Narrative:

An a check was being performed and completed on the [next] morning. The aircraft had some remaining open discrepancies; so the aircraft was finished up and released on the [following] morning. Upon the aircraft leaving it had its rh engine upper nose cowl come loose and depart the aircraft.the mechanic working the engines that night had me take a look before closing to ensure all tools rags and equipment was removed. At that time I went back to the office to complete my paperwork and paperwork/aircraft book closing responsibilities. Approximately 30-45 minutes later I went back out to do my walk around to see it closed up. I walked around to ensure all panels; latches; and cowls were closed up. Then I went on the staircase and took a peek up top to ensure the cowls were installed and no tools and equipment were left on top of the aircraft. Then the aircraft got towed outside to complete ops checks and engine runs. The aircraft was towed back in after completion to check the engines for leaks. No leaks were noted; the lower core cowls were open then closed back up. I did a final walk past to ensure the core cowls have been closed.viewing the upper cowls from the portable staircase provides a good visual to see that the cowls are installed. But not for a detailed visual check of fasteners. From that location the cowls appeared to be installed and had no obvious defect. Would need to do a detailed visual check of all the fasteners and not that just the cowls are installed.

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Original NASA ASRS Text

Title: A Maintenance Technician and Inspector describe the events that led up to the loss of engine upper cowling from CRJ-200.

Narrative: An A check was being performed and completed on the [next] morning. The aircraft had some remaining open discrepancies; so the aircraft was finished up and released on the [following] morning. Upon the aircraft leaving it had its RH engine upper nose cowl come loose and depart the aircraft.The mechanic working the engines that night had me take a look before closing to ensure all tools rags and equipment was removed. At that time I went back to the office to complete my paperwork and paperwork/aircraft book closing responsibilities. Approximately 30-45 minutes later I went back out to do my walk around to see it closed up. I walked around to ensure all panels; latches; and cowls were closed up. Then I went on the staircase and took a peek up top to ensure the cowls were installed and no tools and equipment were left on top of the aircraft. Then the aircraft got towed outside to complete ops checks and engine runs. The aircraft was towed back in after completion to check the engines for leaks. No leaks were noted; the lower core cowls were open then closed back up. I did a final walk past to ensure the core cowls have been closed.Viewing the upper cowls from the portable staircase provides a good visual to see that the cowls are installed. But not for a detailed visual check of fasteners. From that location the cowls appeared to be installed and had no obvious defect. Would need to do a detailed visual check of all the fasteners and not that just the cowls are installed.

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.