Repair seam same as strongest parallel adjacent seam. Repair seam same as strongest parallel adjacent seam. Use original holes and add as needed. Additional Rivets Trimmed hole radiused corners 3/16" 5/32" 1/8" Figure 4-180.  Replacement of an entire panel. Stringer Repair The fuselage stringers extend from the nose of the aircraft  to the tail, and the wing stringers extend from the fuselage  to the wing tip. Surface control stringers usually extend the length of the control surface. The skin of the fuselage, wing,  or control surface is riveted to stringers.  Stringers may be damaged by vibration, corrosion, or  collision. Because stringers are made in many different  shapes, repair procedures differ. The repair may require the  use of preformed or extruded repair material, or it may require  material formed by the airframe technician. Some repairs may  need both kinds of repair material. When repairing a stringer,  first determine the extent of the damage and remove the rivets  from the surrounding area.  [Figure 4-183]  Then, remove the  damaged area by using a hacksaw, keyhole saw, drill, or file.  In most cases, a stringer repair requires the use of insert and  splice angle. When locating the splice angle on the stringer  during repair, be sure to consult the applicable structural  repair manual for the repair piece’s position. Some stringers  are repaired by placing the splice angle on the inside, whereas  others are repaired by placing it on the outside. Figure 4-185  illustrates repair by insertion where damage  exceeds two-thirds of the width of one leg and after a portion  of the stringer is removed.  Figure 4-186  shows repair by  insertion when the damage affects only one stringer and  exceeds 12 inches in length.  Figure 4-187  illustrates repair  by an insertion when damage affects more than one stringer. Figure 4-184  shows a stringer repair by patching. This repair  is permissible when the damage does not exceed two-thirds  of the width of one leg and is not more than 12 inches long.  Damage exceeding these limits can be repaired by one of the  following methods. Extrusions and preformed materials are commonly used to  repair angles and insertions or fillers. If repair angles and  fillers must be formed from flat sheet stock, use the brake.  It may be necessary to use bend allowance and sight lines  when making the layout and bends for these formed parts.  For repairs to curved stringers, make the repair parts so that  they fit the original contour. 4-102