and the spacing is reduced to the minimum in table D of figure 67. When damage occurs near a web flange or cap strip and prevents running the required rivet pattern around the damage, extend the patch to the edge of the web and use the required number of rivets as given in table B of figure 87 for the attachment to the cap strip, at each end of the damage. Run the required rivet pattern, table A, around the damage and up to the cap strip or flange. (See figures 68 and 68.)      c, Damage Reparable by Insertion. - Extensive damage should be repaired by splicing in new sections of the same gage 24ST stock. Splice plates for attaching the inserts to the undamaged parts of the web should also be of the same gage 24T stock. The rivet pattern requirements are in general the same as for patches. Table C, figure 67 gives the minimum number of rivets to be used on each side of the cut between the cap strips. Figures 70 to 73 give cap strip and web flange repairs which are equal in strength to cap strip material including the web material in the cap strip region. When these repairs are made at a cut in the web, the web splice plate does not need to be attached to the cap strip. If, however,the cap strip or web flange is not repaired according to figures 80 to 83,the splice plate should overlap the cap strip and should be attached with the number of rivets specified in table B on each side of the cut. (See figure 67.) Table D gives the minimum allowable spacing for rivets and should be considered in arranging all rivet patterns. Various examples of repairs to spar webs are given in figures 67 to 69 and 74 to 81.      d. Damage Requiring Replacement. - Damaged fittings, small gussets and reinforcements must be replaced. Also all rivets or bolts removed in making repairs must be replaced.      6. Stringers.      a. General. - Several types of stringers are used in reinforcing the wing skin. Cross-sectional views are shown in figures 82 and 83. Figure 82 shows extruded stringers with their Alcoa die numbers. Figure 83 shows formed ÒZÓ stringers and an extruded ÒZÓ stringer with its Alcoa die number. For reference purposes each stringer is given a number as shown in figures 54 and 55.      b. Negligible Damage. - Small isolated dents, free from cracks, abrasions, and sharp corners may be neglected provided no two adjacent stringers are damaged and the skin to which the stringers are attached is not affected. All stringers should be kept as straight as possible in order to withstand compression loads.      c Damage Reparable by Patching. - Do not neglect any nicks or cracks in the stringers. Damage which alter clean-up affects less than one half of the cross- sectional area may be reinforced by using the required patch plates and rivets as given in figures 85, 86, 87, and 88.

Damage affecting more than one-half of the cross section should be repaired according to figures 84, 89, 90, and 91. As shown in these figures an angle may be attached to the skin next tea stringer to reinforce any damaged area located near the outboard end ot the Stringer. Filler pieces should be added wherever needed for the attachment of the skin or fitting.      d. Damage Reparable by Insertion. - Extensive damage should be repaired by cutting away the damaged portion of the stringer and replacing this with an insert of the same section and material. Details Ior the splices to be used in attaching the insert are given in figures 84, 89, 90, and 91 for the various sections.      e. Damage Necessitating Replacement. - Damaged Stringer reinforcements and splice plates should be replaced.      The short stringers supporting the lower surface of the ammunition compartment should be replaced If damaged or may be reinforced by attaching a section of similar stringerts to the skin next to the damaged portion using AN442A.D-4 rivets at 1-inch spacing and at least four rivets at each end of the damage.      f. Gas Tank Door Stringers. - Any damaged gas tank door stringers should be replaced or patched with .051-inch gage 24ST sheet formed to fit over the damaged stringer and long enough intake at least four 3/16-inch rivets at each end through each flange or a total of eight 3/16-inch rivets at each end plus the original 1/8-inch rivets along the length of the damage.      7. Spar Cap Strips.      a. General. - There are four types of cap strips: An extruded angle, an extruded "J" section, an extruded bulb angle and a formed "J" section. Each type requires a special arrangement of patch material and is covered separately in figures 70 to 73. The number of bolts or rivets for each repair is given on the figures according to spar number and span wise location. Cross- sectional views with Alcoa die numbers for each are shown in figure 92.      .Negligible Damage.- Small isolated dents, free from cracks, abrasions, and sharp corners may be neglected.      c. Damage Reparable by Patching.      (1) Nicks and Cracks. - Do not neglect any nicks or cracks in the cap strips. Clean up the damaged area, by rounding out the sharp corners and stopping cracks with an 1/8-inch drilled hole and then reinforce or patch the cap strip according to the data given in figures 70 to 73.      (2) Drilling Bolt Holes. - Care must be exercised to use the correct drill sizes when enlarging rivet holes to take the required bolts. Any looseness of the bolts will throw excessive loads on the nearby rivets,