Narrative:

On initial taxi out I noticed a noise sounding like a pack cycling on/off. I checked the bleed page and the #2 engine hp (high pressure) bleed valve was in fact cycling on/off once every second or two. I called maintenance control. They did not have anything else to try and suggested we return to the gate to defer the hp valve. At the gate I reviewed the MEL and agreed to take the plane with the hp valve deferred. I then called the dispatcher to make sure he was ok with the deferral too. He stated that he hadn't seen the MEL yet and as long as it didn't affect flight into icing conditions he would be ok with the deferral. The mechanic came up and said the valve was locked out and checked the bleed page to verify the valve was closed. After that she asked if I would put a deferral sticker up when she called me with the correct number. I agreed and the cabin door was closed. We installed the sticker as the new maintenance release arrived on the printer. I looked at the maintenance release and it said that the valve was locked out and under 'flight crew' it said to reference the maintenance release for more information. I then used the information on the MEL card I had received earlier from maintenance. I have since found out that the deferral on the maintenance release was for the prv (pressure relief valve) not the hp valve. The MEL card was for the hp valve which is what I thought the actual deferral was and what I agreed to. Before we pushed I queried the dispatcher as to the need for a new flight plan reflecting the changed maintenance status. We were told that the deferral did not require a revised flight plan. To me this meant that the dispatcher was also under the impression we only had the hp valve deferred. The actual deferral used (for the prv) required a second deferral that would alert dispatch to the associated icing restrictions. This 2nd deferral was never accomplished and neither myself nor the dispatcher knew of any icing restrictions. Icing was forecast at our destination and therefore our departure would not have been legal with the whole bleed system deferred. After engine start we made sure to check the hp valve to verify it was closed. Neither of us thought to check the ip (intermediate pressure) valve as we didn't think it was being deferred.

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Original NASA ASRS Text

Title: An A320 flight crew and maintenance techs reported an improperly deferred pneumatic bleed valve that resulted in an inappropriate dispatch into icing conditions.

Narrative: On initial taxi out I noticed a noise sounding like a pack cycling on/off. I checked the bleed page and the #2 engine HP (High Pressure) bleed valve was in fact cycling on/off once every second or two. I called Maintenance Control. They did not have anything else to try and suggested we return to the gate to defer the HP valve. At the gate I reviewed the MEL and agreed to take the plane with the HP valve deferred. I then called the Dispatcher to make sure he was OK with the deferral too. He stated that he hadn't seen the MEL yet and as long as it didn't affect flight into icing conditions he would be OK with the deferral. The Mechanic came up and said the valve was locked out and checked the bleed page to verify the valve was closed. After that she asked if I would put a deferral sticker up when she called me with the correct number. I agreed and the cabin door was closed. We installed the sticker as the new maintenance release arrived on the printer. I looked at the maintenance release and it said that the valve was locked out and under 'Flight Crew' it said to reference the maintenance release for more information. I then used the information on the MEL card I had received earlier from maintenance. I have since found out that the deferral on the maintenance release was for the PRV (Pressure Relief Valve) not the HP valve. The MEL card was for the HP valve which is what I thought the actual deferral was and what I agreed to. Before we pushed I queried the Dispatcher as to the need for a new flight plan reflecting the changed maintenance status. We were told that the deferral did not require a revised flight plan. To me this meant that the Dispatcher was also under the impression we only had the HP valve deferred. The actual deferral used (for the PRV) required a second deferral that would alert dispatch to the associated icing restrictions. This 2nd deferral was never accomplished and neither myself nor the Dispatcher knew of any icing restrictions. Icing was forecast at our destination and therefore our departure would not have been legal with the whole bleed system deferred. After engine start we made sure to check the HP valve to verify it was closed. Neither of us thought to check the IP (Intermediate Pressure) valve as we didn't think it was being deferred.

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.