If one more person mentions long term engine damage i will track you down and bludgeon you with my wireless mouse..
its like talking about long term damage to shoe leather or the tread on your car tyres.
blades are replaced when they meet the time and cyc limits defined as an LLP (Life Limited Part) they are also inspected at intervals as well as trend monitoring, if there is any question as to the longevity they are replaced prior to LLP limits, Also with AD's and SB's they are often overhauled or replaced if they don't meet limits prior to intervals anyway.
As for flight into an ash plume, that will also warrant a bludgeon with a mouse, the plume is what is vented from this volcano.. 500 or a 1,000 miles away we're talking airborne contaminants.
But wouldnt flying through this ash etc cause engine damage and reduce those cycles? and also increase the frequancy of inspections? I'm only asking out of interest before you kill me to death!