Well that was something interesting I didn't expect to find as I trawled through pprune for one last time before bed!
I'm indebted to you for the information about percentages of N in excess of 100% and the trade off with engine life.
Just a quickie (ooh err missus!) - what, briefly, are the other factors that have a bearing on turbine engine life? I imagine cycles are important but any other major factors?
Thanks in anticipation....(I really MUST get out more...)