Hi Silver
The use of non-hard-surfaced runways is not routinely practised by the Don, with the obvious exception of the helicopters, because such unprepared surfaces are not swept regularly and are too risky to use for casual training.Anyone landing on a grass field knows that the possibility of sucking in a stone or eroding the prop blades is very real.The corrosive power of dust has to be seen to be believed.I once flew to Sligo in 240 and there was beach sand blown across the runway.We landed and the pilots applied reverse thrust, as required.When we shut down,I had a look at the props.The paint had been sanded off the blades, along a length of about 15 inches, as effectively as if they had been sandblasted in a workshop.There was no damage to the metal, but the paint removal was the equivalent of a full service life's wear and tear.Airport operators are very conscious of the need to maintain clean runways and ramp areas and sweep them regularly, often with magnetic devices and industrial brush sweepers.It's cheaper than replacing engines!
regards
GttC