Narrative:

I was assigned to defer the high stage valve on aircraft X. I opened the front and rear cowl and 'inoperatived' the wrong valve. I was to 'inoperative' the high pressure valve (hpv). I inadvertently 'inoperatived' the bleed valve to the closed position. Supplemental information from acn 819152: I was assigned to work with mr. X to defer the high stage valve on aircraft X. The condition was snowing heavy and windy. I helped mr. X to open the cowls and the reverser. I went up to the flight deck to pull the breakers. I came back and mr. X was locking out the valve. We both closed the engine up and came in. He put his tools away and I signed off the paperwork and released the aircraft. Callback conversation with reporter revealed the following information: reporter stated the MEL chapter 36-12 for pneumatics (air) has two separate references. One for the bleed pressure regulator valve (prv) and the other for the high pressure bleed valve. The MEL item for the prv valve deferral includes procedures and a reference picture to use in order to close the valve. But the MEL procedure for the high pressure bleed valve does not have a reference picture. Reporter also stated he was given a picture of the prv valve; not realizing the prv was the incorrect valve. He had the correct MEL deferral procedure; but had deactivated the wrong valve. The A320 departed and returned to field due to lack of pneumatic pressure. Callback conversation with reporter acn #819152 revealed the following information: reporter stated they had deactivated the pressure regulator valve (prv) to the closed position on the #1 engine at the 10 o'clock position. They should have deactivated the hpv located on the engine lower side approximately at the six o'clock position.

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Original NASA ASRS Text

Title: Two mechanics assigned to defer a #1 engine high stage valve on an A320; inadvertently deactivated the wrong bleed valve in the closed position.

Narrative: I was assigned to defer the high stage valve on Aircraft X. I opened the front and rear cowl and 'inoperatived' the wrong valve. I was to 'inoperative' the High Pressure Valve (HPV). I inadvertently 'inoperatived' the bleed valve to the closed position. Supplemental information from ACN 819152: I was assigned to work with Mr. X to defer the high stage valve on Aircraft X. The condition was snowing heavy and windy. I helped Mr. X to open the cowls and the reverser. I went up to the flight deck to pull the breakers. I came back and Mr. X was locking out the valve. We both closed the engine up and came in. He put his tools away and I signed off the paperwork and released the aircraft. Callback conversation with Reporter revealed the following information: Reporter stated the MEL Chapter 36-12 for pneumatics (air) has two separate references. One for the Bleed Pressure Regulator Valve (PRV) and the other for the High Pressure Bleed Valve. The MEL item for the PRV valve deferral includes procedures and a reference picture to use in order to close the valve. But the MEL procedure for the High Pressure Bleed valve does not have a reference picture. Reporter also stated he was given a picture of the PRV valve; not realizing the PRV was the incorrect valve. He had the correct MEL deferral procedure; but had deactivated the wrong valve. The A320 departed and returned to field due to lack of pneumatic pressure. Callback conversation with Reporter ACN #819152 revealed the following information: Reporter stated they had deactivated the pressure regulator valve (PRV) to the closed position on the #1 engine at the 10 o'clock position. They should have deactivated the HPV located on the engine lower side approximately at the six o'clock position.

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.