An air carrier first officer reported being dispatched with the left pack inop and losing the right ...

Narrative:

Just as we were leveling off at FL250; the captain and I were monitoring the ecs page; as we had only one working pack and wanted to monitor the aircraft pressurization. We noticed that the right 10th stage bleed valve had closed without any input from the crew and the right pack had subsequently turned off. We referenced the QRH and attempted to re-open the 10th stage bleed valve as well as the 10th stage isol valve. Neither valve responded to our inputs and both remained closed. Since the left pack was on MEL the cabin began to climb at a rate of approximately 600-800 feet per minute. I contacted ATC and told them we required 10000' and the captain began the descent. Upon passing thru 15000' we switched the pack bleed to the APU. We then regained pressurization and decided to divert.

Original NASA ASRS Text

Title: An Air Carrier First Officer reported being dispatched with the left pack Inop and losing the right pack when the bleed valve failed. They regained the pack by starting the APU and then diverted.

Narrative: Just as we were leveling off at FL250; the Captain and I were monitoring the ECS page; as we had only one working pack and wanted to monitor the aircraft pressurization. We noticed that the right 10th stage bleed valve had closed without any input from the crew and the right pack had subsequently turned off. We referenced the QRH and attempted to re-open the 10th stage bleed valve as well as the 10th stage ISOL valve. Neither valve responded to our inputs and both remained closed. Since the left pack was on MEL the cabin began to climb at a rate of approximately 600-800 feet per minute. I contacted ATC and told them we required 10000' and the captain began the descent. Upon passing thru 15000' we switched the pack bleed to the APU. We then regained pressurization and decided to divert.

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	854847
Time
Date	200910
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	Regional Jet 200 ER/LR (CRJ200)
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Component
Aircraft Component	Pneumatic System
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Commercial
Events
Anomaly	Aircraft Equipment Problem Critical

An air carrier first officer reported being dispatched with the left pack inop and losing the right pack when the bleed valve failed. They regained the pack by starting the APU and then diverted.