Crack Stop drill #40 drill hole Stop drill #40 drill hole Crack Doubler Doubler Bulkhead Radius to rest in bulkhead Bulkhead 1.5 "  minimum 1.5 "  minimum OR Radius to rest in bulkhead Figure 4-188.  Bulkhead repair.  extrusions, and they stiffen the leading edges and furnish a  base for the nose ribs and skin. They also fasten the leading  edge to the front spar. The nose ribs are stamped from aluminum alloy sheet or  machined parts. These ribs are U-shaped and may have  their web sections stiffened. Regardless of their design, their  purpose is to give contour to the leading edge. Stiffeners  are used to stiffen the leading edge and supply a base for  fastening the nose skin. When fastening the nose skin, use  only flush rivets. Leading edges constructed with thermal anti-icing systems  consist of two layers of skin separated by a thin air space. The  inner skin, sometimes corrugated for strength, is perforated  to conduct the hot air to the nose skin for anti-icing purposes. Damage can be caused by contact with other objects, namely,  pebbles, birds, and hail. However, the major cause of damage  is carelessness while the aircraft is on the ground. A damaged leading edge usually involves several structural  parts. FOD probably involves the nose skin, nose ribs,  stringers, and possibly the cap strip. Damage involving all  of these members necessitates installing an access door to  make the repair possible. First, the damaged area has to be  removed and repair procedures established. The repair needs  insertions and splice pieces. If the damage is serious enough,  it may require repair of the cap strip and stringer, a new nose  rib, and a skin panel. When repairing a leading edge, follow  the procedures prescribed in the appropriate repair manual  for this type of repair.  [Figure 4-192]  Repairs to leading  edges are more difficult to accomplish than repairs to flat  and straight structures because the repair parts need to be  formed to fit the existing structure. A trailing edge is the rearmost part of an airfoil found on  the wings, ailerons, rudders, elevators, and stabilizers. It is usually a metal strip that forms the shape of the edge by tying  the ends of a rib section together and joining the upper and  lower skins. Trailing edges are not structural members, but  they are considered to be highly stressed in all cases. Damage to a trailing edge may be limited to one point or  extended over the entire length between two or more rib  sections. Besides damage resulting from collision and  careless handling, corrosion damage is often present. Trailing  edges are particularly subject to corrosion because moisture  collects or is trapped in them. Thoroughly inspect the damaged area before starting repairs,  and determine the extent of damage, the type of repair  required, and the manner in which the repair should be  performed. When making trailing edge repairs, remember  that the repaired area must have the same contour and be  made of material with the same composition and temper as  the original section. The repair must also be made to retain  the design characteristics of the airfoil.  [Figure 4-193] Figures 4-194  through  4-198  are examples of repairs for  various structural members. Specific dimensions are not  included since the illustrations are intended to present the  basic design philosophy of general repairs rather than be  used as repair guidelines for actual structures. Remember to  consult the SRM for specific aircraft to obtain the maximum  allowable damage that may be repaired and the suggested  method for accomplishing the repair. Specialized Repairs Trailing Edge Repair 4-107