Help making extruded cut that is normal to curved surface.

[Kaz]

I am not sure how else to explain what I am asking, so I included an image showing the portion I wish to remove. The surface has a thickness to it and I want to have the cut be normal to the curve on all edges.

I assume there is a way to do this, but I am a student and new to the software and cannot figure it out. Help with this will be greatly appreciated.

Thank you in advance.

 

[Kaz]

Perhaps this isn't possible? Or maybe needs to be done entirely different? Either way, I would like to hear some thoughts on how this can be done.

 

[Cadasio]

Depending on what you want to occur afterwards, and how it interacts with the main body, you may want to look at the following features...
Wrap
Intersect
Composite Curve + surfaces