TM 10-1670-287-23&P  0058 00  NOTE NOTE REPLACEMENT (PARTIAL RIB)  NOTE When re-sewing the rib to the top skin, ensure that the  reinforcement tape is aligned with the guide marks made in step 2.,  above. Ensure that the guide marks on the rib are aligned with the  guide marks on the top skin in the case of the unloaded rib.  Ribs may be partially replaced not to exceed 50 percent.  When sewing the rib, pull tension on the bottom or top skin as  required, however, let the rib lay naturally to ensure the rib and the  nose of the canopy fit correctly. Make adjustments as required  using the guide marks made in step 2., above.  1.  Cut stitching to open tail section approximately 12-inches on each side of the damaged rib.  2.  Premark the top and bottom skin where the reinforcement tapes are sewn on the rib and every 3-  inches ribs to be used as guide marks.  3.  Carefully cut and remove any items necessary to expose the damaged rib such as suspension line  attaching loops and reinforcement tapes.  4.  Carefully cut and remove the double row of stitching securing the rib to the top and bottom skin as  necessary to expose only the damaged portion of the rib.  5.  Obtain a new rib from supply stock.  6.  Using the damaged rib as a pattern, mark the new rib as required to allow for a $^{3}$/$_{4}$ -inch seam.  7.  Sew the new and old rib together using two rows of straight stitching.  8.  Again, using the damaged rib as a pattern, transfer the guide marks made in step 2., above on to the  replacement rib as required.  9.  Starting at the tail end of the rib, fold and sew the bottom of the rib to the bottom skin with a double  needle sewing machine, using size E nylon thread and 7 to 11 stitches per inch.  10. If the rib being replaced is a loaded rib, start at the tail end of the rib, fold and sew a second double  row of stitching, using a double needle sewing machine, size E nylon thread and 7 to 11 stitches per  inch. 0058 00-3 