2.  Position the Velcro $^{®}$ and stitch around the perimeter  at .12 inch from the edge. For any pieces, 1 inch in  width or wider, sew a row of stitching down the center.  [Figure A]  This prevents the center from being pulled  up from the material and loading the outside row of  stitching.  [Figure B] •  Description: Replacement of damaged plastic  stiffeners of all types •  Authorized repairmen: FAA Senior or Master  Parachute Rigger  •  Materials: E thread—color to match; grommets—size,  type, and material to match; and plastic stiffeners— type and thickness to match •  Machines: 301 straight stitch—medium duty 7–9 SPI  and 308 zigzag—medium duty 7–11 SPI •  Equipment: Scissors, seam ripper or scalpel, marking  pencil, 6-inch ruler, grommet die set—size to match  grommets, leather mallet, grommet cutting board, hole  punch to match grommet size, basting tip, diagonal  wire cutters—8 inch minimum, heavy shears or tin  snips, electric drill and  3 ⁄8  inch drill bit, and feeler  gauge—.010 inch Procedure Disassembly The term “plastic,” when used in conjunction for the materials  used as stiffeners in modern parachute containers, is a  misnomer. In reality, the composition of the material varies.  The most common material used today is molydisulfide  (MDS) nylon. In addition, Lexan $^{®}$, a clear polycarbonate  material and high density polyethelyne (HDPE), are also used.  The most common thicknesses used are .025 inch, .040 inch,  and .060 inch, which are standard commercial thicknesses  commonly available. Stiffeners are used primarily as backing  for grommets to spread the load placed on closing flaps.  Instead of focusing the load on the diameter of the grommet,  it is spread out across the length of the stiffener, resulting in a  smoother flap and container. Consequently, replacing plastic  stiffeners almost always requires replacing the grommet as  well. Usually the plastic breaks at the grommet location  because the hole for the grommet is the weak point. The  following procedure shows the replacement of the bottom  main flap stiffener of a Javelin container. Reassembly Inspection Container Plastic Stiffener Replacement 1.  Unpick the stitching that holds the binding tape to the  bottom flap.  [Figure A]  Remove the grommet. 2.  Remove the stitching that holds the stiffener in  position. Remove the stiffener. 1.  Use the original stiffener as a template to cut a  new stiffener.  [Figure B]  While many of the older  containers use HDPE or other materials, most of the  newer designs use MDS nylon because of its superior  properties. Because of this, many riggers use MDS  exclusively for replacing any stiffeners. 3.  Some applications have the Velcro $^{®}$ sewn to a piece  of tape for support. Again, if it is 1 inch or more wide,  sew down the center to prevent lifting. 4.  Depending on the application, the mating loop piece  of Velcro$^{®}$ may be wider than the hook to provide  additional protection. That is, the hook may be .75  inch wide and the loop 1 inch wide. •  Check that thread tension is correct. •  Verify orientation is correct. •  Check that center stitching is used where needed. •  Applicable products: All types of containers that use  plastic stiffeners 7-44