Cracks from Rivets

I always read that none proper deburring and dimpling will cause cracks originating from those rivet holes. Makes logical sense to me and I certainly don't advocate slopping building practices. However, I am curious how often this actually happens in practice. So I figured a quick poll would be one way to get some data on this.

Oliver

I can tell you that I have never seen a crack from rivet holes on any of my RV’s - but our Dream Tundra came home from Oshkosh two years ago with spider cracks from dozens of holes on the leading edge of the horizontal stabilizer. Round-head AD3 rivets in all the holes, and since I didn’t build those parts, I have no idea how they were drilled/punched/deburred/riveted. When I drilled out all the rivets to start a repair, the leading edge sprung wide open, suggesting to me that it was underwent, and the tension on the rivet heads was extreme, so that might have had something to do with it....

I like this from NASA for rivet info:
https://www.google.com/url?sa=t&rct...ken=uv5vl1UM&usg=AOvVaw3VCYWa6RT1t9a5_aHctMTX

I always thought it interesting they don't mention deburring hardly at all.

Then there is this study about deburring: the standard method they describe uses drill/reamer/600 grit sanding, don't worry about burrs IN the hole. It's a little bit like using scotchbrite to remove any surface burr.

https://www.google.com/url?sa=t&rct...40110776.pdf&usg=AOvVaw1n2Le6NIT0kp5V-ncIcv7-

The chemical method is what they decide is the best. Not really possible at home.

So what I get from all this is you are better to fine sand a hole than use the deburr tool on thin skins..... I end up sanding the inside surface to prime it, so I'm good there; on the outside I debur as needed.

no cracks or loose rivets, 900 hrs. before paint I spent one day applying Loctite 290 to each external rivet using a q-tip. yes, the entire aircraft. 290 is self wicking and fills any gaps. I don't know if it helps.

MS20603

This rivet is listed as being a "chemically expanded" blind rivet,100* flush head.

Anybody know what chemically expanded means?

Thanks

If posting in the wrong section - sorry. I just found this rivet while reviewing the NASA doc listed earlier.

HFS

MS20603

Looks like the flush version of an explosive rivet that I remember.

The spec was cancelled in '77. I was in the military as a helicopter mechanic then while it was active, and we were never taught about it.

Dave

JDA_BTR said:

I like this from NASA for rivet info:
https://www.google.com/url?sa=t&rct...ken=uv5vl1UM&usg=AOvVaw3VCYWa6RT1t9a5_aHctMTX

I always thought it interesting they don't mention deburring at all.

Click to expand...

Section 4.2.1 is titled "Deburring".

True -> but read what they say. It is minimalist at best. Like you should just know what they mean already! I have a feeling we deburr way more than NASA does.

But I'm gonna edit my post: "hardly at all".

MS20603 - Again

Dave was right on about the chemically enlarged blind rivet, being what is traditionally known as an "explosive" rivet - see attached Mil. Spec.

Good on ya Dave!

HFS

Sorry about the orientation - I don't know how to rotate it?