MD-82
Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Other / Unknown
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance; Flight Crew Overcame Equipment Problem; General Maintenance Action; General Declared Emergency
Aircraft; Weather
On this flight; while level at FL270; we experienced a dual pack shutdown and as a result; declared an emergency in order to start a expedited descent to a lower altitude. At the time the packs shut down we had just finished deviating around rain showers; had just broken out into the clear and were in the process of securing the Anti-Ice System. Prior to the packs shutting down we had been in icing conditions with the complete Anti-Ice System turned on. The system had been turned on prior to entering the area of precipitation and had been on for at least 20-25 minutes by the time we exited icing conditions and this event occurred. We never had any indications of a problem with the system. After breaking out into the clear I ran the tail de-ice and at some point during the process I noticed the pressurization flow light had illuminated. Still with no indications of any issues with the Anti-Ice System I initially assumed the flow light had illuminated due to the system switching between the tail and wing; a temporary anomaly. It became obvious after a short period of time that the cabin was continuing to climb and both packs had inexplicably shut down. I immediately asked ATC for a descent and then decided to declare an emergency to make sure we got down before the cabin reached 10;000 feet. At approximately 16;000 feet I noticed the Left Pack had started working again and had the FO level the aircraft there. A short time later the Right Pack came back online. I told ATC that we were no longer an emergency aircraft and started a gradual climb back up to our cruising altitude of FL300. The cabin never climbed above approximately 7000-7500 feet. I called Dispatch on the phone to let them know of our situation and we agreed that since the Pressurization System had stabilized and we had enough fuel we would continue to ZZZ. We landed at ZZZ with just under 6000 pounds. The aircraft was taken out of service with the cause yet to be determined as I complete this report.
A Captain reports about a dual Air Conditioning Pack shutdown in flight at FL270; resulting in an emergency descent. The MD-82 aircraft had just exited icing conditions with the complete Anti-Ice System turned on. At approximately 16;000 FT the Left and Right Packs came back online. Aircraft was removed from service after arrival.