The LE Stiffeners have to be cut to length and match drilled to match the LE Skins. A line is drawn down the flange a prescribed distance from the edge.
I had made a little T-Piece to help with alignment of the elevator trim tab hinge, so I used this with a little hole drilled in it to act as a guide.
A first hole is drilled at the root end, and this is clecoed to the skin to start off the match drilling process. Having read that its easy to get the orientation and dimensions wrong I checked against the skins prior to cutting! Actually the dimensions in the manual are now correct.
But what I did discover was that aligning the line in the centre of the skin holes placed the “J” of the stiffener very close to the rib clearances. Re-drawing the line a smidge towards the stiffener J solved the problem.
Now the manual says clamp and match drill, but unless you happen to have a clamp with a 250mm throat it’s not possible. So I just used a length of wood to gently wedge the stiffener flange in place during the match drilling, inserting clecoes progressively.
The ribs also need one hole at the top each side match drilled to the skin. I gently clamped the skin in place using one of my well used Irwin Clamps.