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A mechanic reports how he and another mechanic initially installed a new plenum chamber to the secondary heat exchanger for the left-hand air-conditioning pack; on a B737-700 aircraft. After drilling holes to accommodate the internal mounting brackets; they realized they had the incorrect plenum. The holes rendered the plenum unserviceable and had to be condemned after removal.
| Attributes | |
| ACN | 845088 |
| Time | |
| Date | 200907 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Parked |
| Component | |
| Aircraft Component | Air Conditioning and Pressurization Pack |
| Person 1 | |
| Function | Technician |
| Qualification | Maintenance Powerplant Maintenance Airframe |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural Maintenance Deviation - Procedural Published Material / Policy |
Narrative:
I was assigned to install the plenum on the left hand secondary heat exchanger; which was not installed in the aircraft at the time. It was located on a work table. The plenum was being replaced due to delamination on the original plenum. After installing the plenum on the heat exchanger; myself and my work partner realized that we had used the wrong part number plenum for that heat exchanger. We reported the error to our supervisor and removed the incorrect plenum. During installation of the incorrect plenum; we had to drill holes in it to accommodate internal mounting brackets. These holes rendered the plenum unserviceable and we therefore condemned it after removal. None of the parts were ever installed on the aircraft.
Original NASA ASRS Text
Title: A Mechanic reports how he and another Mechanic initially installed a new Plenum chamber to the Secondary Heat Exchanger for the Left-hand Air-Conditioning Pack; on a B737-700 aircraft. After drilling holes to accommodate the internal mounting brackets; they realized they had the incorrect Plenum. The holes rendered the Plenum unserviceable and had to be condemned after removal.
Narrative: I was assigned to install the Plenum on the left hand Secondary Heat Exchanger; which was not installed in the aircraft at the time. It was located on a work table. The Plenum was being replaced due to delamination on the original Plenum. After installing the Plenum on the Heat Exchanger; myself and my work partner realized that we had used the wrong Part Number plenum for that heat exchanger. We reported the error to our Supervisor and removed the incorrect Plenum. During installation of the incorrect Plenum; we had to drill holes in it to accommodate internal mounting brackets. These holes rendered the Plenum unserviceable and we therefore condemned it after removal. None of the parts were ever installed on the aircraft.
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.