DOC AIRBUS | AMM A320FOXYGEN DISTRIBUTION - DESCRIPTION AND OPERATION
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1. General
A crew oxygen-distribution system supplies Low Pressure (LP) oxygen to the crew oxygen stations.
The LP oxygen-supply solenoid-valve controls the supply of the LP crew oxygen.
The LP oxygen-supply solenoid-valve has an electrical shutoff function between the oxygen supply sub-system and the downstream crew-oxygen-distribution sub-system.
Each crew oxygen-distribution system supplies Low Pressure (LP) oxygen to two crew oxygen stations.
One LP oxygen-supply solenoid-valve controls each LP crew oxygen-distribution.
The LP oxygen-supply solenoid-valve has an electrical shutoff function between the oxygen supply sub-system and the downstream crew-oxygen-distribution sub-system.
Each system is mechanically isolated from the other system. Thus, if there is a malfunction in one of the systems, this will not have an effect on the other system.
** ON A/C NOT FOR ALL A crew oxygen-distribution system supplies Low Pressure (LP) oxygen to the crew oxygen stations.
The LP oxygen-supply solenoid-valve controls the supply of the LP crew oxygen.
The LP oxygen-supply solenoid-valve has an electrical shutoff function between the oxygen supply sub-system and the downstream crew-oxygen-distribution sub-system.
Each crew oxygen-distribution system supplies Low Pressure (LP) oxygen to two crew oxygen stations.
One LP oxygen-supply solenoid-valve controls each LP crew oxygen-distribution.
The LP oxygen-supply solenoid-valve has an electrical shutoff function between the oxygen supply sub-system and the downstream crew-oxygen-distribution sub-system.
Each system is mechanically isolated from the other system. Thus, if there is a malfunction in one of the systems, this will not have an effect on the other system.
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
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| 5753HM | MANIFOLD-OXY DISTRIBUTION | 125 | 21-20-00 | ||
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| 5753HM1 | MANIFOLD DISTRIBUTION | 125 | 35-20-00 | ||
| 5753HM2 | MANIFOLD DISTRIBUTION | 126 | 35-20-00 | ||
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| 3HT | SOL VALVE-LP OXY SPLY | 126 | 35-13-51 | ||
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| 3HT | SOL VALVE-LP OXY SPLY | 125 | 35-13-51 | ||
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| 3HT1 | LP SOLENOID SUPPLY VALVE | 125 | 35-13-51 | ||
| 3HT2 | LP SOLENOID SUPPLY VALVE | 126 | 35-13-51 | ||
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| 4WV | PRESS SW-OXYGEN LO PR | 125 | 35-13-14 | ||
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| 4WV1 | PRESSURE SWITCH | 125 | 35-13-14 | ||
| 4WV2 | PRESSURE SWITCH | 125 | 35-13-14 | ||
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| 5755HM | TEST PORT-OXY SYS | 125 | 35-13-41 | ||
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| 5755HM1 | PORT.ASSY TEST | 125 | 35-13-41 | ||
| 5755HM2 | PORT.ASSY TEST | 126 | 35-13-41 | ||
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| 10RN1 | STOWAGE BOX-OXY MASK, CAPT | 101VU | 211 | 35-12-41 | |
| 10RN2 | STOWAGE BOX-OXY MASK, F/O | 700VU | 212 | 35-12-41 | |
| 10RN3 | STOWAGE BOX-OXY MASK, 3RD OCCPNT | 700VU | 212 | 35-12-41 | |
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| 10RN5 | STOWAGE BOX-OXY MASK, 4TH OCCPNT | 101VU | 211 | 23-51-00 | |
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| 5774HM | STOWAGE BOX-OXY MASK, 4TH OCCPNT | 211 | 35-12-41 | ||
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| 5757HM | MASK-FULL FACE/Q.D. OXY, 3RD OCCPNT | 210 | 35-12-41 | ||
| 5760HM | MASK-FULL FACE/Q.D. OXY, 4TH OCCPNT | 210 | 35-12-41 | ||
| 5759HM | MASK-FULL FACE/Q.D. OXY, CAPT | 211 | 35-12-41 | ||
| 5758HM | MASK-FULL FACE/Q.D. OXY, F/O | 212 | 35-12-41 | ||
3. System Description
Oxygen Distribution Circuit - Schematic ** ON A/C NOT FOR ALL
Oxygen Distribution Circuit - Schematic ** ON A/C NOT FOR ALL
The LP oxygen-distribution circuit includes:
** ON A/C NOT FOR ALL Oxygen Distribution Circuit - Schematic ** ON A/C NOT FOR ALL Oxygen Distribution Circuit - Schematic ** ON A/C NOT FOR ALL - An electrical LP oxygen-supply solenoid-valve with a position switch
- A test port connected to the mechanical distribution manifold through a test line
- A mechanical distribution manifold with an oxygen low-pressure switch
- An LP supply distribution-line with the stainless-steel rigid pipes and the flexible hoses
- Four full-face/quick-donning oxygen masks and their related stowage boxes.
- An electrical LP oxygen-supply solenoid-valve with a position switch
- A test port connected to the mechanical distribution manifold through a test line
- A mechanical distribution manifold with an oxygen low-pressure switch
- An LP supply distribution-line with stainless-steel rigid pipes and flexible hoses
- Two full-face/quick-donning oxygen masks and their related stowage boxes.
4. Component Description
A. LP Oxygen-Supply Solenoid-Valve(s)
The LP oxygen-supply solenoid-valve is installed between the pressure regulator/transmitter and the distribution manifold. A 28VDC signal opens/closes this valve (Ref. AMM D/O 35-13-00-00).
On the valve housing, an arrow shows the direction of the LP oxygen flow.
The valve has an integrated electronic circuit which changes the permanent control voltage into a pulse which operates the valve. When there is no pulse, the valve coil is not energized. The valve position agrees with the last control signal.
A switch sends the valve position data to the System Data Acquisition Concentrator (SDAC) for monitoring and display (Ref. AMM D/O 31-54-00-00) (Ref. AMM D/O 35-13-00-00).
The LP oxygen-supply solenoid-valve is installed between the pressure regulator/transmitter and the distribution manifold. A 28VDC signal opens/closes this valve (Ref. AMM D/O 35-13-00-00).
On the valve housing, an arrow shows the direction of the LP oxygen flow.
The valve has an integrated electronic circuit which changes the permanent control voltage into a pulse which operates the valve. When there is no pulse, the valve coil is not energized. The valve position agrees with the last control signal.
A switch sends the valve position data to the System Data Acquisition Concentrator (SDAC) for monitoring and display (Ref. AMM D/O 31-54-00-00) (Ref. AMM D/O 35-13-00-00).
B. Test Port
The test port has an internal filter, an internal shutoff valve and a protective cap. The test port is used for the ground maintenance for the pressure and leak tests of the LP part of the distribution system. The test port has a maximum operating pressure of 102 psi (7.03 bar).
The test port has an internal filter, an internal shutoff valve and a protective cap. The test port is used for the ground maintenance for the pressure and leak tests of the LP part of the distribution system. The test port has a maximum operating pressure of 102 psi (7.03 bar).
C. Distribution Manifold
(1) The LP distribution manifold is an aluminum forged component.
The LP distribution manifold has the components and the connections that follow:
The LP distribution manifold has the components and the connections that follow:
- An LP inlet port to which the oxygen comes from the LP supply solenoid-valve.
- An LP outlet port from which the oxygen goes through the LP oxygen-distribution lines and is supplied to the oxygen-mask stowage-boxes.
- An LP outlet port from which the oxygen goes through the test line.
(2) An oxygen low-pressure switch:
The oxygen low-pressure switch senses if the pressure is too low in the LP distribution circuit. This switch sends an electrical signal to the SDAC to monitor (Ref. AMM D/O 35-13-00-00). It operates at a pressure between 45 psi (3.10 bar) and 60 psi (4.14 bar).
The oxygen low-pressure switch senses if the pressure is too low in the LP distribution circuit. This switch sends an electrical signal to the SDAC to monitor (Ref. AMM D/O 35-13-00-00). It operates at a pressure between 45 psi (3.10 bar) and 60 psi (4.14 bar).
(3) Connections:
- An LP inlet port to which the oxygen comes from the LP supply solenoid-valve.
- An LP outlet port from which the oxygen goes through the LP oxygen-distribution lines and is supplied to the oxygen-mask stowage-boxes.
- An LP outlet port from which the oxygen goes through the test line. The test port is connected at the end of this test line.
D. Distribution Pipes or Distribution Lines
The distribution line is made of stainless steel pipes and flexible (PTFE) hoses.
It supplies oxygen to the flight crew stations that are Captain (CAPT), First Officer (F/O), third Occupant (OCCPNT) and the fourth OCCPNT stations.
The flexible hoses connect the distribution lines to the stowage box assemblies.
Each distribution line is made with rigid aluminum pipes and flexible (PTFE) hoses.
The two distribution lines supply oxygen to the flight crew stations.
One line supplies oxygen to the Captain (CAPT) and third Occupant (OCCPNT) stations and the other line supplies oxygen to the First Officer (F/O) and fourth OCCPNT stations.
The flexible hoses connect the distribution lines to the stowage box assemblies.
The distribution line is made of stainless steel pipes and flexible (PTFE) hoses.
It supplies oxygen to the flight crew stations that are Captain (CAPT), First Officer (F/O), third Occupant (OCCPNT) and the fourth OCCPNT stations.
The flexible hoses connect the distribution lines to the stowage box assemblies.
Each distribution line is made with rigid aluminum pipes and flexible (PTFE) hoses.
The two distribution lines supply oxygen to the flight crew stations.
One line supplies oxygen to the Captain (CAPT) and third Occupant (OCCPNT) stations and the other line supplies oxygen to the First Officer (F/O) and fourth OCCPNT stations.
The flexible hoses connect the distribution lines to the stowage box assemblies.
(1) The stowage box assemblies are installed in the cockpit next to each flight crew station. Each box is the connection point for the full-face quick-donning mask which is kept in the box until we use it. When the mask is removed, the oxygen system is automatically switched on.
(2) Stowage box
Each stowage box includes:
Each stowage box includes:
- A connector for the LP oxygen supply
- An electrical plug for the radio connection
- A two flap door, which keeps the mask in its housing
- A PRESS TO TEST AND RESET control button on the left flap of the door
- A pneumatic supply valve, which operates when you open the door or when you push the PRESS TO TEST AND RESET control button
- An oxygen flow indicator, which flashes when the LP oxygen flows
- An OXY ON flag, which shows that the doors are closed and the LP oxygen continues to supply the mask.
(3) Connection of the mask
Each stowage box has:
Each stowage box has:
- A flexible hose which connects the box oxygen valve to the mask. One end has a quick disconnect connection with a self-sealing coupling. This coupling prevents oxygen leakage when the mask is disconnected and removed.
- A microphone lead with a quick disconnect device for the connection to the radio communication system.
(4) The left door of the stowage box has a reset/test control slide.
The slide is pushed in the direction of the arrow to reset the oxygen supply valve when the left door is closed. It is also pushed in the direction of the arrow to do a test of the oxygen supply without the removal of the mask from the stowage box.
The slide is pushed in the direction of the arrow to reset the oxygen supply valve when the left door is closed. It is also pushed in the direction of the arrow to do a test of the oxygen supply without the removal of the mask from the stowage box.
(5) The oxygen supply valve in the stowage box is a sliding piston valve.
The reset/test control slide, on the left door, will keep the piston in the close position. When the left door is opened the piston moves to the open position. This lets the oxygen to flow through the supply valve and make the OXY ON flag show. Close the doors and push the RESET/TEST in the direction of the arrow to close the supply valve.
The reset/test control slide, on the left door, will keep the piston in the close position. When the left door is opened the piston moves to the open position. This lets the oxygen to flow through the supply valve and make the OXY ON flag show. Close the doors and push the RESET/TEST in the direction of the arrow to close the supply valve.
(6) An oxygen flow indicator is an integral part of the supply valve. The indicator shows when there is an oxygen flow.
(7) A pressure switch is an integral part of the supply valve. When the supply valve is open and oxygen flows, the oxygen pressure will close the pressure switch. With the pressure switch closed, the microphone installed in the mask will set on.
(8) Flexible hoses are used to connect the distribution pipe to the supply valve and the supply valve to the oxygen mask. A microphone lead is attached to the flexible hose that is connected to the supply valve and the oxygen mask.
(9) For the fourth OCCPNT, the mask installed is same to the other masks. The audio communication is not possible because of the stowage box assembly is not connected to the audio circuit of the aircraft.
(1) The full-face/quick-donning oxygen mask is an emergency breathing equipment that gives protection to the eyes and respiratory system of the crew members.
It is necessary in the conditions that follow:
It is necessary in the conditions that follow:
- Cockpit depressurization
- Smoke and poisonous fumes
- You can put on and operate the mask in less than five seconds with its self inflated harness
- The mask has the parts that follow:
(2) Mask and goggles assembly
The mask face piece is a full-face piece that gives protection for the eyes, nose, mouth and respiratory system of the crew members.
The mask has a plastic window.
The mask window has a protective film to prevent damage when you remove the mask from its stowage box to clean or for maintenance.
This protective film is made of electrostatic-adhesive soft plastic.
You can remove it easily with its side strip.
The protective film must not be on the mask when the aircraft is in service.
The mask face piece is a full-face piece that gives protection for the eyes, nose, mouth and respiratory system of the crew members.
The mask has a plastic window.
The mask window has a protective film to prevent damage when you remove the mask from its stowage box to clean or for maintenance.
This protective film is made of electrostatic-adhesive soft plastic.
You can remove it easily with its side strip.
The protective film must not be on the mask when the aircraft is in service.
(3) Inflatable harness
The harness keeps the mask and the goggles assembly in position on the user's head. The harness is made of elastomer tubes which expand with oxygen pressure. The mask is kept in its stowage box with the harness deflated.
When the mask is removed, the harness inflation control-plates are manually pushed. Then, the pneumatic harness inflates with oxygen pressure.
When the harness is inflated, it gets the diameter and rigidity necessary to put it on correctly.
When the user releases the harness control plates, the harness is depressurized and it holds the mask tightly against the users face.
The harness keeps the mask and the goggles assembly in position on the user's head. The harness is made of elastomer tubes which expand with oxygen pressure. The mask is kept in its stowage box with the harness deflated.
When the mask is removed, the harness inflation control-plates are manually pushed. Then, the pneumatic harness inflates with oxygen pressure.
When the harness is inflated, it gets the diameter and rigidity necessary to put it on correctly.
When the user releases the harness control plates, the harness is depressurized and it holds the mask tightly against the users face.
(4) Microphone
In the distribution valve of the stowage box, a pressure switch is used to operate the microphone when the LP oxygen flows in the mask (Ref. AMM D/O 35-13-00-00).
In the distribution valve of the stowage box, a pressure switch is used to operate the microphone when the LP oxygen flows in the mask (Ref. AMM D/O 35-13-00-00).
(5) Regulator
The mask regulator controls the supply of oxygen in the mask:
The mask regulator controls the supply of oxygen in the mask:
- Air/oxygen mixture with an altimetric automatic control
- 100% pure oxygen
- 100% pure oxygen with overpressure manual control.
(6) Flexible supply hose
The oxygen supply hose connects the mask to the stowage box with a quick disconnect coupling.
The oxygen supply hose connects the mask to the stowage box with a quick disconnect coupling.
5. Operation/Control and Indicating
A. Operation of the Regulator
(1) Air and oxygen mixture (normal operation)
When the N/100 % rocker switch is in the N position, the user breathes a mixture of air and oxygen. The position of the air/oxygen mixing aneroid-capsule controls the quantity of external air. This capsule is fully closed at a cabin altitude of 35000 ft. (10668 m) and the pilot breathes 100% oxygen.
When the N/100 % rocker switch is in the N position, the user breathes a mixture of air and oxygen. The position of the air/oxygen mixing aneroid-capsule controls the quantity of external air. This capsule is fully closed at a cabin altitude of 35000 ft. (10668 m) and the pilot breathes 100% oxygen.
(2) 100% oxygen supply without overpressure
When the N/100 % rocker switch is in the 100 % position, the user breathes pure oxygen at all altitudes.
When the N/100 % rocker switch is in the 100 % position, the user breathes pure oxygen at all altitudes.
(3) Emergency function
Overpressure is necessary for breathing if there is smoke or poisonous gas in the cockpit. The user turns the PRESS TO TEST/EMERGENCY knob to get a continuous oxygen-overpressure flow. A 100 % oxygen selection is necessary to operate this overpressure function (rocker switch in 100 % position).
Overpressure is necessary for breathing if there is smoke or poisonous gas in the cockpit. The user turns the PRESS TO TEST/EMERGENCY knob to get a continuous oxygen-overpressure flow. A 100 % oxygen selection is necessary to operate this overpressure function (rocker switch in 100 % position).
(4) Functional test
The PRESS TO TEST/EMERGENCY knob is used to do a functional test of the regulator.
This test is possible when the mask is stowed in its housing, but the user must push the PRESS TO TEST AND RESET button (on the stowage box) at the same time.
The PRESS TO TEST/EMERGENCY knob is used to do a functional test of the regulator.
This test is possible when the mask is stowed in its housing, but the user must push the PRESS TO TEST AND RESET button (on the stowage box) at the same time.
A. By the Maintenance Personnel
Do a leak test when you replace a component in the crew oxygen system. The test point is used to carry out leak tests.
Do a leak test when you replace a component in the crew oxygen system. The test point is used to carry out leak tests.
B. Mask
In emergency conditions (smoke or poisonous gas in the cockpit), a vent valve releases a small quantity of oxygen from the mask cavity into the goggles cavity. This increases the pressure in the mask and thus, smoke or fumes cannot go into it.
In emergency conditions (smoke or poisonous gas in the cockpit), a vent valve releases a small quantity of oxygen from the mask cavity into the goggles cavity. This increases the pressure in the mask and thus, smoke or fumes cannot go into it.