Thanks for taking the time to reply to my question. However something is still not clear to me:
1+4 EEC errors logged. Degraded mode is purely due to loss of sensor inputs/EEC errors. Think of it as the engine in Direct Law (no thrust protections!) (Due EEC not able to calc TPR demand. So N1 commanded as a function of TRA and altitude)
Now I thought that (from an aircraft systems point of view) each engine was completely independent from the other engines and any other aircraft systems. Each engine has its own generator which powers the fuel pumps and FADEC/EEC/whatever, so that with gravity fuel feed it will keep producing power through hell and high-water. (And indeed #1 couldn't be shut down after landing, and had to be drowned with foam after 4 or 5 hours.)
But why did #4 log EEC errors ? Here's an explanation of TPR from a Tech Log thread:
From the RR Trent training notes,
"TPR actual is derived from the P20, P30, T20 and EGT parameters."
From my understanding all these parameters are available from the engine itself. So to (finally !) get to my point - why did an undamaged engine on an undamaged wing generate EEC errors ? In my book that's an unintended consequential failure. Am I missing something ?
BTW, I'm not an anti-Airbus critic - after all it took many years for the 747 designers to realise that it was "a bad idea" to locate all four AC generator control units in the same bay directly under a galley.