If the rudder did fail after an engine failure Airbus has a lot to answer for. That is not an acceptable design if true.
The engine failure could have sprayed engine parts though the side of the plane destroying their radio communications.
The question remains, was it simply an engine failure, sabotage or a bomb in a baggage hold.
The one witness who helped recover wreckage from his boat said that from the time the debris ripped the tail off until the jet hit the ground/water was just a matter of three seconds or so! Once she blew the pilot barely had time to blink before it was all over but the flames.