Patch Surface Flipping

Hey folks,

I need to access the normal lines of points on a series of patch surfaces, but (as shown in the attached picture) some of the patches are flipping to face the opposite direction to that intended. Is there any way of preventing this, or perhaps accessing those that need flipped back automatically? This is a critical point in an otherwise highly successful project. Any help gratefully received.

Best regards

Ewan

P.S. Just to clarify, the 2nd, 3rd and 8th (last) layers in the picture have flipped so the normals (in green) are facing the wrong way.