Narrative:

During the initial climb we were cleared on course and to maintain 280 KTS. Cabin altitude and pressure differential were normal through FL180. Passing FL200 the cabin altitude light illuminated. The cabin altitude then indicated 9;500 ft.we declared an emergency and initiated an emergency descent to 10;000 MSL. We conducted associated checklists and the cabin altitude did not get above 9;500 ft. We leveled at 10;000; and were later cleared to 6;000 ft and given a turn to intercept the localizer for the ILS 25R at our departure airport. We flew the ILS to an uneventful overweight landing at 150;500 pounds and with negligible vertical speed at touchdown. We rolled out long and applied reverse thrust and minimum necessary breaking. During the parking checklist we kept the cabin doors closed due to residual [negative] cabin pressure. I kept the flight attendants and ground personnel away from the cabin doors until the cabin pressure reached air field elevation. While the cabin pressure slowly bled down ground power was plugged in. Shortly after the ground electric was plugged in the cabin pressure dumped and one passenger ruptured her ear drum(s). Operations were notified and crash fire rescue equipment sent an ambulance to assist. The passenger; crash fire rescue equipment personnel and an accompanying agent were gone before our post flight checks were completed.while I was making logbook entries several maintenance personnel swarmed the aircraft. Maintenance advised both pressurization controllers had failed and that the aircraft had an extensive history of pressurization problems.

Google
 

Original NASA ASRS Text

Title: Upon discovery of rapidly rising and uncontrollable cabin altitude; an MD-80 flight crew declared an emergency; descended to 10;000 MSL and returned to their departure airport where the cabin retained significant negative pressure for a period of time until it dumped explosively damaging the ear drums of at least one passenger.

Narrative: During the initial climb we were cleared on course and to maintain 280 KTS. Cabin altitude and pressure differential were normal through FL180. Passing FL200 the cabin altitude light illuminated. The cabin altitude then indicated 9;500 FT.We declared an emergency and initiated an emergency descent to 10;000 MSL. We conducted associated checklists and the cabin altitude did not get above 9;500 FT. We leveled at 10;000; and were later cleared to 6;000 FT and given a turn to intercept the localizer for the ILS 25R at our departure airport. We flew the ILS to an uneventful overweight landing at 150;500 LBS and with negligible vertical speed at touchdown. We rolled out long and applied reverse thrust and minimum necessary breaking. During the parking checklist we kept the cabin doors closed due to residual [negative] cabin pressure. I kept the flight attendants and ground personnel away from the cabin doors until the cabin pressure reached air field elevation. While the cabin pressure slowly bled down ground power was plugged in. Shortly after the ground electric was plugged in the cabin pressure dumped and one passenger ruptured her ear drum(s). Operations were notified and CFR sent an ambulance to assist. The passenger; CFR personnel and an accompanying agent were gone before our post flight checks were completed.While I was making logbook entries several Maintenance Personnel swarmed the aircraft. Maintenance advised both pressurization controllers had failed and that the aircraft had an extensive history of pressurization problems.

Data retrieved from NASA's ASRS site as of July 2013 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.