There appear to be two different scenarios here:-
1) Locking an engine prior to take-off – the limitations on this are somewhat easily managed, with time available for (revised) flight planning. The engine systems and parts can be locked, inhibited et cetera, in accordance with maintenance procedures.
2) Engine failure after (decision to proceed with) take-off – my reading is that this is the “British Airways Flight 268” case in point, that caused much discussion (FAA, CAA, BA and PPRuNe). This is obviously tricky (otherwise such discussion would not have been highlighted (big assumption)) the decision to proceed, or land soonish, needs to consider many things; IMO this includes dumping fuel, heavy landing, increased flight fuel usage, effects of free LP and IP shaft rotation and gearbox load limited rotation of the HP shaft. The windmilling engine effects naturally extend to both the main engine and gearbox accessory lubrication systems...
Time for PPRuNe views on E3OPS regulations
