Hi Anis,

You can't sweep a single profile along the variable helix and stay perpendicular with the curvature of the solid, you'll have to set up some additional profiles, you can array along curve (magenta in picture) the profile in four positions as shown, you can get an accurate distance using the 'Curve length' script for the pitch of the helix along the curve.



I've attached your file set up ready for the sweep operation.

Cheers