I am noticing a striking similarity to the 1990 G-BJRT depressurisation.
In that incident, the primary cause was quickly identified as the failure of engineering to properly carry out a safety critical task.
The correct procedure was documented in company maintenance manuals, but not followed.
Have a read of the
AAIB's summary report on G-BJRT.
Same operator, 23 years later - something to think about?