AC 43.13-1A Page 53 1972 -1žD 650 (ID MIN.) + 1¿0→ (MIN.) (gO MIN.)
(8) DIMENSIONS FOR FORMED RIVET HEADS,
INCORRECT CORRECT SHAPE FOR
RIVET OR SEE SET.
BUCKING BAR
(6) RIVETING TOOLS OR DOLLY.
RIVET DRIVEN AT SLANT RIVET DRIVEN RIVET FLAT ON ONE
CORRECTLY, DOLLY SIDE OR DOLLY HELD HEAD AT SLANT. FLAT.
BODY OF RIVET TOO RIVET NOT PULLED RIVET TIGHT, PLATES SHORT. CLOSING HEAD TIGHT, CLINCHES BULGED ON ACCOUNT SHAPED TOO MUCH BETWEENPLATES, OF POOR FIT.
WITH SNAP DIE. CLOSING HEAD TOO FLAT.
RIVETED TOO MUCH. RIVET BODY CLINCHED TOO MUCH, HEAD CRACKED.
PLATES CLINCHED AT RIVET MATERIAL TOO AND DRIVEN APART. HARD WHEN RIVETING TOOL FORMED.
DAMAGED PLATE 1C) RIVET, IMPERFECTIONS:
FIGURE 2.19.-Riveting practice and rivet imperfections.
Par 99
proximately 8 times the thickness of the thicker sheet. Do not use rivets where they would be placed in tension tending to pull the heads off. Back up a lap joint of thin sheets by a stiffening section.
100. REPAIR METHODS AND PRECAUTIONS FOR ALUMINUM STRUCTURE. Carefully examine all adjacent rivets after the repair or alteration is finished to ascertain that they have not been harmed by operations in adjacent areas.
Drill rivet holes round, straight, and free from cracks. The rivet-set used in driving the rivets must be cupped slightly flatter than the rivethead as shown in figure 2.19. Rivets are to be driven straight and tight, but not overdriven or driven while too hard, since the finished rivet must be free from cracks. Information on special methods of riveting, such as flush riveting, usually may be obtained from manufacturer's service manuals.
a. Splicing of Tubes. Round or streamline tubular members may be repaired by splicing as shown in figure 2.20. Splices in struts that overlap fittings are not acceptable.
When solid rivets go completely through hollow tubes, their diameter must be at least one-eighth of the outside diameter of the outer tube. Rivets which are loaded in shear should be hammered only enough to form a small head, and no attempt made to form the standard roundhead. The amount of hammering required to form the standard roundhead often causes the rivet to buckle inside the tube. Satisfactory rivetheads may be produced in such installations by spinning, if the proper equipment is available. (Correct and incorrect examples of this type of rivet applications are incorporated in figure 2.20.)
b. Repairs to Aluminum Alloy Members, Make repairs to aluminum alloy members with the same material or with suitable material of higher strength. The 7075 alloy has greater tensile strength than other commonly used aluminum alloys such as 2014 and 2024, but is subject to somewhat greater notch sensitivity.
In order to take advantage of its strength characteristics, pay particular attention to de- Par 99 AC 43.13-11 1971 sign of parts to avoid notches, small radil large or rapid changes in cross sectional areas In fabrication, exercise caution to avoid proc essing and handling defects, such as machine marks, nicka, dents, burrs, scratches, and forming cracks. Cold straightening or forming of 7075-16 can cause cracking; hence, it may be advisable to limit this processing to minor cold straightening.
c. Wing and Tail Surface Ribs. Damaged aluminum alloy ribs either of the stamped sheetmetal type or the built-up type employing special sections, square or round tubing, may be repaired by the addition of suitable reinforcement. (Acceptable methods of repair are shown in figures 2.21 and 2.22.) These examples deal with types of ribs commonly found in small and medium aircraft. Repair schemes developed by the aircraft manufacturer are acceptable, and any other methods of reinforcement will be specifically approved by a representative of the FAA.
(1) Trailing and Leading Edges and Tip Strips Repairs to wing and control surface trailin and leading edges and tip strips should made by properly executed and reinforce splices. Acceptable methods of trailing edge r pairs are shown in figure 2.23.
d. Repair of Damaged Skin. In case metal ski is damaged extensively, make repairs replacir an entire sheet panel from one structural mer ber to the next. The repair seams are to along stiffening members, bulkheads, etc., ai each seam must be made exactly the same i regard to rivet size, splicing, and rivet patter as the manufactured seams at the edges of th original sheet. If the two manufactured sear are different, the stronger one will be copi (See figure 2.24 for typical acceptable meth of repairs.)
(1) Patching of Small Holes. Small hole skin panels which do not involve damage to stiffening members may be patched by c ing the hole with a patch plate in the me shown in figure 2.24.
Flush patches also may be install stressed skin-type construction. An acce and easy flush patch may be made by trit
AC 43.13-1A 1972 maining reinforcement tube. Allow one sleeve weld to cool before welding the remaining tube to prevent undue warping.
76. SPLICING USING LARGER DIAMETER REPLACE- MENT TUBES. The method of splicing structural tubes, as shown in figure 2.10, requires the least amount of cutting and welding. However, this splicing method cannot be used where the damaged tube is cut too near the adjacent cluster-joints, or where bracket-mounting provisions make it necessary to maintain the same replacement tube diameter as the original. As an aid in installing the replacement tube, squarely cut the original damaged tube leaving a minimum short stub equal to 2 1/2-tube diameters on one end and a minimum long stub equal to 41/2-tube diameters on the other end.
Select a length of steel tube of the same material and at least the same wall thickness, having an inside diameter approximately equal to he outside diameter of the damaged tube. Fit Page 39 this replacement tube material snugly about the original tube with a maximum diameter difference of 1/16 inch. From this replacement tube material, cut a section of tubing diagonally (or fishmouth) of such a length that each end of the tube is a minimum distance of 11/2-tube diameters from the end of the cut on the original tube. Use a fishmouth cut replacement tube wherever possible. Remove the burr from the edges of the replacement tube and original tube stubs. If a fishmouth cut is used, file out the sharp radius of the cut with a small round file. Spring the long stub of the original tube from the normal position, slip the replacement tube over the long stub, then back over the short stub. Center the replacement tube between the stubs of the original tube. In several places tack-weld one end of the replacement tube, then weld completely around the end. In order to prevent distortion, allow the weld to cool completely, then weld the remaining end of the replacement tube to the original tube,
ZZA- REPLACEMENT TUBE ORIGINAL → ZA TUBE
- ІзА-→
FREPLACEMENT TUBE 47 A
ORIGINAL TUBE
•А- FIGURE 2.10. Splicing using larger diameter replacement tube.
Par 75
77. REPAIRS AT BUILT-IN FUSELAGE FITTINGS.
Make splices in accordance with the methods described in paragraphs 70 through 75. Repair built-in fuselage fittings in the manner shown in figure 2.11. The following paragraphs outline the different methods as shown in the figure:
a. Tube of Larger Diameter Than Original. A tube (sleeve) of larger diameter than original is used in the method shown in figure 2.11(A).
This necessitates reaming the fitting holes (at longeron) to a large diameter. The forward splice is to be a 80° scarf splice. Cut the rear longeron (right) approximately 4 inches from the centerline of the joint and a spacer 1 inch long fitted over the longeron. Edge-weld this spacer and longeron; make a tapered "V" cut approximately 2 inches long in the aft end of the outer sleeve and swage the end of the outer sleeve to fit the longeron and weld.
b. Tube of Same Diameter as Original. In the method shown in figure 2.11(B) the new section is the same size as the longeron forward (left) of the fitting. The rear end (right) of the tube is cut at 80° and forms the outside sleeve of the scarf splice. A sleeve is centered over the forward joint as indicated.
c. Simple Sleeve. It is assumed the longeron is the same size on each side of the fitting in this case, figure 2.11(C), and it is repaired by a simple sleeve of larger diameter than the longeron.
d. Large Difference in Longeron Diameter Each Side of Fitting. Figure 2.11(D) assumes that there is 1/4 inch difference in the diameter of the longeron on the two sides of the fitting.
The section of longeron forward (left) of the fitting is cut at 30°, and a section of tubing of the same size as the tube and of such length as to extend well to the rear (right) of the fitting is slipped through it. One end is cut at 30° to fit the 30° scarf at left and the other end fishmouthed as shown. This makes it possible to insert a tube of such diameter as to form an inside sleeve for the tube on the left of the fitting and an outside sleeve for the tube on the right of the fitting.
Par 77 AC 43.13-1 19
78. ENGINE MOUNT REPAIRS. All welding on a engine mount should be of the highest qualit since vibration tends to accentuate any minc defect. Engine-mount members should prefers bly be repaired by using a larger diameter r placement tube telescoped over the stub of th original member and using fishmouth and r‹ sette welds. However, 30° scarf welds in plac of the fishmouth welds will be considered ac ceptable for engine-mount repair work.
a. Check of Alignment. Repaired engin mounts must be checked for accurate align ment. When tubes are used to replace bent o damaged ones, the original alignment of th structure must be maintained. This can b done by measuring the distance betwee points of corresponding members that have no been distorted, and by reference to the manu facturer's drawings.
b. Cause for Rejection. If all members are out of alinement, reject the engine mount and re place by one supplied by the manufacturer one which was built to conform to the man facturer's drawings. The method of checki, the alignment of the fuselage or nacelle poir should be requested from the manufacturer.
c. Engine Mount Ring Damage. Repair mino damage, such as a crack adjacent to an engir attachment lug, by rewelding the ring and etending & gusset or a mounting lug past th damaged area. Engine mount rings which a extensively damaged must not be repaired, u less the method of repair is specifically a proved by an authorized representative of t FAA, or the repair is accomplished in acco!
ance with FAA approved instructions nished by the aircraft manufacturer.
79. LANDING GEAR REPAIR.
a. Round Tube Construction. Repair lar gears made of round tubing using standa pairs and splices as shown in figures 2.
2.11.
b. Streamline Tube Construction. Repaiz ing gears made of streamlined tubing by one of the methods shown in figures 2.
2.15.
lAC 49.13-1A Page 45 1978
- GAP}"
• 6А ЗА 2t 2t ЗА ЗА 6A - 30° ттт A- STREAMLINE TUBE LENGTH OF MINOR AXIS, PLATE WIDTHS.
B- DISTANCE OF FIRST PLATE FROM LEADING EDGE, /3 A.
C- STREAMLINE TUBE LENGTH OF MAJOR AXIS.
S.L. SIZE ,572 „382 1,340 3,43 .714 ,476 1,670 4.28 1-/₴ .858 .572 2.005 5.15 1-4 1,000 ,667 2,339 6,00 . 2 1,144 ,762 2,670 6.86 2-¼ 1,286 .858 3.008 7,72 2-2 1.430 .954 3.342 8.58 FIGURE 2.15.-Streamline tube splice using plates (applicable to landing gears).
Par 79
Page 46 AG 43.131 (A)
(8) (C) (A), (B), AND (C) ARE TYPES OF REPAIRABLE AXLE
ASSEMBLIES, ASSEMBLIES ORIGINALLY HEAT-TREATED MUST BE REHEAT-TREATED AFTER WELDING.
(D) (D) IS A TYPE OF AXLE ASSEMBLY WHICH IS GENERALLY NONREPAIRABLE.
FIGURE 2.16.-Representative types of repairable and nonrepairable axle assemblies.
Par 79
L= SPAGES SPAGES d EACH TOTAL NO. OF RIVETS = 18(9 EACH SIDE OF SPLI A= ORIGINAL TUBE C = REP B= SLEEVE D USE AI7S ALUM. ALL
RIVETS, SMALL HEAD
HAMMER STANDARD SPLICES MAY BE USED ON LIGHTLY- ROUND HEAD LONGERONS OR WEB MEMBERS.
APPROX. THICKNESS CORRECT WAY OF BRAZIER HEAD. INCORRECT WAY A, C * 3/4 7/8 065 065 7/8 1-178 065 1-1/8 1-1/411-3/81-1/2 065 11-1/41-3/8 058 .058 d MUST NOT BE LESS THAN D/8.
ALL .058 THICK R= 3 d RIVET DIA 5 / 32 5/32 3/16 3/16 3/16 3 / 16 0000.0000 L 19-3/8|9-3/8111-1/4/11-1/4/11-1/4|11-1/4 0000: 0000 * INCLUDES ALL THICKNESSES UP TO AND IN MEACH. (USE BASIC ROUND SIZES IN TABLE STREAMLINE NOTE: USE SAME MATERIAL AS ORIGINAL FOR SLEE FOR SIZE OF RIVETS ETC.)
FIGURE 2.20.-Typical repair method for tubular members of aluminum allo;
AC 43.13 D CRACK 30 30 3020203030301 - D NOTE: FOR MINIMUM NUMBER OF RIVETS REQUIRED, SEE PARAGRAPH 100e. AND SUBSEQUENT.
AT LEAST AS THICK
AS ORIGINAL
ORIGINAL TER • REINFORCEMENT MATERIAL - DURAL. OR 2117-AD RIVETS ALUMINUM ALLOY USED IN 3/32" DIA. MIN.
ORIGINAL CONSTRUCTION.
SCALE - TWICE SIZE SECTION A-A
SCALE - TWICE SIZE 2017-T3 10000 SQ. ROD 3D 30 3D 3D _30 30 _ 3D • 2117-AD RIVETS 1/8" DIA: MIN FIGURE 2.21.-Typical repair for buckled or cracked formed metal wing rib capstrips.
Par 100
- 1A
SEE (C) SEE (D) 0000 OO10 (A)
• SEE (E) (B) D * RIVET DIA.
2 1.5 t (APPROX.) (MINIMUM 3/32")
BEND RADI TO FIT
ORIGINAL RIB.
(G) /I6PLYWOOD TO STIFFEr BENT RIBS.
- MACHINE SCREW D OR RIVET.
1.5 t l APPROX.
- PEEN (E) NOTE: FOR MINIMUM NUMBER
OF RIVETS REQUIRED, SEE PARAGRAPH 100e. AND 3030 30 20) (D) SUBSEQUENT.
FIGURE 2.22.—Typical metal rib repalrs (usually found on small and medium-size aircraft).
Par 100
Pago 58 AC "А" •040" 2017-T3 SPACER 20, 30, 30,2020,30 3D 20 "B" 2024-T3 SPLICE BAR "Д" "в" 2117-AD RIVETS 3/32" DIA, MIN. CRACK 2117-AD RIVETS 3/32i DIA. MIN.
- ЗА - ЗА
1. STRAIGHTEN CRIMPED OVER PORTION. • CRACK
2. INSERT HARDWOOD (ASH) INSERT SHAPED.
TO CONFORM TO T.E. PIECE.
2117-AD RIVETS 20 2D 2D 3/32" DIA. MIN.
FLATTEN HEADS (APPROX. 1.5t ) OUTSIDE I. STRAIGHTEN CRIMPED PORTION. •CRACK
2. USE SAME AL. ALLOY AS IN ORIGINAL.
NOTE: FOR MINIMUM NUMBER OF RIVETS REQUIRED, SEE PARAGRAPH 100e. AND SUBSEQUENT.
FroURE 2.28.- Typical repairs of trailing edges.
Per 100
(A) ADDED STIFFEN"
ERS TO BACK UP SEAM OF PATCH.
2 EACH PATOH PLATE TO 24-5/32" REQ'D BE OF SAME MAT- 12117-74 ¡RIVETS BY SAME BACKED ERIAL AS ORIGIN- AL AND SAME OR NEXT HEAVIER GAUGE. RIVET 3" HOLE MAX. DIA. SIZE, SPACING,
MAX DIA MATERIAL AND
PATTERN SAME 16-5/32 AS ORIGINAL AB.
PII7-T4 RIVETS DAMAGED SKIN
SHOULD BE
CLEANED OUT "G", "H", AND "K" SMOOTHLY AS
ARE INDICATED BY CIRCULAR PATCH PLATES. COEF.
DESIGNATION DIE SIONATION OF CIR. PATCH LATES H "G DIAMETER (OUTSIDE) 12-1/2" 7-1/2" DIA. INNER RIVET CIRCLE 1-3/4° DIA. OUTER RIVET CIRCLE 16-1/2
SAME RIVET SIZE, SPACING, MATERIAL
• PATTERN AS BO.. SAME RIVET SIZE, SPAGING, MATERIAL & PATTERN AS AD.
, PATGH PLATE 8-5/32"2112 RIVETS. MAX DIA I' HOLE TO BE OF SAME MATERIAL AS ORIGINAL AND SAME OR NEXT
HEAVIER BAUGE "K" - GRACA -NOT LESS THAN 2 TIMES, _PORTION OF SKIN REPLACED OF GRACK.-
- ORIGINAL SKIN SHEET. 4 RIVETS RECD EACH SIDE.
RIVET SPACING AT HOLES DRILLED TO LEAST 3 X RIVET DIA PREVENT CRACK SPREADING.
SKIN GAUGE = ,028 (B) RIVET DIA. "=" CRACK 2,5" LONG" FroURE 2.24-Typical repairs of stressed sheet metal covering.
Par 100
Раде 60 out the damaged area and then installing a conventional patch on the underneath side or back of the sheet being repaired. A plug patch plate of the same size as the opening may then be inserted and riveted to the patch plate.
Other types of flush patches similar to those used for patching plywood may be used (ref.
Chapter 1). The riveting pattern used, however, must follow standard practice to maintain satisfactory strength in the sheet.
In general, patches in metal skin are not restricted as to size or shape; however, those of rectangular, circular, square, oval, and rectangular with round ends usually are more desirable because of appearance and ease of installation.
e. Splicing of Sheets. The method of copying the seams at the edges of a sheet may not always be satisfactory; for example, when the sheet has cutouts, or doubler-plates at an edge-seam, or when other members transmit loads into the sheet, the splice must be designed as illustrated in the following exam-
(1) Material: Clad 2024 sheet, 0.032-inch thickness. Width of sheet (i.e., length at splice) - "W" = 10 inches.
(2) Determine rivet size and pattern for a single-lap joint similar to figure 2.18.
(a) Use rivet diameter of approximately three times the sheet thickness, 8 × 0.032 =
0.096-inch. Use 1/8-inch 2117 AD rivets (5/82- inch 2117-AD would be satisfactory).
(b) Use the number of rivets required per inch of width "W" from figure 2.29. (Number per inch 4.9 × .75 = 8.7 or the total number of rivets required = 10 × 8.7 or 87 rivets.)
(e) Lay out rivet pattern with spacing not less than shown in figure 2,18. Referring to figure 2.18(A), it seems that a double row pattern with the minimum spacing will give a total of 40 rivets. However, as only 87 rivets are required, two rows of 19 rivets each equally spaced over the 10 inches will result in a satisfactory splice.
f. Straightening of Stringers or Intermediate Framer. Members which are slightly bent may be straightened cold and examined with a mag- Far 100 AC 43.13-1 197 nifying glass for injury to the material. Rein force the straightened parts to an extent, de pending upon the condition of the material an the magnitude of any remaining kinks or buc kles. If any strain cracks are apparent, mak complete reinforcement in sound metal beyon the damaged portion.
(1) Local Heating. Do not apply local heat ing to facilitate bending, swaging, flattening or expanding operations of heat-treated alumi num alloy members, as it is difficult to contro the temperatures closely enough to prevent possible damage to the metal, and it may im pair its corrosion resistance.
g. Splicing of Stringers and Flanges. Make splices in accordance with the manufacturer's recommendations, which are usually contained in a repair manual.
Typical splices for various shapes of sections are shown in figures 2.25 and 2.26. Design splices to carry both tension and compression and use the splice shown in figure 2.26 as an ex ample illustrating the following principles:
(1) Statement of Principles:
(a) To avoid eccentric loading and conse quent buckling in compression, place splicin or reinforcing parts as symmetrically as poss ble about the centerline of the member, and a tach to as many elements as necessary to pr vent bending in any direction;
(b) To avoid reducing the strength tension of the original bulb angle the rive holes at the ends of the splice are made sma (no larger than the original skin attaching riv ets), and the second row of holes (thos through the bulbed leg) are staggered bi from the ends. In general arrange the rivet the splice so that the design tensile load for member and spliceplate can be carried into splice without failing the member at the most rivet holes;
(c) To avoid concentration of loa end rivet and consequent tendency tow gressive rivet failure, the splice is ta the ends, in this case, by tapering the angle and by making it shorter than th bar (ref. figure 2.26) ; and
(d) The preceding principles are