Originally Posted by
aircraftmaintenance
You may find this YouTube video interesting: 'The Airbus A320 family engine access doors case'
As well as a relevant journal article: 'The airbus A320 family fan cowl door safety modification: a human factors scenario analysis'
Interesting (links would have been good), but not necessarily relevant in this instance.
The fan cowl door mods are indeed intended to ensure that they get correctly latched and therefore cannot open of their own accord.
But even correctly latched fan cowl doors don't stand much of a chance if they are being prised open by a departing reverser door, as may well have happened in this case.