Abnormal Flashing of the CABIN PRESSURE Warning Light Panels of the Passenger/ Crew Doors
TASK 52-73-00-810-801-A
Abnormal Flashing of the CABIN PRESSURE Warning Light Panels of the Passenger/ Crew Doors
1. Possible Causes
A. Referenced Information
3. Fault Confirmation
Subtask 52-73-00-710-050-A ** ON A/C NOT FOR ALL 4. Fault Isolation
Subtask 52-73-00-810-050-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:34:55 UTC
Abnormal Flashing of the CABIN PRESSURE Warning Light Panels of the Passenger/ Crew Doors
1. Possible Causes
- PRESS SW-CABIN PRESS DET [14WN]
- wiring
- WARN LT PNL-CABIN PRESSURE, AFT L DOOR [17WN1]
- WARN LT PNL-CABIN PRESSURE, AFT R DOOR [17WN2]
- WARN LT PNL-CABIN PRESSURE, FWD R DOOR [16WN2]
- WARN LT PNL-CABIN PRESSURE, FWD L DOOR [16WN1]
- RELAY-ENG2 ON/OFF [18WN2]
- RELAY-ENG2 OIL LOW PRESS [3EN2]
- CTL SW-ENG/MASTER 2 [2KC]
- RELAY-ENG1 ON/OFF [18WN1]
- RELAY-ENG1 OIL LOW PRESS [3EN1]
- CTL SW-ENG/MASTER 1 [3KC]
- RELAY-ENG2 OIL PRESS [11KC2]
- RELAY-ENG1 OIL PRESS [11KC1]
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| AMM 52-73-00-710-004 | Operational Test of the Cabin Overpressure Warning-System |
| ASM 527302 | |
| AMM 52-73-12-000-001 | Removal of the Cabin-Pressure Detection Pressure-Switch |
| AMM 52-73-12-400-001 | Installation of the Cabin-Pressure Detection Pressure-Switch |
| AMM 52-73-22-000-001 | Removal of the CABIN PRESSURE Warning Light Panel of the FWD Passenger/Crew Door |
| AMM 52-73-22-000-002 | Removal of the CABIN PRESSURE Warning Light Panel of the Aft Passenger/Crew Door |
| AMM 52-73-22-400-001 | Installation of the CABIN PRESSURE Warning Light Panel of the FWD Passenger/Crew Door |
| AMM 52-73-22-400-002 | Installation of the CABIN PRESSURE Warning Light Panel of the Aft Passenger/Crew Door |
| ASM 761201 | |
| ASM 793601 |
Subtask 52-73-00-710-050-A ** ON A/C NOT FOR ALL 4. Fault Isolation
Subtask 52-73-00-810-050-A ** ON A/C NOT FOR ALL
A. If the CABIN PRESSURE warning light panels flash without overpressure:
(a) Disconnect the connector of the warning light panel 17WN1.
(b) If the warning light panels of the FWD doors do not flash:
b If the warning light panels flash at the other doors:
Subtask 52-73-00-810-052-A ** ON A/C NOT FOR ALL - disconnect the cabin pressure detection pressure switch 14WN.
- replace the PRESS SW-CABIN PRESS DET [14WN] AMM 52-73-12-000-001 and AMM 52-73-12-400-001.
(a) Disconnect the connector of the warning light panel 17WN1.
(b) If the warning light panels of the FWD doors do not flash:
- do a check for a short to ground at pin D of the connector of the warning light panel 17WN1 ASM 527302.
- Do a check and repair the wiring from the warning light panel 17WN1 to the warning light panel 17WN2, pin D to pin C, ASM 527302.
- connect the connector of the warning light panel 17WN1 again and disconnect the connector of the warning light panel 17WN2.
b If the warning light panels flash at the other doors:
- replace the WARN LT PNL-CABIN PRESSURE, AFT L DOOR [17WN1] AMM 52-73-22-000-002 and AMM 52-73-22-400-002.
- replace the WARN LT PNL-CABIN PRESSURE, AFT R DOOR [17WN2] AMM 52-73-22-000-002 and AMM 52-73-22-400-002.
- disconnect the connector of the warning light panel 16WN2.
- do a check for a short to ground at pin C of the connector of the warning light panel 16WN2.
- do a check and repair the wiring from the cabin pressure detection pressure switch 14WN and the warning light panel 16WN2, pin B to pin C, ASM 527302.
- replace the WARN LT PNL-CABIN PRESSURE, FWD R DOOR [16WN2] AMM 52-73-22-000-001 and AMM 52-73-22-400-001.
- do a check for a short to ground at pin D of the connector of the warning light panel 16WN2 ASM 527302,
- disconnect the connector of the warning light panel 17WN1 and do a check for a short to ground at pin C of the connector of the warning light panel 17WN1 ASM 527302.
- do a check and repair the wiring from the warning light panel 16WN2 pin D to the warning light panel 16WN1 pin C, ASM 527302.
- do a check and repair the wiring from the warning light panel 16WN1 pin D to the warning light panel 17WN1 pin C, ASM 527302.
- replace the WARN LT PNL-CABIN PRESSURE, FWD L DOOR [16WN1] AMM 52-73-22-000-001 and AMM 52-73-22-400-001.
B. If the CABIN PRESSURE warning light panels flash or do not flash with overpressure:
Subtask 52-73-00-810-052-B ** ON A/C NOT FOR ALL - disconnect the connector of the cabin pressure detection pressure switch 14WN and install a jumper wire between pin B and C.
- replace the PRESS SW-CABIN PRESS DET [14WN] AMM 52-73-12-000-001 and AMM 52-73-12-400-001.
- connect the connector of the cabin pressure detection pressure switch 14WN again and disconnect pin A/B of the relay 18WN1.
- connect pin A/B of the relay 18WN1 again,
- disconnect pin A/Z of the relay 3EN2,
- do a check for 28VDC at the relay 18WN2 pin A/X.
- do a check for ground at pin G of the connector of the warning light panel 16WN1.
- replace the RELAY-ENG2 ON/OFF [18WN2] ASM 527302.
- repair the wiring ASM 527302 between:
.the warning light panel 16WN1 pin G and the relay 18WN2 pin A/B
.the relay 18WN2 pin A/3 and the ground.
- replace the RELAY-ENG2 OIL LOW PRESS [3EN2] ASM 793601.
- repair the wiring ASM 527302 between:
.the relay 3EN2 pin A/1 and the circuit breaker 2EN2
.the relay 3EN2 pin A/A and the relay 18WN2 pin A/X.
- connect pin A/Z of the relay 3EN2 again,
- replace the CTL SW-ENG/MASTER 2 [2KC] ASM 761201.
- repair the wiring ASM 793601 between:
.the control switch 2KC pin 3A and the relay 3EN2 pin A/Z
.the control switch 2KC pin 1A and the ground.
- connect pin A/B of the relay 18WN1 again,
- disconnect pin A/Z of the relay 3EN1,
- do a check for 28VDC at the relay 18WN1 pin A/X.
- do a check for ground at pin G of the connector of the warning light panel 16WN1.
- replace the RELAY-ENG1 ON/OFF [18WN1] ASM 527302.
- repair the wiring ASM 527302 between:
.the warning light panel 16WN1 pin G and the relay 18WN1 pin A/B
.the relay 18WN1 pin A/3 and the ground.
- replace the RELAY-ENG1 OIL LOW PRESS [3EN1] ASM 793601.
- repair the wiring ASM 527302 between:
.the relay 3EN1 pin A/1 and the circuit breaker 2EN1
.the relay 3EN1 pin A/A and the relay 18WN1 pin A/X.
- connect pin A/Z of the relay 3EN1 again,
- replace the CTL SW-ENG/MASTER 1 [3KC] ASM 761201.
- repair the wiring ASM 793601 between:
.the control switch 3KC pin 3A and the relay 3EN1 pin A/Z
.the control switch 3KC pin 1A and the ground.
B. If the CABIN PRESSURE warning light panels flash or do not flash with overpressure:
Subtask 52-73-00-710-051-A ** ON A/C NOT FOR ALL - Disconnect the connector of the cabin pressure detection pressure switch 14WN and install a jumper wire between pin B and C.
- Replace the PRESS SW-CABIN PRESS DET [14WN] AMM 52-73-12-000-001 and AMM 52-73-12-400-001.
- Connect the connector of the cabin pressure detection pressure switch 14WN again and disconnect pin A/B of the relay 18WN1.
- Connect pin A/B of the relay 18WN1 again,
- Disconnect pin A/Z of the relay 11KC2,
- Do a check for 28VDC at the relay 18WN2 pin A/X.
- Do a check for ground at pin G of the connector of the warning light panel 16WN1.
- Replace the RELAY-ENG2 ON/OFF [18WN2] ASM 527302.
- Repair the wiring ASM 527302 between:
.the warning light panel 16WN1 pin G and the relay 18WN2 pin A/B
.the relay 18WN2 pin A/3 and the ground.
- Replace the RELAY-ENG2 OIL PRESS [11KC2] ASM 761201.
- Repair the wiring ASM 527302 between:
.the relay 11KC2 pin A/1 and the circuit breaker 10KC2
.the relay 11KC2 pin A/A and the relay 18WN2 pin A/X.
- Connect pin A/Z of the relay 11KC2 again,
- Replace the CTL SW-ENG/MASTER 2 [2KC] ASM 761201.
- Repair the wiring ASM 761201 between:
.the control switch 2KC pin 3A and the relay 11KC2 pin A/Z
.the control switch 2KC pin 1A and the ground.
- Connect pin A/B of the relay 18WN1 again,
- Disconnect pin A/Z of the relay 11KC1,
- Do a check for 28VDC at the relay 18WN1 pin A/X.
- do a check for ground at pin G of the connector of the warning light panel 16WN1.
- Replace the RELAY-ENG1 ON/OFF [18WN1] ASM 527302.
- Repair the wiring ASM 527302 between:
.the warning light panel 16WN1 pin G and the relay 18WN1 pin A/B
.the relay 18WN1 pin A/3 and the ground.
- Replace the RELAY-ENG1 OIL PRESS [11KC1] ASM 761201.
- Repair the wiring ASM 527302 between:
.the relay 11KC1 pin A/1 and the circuit breaker 10KC1
.the relay 11KC1 pin A/A and the relay 18WN1 pin A/X.
- Connect pin A/Z of the relay 11KC1 again,
- Replace the CTL SW-ENG/MASTER 1 [3KC] ASM 761201.
- Repair the wiring ASM 761201 between:
.the control switch 3KC pin 3A and the relay 11KC1 pin A/Z
.the control switch 3KC pin 1A and the ground.
C. After the subsequent flight, make sure that the fault does not continue.