Damage area Insertion Splice angles Damaged area cut out smooth Assembled repair Damage area Reinforcements Rib repaired Damaged skin cut  back to smooth contour  with corner radii Assembled repair Stringer insertion Damaged area cut  back so joints will be staggered Section A-A Skin Rib Figure 4-186.  Stringer repair by insertion when damage affects  only one stringer.  Figure 4-187.  Stringer repair by insertion when damage affects  more than one stringer.  Most damages involve two or more members, but only one  member may be damaged and need repairing. Generally,  if the web is damaged, cleaning out the damaged area and  installing a patch plate are all that is required. The patch plate should be of sufficient size to ensure room for  at least two rows of rivets around the perimeter of the damage  that includes proper edge distance, pitch, and transverse pitch  for the rivets. The patch plate should be of material having the  same thickness and composition as the original member. If  any forming is necessary when making the patch plate, such  as fitting the contour of a lightning hole, use material in the  “0” condition and then heat treat it after forming.  Damage to ribs and webs, that require a repair larger than a  simple plate, probably needs a patch plate, splice plates, or  angles and an insertion.  [Figure 4-191] The leading edge is the front section of a wing, stabilizer, or  other airfoil. The purpose of the leading edge is to streamline  the forward section of the wings or control surfaces to  ensure effective airflow. The space within the leading edge  is sometimes used to store fuel. This space may also house  extra equipment, such as landing lights, plumbing lines, or  thermal anti-icing systems. The construction of the leading edge section varies with the  type of aircraft. Generally, it consists of cap strips, nose ribs,  stringers, and skin. The cap strips are the main lengthwise  Leading Edge Repair 4-106