Narrative:

Electronic centralized aircraft monitoring (ECAM) pressurization #2 control failure -- no automatic switching to #1. Drove outflow valve full open, caused cabin vertical speed to climb approximately 7000 FPM. Cabin above 10000 ft, donned oxygen masks and started emergency descent. Cabin exceeded 14700 ft, passenger masks deployed. Notified ATC of descent and emergency. Descending through 34300 ft got TA on TCASII, leveled off, saw aircraft on TCASII go by. No loss of separation and continued descent to 9000 ft. Aircraft structure ok, landed overweight at 143400 pounds (maximum 142200 pounds). All passenger and flight attendants ok. A turn sooner off airway would have provided more vertical separation. Opposing aircraft at 33000 ft. Callback conversation with reporter revealed the following information: the reporter stated the aircraft, an airbus A320, was a relatively new airplane with all the latest modifications and updated computers. The reporter said two previous log entries indicated that cabin pressure was lost but both reports were signed off as ground checks ok. The reporter said the aircraft was at FL350 when the ECAM warning advised the #2 pressurization system failed and immediately the outflow valve went to full open depressurizing the cabin. The reporter said the system is supposed to switch electronically to the #1 system to prevent depressurization but it is suspected that the switch timing is too slow. The reporter said after the diversion and the replacement of the #2 pressure controller the flight crew maintenance ferried the aircraft to the air carrier overhaul facility and was OTS for a period of time and then was returned to service again with the ground checks ok signoff. The reporter stated the next flight was a short 400 mi trip that was uneventful but on the return flight the cabin again lost pressurization with an ECAM #2 fail indication. The reporter said a conference call was arranged with all the capts who flew this aircraft and others who experienced A320 cabin pressure system failures and the details were in accordance with what the reporter experienced. The reporter stated that to the reporter's knowledge the problem has not been solved. Supplemental data received from maintenance indicates the #2 pressure controller removed at the diversion station was reinstalled in the aircraft at the air carrier overhaul facility in error and this unit was the cause of two depressurization incidents.

Related reports:

Google
 

Original NASA ASRS Text

Title: AN AIRBUS A320 IN CRUISE AT FL350 DECLARED AN EMER AND MADE AN EMER DSCNT DUE TO INSTANTANEOUS LOSS OF CABIN PRESSURE.

Narrative: ELECTRONIC CENTRALIZED ACFT MONITORING (ECAM) PRESSURIZATION #2 CTL FAILURE -- NO AUTO SWITCHING TO #1. DROVE OUTFLOW VALVE FULL OPEN, CAUSED CABIN VERT SPD TO CLB APPROX 7000 FPM. CABIN ABOVE 10000 FT, DONNED OXYGEN MASKS AND STARTED EMER DSCNT. CABIN EXCEEDED 14700 FT, PAX MASKS DEPLOYED. NOTIFIED ATC OF DSCNT AND EMER. DSNDING THROUGH 34300 FT GOT TA ON TCASII, LEVELED OFF, SAW ACFT ON TCASII GO BY. NO LOSS OF SEPARATION AND CONTINUED DSCNT TO 9000 FT. ACFT STRUCTURE OK, LANDED OVERWT AT 143400 LBS (MAX 142200 LBS). ALL PAX AND FLT ATTENDANTS OK. A TURN SOONER OFF AIRWAY WOULD HAVE PROVIDED MORE VERT SEPARATION. OPPOSING ACFT AT 33000 FT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT, AN AIRBUS A320, WAS A RELATIVELY NEW AIRPLANE WITH ALL THE LATEST MODIFICATIONS AND UPDATED COMPUTERS. THE RPTR SAID TWO PREVIOUS LOG ENTRIES INDICATED THAT CABIN PRESSURE WAS LOST BUT BOTH RPTS WERE SIGNED OFF AS GND CHKS OK. THE RPTR SAID THE ACFT WAS AT FL350 WHEN THE ECAM WARNING ADVISED THE #2 PRESSURIZATION SYS FAILED AND IMMEDIATELY THE OUTFLOW VALVE WENT TO FULL OPEN DEPRESSURIZING THE CABIN. THE RPTR SAID THE SYS IS SUPPOSED TO SWITCH ELECTRONICALLY TO THE #1 SYS TO PREVENT DEPRESSURIZATION BUT IT IS SUSPECTED THAT THE SWITCH TIMING IS TOO SLOW. THE RPTR SAID AFTER THE DIVERSION AND THE REPLACEMENT OF THE #2 PRESSURE CTLR THE FLC MAINT FERRIED THE ACFT TO THE ACR OVERHAUL FACILITY AND WAS OTS FOR A PERIOD OF TIME AND THEN WAS RETURNED TO SVC AGAIN WITH THE GND CHKS OK SIGNOFF. THE RPTR STATED THE NEXT FLT WAS A SHORT 400 MI TRIP THAT WAS UNEVENTFUL BUT ON THE RETURN FLT THE CABIN AGAIN LOST PRESSURIZATION WITH AN ECAM #2 FAIL INDICATION. THE RPTR SAID A CONFERENCE CALL WAS ARRANGED WITH ALL THE CAPTS WHO FLEW THIS ACFT AND OTHERS WHO EXPERIENCED A320 CABIN PRESSURE SYS FAILURES AND THE DETAILS WERE IN ACCORDANCE WITH WHAT THE RPTR EXPERIENCED. THE RPTR STATED THAT TO THE RPTR'S KNOWLEDGE THE PROB HAS NOT BEEN SOLVED. SUPPLEMENTAL DATA RECEIVED FROM MAINT INDICATES THE #2 PRESSURE CTLR REMOVED AT THE DIVERSION STATION WAS REINSTALLED IN THE ACFT AT THE ACR OVERHAUL FACILITY IN ERROR AND THIS UNIT WAS THE CAUSE OF TWO DEPRESSURIZATION INCIDENTS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.