I think your comment is right on for modern airplanes (the last 40 or 50
years) when you go past that, there are often no inserts to receive the
screws (wood screws and machine screws). They often go into wood, or
directly into steel/aluminum. As a result they get bigger screws over
the years until you have a mix of #6 #8 and #10 throughout the plane
followd by often more significant action (after #10 is too small) (makes
putting it back together fun
Much of this "wear" is from taking apart fairings and panels of
vintage/antique planes for annual that don't fly nearly the hours of
your local airport rental plane, yet the same requirements apply.

Mike

scott moore wrote:
pittss1c wrote:

The other relevant arguement is that we are "wearing them out taking
them apart every year"
There are only so many times you can remove and replace screws into
wood and thin metal before some strip.


I have an answer for that, after doing my owner assisted annual for 7+
years now. As an engineer, and as someone who formerly worked on cars,
I really appreciate the way my airplane is put together. Virtually every
screw that has any important function has a replaceable insert it screws
into. After performing a few annuals, I started to get the bad ones
replaced. It became clear that it was me who was going to deal with
these stripped and broken fasteners year after year. I also started to
replace the odd assortment of screws various mechanics had put in over
the years with the original screws. In one case, the back seat nut plate
had been stripped and pushed aside, then replaced with a bolt. This
meant putting it together required pulling several floor inspection
plates and contorting my arm to hold the bolt underneath. Thats fixed
now, and it saves time and swearing.

All and all, my airplane is in far better shape than it ever was, and
getting better year by year.