A lot of it is cost. To have our aircraft at Ronaldsway in a hangar, it would cost about £3000+VAT more than it does to keep it at Andreas, which belongs to a farm.
I have been to Andreas (by road, thankfully 
) and against the 3k you have the prop overhaul 
According to rumour somebody with a TBM offered to resurface Andreas but Ronaldsway did some under the table stuff to block it because while they don’t want SEP money they do want ME money and Andreas would take most of that away.
The prop only has to last a year for me to be ahead on that count (and with a tailwheel aircraft, we don’t get any nicks or damage anyway, since our prop clearance is so great). Even the Cherokee based there doesn’t really pick up prop damage.
A much bigger issue with what is effectively a compressed stone/gravel runway we have is tailwheel damage. But given the Auster tailwheel is a glorified shopping trolley wheel, it only has to last a month for us to be ahead on that count…
