Random person, before you start scaring pilots out there.
Engines do not become derated over time. They always produce rated thrust if requested.
As the engines get older the EGT margin decreases. ie The older the engines get the closer they get to max EGT on a max rated thrust takeoff. When this happens you can remove them from a CF6-80C2B5F rated aircraft and install them on a CF6-80C2B1F rated aircraft (Rating change via plug change/pin programming). You then get longer out of them before you have to overhaul because at a lower rating it is like doing a derated takeoff and the EGT margin returns.For a while at least anyway.
So in summary. If the book says the engine is good for 63500 lbs. Then a new engine and a 30000hr engine will produce said thrust. The older one will be hotter.
I believe the 744's EECs don't qualify as FADECs because they don't control variable bleed valves or variable stator vanes (VIGVs for the RR), but I defer to any engineer on these finer points of engine control
744's do have EEC's. EEC is a generic term, possibly even a Boeing term. Each manufacturer has their own term.
Rolls Royce call them FAFC. Full authority fuel control.
Pratt & Whitney call them FADEC. Full authority digital engine control.
GE call them ECU. Electronic control unit.
You are correct that on a 744 RR that the FAFC doesn't control the VIGV's or bleed valves, but thats only because RR choose to do it that way. (They are pneumatically controlled)
GE do however control both of those items by the ECU via the HMU (Hydromechanical unit or carby)
