Narrative:

After takeoff from ZZZ1 at XA00 local; while in climb and transitioning from APU air to engine bleed air we had a left acu over pressure. After consulting and completing the checklist for this procedure we continued as planned. After approximately 10 mins into flight we had a wow (weight on wheels) input failure light. This indication went away within approximately 10 mins. As we continued on our planned flight at FL340 all was normal. Approximately 2 hours into the flight at FL340 we had an indication that the cabin pressure was rising. As the PF I elected to descend to FL240. At FL240 the cabin continued to climb. It was obvious at this point the automatic cabin controller was not functioning properly. With this information and with 1 acu shut down already due to the overpressure plus in wow input failure light situation we decided to continue the descent to 10000 ft and divert to ZZZ2. When we leveled at 10000 ft the cabin was at or near the cabin limit of about 8800 ft. Differential cabin pressure was at about 2 psi. At this point the cabin altitude started descending approximately 200-300 FPM. At 10000 ft and approximately 240 mi to ZZZ2 we were able to burn off enough fuel to land at maximum landing weight and the cabin was able to descend at a comfortable rate for the passenger and crew. Callback conversation with reporter revealed the following information: the reporter stated the problem was operating with only 1 air-conditioning pack as the left pack was shut down for overpressure warning. Maintenance discovered the right pack ducting was leaking excessively and could not meet the pressurization controller demands.

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Original NASA ASRS Text

Title: A CL600 AT FL340 NOTED CABIN ALT CLBING. HAD ONLY R PACK OPERATING AS L PACK HAD BEEN SHUT DOWN EARLIER. DISCOVERED R PACK DUCTING LEAKING.

Narrative: AFTER TKOF FROM ZZZ1 AT XA00 LCL; WHILE IN CLB AND TRANSITIONING FROM APU AIR TO ENG BLEED AIR WE HAD A L ACU OVER PRESSURE. AFTER CONSULTING AND COMPLETING THE CHKLIST FOR THIS PROC WE CONTINUED AS PLANNED. AFTER APPROX 10 MINS INTO FLT WE HAD A WOW (WT ON WHEELS) INPUT FAILURE LIGHT. THIS INDICATION WENT AWAY WITHIN APPROX 10 MINS. AS WE CONTINUED ON OUR PLANNED FLT AT FL340 ALL WAS NORMAL. APPROX 2 HRS INTO THE FLT AT FL340 WE HAD AN INDICATION THAT THE CABIN PRESSURE WAS RISING. AS THE PF I ELECTED TO DSND TO FL240. AT FL240 THE CABIN CONTINUED TO CLB. IT WAS OBVIOUS AT THIS POINT THE AUTO CABIN CTLR WAS NOT FUNCTIONING PROPERLY. WITH THIS INFO AND WITH 1 ACU SHUT DOWN ALREADY DUE TO THE OVERPRESSURE PLUS IN WOW INPUT FAILURE LIGHT SITUATION WE DECIDED TO CONTINUE THE DSCNT TO 10000 FT AND DIVERT TO ZZZ2. WHEN WE LEVELED AT 10000 FT THE CABIN WAS AT OR NEAR THE CABIN LIMIT OF ABOUT 8800 FT. DIFFERENTIAL CABIN PRESSURE WAS AT ABOUT 2 PSI. AT THIS POINT THE CABIN ALT STARTED DSNDING APPROX 200-300 FPM. AT 10000 FT AND APPROX 240 MI TO ZZZ2 WE WERE ABLE TO BURN OFF ENOUGH FUEL TO LAND AT MAX LNDG WT AND THE CABIN WAS ABLE TO DSND AT A COMFORTABLE RATE FOR THE PAX AND CREW. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE PROB WAS OPERATING WITH ONLY 1 AIR-CONDITIONING PACK AS THE L PACK WAS SHUT DOWN FOR OVERPRESSURE WARNING. MAINT DISCOVERED THE R PACK DUCTING WAS LEAKING EXCESSIVELY AND COULD NOT MEET THE PRESSURIZATION CTLR DEMANDS.

Data retrieved from NASA's ASRS site as of January 2009 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.