Notching Rib 1 (Root Rib)

[GNL]

I have started notching the upper cap strip on the root rib per the build manual, section R "Swing the Wings" to clear the carry-through spar but am getting nervous about how far to go without weakening the rib to the point of failure once the fabric is shrunk. I have taken out about 1/4" but will need to go to 3/8" to allow room for the fabric. Similar notching will need to be done on the lower cap strip to allow the opening to be covered and the fabric clear the carry-through spar when the wing is folded back.

Is this common? Has anyone had any rib failures when the fabric is tightened.