Oh and all AD's are upto date, it had a 100 inspection a few months ago.
As for area, I don't think it's particuarly a corrosive atmosphere. It's east coast about 3NM from the sea but it's ALWAYS put back in the hangar. Don't fly it through rain or crap unless caught out by the odd shower.
No haven't used WD40 or anything like that, only use a damp cloth to clean the blades and anything other than paintwork or screen. Do them often enough so it's not caked with flies.
I'm just a bit miffed by it really. Seems nobody else has had this problem with similar hours and year machine then?