Master riggers may perform repairs that do not involve taking  apart any bartacks on the canopy unless they have the correct  bartack machine or equivalent. Special bartack patterns are  used that are not normally found in the field. In addition,  removal and replacement of these stitch patterns usually  weakens the fabric to the point that it is necessary to replace or  reinforce portions of the panels. This should also be considered  in the repairs of load bearing and non load bearing ribs as most  have these types of bartack stitches located at the ends. for many years but are currently still in use. Contact with  current certificated parachute manufacturers has proven that  none currently recognize or accept this type of repair as an  approved procedure and do not recommend the use of ripstop  tape on any parachute in production. It is highly advised that  before affecting any type of repair with the use of ripstop tape  on an approved parachute that the manufacturer be contacted  for confirmation and the request of an approval document  before completing this type of repair. Figure 7-15  shows a table of square canopy repairs  and limitations. These are for reference only. Not all  manufacturers recognize the same types of repairs. The  information in this table is an excepted cross-section of  allowable repairs. The rigger should consult with the  manufacturers to confirm what repairs are allowed on any  particular canopy. Before performing a repair, contact with the canopy  manufacturer is very important, as some of these repair  standards and limitations may vary slightly.  Certified canopies should only be repaired using certified  materials or equivalent. All replacement materials should  come from the manufacturer or meet production quality  and shelf life standards. Under-strength thread and fabric is  frequently found in the field. The only way to be sure the  material meets manufacturer standards is to obtain them  directly from manufacturer or locate materials recognized by  the manufacturer as acceptable for the repair needed. Holes or snags smaller than the size of one ripstop box ( 1 ⁄8 inch, 3.2 mm) may remain unrepaired as long as no more  than one hole exists within any 10-inch (25.4 cm) circle. A  maximum of three such holes or snags per cell are allowed. Ripstop tape is not authorized for use on parachutes. If the  damage is enough to warrant a repair, a sewn repair must be  performed. Darning is not a means of repairing any parachute  currently in production.  The following are the repairs found in Section 1, Canopy  and Lines: Any hole or tear up to 10 inches (25.4 cm) in length may  be repaired by a Senior Rigger as long as the closest area  of the completed repair is at least 1 inch from the nearest  seam and at least 5 inches from the nearest tape or line  attachment. These are minor repairs. Any damage or hole  larger than 10 inches (25.4 cm) may be repaired by a Master  Rigger, in either direction or involving a seam or tape. This  is a major repair. Any damage that requires a repair of an area that is larger  than 50 percent of the total area of a cell skin (upper or  lower) requires cell skin replacement and should be returned  to the manufacturer. Materials Detailed Information on Square Canopy Repairs •  Seam re-stitching •  Canopy ripstop tape repair •  Round and square canopy—basic patch •  Round canopy—panel replacement •  Square canopy—partial panel replacement •  Square canopy—rib repair •  Square canopy—pilot chute attachment point repair •  Round canopy—non-continuous line replacement •  Square canopy—main line replacement •  Square canopy—control line replacement •  Square canopy—crossport repair •  Square canopy—trim check and re-trim Square Canopy Repairs and Limitations Type Certificated Non-certificated “Recommendations” Limits Restitching Ripstop tape Basic patch Panel patch Suspension lines  Line splice No limit to length and number overstitch 4 to 6 inches from start. Not allowed. Size limit 10 inches, senior rigger. 50% cell skin, master rigger. Senior rigger, not allowed. Master rigger, no limit. Senior rigger, not allowed. Not allowed. No limit to length and number overstitch 4 to 6 inches from start. Not allowed. Size limit 10 inches, senior rigger. 50% cell skin, master rigger. Senior rigger, not allowed. Master rigger, no limit. Senior rigger, not allowed. Not allowed. Figure 7-15.  Table of square canopy repairs and limitations. 7-14