MD83 first officer reports pressurization flow light at FL350 with the cabin climbing. A descent is ...

Narrative:

At FL350 the first officer noticed that the pressurization flow light had illuminated. The cabin was at 7;000 ft (normal) but the cabin vertical speed (V/south) was climbing at 600 FPM. The captain informed ATC that the flight would need to descend. Center turned the flight 30 left and issued a descent to FL300 and soon to FL240. The first officer pulled full spoilers and began the descent. When the thrust was pulled to idle; the cabin V/south showed a climb at the peg (at least 1;500 FPM). The first officer added enough power to bring the cabin V/south to 1;100 FPM climb and still descend about 2;500 FPM. At FL260 the cabin stabilized for about 30 seconds and then began climbing again. The crew continued the descent and received clearance to lower altitude. At 17;000 ft the cabin altitude reached 15;000 ft and the passenger oxygen masks deployed. The crew continued the descent to 13;000 ft when the cabin stabilized and began to descend at about 300 FPM. The rest of the flight was relatively normal; considering the weather conditions.[it is] unknown why the depressurization occurred. Note: the previous day on this aircraft the flow light illuminated during the descent; but the cabin V/south showed a 300 FPM descent and the cabin altitude was decreasing. The flow light went out after a couple of minutes and the arrival was uneventful. The crew oxygen masks were used intermittently during the descent.

Original NASA ASRS Text

Title: MD83 First Officer reports pressurization flow light at FL350 with the cabin climbing. A descent is initiated with ATC approval but the passenger oxygen masks deploy with the aircraft descending through 17;000 FT.

Narrative: At FL350 the First Officer noticed that the pressurization flow light had illuminated. The cabin was at 7;000 FT (normal) but the cabin vertical speed (V/S) was climbing at 600 FPM. The Captain informed ATC that the flight would need to descend. Center turned the flight 30 left and issued a descent to FL300 and soon to FL240. The First Officer pulled full spoilers and began the descent. When the thrust was pulled to idle; the cabin V/S showed a climb at the peg (at least 1;500 FPM). The First Officer added enough power to bring the cabin V/S to 1;100 FPM climb and still descend about 2;500 FPM. At FL260 the cabin stabilized for about 30 seconds and then began climbing again. The crew continued the descent and received clearance to lower altitude. At 17;000 FT the cabin altitude reached 15;000 FT and the passenger oxygen masks deployed. The crew continued the descent to 13;000 FT when the cabin stabilized and began to descend at about 300 FPM. The rest of the flight was relatively normal; considering the weather conditions.[It is] unknown why the depressurization occurred. Note: the previous day on this aircraft the FLOW light illuminated during the descent; but the cabin V/S showed a 300 FPM descent and the cabin altitude was decreasing. The FLOW light went out after a couple of minutes and the arrival was uneventful. The crew oxygen masks were used intermittently during the descent.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	944451
Time
Date	201104
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical

MD83 first officer reports pressurization flow light at FL350 with the cabin climbing. A descent is initiated with ATC approval but the passenger oxygen masks deploy with the aircraft descending through 17;000 ft.