Loss of the REGUL LO PR Indication

TASK 35-10-00-810-828-A
Loss of the REGUL LO PR Indication

1. Possible Causes

wiring
SOL VALVE-LP OXY SPLY [3HT]
P/BSW-OXYGEN/CREW SUPPLY (2HT)
LP SOLENOID SUPPLY VALVE [3HT1]
LP SOLENOID SUPPLY VALVE [3HT2]
PRESS SW-OXYGEN LO PR [4WV]
PRESSURE SWITCH [4WV1]
PRESSURE SWITCH [4WV2]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power
AMM 31-60-00-860-001	EIS Start Procedure
AMM 31-60-00-860-002	EIS Stop Procedure
ASM 351301
AMM 35-13-14-000-001	Removal of the Low-Pressure Oxygen Pressure-Switch
AMM 35-13-14-000-802	Removal of the Low-Pressure Oxygen Pressure-Switches
AMM 35-13-14-400-001	Installation of the Low-Pressure Oxygen Pressure-Switch
AMM 35-13-14-400-802	Installation of the Low-Pressure Oxygen Pressure-Switches
AMM 35-13-51-000-001	Removal of the Low-Pressure Oxygen-Supply Solenoid-Valve
AMM 35-13-51-000-802	Removal of the Low-Pressure Oxygen-Supply Solenoid-Valves
AMM 35-13-51-400-001	Installation of the Low-Pressure Oxygen-Supply Solenoid-Valve
AMM 35-13-51-400-802	Installation of the Low-Pressure Oxygen-Supply Solenoid-Valves

3. Fault Confirmation
Subtask 35-10-00-860-076-A

A. Job Set Up
(1) Aircraft Maintenance Configuration
(a) Energize the aircraft electrical circuits
AMM 24-41-00-861-002.
(b) Do the EIS start procedure (Upper ECAM DU and lower ECAM DU only)
AMM 31-60-00-860-001.
(c) On the ECAM control panel, push the DOOR key to get the DOOR/OXY page.

Subtask 35-10-00-865-064-A

B. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	OXYGEN/CREW/OXY/SPLY	1HT	HA01

Subtask 35-10-00-710-078-A ** ON A/C NOT FOR ALL

C. Test
(1) Make sure that the crew oxygen system is in the configuration that follows:

The oxygen storage cylinder (5750HM) is not empty (the pressure shown on the pressure gage is in the green band).
The valve of the oxygen storage cylinder (5750HM) is fully open.

(2) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU, push the CREW SUPPLY pushbutton switch (2HT) (the OFF legend goes off).
(3) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU, release the CREW SUPPLY pushbutton switch (2HT) (the OFF legend comes on).
(4) Do a test of the oxygen flow in the mask:

ACTION	RESULT
On one oxygen-mask stowage box, push and hold the PRESS TO TEST AND RESET control lever. At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.	The flow rate indicator comes into view. You can hear the oxygen flow.

(a) If the volume and the sound of the oxygen flow do not stop and the REGUL LO PR indication does not come into view on the DOOR/OXY page:

Go to Para. 4.A.

(b) If the volume and the sound of the oxygen flow decrease and stop and the REGUL LO PR indication does not come into view on the DOOR/OXY page:

Go to Para. 4.B.

(c) If the volume and the sound of the oxygen flow decrease and stop and the REGUL LO PR indication comes into view on the DOOR/OXY page:

Go to Para. 5.

Subtask 35-10-00-710-078-C ** ON A/C NOT FOR ALL

C. Test
(1) Make sure that the two crew oxygen systems are in the configuration that follows:

The crew oxygen-storage cylinders (5750HM1) and (5750HM2) are not empty (the pressure values shown on their pressure gages are correct).
The manual shutoff valves of the crew oxygen-storage cylinders (5750HM1) and (5750HM2) are fully open.

(2) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU:

Push the CREW SUPPLY pushbutton switch (2HT) (the OFF legend goes off).
Release the CREW SUPPLY pushbutton switch (2HT) (the OFF legend comes on).

(3) Do a test of the oxygen flow in the two oxygen masks as follows:
(a) On the Captain oxygen-mask stowage-box, push and hold the PRESS TO TEST AND RESET control button.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
Keep them pushed for a minimum time of three seconds.
1 If the oxygen flow and sound do not stop and the REGUL 1 LO PR indication does not come into view on the DOOR/OXY page:

Go to Para. 4.A.

2 If the oxygen flow and sound decrease and stop and the REGUL 1 LO PR indication does not come into view on the DOOR/OXY page:

Go to Para. 4.B.

3 If the oxygen flow and sound decrease and stop and the REGUL 1 LO PR indication comes into view on the DOOR/OXY page:

Do the test of the oxygen flow in the First Officer oxygen-mask given in the next step.

(b) On the First-Officer oxygen-mask stowage-box, push and hold the PRESS TO TEST AND RESET control button.
At the same time, push and hold the PRESS TO TEST/EMERGENCY knob on the mask regulator.
Keep them pushed for a minimum time of three seconds.
1 If the oxygen flow and sound do not stop and the REGUL 2 LO PR indication does not come into view on the DOOR/OXY page:

Go to Para. 4.A.

2 If the oxygen flow and sound decrease and stop and the REGUL 2 LO PR indication does not come into view on the DOOR/OXY page:

Go to Para. 4.B.

3 If the oxygen flow and sound decrease and stop and the REGUL 2 LO PR indication comes into view on the DOOR/OXY page:

Go to Para. 5.

4. Fault Isolation
Subtask 35-10-00-810-082-A ** ON A/C NOT FOR ALL

A. When the CREW SUPPLY pushbutton switch (2HT) is released (OFF legend on), the volume and the sound of the oxygen flow do not stop, and the REGUL LO PR indication does not come into view on the DOOR/OXY page:
(1) Do a check of the wiring :

From CREW SUPPLY pushbutton switch (2HT) pin A/B1 to LP oxygen-supply solenoid-valve (3HT) pin A/A
From CREW SUPPLY pushbutton switch (2HT) pin A/B2 to LP oxygen-supply solenoid-valve (3HT) pin A/C, ASM 351301.

(a) If the wiring is not correct:

Repair it.

(2) Do a check for a ground signal at pins A/B and A/E of the LP oxygen-supply solenoid-valve (3HT), ASM 351301.
(a) If there is no ground signal:

Repair the wiring.

(3) If the fault continues:
(a) Replace SOL VALVE-LP OXY SPLY [3HT] AMM 35-13-51-000-001 and AMM 35-13-51-400-001.
(4) If the fault continues:
(a) Replace P/BSW-OXYGEN/CREW SUPPLY (2HT), ASM 351301.
(5) Do the test in Para 3.C. again.

Subtask 35-10-00-810-084-A ** ON A/C NOT FOR ALL

B. When the CREW SUPPLY pushbutton switch (2HT) is released (OFF legend on), the volume and the sound of the oxygen flow decrease and stop, and the REGUL LO PR indication does not come into view on the DOOR/OXY page:
(1) Do a check of the wiring:

From oxygen LP pressure-switch (4WV) pin A/B to SDAC1 (1WV1) pin AA/10H, and
From oxygen LP pressure-switch (4WV) pin A/B to SDAC2 (1WV2) pin AA/10H, ASM 351301.

(a) If the wiring is not correct:

Repair it.

(2) Do a check for a ground signal at pin A/A of the oxygen LP pressure-switch (4WV), ASM 351301.
(a) If there is no ground signal:

Repair the wiring.

(3) If the fault continues:
(a) Replace PRESS SW-OXYGEN LO PR [4WV] AMM 35-13-14-000-001 and AMM 35-13-14-400-001.
(4) Do the test in Para 3.C. again.

Subtask 35-10-00-810-082-B ** ON A/C NOT FOR ALL

C. If the oxygen flow and sound do not stop and:
(1) The REGUL 1 LO PR indication does not come into view on the DOOR/OXY page, on the Captain oxygen system:
(a) Do a check of the wiring :

From the CREW SUPPLY pushbutton switch (2HT) pin A/B1 to the LP oxygen-supply solenoid-valve (3HT1) pin A/A
From the CREW SUPPLY pushbutton switch (2HT) pin A/B2 to the LP oxygen-supply solenoid-valve (3HT1) pin A/C, ASM 351301.

1 If the wiring is not correct:

Repair it.

(b) Do a check for a ground signal at pins A/B and A/E of the LP oxygen-supply solenoid-valve (3HT1), ASM 351301.
1 If there is no ground signal:

Repair the wiring.

(c) If the fault continues:
1 Replace the LP SOLENOID SUPPLY VALVE [3HT1] AMM 35-13-51-000-802 and AMM 35-13-51-400-802.
(d) If the fault continues:
1 Replace the P/BSW-OXYGEN/CREW SUPPLY (2HT), ASM 351301.
(e) Do the test given in Para 3.C. again.
(2) The REGUL 2 LO PR indication does not come into view on the DOOR/OXY page, on the First Officer oxygen-system:
(a) Do a check of the wiring :

From the CREW SUPPLY pushbutton switch (2HT) pin A/D1 to the LP oxygen-supply solenoid-valve (3HT2) pin A/A
From the CREW SUPPLY pushbutton switch (2HT) pin A/D2 to the LP oxygen-supply solenoid-valve (3HT2) pin A/C, ASM 351301.

1 If the wiring is not correct:

Repair it.

(b) Do a check for a ground signal at pins A/B and A/E of the LP oxygen-supply solenoid-valve (3HT2), ASM 351301.
1 If there is no ground signal:

Repair the wiring.

(c) If the fault continues:
1 Replace the LP SOLENOID SUPPLY VALVE [3HT2] AMM 35-13-51-000-802 and AMM 35-13-51-400-802.
(d) If the fault continues:
1 Replace the P/BSW-OXYGEN/CREW SUPPLY (2HT), ASM 351301.
(e) Do the test given in Para 3.C. again.

Subtask 35-10-00-810-084-B ** ON A/C NOT FOR ALL

D. If the oxygen flow and sound decrease and stop and:
(1) The REGUL 1 LO PR indication does not come into view on the DOOR/OXY page, on the Captain oxygen system:
(a) Do a check of the wiring :

From the oxygen LP pressure-switch (4WV1) pin A/B to the SDAC-1 (1WV1) pin AA/10H, and
From the oxygen LP pressure-switch (4WV1) pin A/B to the SDAC-2 (1WV2) pin AA/10H, ASM 351301.

1 If the wiring is not correct:

Repair it.

(b) Do a check for a ground signal at pin A/A of the oxygen LP pressure-switch (4WV1), ASM 351301.
1 If there is no ground signal:

Repair the wiring.

(c) If the fault continues:
1 Replace the PRESSURE SWITCH [4WV1] AMM 35-13-14-000-802 and AMM 35-13-14-400-802.
(d) Do the test given in Para 3.C. again.
(2) The REGUL 2 LO PR indication does not come into view on the DOOR/OXY page, on the First Officer oxygen-system:
(a) Do a check of the wiring :

From the oxygen LP pressure-switch (4WV2) pin A/B to the SDAC-1 (1WV1) pin AD/8F, and
From the oxygen LP pressure-switch (4WV2) pin A/B to the SDAC-2 (1WV2) pin AD/8F, ASM 351301.

1 If the wiring is not correct:

Repair it.

(b) Do a check for a ground signal at pin A/A of the oxygen LP pressure-switch (4WV2), ASM 351301.
1 If there is no ground signal:

Repair the wiring.

(c) If the fault continues:
1 Replace the PRESSURE SWITCH [4WV2] AMM 35-13-14-000-802 and AMM 35-13-14-400-802.
(d) Do the test given in Para 3.C. again.

5. Close-up
Subtask 35-10-00-860-077-A

A. Put the aircraft back to its initial configuration.
(1) On the ECAM control panel, set the UPPER DISPLAY and LOWER DISPLAY potentiometers to OFF AMM 31-60-00-860-002.
(2) In the cockpit, on the OXYGEN section of the overhead control and indicating panel 21VU:

Make sure that the CREW SUPPLY pushbutton switch (2HT) is released (OFF legend on).

(3) De-energize the aircraft electrical circuits
AMM 24-41-00-862-002.

[Rev.8 from Aug 2018] 2026.04.04 04:33:38 UTC