Narrative:

In troubleshooting an idg problem; I swapped generator control unit (GCU1) with GCU2 on aircraft X; a B737-700. After changing the integrated drive generator (idg) and running the engine for the operational check; I went on to another problem on this aircraft. The water tank was on MEL and needed to be changed. At the end of every night I always check the electrical equipment (east/east) doors. Last night I remember closing the east/east door on this plane. That bothered me all day. I came in to work tonight and remembered the gcu troubleshooting. I'm not 100% positively sure that I secured or swapped back the gcu's. Human factor: last week I called in sick for a cold/flu. I still have this stubborn cold but I came into work this week anyway. I remember that the workload for the night was just two overnight checks with a water tank change. But aircraft X came in later [than expected] and I was distracted with having to troubleshoot an idg problem before changing the [water] tank. It turned into a very long night. I think if I were not sick that I would have been thinking more clearly. I think I could have avoided this problem all together if I had felt better. Next time I will make sure that I'm physically fit for work.

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Original NASA ASRS Text

Title: A Line Mechanic forgot to reposition Generator Control Unit-1 (GCU1) and GCU2 back to their proper position in the E/E compartment of a B737-700 aircraft. He had swapped the two GCU units during trouble shooting of a # 1 Engine Integrated Drive Generator (IDG) failure.

Narrative: In troubleshooting an IDG problem; I swapped Generator Control Unit (GCU1) with GCU2 on Aircraft X; a B737-700. After changing the Integrated Drive Generator (IDG) and running the engine for the Operational Check; I went on to another problem on this aircraft. The Water Tank was on MEL and needed to be changed. At the end of every night I always check the Electrical Equipment (E/E) doors. Last night I remember closing the E/E door on this plane. That bothered me all day. I came in to work tonight and remembered the GCU troubleshooting. I'm not 100% positively sure that I secured or swapped back the GCU's. Human factor: Last week I called in sick for a cold/flu. I still have this stubborn cold but I came into work this week anyway. I remember that the workload for the night was just two Overnight Checks with a Water Tank change. But Aircraft X came in later [than expected] and I was distracted with having to troubleshoot an IDG problem before changing the [Water] tank. It turned into a very long night. I think if I were not sick that I would have been thinking more clearly. I think I could have avoided this problem all together if I had felt better. Next time I will make sure that I'm physically fit for work.

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.