Difference between amateur-built and amateur-built (experimental)

[jonathan102]

For part of my uni assignments, I have to look at the regulations regarding amateur-built (experimental) aircraft. During my research, I came across two sets of regulations, one is for amateur-built (AC 21.11) while the other one is for amateur-built (experimental) aircraft (AC 21.04). The regulations regarding ABAA are fairly strict, with restrictions on MTOW, stall speed etc. But CASA has basically no restriction on the design of amateur-built (experimental) aircraft.

 

So my question is what allows an aircraft to be classified as a amateur-built (EXPERIMENTAL), but not a conventional amateur-built aircraft?

 

Thanks.