher pressure will close the check valve in the other supply line.
From the unit the air supply divides into three flows (one to each reservoir). Each air supply goes through its applicable check valve (1388GM, 2388GM or 3388GM) and to its related reservoir (1000GQ, 2000GQ and 3000GQ). It also goes to its:
A malfunction of the reservoir pressurization unit caused by freezing is prevented without bleed air warming flow.
The water separator of the reservoir pressurization unit has in addition to a manual draining device an automatic draining function. The low pressure circuit of the reservoir pressurization system activates the automatic draining function as follows:
In flight, two sources of air supply are available to the reservoir pressurization unit (HP air from the left engine and LP air from both engines and the APU). The air supply from the left engine goes through the restrictor (1392GM) (located in the pylon) and then into the unit (1360GM) through the check valve. On the ground the air supply by means of a ground supply cart goes directly into the unit. In the unit the HP air supply, or ground air supply goes through the filter and the water separator and the pressure reducing valve to the check valve. The LP air supply from the bleed air system goes directly into the unit via the LP relief valve through the filter and the water separator and the pressure reducing valve to the check valve. The air supply of the higher pressure will close the check valve in the other supply line.
From the unit the air supply divides into three flows (one to each reservoir). Each air supply goes through its applicable check valve (1388GM, 2388GM or 3388GM) and to its related reservoir (1000GQ, 2000GQ and 3000GQ). It also goes to its:
- air pressure gage (1383GM, 2383GM and 3383GM),
- low pressure switch (1384GM, 2384GM and 3384GM),
- pressure relief valve (1005GM, 2005GM and 3005GM),
- reservoir depressurization valve (1087GM, 2087GM and 3087GM).
A malfunction of the reservoir pressurization unit caused by freezing is prevented without bleed air warming flow.
The water separator of the reservoir pressurization unit has in addition to a manual draining device an automatic draining function. The low pressure circuit of the reservoir pressurization system activates the automatic draining function as follows:
- After each engine or APU shutdown a spring loaded plunger releases a hole on the backside of the unit. Any collected water drains out of the hole.
- When the APU or the engines start again, the pressure in the low pressure circuit of the reservoir pressurization system moves the plunger back to its initial position. The hole on the backside of the unit is now closed and a green indicator is visible on the water separator, to show that the automatic drain device is non-activated.