Damage area Filler Reinforcement Damaged area cut out smooth with corner radil Assembled repair Damage area Filler Reinforcement Damaged area cut out smooth Assembled repair Figure 4-185.  Stringer repair by insertion when damage exceeds  two-thirds of one leg in width. Figures 4-189  and  4-190  are examples of typical spar repairs.  The damage to the spar web can be repaired with a round or  rectangular doubler. Damage smaller than 1-inch is typically  repaired with a round doubler and larger damage is repaired  with a rectangular doubler.  Web sections must be repaired in such a way that the original  strength of the member is restored. In the construction of  a member using a web, the web member is usually a light  gauge aluminum alloy sheet forming the principal depth of  the member. The web is bounded by heavy aluminum alloy  extrusions known as cap strips. These extrusions carry the  loads caused by bending and also provide a foundation for  attaching the skin. The web may be stiffened by stamped  beads, formed angles, or extruded sections riveted at regular  intervals along the web. The stamped beads are a part of the web itself and are stamped  in when the web is made. Stiffeners help to withstand the  compressive loads exerted upon the critically stressed web  members. Often, ribs are formed by stamping the entire piece  from sheet stock. That is, the rib lacks a cap strip, but does  have a flange around the entire piece, plus lightning holes in  the web of the rib. Ribs may be formed with stamped beads  for stiffeners, or they may have extruded angles riveted on  the web for stiffeners. Rib and Web Repair 1.  Remove the damage and radius all corners to 0.5-inch. 2.  Fabricate doubler; use same material and thickness.  The doubler size depends on edge distance (minimum  of 2D) and rivet spacing (4-6D). 3.  Drill through the doubler and the original skin and  secure doubler with Clecos. 4.  Install rivets. Figure 4-184.  Stringer repair by patching.  Web repairs can be classified into two types: 1.  Those made to web sections considered critical, such  as those in the wing ribs. 2.  Those considered less critical, such as those in  elevators, rudders, flaps, and the like. 4-105