Maintenance Airframe; Maintenance Powerplant
Training / Qualification; Situational Awareness; Communication Breakdown; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action; General Flight Cancelled / Delayed
Aircraft; Chart Or Publication; Human Factors; Incorrect / Not Installed / Unavailable Part; Manuals; Procedure
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.
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.