During the take-off run at Buenos Aires/Ezeiza Airport, BA (SAEZ), the cowlings of engine No. 2, came off. The right panel remained where the takeoff run began (runway 11) and the left cowling near the end of the takeoff run. Some metallic debris was found between both runway ends. The detachment occurred without the crew noticing the situation, although they did perceive a continuous dull noise, which was attributed to the sounds sometimes produced by the air conditioning packs, which was recorded in the Technical Flight Log (TFR). As there was no vibration or any indication of any new development, the flight continued as usual, according to schedule. During a routine check of the runway by the airport’s ground control team, the aforementioned debris was found, which was identified as the “hoods” of a large aircraft, but it was not immediately clear which one it belonged to. In view of this circumstance, messages were sent to the different destinations of the aircraft that had operated on that runway. In the meantime, technical personnel of the operating airline, who had been called, identified the parts as belonging to the Boeing 747-287 aircraft, registration LV-OOZ, belonging to the same company. Upon learning of the news, the Technical Shift personnel tried to establish contact with LV-OOZ, for which they made twelve calls in approximately one hour, without positive results. The flight proceeded normally without the lack of the cowlings affecting the performance of the aircraft. At dawn the following day, while flying over the Canary Islands, and as a direct result of a direct request from a passenger and a crew member, it was learned that the cowlings were missing, which was later confirmed by the Company’s Operations in Madrid. As a precautionary measure, during the landing phase, the flaps were deployed at a higher altitude and when the landing took place, no reverse thrusters were used on engines No. 2 and No. 3. Cause During the take-off phase of an international commercial flight, detachment of the cowlings of engine No. 2, due to an incorrect adjustment of the cowlings following a maintenance task. Contributing factors 1) Prioritizing the rush to move the aircraft from the hangar to the gate, over the completion of the technical tasks, including the closing of the cowlings, at the place where they were being performed and by the same team that was performing the task, which made the control and inspection function ineffective. 2) Ineffective external pre-flight inspection, which foresees the verification of the correct closing of the engine cowlings, with the specific indication that these cowlings must be firmly fastened.During the take-off run at Buenos Aires/Ezeiza Airport, BA (SAEZ), the cowlings of engine No. 2, came off. The right panel remained where the takeoff run began (runway 11) and the left cowling near the end of the takeoff run. Some metallic debris was found between both runway ends. The detachment occurred without the crew noticing the situation, although they did perceive a continuous dull noise, which was attributed to the sounds sometimes produced by the air conditioning packs, which was recorded in the Technical Flight Log (TFR). As there was no vibration or any indication of any new development, the flight continued as usual, according to schedule. During a routine check of the runway by the airport’s ground control team, the aforementioned debris was found, which was identified as the “hoods” of a large aircraft, but it was not immediately clear which one it belonged to. In view of this circumstance, messages were sent to the different destinations of the aircraft that had operated on that runway. In the meantime, technical personnel of the operating airline, who had been called, identified the parts as belonging to the Boeing 747-287 aircraft, registration LV-OOZ, belonging to the same company. Upon learning of the news, the Technical Shift personnel tried to establish contact with LV-OOZ, for which they made twelve calls in approximately one hour, without positive results. The flight proceeded normally without the lack of the cowlings affecting the performance of the aircraft. At dawn the following day, while flying over the Canary Islands, and as a direct result of a direct request from a passenger and a crew member, it was learned that the cowlings were missing, which was later confirmed by the Company’s Operations in Madrid. As a precautionary measure, during the landing phase, the flaps were deployed at a higher altitude and when the landing took place, no reverse thrusters were used on engines No. 2 and No. 3. Cause During the take-off phase of an international commercial flight, detachment of the cowlings of engine No. 2, due to an incorrect adjustment of the cowlings following a maintenance task. Contributing factors 1) Prioritizing the rush to move the aircraft from the hangar to the gate, over the completion of the technical tasks, including the closing of the cowlings, at the place where they were being performed and by the same team that was performing the task, which made the control and inspection function ineffective. 2) Ineffective external pre-flight inspection, which foresees the verification of the correct closing of the engine cowlings, with the specific indication that these cowlings must be firmly fastened.