A-Floor
It was a mechanic doing a pressurisation run after maintenance he was on his own and using a 'home made' guage! Unfortunately said guage didn't have a max stop and he apparently did not notice when it went past the stop
Twice!
The resulting failure also blew the rear hatch some 70 yds. over a blast fence.
Actually this could also go into the 'outsourcing maint' thread on R and N 