What Type of Rivet is this?

[Bubba L]

Does anyone know what type of rivets are shown in the photos (outside and inside views)? A PO on our 55 installed these in an exterior skin repair. They appear to have a mandrel that has been shaved. It doesn't look like the typical Olympic. If these are not structural and could potentially leak, I will drill them out and replace with bucked rivets. Thanks

[Aerowood]

Those are an early type of blind rivet. They were called "self plugging friction lock blind rivets". They were made by both the Olympic and Cherry companies. I believe they are obsolete but I could be wrong. They were not used in any structural applications due to the low shear strength. I haven't seen them for many decades in the aviation world that I live in.

[Bubba L]

Thanks for the info. There's only about 100. I will drill them out and replace.