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e.Bulkhead No, 5. (1) General. - This bulkhead is designed to support the fuselage in the event of a "Turn-over." The fittlng at the top of the bulkhead transmits the load to the skin and stringers at the top of the fuselage aft of the bulkhead and to the armor plate which ls attached to this bulkhead. The armor plate through its attachment at each side and along the bottom transmlts the loads into the bulkheads which ln turn transmits the loads to the fuselage skln and longerons. (2) Upper Section. - Damage to the upper part of thebulkhead should be patched or reinforced with .064lnch gage 24ST aluminum -alloy stock attached with 1/8 inch A17ST rivets as shown in figures 16 and 39. Form a flange on the patch ff an inside bulkhead flange is damaged. For extensive damage insert a new section or splice a new material as shown ln the drawing. Damages which do not injure the flanges or the armor plate attachments may be neglected. (3) Lower Section. - Damage to any of the lower sections of the bulkhead will ln general necessitate replacing the damaged parts. (See figure 17.) Splices which may be used at the bottom of the bulkhead are shown in figure 38. Any damage which injures a bulkhead flange, splice, armor plate attachment or any fitting to the bulkhead must be repaired using equivalent material and methodof attachment. Minor dents ln the armor plate may beneglected. Do not, however, neglect large horizontal buckles as these will cause the bulkhead tocollapse should the airplane turn over. The bolts attaching the armor plate to the bulkhead have a low margin of safety; consequently, any damaged bolts should be replaced or new bolts should be added on each side of each damaged bolt. (4) Turn-Over Fitting. - The attachment of the large fitting at the top of the bulkhead to the fuselage has a low margin of safety. If the fuselage skin is damaged directly aft of this fitting, add a .040-inch gage 24ST patch large enough to take three rows of 3/16-inch A1'IST rivets at 1-inch spacing around the damage plus all of the rivets and bolts in the fitting which are directly forward of the damage. Arrange the rivet pattern so as to use the original holes. Do not drill any additional holes ln the fuselage skin lmmedfately aft of this flttlm. The stringer at the top of the fuselage which attaches to the bulkhead fitting should be spliced if damaged with a similiar stringer section and at least six 3/18 -Inch Al7ST rivets on each side of the splice cut. f. Bulknead Nos. 6 to 12. (1) Narrow Section. - In general any portion of these bulkheads which is not over2-l/2 inches wide between flanges may be patchgd or spll?ed by adding a flanged plate as shown in figures 17 an 39. The plate should be of the same gage and material as the damaged portion of the bulkhead and should be shaped to fit the outer edge of the bulkhead. The flange on the |
inner edge should be the same a the inner flange on the bulkhead but maybe formed straight. To attach the patch or splice use six 5/32-inch A17ST rivets for a .040-inch bulkhead or six 3/16-inch rivets for a .064-inch bulkhead spaced at 1-inch minimum fn the channel web on each side of the damage or cut. (2) Hide Sections. - Minor damage to the wider portions of these bulkheads may ln general be repaired by patchlng with a sheet of the same gage and materlal and two rows of 5/32-Inch A l7IST rivets completely around the damage. (See figure 40.) Extensive damage may be repaired by the use of insert; use two rows of 5/32-inch rivets along each side of the line of cut as illustrated in figure 42. For .040-inch bulkheads use a maximum spacing of 1 Inch for the rivets and on the .084-inch bulkheads use a maximum spaclng of 3/4 inch. (3) Lower Sections. - Nos. 8 and 'I have reinforcing angles at the bottom. (See figure 17.) These angles may be spliced or patched by nestlfng a similar angle into the damaged angle and attaching with AN442AD-5 rivets in both flanges. The required number of rivet per flange on each side of the damage is flve minus one -ftfth the number of rivets in one flange of the angle between the damage and the vertical center line of the bulkhead. (4) Speclal Regirs. - Exceptions to the preceding general rules are as follows: (a) Bulkhead No. 8. - Any splice below stringer 10 requires a minimum of eight 3/18-inch rivets at 3/4-inch spacing on each side of a spllce cut. (b) Bulkhead No. 9. - Use two rows of 5/32-inch rivets at 3/4-inch spacing around any damage below strlnger 11. For a splice in this region use eight 5/ 32-inch rivets at 3/4 -inch to 1-inch spacing on each side of splice cut. (c) Bulkhead No. 10. - Use three rows of 1/8lnch rivets at 1-inch spacing around any damage below stringer 11. For a splice in this region use nine 1/8-inch rivets at 3/4-inch to 1-inch spacing on each side of splice cut. (5) Strugtural Clips. - Stringer 10 is attached. to bulkheads Nos. 7 and 8 by structural clips. Any damage to the attachmentof these clips will require reinforcement or replacement of the damaged portion of the bulkhead. All damaged gussets, clips, spllces, etc., must be replaced. g. Bulkhead NO. 13. (1)Upper Section. - Minor damage to the upper half of this bulkhead may be repaired with .084-inch 24ST sheet attached by two rows of 1/8-inch rivets at 5/8-inch spacing completely around the damage. |
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