Narrative:

While on the ground performing preflight checks; the crew noticed a 'duct mon fault' white status message. The crew followed the company procedure and the message was deferred over the phone with maintenance control per the MEL. The rest of the preflight; taxi; takeoff; and initial climbout took place normally and without issue. While leveling at 17;000 ft during the climbout; the crew received a 'right bleed duct' red master warning. Standard operating procedures were followed and the pilot monitoring began the appropriate non-normal checklist. Per the checklist; the flying pilot requested a descent to 10;000 MSL due to 'a pressurization problem' and ATC gave the clearance to do so. Following the checklist required the crew to shut the prsovs [pressure shut off valves](which had already automatically closed); shut off the packs and complete the 'unpressurized flight procedure'. The crew notified ATC that they had lost pressurization and would be returning to their departure airport. While completing the non-normal procedures and preparations for landing; the crew noted that; should they land now; they would be overweight. Because it was a hot day; the cabin temperature was already over 33 celsius and continuing to climb. At this point; the crew decided that the combined factors of pressurization loss; excessive cabin temperature; and landing overweight created an emergency condition and so the crew declared an emergency. The crew completed all necessary checklists and procedures and landed overweight on 31L without further incident and taxied to the gate and unloaded the passengers as soon as practical.the caution at the beginning of the 'right bleed duct' non-normal checklist states that both prsovs will automatically close if the warning persists for longer than 30 seconds. If the checklist is completed before this happens; it is possible to isolate the bad bleed duct and continue running pressurization and air conditioning from the good engine bleed source. It is simply impossible to safely identify; locate; and complete an emergency/non-normal checklist within 30 seconds of being aware of the problem. There was nothing at the beginning of the checklist that made it clear the crew should try to complete it as quickly as possible before the bleeds closed. This is what led to the complete loss of pressurization. It was the initial reaction of the crew; based on the caution at the beginning of the checklist; to start a timer and wait to see if the bleeds automatically closed as the pom stated they would.the loss of pressurization and; therefore; air conditioning led to an excessively high cabin temperature which is what led the crew to choose to land overweight so that everyone could get off and try to cool down as soon as possible.the crew believes that the checklist is poorly written and ordered for this event. By the time the crew has a chance identify the master warning; pull out the pom; locate the checklist; and begin reading it; the engine bleeds are already automatically closing. If the crew is to have any chance of isolating the problematic bleed source and continuing to run pressurization before both engine bleeds close automatically; doing so should be the very first thing on the checklist. Ideally; this procedure would be made a memory item. If it is found that the 'duct mon fault' status message is directly related to this event; it might also be a good idea to review and possibly revise the deferral and repair procedures associated with that message.

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Original NASA ASRS Text

Title: A CRJ-900 flight crew suffered a Right Bleed Duct failure which caused the associated PRSOV to close. While performing the appropriate checklist they discovered it's last step must be completed within 60 to prevent the left PRSOV from also closing rendering the aircraft unable to pressurize. The were unable to do so; the aircraft depressurized and they had to return to their departure airport.

Narrative: While on the ground performing preflight checks; the crew noticed a 'duct mon fault' white status message. The crew followed the company procedure and the message was deferred over the phone with Maintenance Control per the MEL. The rest of the preflight; taxi; takeoff; and initial climbout took place normally and without issue. While leveling at 17;000 FT during the climbout; the crew received a 'right bleed duct' red master warning. Standard operating procedures were followed and the pilot monitoring began the appropriate non-normal checklist. Per the checklist; the flying pilot requested a descent to 10;000 MSL due to 'a pressurization problem' and ATC gave the clearance to do so. Following the checklist required the crew to shut the PRSOVs [PRessure Shut Off Valves](which had already automatically closed); shut off the packs and complete the 'unpressurized flight procedure'. The crew notified ATC that they had lost pressurization and would be returning to their departure airport. While completing the non-normal procedures and preparations for landing; the crew noted that; should they land now; they would be overweight. Because it was a hot day; the cabin temperature was already over 33 Celsius and continuing to climb. At this point; the crew decided that the combined factors of pressurization loss; excessive cabin temperature; and landing overweight created an emergency condition and so the crew declared an emergency. The crew completed all necessary checklists and procedures and landed overweight on 31L without further incident and taxied to the gate and unloaded the passengers as soon as practical.The caution at the beginning of the 'right bleed duct' non-normal checklist states that both PRSOVs will automatically close if the warning persists for longer than 30 seconds. If the checklist is completed before this happens; it is possible to isolate the bad bleed duct and continue running pressurization and air conditioning from the good engine bleed source. It is simply impossible to safely identify; locate; and complete an emergency/non-normal checklist within 30 seconds of being aware of the problem. There was nothing at the beginning of the checklist that made it clear the crew should try to complete it as quickly as possible before the bleeds closed. This is what led to the complete loss of pressurization. It was the initial reaction of the crew; based on the caution at the beginning of the checklist; to start a timer and wait to see if the bleeds automatically closed as the POM stated they would.The loss of pressurization and; therefore; air conditioning led to an excessively high cabin temperature which is what led the crew to choose to land overweight so that everyone could get off and try to cool down as soon as possible.The crew believes that the checklist is poorly written and ordered for this event. By the time the crew has a chance identify the Master Warning; pull out the POM; locate the checklist; and begin reading it; the engine bleeds are already automatically closing. If the crew is to have any chance of isolating the problematic bleed source and continuing to run pressurization before both engine bleeds close automatically; doing so should be the VERY FIRST thing on the checklist. Ideally; this procedure would be made a memory item. If it is found that the 'duct mon fault' status message is directly related to this event; it might also be a good idea to review and possibly revise the deferral and repair procedures associated with that message.

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.