Airbus doesn't make engines but they must had 2 types engines, 1 of them was bad in mechanical problem... And why would an airline employee lose his job, maybe he was putting oil, and necessary things in egines before take-off as their job. Otherwise something was wrong.
If the Captain or First Officer didnt check the entire plane like he/she suppose to while it sitting at the ramp.
October 27, 2001, I was @ New York JFK Airport all day, was checked out from a hotel from an overnight stay from October 26, I was @ American Airlines Gate 48, and a Captain checked his Airbus 300-600R just 15 minutes before pushback from Gate 48, (not sure what it destination was). I was on a flight arriving @ Gate 48 after this AB6R, it was my MD80 flight to DFW that evening.
On November 12, Did the pilots checked their plane before pushing back, and flight for Dom. Republic. No ones saw anything, but it happened.