From an engineer's point of view this is one of the most disturbing aviation news this year. Here we have a commercial airline in an industrial country, operating a quite common type, following (I suppose) well-audited rules, all the paperwork (supposedly) in order, and we have a major structural failure which had a 50% chance of really messing up the aircraft. Any human error, any aggravating circumstances must have occurred on ground, where they were supposed to be identified and corrected by the supposedly well-audited quality control system. It's just a combination of luck and crew skill the passengers and crew needed no more than counseling (if they even really needed that).
So where's the original problem and what can we learn from the incident?