Why do I need AP supervision on a " certified " aircraft and not with a homebuilt?
In the eyes of the FAA....you built that homebuilt, you know it inside out, so it's OK for you to work on it. From what I understand, you can't just work on ANY homebuilt. It has to be one that you built (51% or more), you attended some approved workshops for that model and you get a certificate authorizing you to work on that homebuilt only.