Official thing which involves the relevant exams, tests to make sure everything is in working order, make sure everything is to the required standard, ensure the AWS etc is in working order (if already fitted - if not fitted it has to be fitted) etc. FS was certified but once you touch certain parts it has to be re-certified. An example is the BEP at the EKR. As soon as the EPBPG changed the bogie it automatically became non-certified. To find out exact details on this sort of thing you might want to contact 'TheSlash' as he is an ex-fitter.EmergencyBrake said:BTW, what needs to be done to make a steam loco "mainline certified" ?