Gap  1 /8 Weld at least 1  1 /2 C at least 1  1 /2 C 30° 3C R =  A 2 Form inside tube to fit A B C S.L. size A B C 6A 0.496 0.619 0.743 0.867 0.991 1.115 1.239 1.340 1.670 2.005 2.339 2.670 3.008 3.342 0.560 0.690 0.875 1.000 1.125 1.250 1.380 0.380 0.380 0.500 0.500 0.500 0.500 0.500 1" 1$^{1}$/4" 1$^{1}$/2" 1$^{3}$/4" 2"  2$^{1}$/4"  2$^{1}$/2"  Round insert tube (B) should be of same material and one gauge thicker than original streamline tube (C). A = Slot width (original tube) B = Outside diameter (insert tube) C = Streamline tube length of major axis Gap  1 /8 Size of rosettes =  $^{1}$/4 C  Drill outside tubes only. 45° L = maximum insert length Saw .08 C off of T.E. and weld A B C Weld A A 1 1 /2 A A A 1 /2 A B 2A 2A 1 /2 A 1 /2 A S.L. size A B C 6A 5.160 6.430 7.720 9.000 10.300 11.580 12.880 1.340 1.670 2.005 2.339 2.670 3.008 3.342 0.572 0.714 0.858 1.000 1.144 1.286 1.430 0.382 0.476 0.572 0.667 0.763 0.858 0.954 1" 1$^{1}$/4" 1$^{1}$/2" 1$^{3}$/4" 2"  2$^{1}$/4"  2$^{1}$/2"  Insert tube is of same streamline tubing as original. A = $^{2}$/3" B B = minor axis length of original streamline tube C = major axis length of original streamline tube Figure 5-53. Streamline tube splice using split insert. Figure 5-52. Streamline landing gear repair using round tube. If all members of the mount are out of alignment, the mount  should be replaced with one supplied by the manufacturer  or with one built to conform to the manufacturer’s drawings  and specifications. The streamline landing gear tube may also be repaired by  inserting a tube of the same streamline original tubing and  welding. This can be accomplished by cutting off the trailing  edge of the insert and fitting it into the original tube. Once  fitted, remove the insert, weld the trailing edge back together,  and reinsert into the original tube. Use the figures and weld  as indicated in  Figure 5-53 . All welding on an engine mount should be performed by  an experienced welder and be of the highest quality, since  vibration tends to accentuate any minor defect.  The preferred method to repair an engine mount member  is by using a larger diameter replacement tube telescoped  over the stub of the original member using fish-mouth and  rosette welds. 30° scarf welds are also acceptable in place  of the fish-mouth welds. One of the most important aspects to keep in mind when  repairing an engine mount is that the alignment of the  structure must be maintained. This can be accomplished by  attaching to a fixture designed for that purpose, or bolting the  mount to an engine and/or airframe before welding.  All cracked welds should be ground out and only high-grade  filler rod of the appropriate material should be used. Rosette welds are used on many of the type repairs that were  previously discussed. They are holes, typically one-fourth  the diameter of the original tube, drilled in the outer splice  and welded around the circumference for attachment to the  inner replacement tube or original tube structure. If the manufacturer stress relieved the engine mount after  welding, the engine mount should again be stress relieved  after weld repairs are made. Minor damage, such as a crack adjacent to an engine  attachment lug, can be repaired by rewelding the ring and  extending a gusset or a mounting lug past the damaged  area. Engine mount rings that are extensively damaged must  not be repaired unless the method of repair is specifically  approved by FAA Engineering, a Designated Engineering  Representative (DAR), or the repair is accomplished in  accordance with FAA-approved instructions. Engine Mount Repairs Rosette Welding 5-36