j.t.:
One needs to look at the history.
Pre-ETOPS, the design/operating standards required that multi-engine aircraft be able to meet certain performance standards with two failed engines else they were restricted by the 90 minute rule.
Clearly this affected all twins but, also, restricted some 3/4 engined machines.
John,
Pre-ETOPS, twins couldn't make "crossings."
As I recall with 3 or 4 engine birds, we had to turn around under circumstances.