Soft Rivets?

I am at the point of attaching the hinges to the cowl on my -9A. The instructions say to use regular structural AN426-3 rivets. Because they go through fiberglass, I was wondering if this would be a good place to use AN426 soft rivets. How important is the structural strength of the rivet vs. reducing the possible damage to the fiberglass cowl material? Has anyone tried soft rivets for this application?

Rivets

If the instructions call for the hard rivets, that?s what I would use...

Soft rivets

Just did this two days ago and had no problem using regular rivets.Used epoxy also as Vans suggested.

One thing I noticed was using a hand squeezer for these, vs the pneumatic squeezer seemed to work better with no cracking.

Just my 2cents.

Lynn

Just did my hinges over the weekend with the soft rivets. I have the manufactured head on the hinge and the shop head going into a deep countersink in the glass. A light pass with a sanding block makes the shop head disappear.

I used the regular rivets, but also did a couple of additional steps to assure that the hinges are going to be on there for good.

You can see in this photo on the left side I have drilled some extra holes in between the rivet locations.



Go get some West System G/Flex epoxy and put that under the hinge before you rivet on the hinge. The excess will fill the extra drilled holes and provide additional strength to the bond that the rivets provide.

You can sort of see the epoxy filling the holes in the bottom of this photo.



650 hours later, I haven't seen any issues with separation of the hinge from the cowling.

In a number of places in the RV-14 instructions, Vans recommends soft rivets and/or hand squeeze for fiberglass rivets. I used soft rivets and found them to work great. One big advantage is that they flatten very flush to countersunk holes (always looks and feels smooth). I usually use a slightly longer rivet - like a -4 where -3.5 is called out.

Soft A rivets

The soft rivets will work fine. I expect you are also bonding the hinge.

I shipped soft rivets with the F1 kits - for the cowling, and for the elev and rudder TE. I did not hear any complaints from the owners!

For the record, how does one tell soft from hard rivets (other than the final product)? Color difference?

Soft

Greg Arehart said:

For the record, how does one tell soft from hard rivets (other than the final product)? Color difference?

Click to expand...

I believe the hard AD rivets have a little dimple in the head, while soft A rivets don?t have the dimple. Color just varies by manufacturer..