That is normal on most RV-4 builds. Mine wasnt as severe of a cut, and you need to make smooth and raduised to eliminate stress points. Make sure the rest of your geometry is correct, such as flap rod lengths ect. Mine is the electric flap set-up, so there are variables that will change how far down the weldment travels. You need wings on and flaps on before you can dial it in. All my flap linkage is covered with side panels (removed in pic), but you can zoom in this picture and get an idea where mine is with flaps full down. My trim out of the gusset just clears the weldment.