Originally Posted by
eckhard
I think RR engines adjust fuel flow to keep the EPR constant, whether or not engine TAI is selected, hence no perf correction?
All FADEC engines (in "Normal" mode) adjust the fuel flow to keep the target N1 or EPR - Rolls is no way unique in the that regard. The EAI debit is to protect EGT margins.
However, since anti-ice is normally only used when it's cold - well below the rating corner point for the Takeoff rating range - not everyone bothers to take a performance debit for anti-ice for Takeoff. Max Climb/Max Con are a different issue.
Some models permit dispatch with an EAI valve locked open (which can happen when it's pretty warm), but that's typically handled via the MEL.