The “years” of data is one unit running up and down with Stadler staff onboard and a driver manager driving. The testing and mileage accumulation isn’t a patch on actually running them in service, it just proves they are safe and don’t have defects that need fixing immediately.They surely have years of data on how often that happens, and wouldnt they have produced spares assuming that a lot more 777s would be in service by now?
I haven’t done the math but I’d bet that the units running in service now will have, combined, done more mileage and hours than all the testing so far. It’s very hard to replicate real world, revenue service.