Some methods are covered with older processes and  procedures of repair; some include the newest methods as  are used by most riggers today. All methods are acceptable to  provide a safe and airworthy repair, but it should always be  the focus of the rigger to understand all methods and strive  to utilize the best possible technique to allow for repairs to  be completed to the highest possible standards. On lightweight material, the rigger should first set up the  machine with similar material and thickness to set the tension  of the machine before sewing the actual parachute. Seam Restitching Procedure Inspection •  Applicable products: All canopies—round and square;  main and reserve •  Description: Replacement of broken or damaged  seam threads. •  Authorized repairmen: FAA Senior or Master  Parachute Rigger  •  Materials: E thread—color to match original •  Machines: 301 straight stitch—light duty 7–11 stitches  per inch (SPI), 308 zigzag—medium duty 7–11 SPI •  Equipment: Scissors, seam ripper 3.  If the restitching was done on a radial seam of a round  canopy, which has a tape or suspension line within the  seam, make sure you did not catch the tape or line in  the stitching. 4.  For zigzag stitching, such as on suspension lines, a .25  inch overstitch on each end is standard.  [Figure C] 1.  Inspect the damaged thread or seam area. If the thread  is merely broken or frayed, overstitch the seam with  a minimum of 4 to 6 inches at each end. 2.  If the seam is gathered or bunched up, it may be  necessary to cut the thread in order to smooth out  the seam and then overstitch the damaged area  with a minimum of 4 to 6 inches at each end.  •  Check that the seam tension and stitch length match  the original. Make sure to check top and bottom.  •  Make sure that you have not captured any adjacent  fabric in the seam. This is a common mistake on  square canopies where you may have three panels  joining together.  •  On radial seams, slide the seam material up and down  over the tape or line to check for free movement. [Figure A  and  Figure B] 7-15