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1. General. The stabilizer and fin are of aluminum-alloy construction consisting of spars, stringers, and intercostal ribs which are covered with an aluminum-alloy highly stressed skin. (See figures 104 and l05.) 2. Stabilizer. a. Negligible Damage. - Smooth dents free from cracks, abrasions, and sharp corners may be neglected provided the adjacent rivets are intact, and there is good reason for assuming that the damage has not affected the internal structure. Wherever possible these dents should be restored to shape taking care to avoid cracks. b. Damage Reparable by Patching. (1) Nose Skin. - The method of repairing the nose skin is shown in figure 106. Attach the .051-inch splice plates to the undamaged skin with 1/8-inch solid rivets. The .051-inch 24S'lÔ aluminum-alloy skin insert may be attached with Cherry blind rivets after the plates are in position. (2) Main Skin. - Repair to the stabilizer skin may be effected as shown in figure 101. For attaching the strap plates to the .020-inch skin use AN426AD-4-4 rivets spaced at 3/4 inch. For the .025-inch skin use AN426AD-4-4 rivets at 1-inch spacing in two staggered rows as shown in figure 107. For attaching a .020-inch skin patch to a strap plate use two rows of Cherry blind - 1/ 8-inch diameter countersunk rivets. For attaching .025-inch skin patch, use two staggered rows of Cherry blind 5/32-inch diameter countersunk rivets. (3) Flanges and Webs. - For flange and web repair of the spar, see figure 108. When effecting repairs, refer to the chart on figure 10 for the number and spacing of rivets. Use the existing rivet holes for the skin rlvet pattern. (4) Stiffening Beads. - For repair over a stiffening bead of the spar use the same material, one gage higher than the damaged member, using AN442AD4 rivets as shown in figure 109. (5) Spars Containing Lightening Holes,\. - For repair of a spar section where there are lightening holes use 24ST aluminum-alloy material of the next higher gage and attach with AN442AD-4 rivets as shown in figure 109. (6) Reinforced ¤par Sections. - Damage to reinforced sections of the spars should be repaired by splicing in new sections or by adding two pieces of stock, one on each side of the web and doubler. The a 153 total thickness of these two repair plates is to be equal to the total thickness d the web and doubler. The required number of rivets is the same as given in figure 108. |
(7) Rib Flanges. - For damage to any flange of the rib patch by a bent -up angle attached to the web by a minimum of three 1/8-inch rivets on each side of the damaged area as specified in the chart. (See figure 110.) (8) "V" Stringers. - For repair of a "V" stringer, see figure 110. Drill and punch out the necessary skin rivets according to section 1, paragraph 9. Cut away and clean the damaged area of the stringer. Insert a filler plate of the same gage material (24ST) and rivet the section as shown in the figure using three rows of 1/8-inch rivets on each side of the damage. c. Damage Reparable by Insertion. - For a "V" stringer insertion splice, see figure 110. Drill and punch out the skin rivets, cut away and clean the damaged area and insert a new section of Alclad 24ST, leaving a 1/32-inch clearance at each end. Splice the new section ends, using three rows of rivets on each side of the cut, leaving a rivet edge distance of 2-1/2 diameters. d. Damage Necessitating Replacement. - Sections of the spars between the fin and fuselage attachment fittings should generally be replaced lf damaged. The webs should be spliced at least 8 inches outboard of the fuselage fittings. Replace all damaged gussets, fittings, etc. 3. Fin a. Spars. (1) Webs and Flanges. - Web and flange damage shouldbe repaired according to data given in figure 108. (2) Reinforcement Angles. -Reinforcement angles on spars No. 1, 3, and 4 should be either replaced if damaged or repaired by attaching a .025-inch 24ST angle over the damaged section with 1/8-inch rivets. Use at least 4-1/8 inch rivets, two in each leg of the angle, at each end of the damage. b. Ribs. - For web damage a minimum of two 1/8 inch rivets are necessary on each side of the damage. The flange repair should be the same as used on the stabilizer as in this section, paragraph 1.11. (3). (See figure 108.) c. Stringers. - Patch the damage with four rivets on each side of the damage, same as the tail plane repair. (See figure 110.) d. Skin Patches. - Use 1/8-inch rivets at 3/ 4-inch spacing around the damaged area of .020-inch skin; |
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