Narrative:

On a climb to FL390, we were stopped at FL270 by ATC for other traffic. The cabin was holding 6000 ft, which it was set for. The cabin started to climb and when the cabin reached 7000 ft, I could not control the cabin rate. We asked ATC for lower due to pressurization problems. They told us to descend to 10000 ft and after we started the descent, the cabin continued to climb. The cabin climbed to 10000 ft, and by the time the cabin reacted maximum differential we were leveling at 10000 ft. We asked to return to our home base (bdl). ATC asked if we were declaring an emergency. We said no, and ATC gave us vectors back to bdl at 8000 ft. After landing, maintenance looked at problem. Callback conversation with reporter revealed the following information: the reporter stated the maintenance department replaced a pressurization controller for a previous report and left the ground mode test switches in the test position. The reporter said the flight crew missed the position of the switches on the cockpit preflight check.

Related reports:

Google
 

Original NASA ASRS Text

Title: A BAE125 IN CLB AT FL270 DIVERTED DUE TO INABILITY TO CTL CABIN PRESSURE CAUSED BY MAINT LEAVING GND TEST SWITCHES TO GND MODE.

Narrative: ON A CLB TO FL390, WE WERE STOPPED AT FL270 BY ATC FOR OTHER TFC. THE CABIN WAS HOLDING 6000 FT, WHICH IT WAS SET FOR. THE CABIN STARTED TO CLB AND WHEN THE CABIN REACHED 7000 FT, I COULD NOT CTL THE CABIN RATE. WE ASKED ATC FOR LOWER DUE TO PRESSURIZATION PROBS. THEY TOLD US TO DSND TO 10000 FT AND AFTER WE STARTED THE DSCNT, THE CABIN CONTINUED TO CLB. THE CABIN CLBED TO 10000 FT, AND BY THE TIME THE CABIN REACTED MAX DIFFERENTIAL WE WERE LEVELING AT 10000 FT. WE ASKED TO RETURN TO OUR HOME BASE (BDL). ATC ASKED IF WE WERE DECLARING AN EMER. WE SAID NO, AND ATC GAVE US VECTORS BACK TO BDL AT 8000 FT. AFTER LNDG, MAINT LOOKED AT PROB. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE MAINT DEPT REPLACED A PRESSURIZATION CONTROLLER FOR A PREVIOUS RPT AND LEFT THE GND MODE TEST SWITCHES IN THE TEST POS. THE RPTR SAID THE FLC MISSED THE POS OF THE SWITCHES ON THE COCKPIT PREFLT CHK.

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.