Narrative:

On climb out, the right engine bleed tripped. The bleed valve would not reset, so in accordance with the appropriate abnormal procedure, I said to reduce right engine power in an attempt to reset the valve. It still did not reset. However, the cabin altitude appeared to be normal so we continued to climb. I recall checking, cabin altitude at FL230 read approximately 3500 ft. At approximately FL280, the cabin altitude warning sounded. The cabin gauge indicated 9500 ft. We selected standby mode on the pressurization controller and the cabin started descending at approximately 800 FPM. I was cleared to FL240. During descent, cabin altitude appeared to be under control, so we leveled at FL240. The first officer called the flight attendants to inform them of the pressurization problem. We were then informed that some passenger were feeling sick and passing out. An emergency was declared, descent to 10000 ft was accomplished. We requested to divert to orlando (the closest airport). Subsequent cabin reports indicated that the passenger who had experienced difficulty were improving. Company personnel at orlando were informed and we requested paramedics to meet the aircraft. An uneventful landing was accomplished. Right bleed valve did reset during descent at approximately 8000 ft. Preliminary maintenance investigation revealed left pack partial failure. An impeller in air cycle machine failed resulting in diminished air output. 3 of 118 passenger experienced difficulties. One was 41 yrs old, asthmatic, who apparently passed out. Another had dental work day prior and third medics examined -- nasal congestion. Supplemental information from acn 264312: the aircraft handbook stated that 1 pack should be adequate in normal circumstances and gave no altitude restriction. Maintenance found a bad impeller in the left pack which restr its airflow. That is why the left pack could not hold cabin pressurization after the right pack was lost. 1 lady elected to go to the hospital but was back in time to fly to clt with us in a replacement aircraft.

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Original NASA ASRS Text

Title: MLG HAS ENG BLEED VALVE TRIP. UNABLE RESET, CABIN ALT CLBS. DSND.

Narrative: ON CLBOUT, THE R ENG BLEED TRIPPED. THE BLEED VALVE WOULD NOT RESET, SO IN ACCORDANCE WITH THE APPROPRIATE ABNORMAL PROC, I SAID TO REDUCE R ENG PWR IN AN ATTEMPT TO RESET THE VALVE. IT STILL DID NOT RESET. HOWEVER, THE CABIN ALT APPEARED TO BE NORMAL SO WE CONTINUED TO CLB. I RECALL CHKING, CABIN ALT AT FL230 READ APPROX 3500 FT. AT APPROX FL280, THE CABIN ALT WARNING SOUNDED. THE CABIN GAUGE INDICATED 9500 FT. WE SELECTED STANDBY MODE ON THE PRESSURIZATION CTLR AND THE CABIN STARTED DSNDING AT APPROX 800 FPM. I WAS CLRED TO FL240. DURING DSCNT, CABIN ALT APPEARED TO BE UNDER CTL, SO WE LEVELED AT FL240. THE FO CALLED THE FLT ATTENDANTS TO INFORM THEM OF THE PRESSURIZATION PROB. WE WERE THEN INFORMED THAT SOME PAX WERE FEELING SICK AND PASSING OUT. AN EMER WAS DECLARED, DSCNT TO 10000 FT WAS ACCOMPLISHED. WE REQUESTED TO DIVERT TO ORLANDO (THE CLOSEST ARPT). SUBSEQUENT CABIN RPTS INDICATED THAT THE PAX WHO HAD EXPERIENCED DIFFICULTY WERE IMPROVING. COMPANY PERSONNEL AT ORLANDO WERE INFORMED AND WE REQUESTED PARAMEDICS TO MEET THE ACFT. AN UNEVENTFUL LNDG WAS ACCOMPLISHED. R BLEED VALVE DID RESET DURING DSCNT AT APPROX 8000 FT. PRELIMINARY MAINT INVESTIGATION REVEALED L PACK PARTIAL FAILURE. AN IMPELLER IN AIR CYCLE MACHINE FAILED RESULTING IN DIMINISHED AIR OUTPUT. 3 OF 118 PAX EXPERIENCED DIFFICULTIES. ONE WAS 41 YRS OLD, ASTHMATIC, WHO APPARENTLY PASSED OUT. ANOTHER HAD DENTAL WORK DAY PRIOR AND THIRD MEDICS EXAMINED -- NASAL CONGESTION. SUPPLEMENTAL INFORMATION FROM ACN 264312: THE ACFT HANDBOOK STATED THAT 1 PACK SHOULD BE ADEQUATE IN NORMAL CIRCUMSTANCES AND GAVE NO ALT RESTRICTION. MAINT FOUND A BAD IMPELLER IN THE L PACK WHICH RESTR ITS AIRFLOW. THAT IS WHY THE L PACK COULD NOT HOLD CABIN PRESSURIZATION AFTER THE R PACK WAS LOST. 1 LADY ELECTED TO GO TO THE HOSPITAL BUT WAS BACK IN TIME TO FLY TO CLT WITH US IN A REPLACEMENT ACFT.

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.