Narrative:

An airbus A320 departed ZZZ in the early morning hours and encountered an event in which the fan cowls separated the #2 engine. Prior to that this; aircraft X had an overnight maintenance visit which included routine and non-routine work; the focal point of this summary is the #2 engine. The following is a brief summary. Myself and another tech were working #2 engine; that included an oil lube unit filter check; I.D.G differential pressure indicator check; [and] also an igniter change (2 per engine).the conditions for this night is cold; windy; poor lighting and disruptive. In the course of the overnight maintenance visit; the aircraft was positioned at the remote pad. Just prior to completing the task at hand on the #2 engine; the ground crew needed the aircraft to be repositioned to gate. In order to accomplish this; any work being done to aircraft X [was] ceased and [we] proceeded to prep the airplane for movement which included the closing of #2 engine 'C' ducts and #2 engine fan cowls; this caused a workflow disruption. Upon arriving at gate; the plan was to continue work on engine 2; however; I was immediately tasked with assisting another tech/lead in the installation of the #2 TCAS antennae which is located on forward upper half of the fuselage. Upon completion of this task; aircraft X is down to paperwork activity; I had no further involvement with aircraft X and proceeded to the office. At this time; the aircraft is being readied for flight by various ground personnel. The incident; which occurred shortly after take-off; by where the fan cowl(s) separated engine #2 after takeoff and successfully returned to the field. The fact that the fan cowl latches and thrust reverser latches may have been not completely latched is the issue; however; this was missed by maintenance and flight crews during final walk around.

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Original NASA ASRS Text

Title: Maintenance Technician reported the engine cowling departed the aircraft after takeoff; likely due to the cowling not being properly latched.

Narrative: An Airbus A320 departed ZZZ in the early morning hours and encountered an event in which the fan cowls separated the #2 engine. Prior to that this; Aircraft X had an overnight maintenance visit which included routine and non-routine work; the focal point of this summary is the #2 engine. The following is a brief summary. Myself and another tech were working #2 engine; that included an oil lube unit filter check; I.D.G differential pressure indicator check; [and] also an igniter change (2 per engine).The conditions for this night is cold; windy; poor lighting and disruptive. In the course of the overnight maintenance visit; the aircraft was positioned at the remote pad. Just prior to completing the task at hand on the #2 engine; the ground crew needed the aircraft to be repositioned to gate. In order to accomplish this; any work being done to Aircraft X [was] ceased and [we] proceeded to prep the airplane for movement which included the closing of #2 engine 'C' ducts and #2 engine fan cowls; this caused a workflow disruption. Upon arriving at gate; the plan was to continue work on engine 2; however; I was immediately tasked with assisting another tech/Lead in the installation of the #2 TCAS antennae which is located on forward upper half of the fuselage. Upon completion of this task; Aircraft X is down to paperwork activity; I had no further involvement with Aircraft X and proceeded to the office. At this time; the aircraft is being readied for flight by various ground personnel. The incident; which occurred shortly after take-off; by where the fan cowl(s) separated engine #2 after takeoff and successfully returned to the field. The fact that the fan cowl latches and thrust reverser latches may have been not completely latched is the issue; however; this was missed by Maintenance and flight crews during final walk around.

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.