I find it interesting that the ETOPS failure mode in this thread only refers to engine failures
During the test program one one of the 7's ( 767/777 ?)
They suffered a failure of a fuselage pressurisation Non return valve which not only got them down from flightlevel tremendous very quickly but on one of them ( I think there were 2 incidents) put some of the crew in hospital
Of course the valve has been modified so this cannot possibly happen again
