Yes, the new buzz word is EROPS or extended range operations which takes a bigger view of what might happen beyond a simple engine failure.
The limit for twins was 60mins, 4 piston/3 turbine engines were exempt from the requirement.
Richard Branson wanted "Four engines for long haul." hence the B747 and A340 for Virgin Atlantic. Trams Atlantic flying became routine and the B767 became the most popular type on the route.
The A350 entered service with 180 mins approval and there is a provision to go to 370 mins or about 2500nm.
As with all things in aviation its risk management, an autoland system is allowed to fail resulting in a disaster, once in every 100 million landings. Once this reliability level is reached single engined airliners could be entering service.
However, what happens if an engineer fails to install a simple oil seal correctly resulting in that precious fluid leaking away ? The Cessna Caravan has restrictions in some countries regarding passenger flights under IFR and overwater, it's PT6 engine is extremely reliable and has been in service for decades but there have still been some failures.
Last edited by Metro man; 10th Nov 2015 at 22:26.