Excellent thread gents!
For some reason EPR synch had not occurred to me. That would indeed explain the difference.
I'm not sure I understand exactly how
"the fan of one of the engines is more worn than the other(s)"
, thinking that it would be more likely that the combustion/power turbine stage would be the point where "wear" would introduce power loss, and hence imbalance the RPMs as a function of equalizing EPR.
- GY
