How the door opened remains a mystery but the AAIB have the FDR and it is certain that they will resolve the issue. Dornier moved swiftly to order checks on all 328s last week.. .. .As for the comments of Lenny Godber, while essentially correct the implication is that the door can only be opened from the inside. This is clearly incorrect otherwise getting in first flight of the day would be a bit tricky as would access on the ground in an emergency.. .. .The door on the 328 is held closed by a conventional pin latch. It is not a plug door. This is not the point however. The real concern is that the door still appears to function correctly although damaged from the incident which was essentially an explosive decompression even if it was at low differential pressure. We await the results of the enquiry.