does this archer have the standard engine installed??

I think so.

if there was an STC for a larger or different engine prop
combination, then that may require the red arc area...

I'll have to check the logs.

this sounds like something from an Arrow with 3 prop blades..

I believe that it's the Arrow 2-blade that has the limitation. We
have one with 3 blades that the mechanic says doesn't need the red
arc, but they left it on anyway.

Thanks