Narrative:

At cruise; level FL360; the red cabin altitude horn and warning light illuminated to alert us to the fact that the cabin was climbing above 10000 ft. We were on automatic controller #2. We donned our masks and performed the qrc for rapid decompression; down to performing a rapid descent due to uncontrollable cabin. The cabin at the time was climbing 300-500 FPM. We asked ATC for a lower altitude; and started down using flight level change and a 2000 FPM rate of descent. The first officer looked for reference action items checklist; but there is none. I switched to automatic controller #1 in attempt to arrest the cabin. It initially started to drive the cabin down; but then was ineffective as well. I then switched to manual. At that point; the cabin control fail EICAS light illuminated due to placing the switch in manual. We were able to start bringing the cabin down using manual. We leveled off at FL240; after bringing the cabin down to 5500 ft or so. The first officer assumed flying and ATC communication duties while I called dispatch and maintenance. At that time; we had the EICAS amber message and 2 status messages for #1 and #1 automatic controller failure. We discussed the previous log history of pressurization failure on the day previous for which maintenance had replaced one of the automatic controllers. Maintenance pointed out that the only common element between the automatic controllers was the drive motor to the outflow valve. As the manual mode uses a separate dc motor; and it seemed to be functioning properly; we all agreed to continue to ZZZ1. Maintenance offered to put the write-up in the logbook for us. We climbed back to FL340 and continued without further incident to ZZZ1; after writing up the first officer oxygen mask microphone. When we got to ZZZ1; maintenance was unaware of the problem and maintenance control had not made the entry into the logbook. We spoke to ZZZ1 about the issue; and also briefed the outgoing crew. On the way to the hotel; I called maintenance control and asked why the item had not been entered. In both cases; the shift had changed; and I spoke with different individuals. The maintenance controller that I spoke to said that he would make the proper entry. I thanked him and let him know that we would be filing this report. A couple of questions for the fleet -- we did not get the EICAS cabin altitude control fail until we put the switch to manual. That is the checklist that directs you to try manual. I would suggest that the fleet perhaps mention this checklist in reference action items for the qrc. More on this next week! Thank you!

Related reports:

Google
 

Original NASA ASRS Text

Title: B757-200 EXPERIENCED FAILURE OF BOTH PRESSURIZATION AUTO CONTROLLERS. FLT CREW DESCENDED AND WAS ABLE TO CONTROL CABIN MANUALLY; SO FLT WAS CONTINUED TO DEST.

Narrative: AT CRUISE; LEVEL FL360; THE RED CABIN ALT HORN AND WARNING LIGHT ILLUMINATED TO ALERT US TO THE FACT THAT THE CABIN WAS CLBING ABOVE 10000 FT. WE WERE ON AUTO CONTROLLER #2. WE DONNED OUR MASKS AND PERFORMED THE QRC FOR RAPID DECOMPRESSION; DOWN TO PERFORMING A RAPID DSCNT DUE TO UNCTLABLE CABIN. THE CABIN AT THE TIME WAS CLBING 300-500 FPM. WE ASKED ATC FOR A LOWER ALT; AND STARTED DOWN USING FLT LEVEL CHANGE AND A 2000 FPM RATE OF DSCNT. THE FO LOOKED FOR REF ACTION ITEMS CHKLIST; BUT THERE IS NONE. I SWITCHED TO AUTO CONTROLLER #1 IN ATTEMPT TO ARREST THE CABIN. IT INITIALLY STARTED TO DRIVE THE CABIN DOWN; BUT THEN WAS INEFFECTIVE AS WELL. I THEN SWITCHED TO MANUAL. AT THAT POINT; THE CABIN CONTROL FAIL EICAS LIGHT ILLUMINATED DUE TO PLACING THE SWITCH IN MANUAL. WE WERE ABLE TO START BRINGING THE CABIN DOWN USING MANUAL. WE LEVELED OFF AT FL240; AFTER BRINGING THE CABIN DOWN TO 5500 FT OR SO. THE FO ASSUMED FLYING AND ATC COM DUTIES WHILE I CALLED DISPATCH AND MAINT. AT THAT TIME; WE HAD THE EICAS AMBER MESSAGE AND 2 STATUS MESSAGES FOR #1 AND #1 AUTO CONTROLLER FAILURE. WE DISCUSSED THE PREVIOUS LOG HISTORY OF PRESSURIZATION FAILURE ON THE DAY PREVIOUS FOR WHICH MAINT HAD REPLACED ONE OF THE AUTO CONTROLLERS. MAINT POINTED OUT THAT THE ONLY COMMON ELEMENT BTWN THE AUTO CONTROLLERS WAS THE DRIVE MOTOR TO THE OUTFLOW VALVE. AS THE MANUAL MODE USES A SEPARATE DC MOTOR; AND IT SEEMED TO BE FUNCTIONING PROPERLY; WE ALL AGREED TO CONTINUE TO ZZZ1. MAINT OFFERED TO PUT THE WRITE-UP IN THE LOGBOOK FOR US. WE CLBED BACK TO FL340 AND CONTINUED WITHOUT FURTHER INCIDENT TO ZZZ1; AFTER WRITING UP THE FO OXYGEN MASK MIKE. WHEN WE GOT TO ZZZ1; MAINT WAS UNAWARE OF THE PROB AND MAINT CTL HAD NOT MADE THE ENTRY INTO THE LOGBOOK. WE SPOKE TO ZZZ1 ABOUT THE ISSUE; AND ALSO BRIEFED THE OUTGOING CREW. ON THE WAY TO THE HOTEL; I CALLED MAINT CTL AND ASKED WHY THE ITEM HAD NOT BEEN ENTERED. IN BOTH CASES; THE SHIFT HAD CHANGED; AND I SPOKE WITH DIFFERENT INDIVIDUALS. THE MAINT CTLR THAT I SPOKE TO SAID THAT HE WOULD MAKE THE PROPER ENTRY. I THANKED HIM AND LET HIM KNOW THAT WE WOULD BE FILING THIS RPT. A COUPLE OF QUESTIONS FOR THE FLEET -- WE DID NOT GET THE EICAS CABIN ALT CTL FAIL UNTIL WE PUT THE SWITCH TO MANUAL. THAT IS THE CHKLIST THAT DIRECTS YOU TO TRY MANUAL. I WOULD SUGGEST THAT THE FLEET PERHAPS MENTION THIS CHKLIST IN REF ACTION ITEMS FOR THE QRC. MORE ON THIS NEXT WK! THANK YOU!

Data retrieved from NASA's ASRS site as of January 2009 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.