Further conversation from Vans support...
Here's one more correspondence I had with Vans technical support concerning replacing rivets:
We recently added this paragraph to section five in the manual.
EXCERPT from Alcoa Aluminum Rivet Book, dated 1984.
"The standards to which driven rivets should conform are frequently uncertain. In addition to dimensions and perfection of shape, inspection is concerned with whether the drive head is coaxial with the shank (not ?clinched?) and whether there is excessive cracking of the heads. It has been determined that even badly cracked heads are satisfactory from the standpoint of static strength, fatigue strength and resistance to corrosion. (Poorly set and cracked) rivet heads were tested in tension to determine how well formed a head has to be in order to develop full strength. The tensile strengths of all the rivets were within five per cent of the strongest. The test indicated that minor deviations from the theoretically desired shape of head are not cause for concern or replacement. The second rivet that is driven in any one hole is likely to be more defective than the first because the hole is enlarged and rivet will be more likely to buckle and form an imperfect head.
Tests have shown that very small rivet heads are sufficient to develop the strength of the rivet shank, even when the rivets are subject to a straight tensile pull?.where a large head is not needed for appearance, smaller sizes of drive head should be used to decrease the required driving pressures."
Most builders end up drilling out the hole oversize and call or email us to find out how to fix the situation. Usually they do more harm than good, so we tell them to just leave the ugly rivet in place and move on.
My section five doesn't have this. So its information I'm glad to have. Hope others find it useful.
RV-9A Flying 340 hours!
Last Donation: December 2020