Narrative:

An erj-145 aircraft was at the hanger for a service check and two mels for the pack-2 and pack-1 systems. Mechanic Y and myself; did troubleshoot the pack problems outside; finding that pack-2 had a hole in one of the duct boots and that pack-1 had a seized up air cycle machine (acm). After bringing the aircraft into the hangar; mechanic Y started work on the pack-2 duct that was damaged and I started on the service check. Mechanic Y finished the work on pack-2 and started the removal of the pack-1 acm; while I finished completing the service check and changed a pair of nose tires. I next came over to see at what point mechanic Y was at with the acm; he had just finished removing the old acm. I took over the project at that point; completing the installation of the new acm. The aircraft was than pushed back outside to perform operational checks of both pack-1 and pack-2 systems. Mechanic Y was in the aircraft performing the operational (ops) checks for quite some time. After he shut down the aircraft; I spoke with him about the results of the ops checks at which time he told me that all the ops checks had been good. We then proceeded to sign-off the work we had preformed in the logbook. Mechanic Y signing-off the pack-2 MEL and myself signing-off pack-1. In the morning the aircraft was taken to the gate and left for the [flight] crews arrival. At about xa:30am; the captain of that flight of the day arrived and found one of the aircraft's outflow valves in the forward crew closet. This event occurred due to a missed step in the MEL manual when putting the pack systems back into service.

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Original NASA ASRS Text

Title: An Aircraft Maintenance Technician (AMT) reports a Captain had found an outflow valve in the crew forward closet on an ERJ-145 aircraft. Maintenance had missed a step in the MEL Manual when putting the Air Conditioning Pack System back into service after troubleshooting and repairs.

Narrative: An ERJ-145 aircraft was at the hanger for a Service Check and two MELs for the Pack-2 and Pack-1 Systems. Mechanic Y and myself; did troubleshoot the pack problems outside; finding that Pack-2 had a hole in one of the duct boots and that Pack-1 had a seized up Air Cycle Machine (ACM). After bringing the aircraft into the hangar; Mechanic Y started work on the Pack-2 duct that was damaged and I started on the Service Check. Mechanic Y finished the work on Pack-2 and started the removal of the Pack-1 ACM; while I finished completing the Service Check and changed a pair of nose tires. I next came over to see at what point Mechanic Y was at with the ACM; he had just finished removing the old ACM. I took over the project at that point; completing the installation of the new ACM. The aircraft was than pushed back outside to perform Operational Checks of both Pack-1 and Pack-2 Systems. Mechanic Y was in the aircraft performing the Operational (Ops) Checks for quite some time. After he shut down the aircraft; I spoke with him about the results of the Ops Checks at which time he told me that all the Ops Checks had been good. We then proceeded to sign-off the work we had preformed in the Logbook. Mechanic Y signing-off the Pack-2 MEL and myself signing-off Pack-1. In the morning the aircraft was taken to the gate and left for the [Flight] crews arrival. At about XA:30am; the Captain of that flight of the day arrived and found one of the aircraft's outflow valves in the forward crew closet. This event occurred due to a missed step in the MEL Manual when putting the Pack Systems back into service.

Data retrieved from NASA's ASRS site as of July 2013 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.