In article
, Orval
Fairbairn says...

You should note that I specified STRUCTURAL aluminum. Yes, nonstructural
parts are made for other reasons and have a places for other grades of
aluminum.

BTW, Zenith also uses pop rivets rather than driven rivets, so they
should not be used as an example.

Thorp used pop rivets on the T-18 as well .Cherry Max's are pop rivets too and
are used all over the place. Zenith doesn't have parts coming apart because
of pop rivets. You just have to use the right ones and have them sized for the
loads.
See ya

Chuck S