What causes a V1 to become out of tune? Why do V1's get out of tune (that is, what parts of them change/deteriorate)? Are the parts that become out of tune electronic, or mechanical (like a tuning fork) due to expansion or contraction?
I have heard that V1's should be tuned annually. This must be an average. Should they be done more often in a hot climate than cold, or wet than dry?