Narrative:

I was asked to assist two other mechanics that had a heavy workload on an aircraft. Upon arriving to the aircraft I noticed two emergency evacuation slide boxes in the back of the truck that they were driving that night. I confirmed that they were for this aircraft and I offered to swap them out. I checked the paperwork for the serial numbers of the slides that required replacement and verified those serial numbers with the slides that were installed on the aircraft. After removing the fwd entry slide I walked down the jet bridge stairs to retrieve a new slide to install. When comparing part numbers between slide removed and slide installed I was so focused on the 'dash' number of the part that I neglected to notice that there was a difference between fwd and aft. I assumed that the slides were the same and installed them in the incorrect positions. A P/a system alert was being worked in the aft galley at the same time that I was installing the aft entry slide and I was in a hurry to be out of the way. The problem was discovered by the flight attendant when the girt bar would not align properly.no matter how many times you complete a job it is imperative to read procedures very carefully. Some part numbers may appear to be identical but each number and letter must be checked at least twice; you should not assume.

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Original NASA ASRS Text

Title: An air carrier maintenance Technician reported on the events that led to the incorrect installation of escape slides on a B737-700.

Narrative: I was asked to assist two other Mechanics that had a heavy workload on an aircraft. Upon arriving to the aircraft I noticed two emergency evacuation slide boxes in the back of the truck that they were driving that night. I confirmed that they were for this aircraft and I offered to swap them out. I checked the paperwork for the serial numbers of the slides that required replacement and verified those serial numbers with the slides that were installed on the aircraft. After removing the FWD entry slide I walked down the jet bridge stairs to retrieve a new slide to install. When comparing part numbers between slide removed and slide installed I was so focused on the 'dash' number of the part that I neglected to notice that there was a difference between FWD and AFT. I assumed that the slides were the same and installed them in the incorrect positions. A P/A system alert was being worked in the AFT galley at the same time that I was installing the AFT entry slide and I was in a hurry to be out of the way. The problem was discovered by the Flight Attendant when the girt bar would not align properly.No matter how many times you complete a job It is imperative to read procedures very carefully. Some part numbers may appear to be identical but each number and letter must be checked at least twice; you should not assume.

Data retrieved from NASA's ASRS site 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.