>>1179331My guess is that an engine fan cowling wasn't properly secured after an inspection on the ground.
A British Airways A319 had an incident when a fan cowling on an International Aero Engine was unlatched and was ripped off by aerodynamic forces on rotation. No engine failures occurred though. The A319 immediately returned back to to Heathrow after take off, but the incident showed failures in maintainance.
A Skyservice A320 had a similar incident as well, but that lead to an uncontained fan failure. The A320 landed with no incident.
An Emirates A330 had a Trent 700 engine experience a cowling failure as well. The fan blades were damaged, but the cause was unknown, and the damage was caused to the cowling first and foremost. It was suspected that the cowlings had a manufacturing defect from when they were manufactured by Bombardier.
Oddly enough, it seems the Airbus A320 has had more incidents of cowlings not being secured properly, though the vast majority of these incidents only lead to the cowling being lost and no real damage being caused.
