W DOC AIRBUS | TSM A320F

Excessive Cabin Altitude

TASK 21-31-00-810-809-A
Excessive Cabin Altitude

1. Possible Causes
  • SKIN AIR-INLET VALVE and AIR-INLET CHECK VALVE
  • SKIN AIR-OUTLET VALVE
  • air conditioning pack ducts
  • trim air ducts
  • isolation valves
  • bleed air system
  • toilet flush valves
  • structural damage
  • cargo door seals
  • avionics compartment hatch seals
  • passenger door seals
  • emergency exit seals
  • outflow valve seals
  • emergency ram air check valve
  • hydraulic pipe connections/seals
  • water drain valves
  • outflow valve strip seal
  • PRESS CONT 1 [11HL]
  • wiring
  • PRESS CONT 2 [12HL]
  • OUTFLOW VALVE [10HL]
  • LGCIU-1 [5GA1]
  • LGCIU-2 [5GA2]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 21-26-00-810-803-A
Failure of the Skin Air-Inlet Valve
TSM TASK 21-26-00-810-804-A
Failure of the Skin Air-Outlet Valve
TSM TASK 21-31-00-810-827-A
Excessive Cabin Altitude associated with CAB PR SYS FAULT
AMM 05-53-00-780-003
Test to Measure the Structural Leakage
ASM 213100
AMM 21-31-00-100-001
Cleaning of the Moveable Seals of the Outflow-Valve
ASM 213103
CMM 213121
AMM 21-31-34-000-001
Removal of the Cabin Pressure Controller
AMM 21-31-34-400-001
Installation of the Cabin Pressure Controller
AMM 21-31-51-000-001
Removal of the Outflow Valve (From Inside)
AMM 21-31-51-000-006
Removal of the Outflow Valve (From Outside)
AMM 21-31-51-400-001
Installation of the Outflow Valve (From Inside)
AMM 21-31-51-400-006
Installation of the Outflow Valve (From Outside)
AMM 21-52-00-200-001
Detailed Inspection of the Plenum Chamber for Signs of Delamination
AMM 21-55-41-210-001
Detailed Visual Inspection of Emergency Ram-Air/Low Pressure Ground-Air Check-Valve Flappers for Condition and Operation
AMM 31-50-00-710-002
Operational Test of the Flight Warning Computer (FWC)
AMM 32-31-71-000-001
Removal of the LGCIU
AMM 32-31-71-400-001
Installation of the LGCIU
AMM 52-10-00-220-006
Detailed Inspection of Door Seals
AMM 52-21-00-200-002
Inspection of the Emergency Exit Hatch Mechanism
AMM 52-30-00-200-002
Visual Inspection of Cargo-Compartment Door Seals
AMM 52-41-00-210-001
Detailed Inspection of the Door Seals.
AMM 53-00-00-210-001
Remove and Detailed Inspection of Piston Type Drain Valves in Lower Fuselage Shell
3. Fault Confirmation
Subtask 21-31-00-710-067-A
A. Not applicable, you cannot confirm this fault on the ground.
4. Fault Isolation
Subtask 21-31-00-810-107-A
A. If the crew or the POST FLIGHT REPORT confirms the fault and the POST FLIGHT REPORT gives a maintenance message associated to the cabin pressure control system refer to (Ref. TSM TASK 21-31-00-810-827).
Subtask 21-31-00-810-214-A
B. If the crew or the POST FLIGHT REPORT confirms the fault and the POST FLIGHT REPORT gives the ECAM warning VENT BLOWER FAULT and the maintenance message SKIN AIR INLET V 15HQ:
Subtask 21-31-00-810-215-A
C. If the crew or the POST FLIGHT REPORT confirms the fault and the POST FLIGHT REPORT gives the ECAM warning VENT BLOWER FAULT and the maintenance message SKIN AIR OUTLET V 22HQ:
Subtask 21-31-00-810-068-A
D. If the crew or the POST FLIGHT REPORT confirms the fault but the POST FLIGHT REPORT gives no maintenance message associated to the cabin pressure control system or to the avionics equipment ventilation system:
   (1) Do a check for,
     (a) cracks or malfunctions of,
  • the air conditioning pack ducts ,
  • the trim air ducts , the isolation valves and the bleed air system AMM 21-52-00-200-001. toilet flush valves
     (b) correct function of the toilet system / toilet flush valves
     (c) structural damage AMM 05-53-00-780-003 and with special attention to,
   (2) If no damage is found:
     (a) compare the cabin altitude between the auto and manual mode as follows,
  • make sure that the MODE SEL pushbutton switch is in the AUTO mode,
  • on the CAB PRESS page of the lower ECAM display unit, read the CAB ALT in FT,
  • push the MODE SEL pushbutton switch to the MAN mode position (the MAN legend comes on),
  • on the CAB PRESS page, read the CAB ALT in FT. Make sure that the cabin altitude between the auto and the manual mode is +/-1000FT,
  • push the MODE SEL pushbutton switch to the AUTO mode (the MAN legend goes off).
     (b) If the difference between the auto and manual cabin altitude is more then 1000FT.
   (3) If the fault continues:
   (4) If the fault continues:
  • do a check and repair the wiring ASM 213103 from:
  • the CPC 1 (11HL) to the FWC 1 (1WW1) and FWC 2 (1WW2),
  • the CPC 1 (11HL) to the SDAC 1 (1WV1) and,
  • the CPC 1 (11HL) to the SDAC 2 (1WV2).
Subtask 21-31-00-810-069-A
E. If the crew or the POST FLIGHT REPORT confirms the fault but,
  • the outflow valve does not close during the flight and,
  • the POST FLIGHT REPORT gives no maintenance message associated to the cabin pressure control system,
   (1) Make a print out of:
  • the POST FLIGHT REPORT,
  • the CPC1 and CPC2 LAST LEG REPORT and the PREVIOUS LEG REPORT and,
  • if available the ECS REPORT 19.
   (2) Replace the PRESS CONT 1 [11HL] and the PRESS CONT 2 [12HL]
AMM 21-31-34-000-001 and,
AMM 21-31-34-400-001.
     (a) If possible do print out of the NON-VOLATILE MEMORY read-out CMM 213121.
NOTE: It is recommended to:
  • advise Airbus Industrie in case excessive cabin altitude is experienced and,
  • provide Airbus Industrie with the information given by the reports in work steps (1) and (2)(a).
   (3) Replace the OUTFLOW VALVE [10HL]
AMM 21-31-51-000-001,
AMM 21-31-51-400-001,
AMM 21-31-51-000-006 and,
AMM 21-31-51-400-006.
NOTE: It is recommended that the removed outflow valve and controllers should be returned to the vendor for a detailed examination.
Subtask 21-31-00-810-166-A
F. If the crew or the POST FLIGHT REPORT confirms the fault but the outflow valve remains open after take-off and,
  • the POST FLIGHT REPORT does not give a maintenance message associated to the cabin pressure control system,
   (1) Do a check of the wiring for open circuit or ground at the:
LGCIU-1 connector (5GA1/AB) pin C3 and,
LGCIU-2 connector (5GA2/AB) pin C3.
NOTE: Ground signal could be determined by connecting 28V with a 30 kOhm series resistance to the pin. The voltage at the pin should be less than 5V.
     (a) If there is an open circuit replace the LGCIU-1 [5GA1] or the LGCIU-2 [5GA2]
AMM 32-31-71-000-001 and,
AMM 32-31-71-400-001.
     (b) If there is no open circuit do check and repair the wiring from the:
  • CPC1 connector (11HL/AB) pin 1B to the LGCIU-1 connector (5GA1/AB) pin C3,
  • CPC2 connector (12HL/AB) pin 1B to the LGCIU-1 connector (5GA1/AB) pin C3,
  • CPC1 connector (11HL/AB) pin 2B to the LGCIU-2 connector (5GA2/AB) pin C3 and,
  • CPC2 connector (12HL/AB) pin 2B to the LGCIU-2 connector (5GA2/AB) pin C3.
    ASM 213100.
   (2) If the fault continues:
Subtask 21-31-00-810-200-A
G. If the crew or the POST FLIGHT REPORT confirms the fault but:
  • the outflow valve remains more than half open after take-off and,
  • the POST FLIGHT REPORT does not give a maintenance message associated to the cabin pressure control system,
   (1) Replace the OUTFLOW VALVE [10HL]
AMM 21-31-51-000-001,
AMM 21-31-51-400-001,
AMM 21-31-51-000-006 and,
AMM 21-31-51-400-006.
   (2) If the fault continues:
Subtask 21-31-00-810-201-A
H. If the crew or the POST FLIGHT REPORT confirms the fault but:
  • the outflow valve is less than half open after take-off and the cabin is constantly depressurized and,
  • the POST FLIGHT REPORT does not give a maintenance message associated to the cabin pressure control system,
   (1) Do a check of the wiring for open circuit or ground at the:
LGCIU-1 connector (5GA1/AB) pin C3 and,
LGCIU-2 connector (5GA2/AB) pin C3.
NOTE: Ground signal could be determined by connecting 28V with a 30 kOhm series resistance to the pin. The voltage at the pin should be less than 5V.
     (a) If there is an open circuit replace the LGCIU-1 [5GA1] or the LGCIU-2 [5GA2]
LGCIU-1 connector (5GA1/AB) pin C3 and,
LGCIU-2 connector (5GA2/AB) pin C3.
     (b) If there is an open circuit replace the LGCIU-1 [5GA1] or the LGCIU-2 [5GA2]
AMM 32-31-71-000-001 and,
AMM 32-31-71-400-001.
     (c) If there is no open circuit do check and repair the wiring from the:
  • CPC1 connector (11HL/AB) pin 1B to the LGCIU-1 connector (5GA1/AB) pin C3,
  • CPC2 connector (12HL/AB) pin 1B to the LGCIU-1 connector (5GA1/AB) pin C3,
  • CPC1 connector (11HL/AB) pin 2B to the LGCIU-2 connector (5GA2/AB) pin C3 and,
  • CPC2 connector (12HL/AB) pin 2B to the LGCIU-2 connector (5GA2/AB) pin C3.
    ASM 213100.
   (2) If the fault continues:
Subtask 21-31-00-810-202-A
I. If the crew or the POST FLIGHT REPORT confirms the fault but:
  • the outflow valve is fully closed after take-off and,
  • the POST FLIGHT REPORT does not give a maintenance message associated to the cabin pressure control system,
   (1) Do a check for,
     (a) cracks or malfunctions of,
  • the air conditioning pack ducts ,
  • the trim air ducts , the isolation valves and the bleed air system AMM 21-52-00-200-001.
     (b) structural damage AMM 05-53-00-780-003 and with special attention to,
5. Close-up
Subtask 21-31-00-860-058-A
A. Put the aircraft back to its initial configuration.
[Rev.8 from Aug 2018] 2026.04.04 04:24:41 UTC
"WTRUIB" 2025