Pic 3 shows the separated fan hatch, cut from the fuselage along existing engraved panel lines using a razor saw. Removing such a large section from the fuselage reduced its torsional rigidity. To restore fuselage stiffness I edged the hatch and the fuselage aperture with a double layer of 1/32in plywood strips 3/8in wide, and added laminated plywood lugs on the fuselage onto which the hatch is firmly screwed to restore fuselage stiffness. These lugs are curved during lamination to match the curve of the fuselage.