VP & Dan,
Excuse my ignorance for chipping in here - I am neither aircrew nor an engineer.
However, I do have a memory of discussing the Falklands War with personnel at Marham in the '80s: I was told that the ops did not adversely impact on the fatigue life - indeed, as there was no circuit-bashing around Ascension they actually benefited. Also, I was told that the volcanic soil polished-up the turbine blades nicely.
Was I being told a load of eyewash?