Narrative:

While in cruise at FL350, flight attendants called to complain that it was cold in aft cabin. At the time both pack temperature controllers were in automatic and both indicated 110 degrees duct temperature and 72 degrees cabin temperature. First officer selected a higher automatic setting on right pack but 2 mins later flight attendants again called to say that it was getting even colder. Right temperatures remained the same, so first officer turned temperature up again with no effect. When flight attendants called a third time, he went to manual on right pack in an effort to get it to move up from 110 degrees but it immediately jumped to 150 degrees -- full scale. All attempts to lower temperature failed, so we initiated a descent to FL240 in anticipation of losing the pack. As we descended, the right pack did trip off and the cabin altitude started a climb of at least 1500 FPM -- full scale. At FL240 the cabin continued to climb, now passing 10000 ft, so we declared an emergency and continued descent to 10000 ft MSL. During the descent, the cabin passed through 14000 ft which initiated the passenger oxygen system. All attempts to restore packs failed. ATC indicated that ama was the closest suitable airport to our location, so we proceeded there and executed an uneventful approach and landing. Passenger were immediately xferred to an outgoing dfw flight and later that night the first officer and I ferried the aircraft to ZZZ. Callback conversation with reporter revealed the following information: the reporter stated the direct cause of the loss of cabin pressure was the failure of the right and left air conditioning pack system. The reporter said the right pack trip was caused by an overheat condition but the cause of the left pack malfunction is unknown. The reporter said maintenance does not routinely feedback information on the malfunctioning component or repair accomplishment.

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Original NASA ASRS Text

Title: AN MD80 IN CRUISE AT FL350 DECLARED AN EMER AND DIVERTED DUE LOSS OF CABIN PRESSURE CAUSED BY THE R AND L PACK FAILURE.

Narrative: WHILE IN CRUISE AT FL350, FLT ATTENDANTS CALLED TO COMPLAIN THAT IT WAS COLD IN AFT CABIN. AT THE TIME BOTH PACK TEMP CONTROLLERS WERE IN AUTO AND BOTH INDICATED 110 DEGS DUCT TEMP AND 72 DEGS CABIN TEMP. FO SELECTED A HIGHER AUTO SETTING ON R PACK BUT 2 MINS LATER FLT ATTENDANTS AGAIN CALLED TO SAY THAT IT WAS GETTING EVEN COLDER. R TEMPS REMAINED THE SAME, SO FO TURNED TEMP UP AGAIN WITH NO EFFECT. WHEN FLT ATTENDANTS CALLED A THIRD TIME, HE WENT TO MANUAL ON R PACK IN AN EFFORT TO GET IT TO MOVE UP FROM 110 DEGS BUT IT IMMEDIATELY JUMPED TO 150 DEGS -- FULL SCALE. ALL ATTEMPTS TO LOWER TEMP FAILED, SO WE INITIATED A DSCNT TO FL240 IN ANTICIPATION OF LOSING THE PACK. AS WE DSNDED, THE R PACK DID TRIP OFF AND THE CABIN ALT STARTED A CLB OF AT LEAST 1500 FPM -- FULL SCALE. AT FL240 THE CABIN CONTINUED TO CLB, NOW PASSING 10000 FT, SO WE DECLARED AN EMER AND CONTINUED DSCNT TO 10000 FT MSL. DURING THE DSCNT, THE CABIN PASSED THROUGH 14000 FT WHICH INITIATED THE PAX OXYGEN SYS. ALL ATTEMPTS TO RESTORE PACKS FAILED. ATC INDICATED THAT AMA WAS THE CLOSEST SUITABLE ARPT TO OUR LOCATION, SO WE PROCEEDED THERE AND EXECUTED AN UNEVENTFUL APCH AND LNDG. PAX WERE IMMEDIATELY XFERRED TO AN OUTGOING DFW FLT AND LATER THAT NIGHT THE FO AND I FERRIED THE ACFT TO ZZZ. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE DIRECT CAUSE OF THE LOSS OF CABIN PRESSURE WAS THE FAILURE OF THE R AND L AIR CONDITIONING PACK SYS. THE RPTR SAID THE R PACK TRIP WAS CAUSED BY AN OVERHEAT CONDITION BUT THE CAUSE OF THE L PACK MALFUNCTION IS UNKNOWN. THE RPTR SAID MAINT DOES NOT ROUTINELY FEEDBACK INFO ON THE MALFUNCTIONING COMPONENT OR REPAIR ACCOMPLISHMENT.

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.