Line Trim and a Burred Connector Link
A skydiver brings a used 9-cell ram-air main canopy to your loft for inspection. The canopy has 50 jumps and a manufacturer trim chart in its manual. One suspension line was replaced after a break: it is from a different manufacturer, has the same diameter but is made of a different material, and measures 0.25 inch longer than the opposite line when both are loaded to the manual specified tension. The manual line-trim tolerance is plus or minus 0.125 inch. A stainless steel connector link on the same riser has a sharp burr at the gate. The owner wants you to just trim the long line and file the burr smooth so he can jump this weekend. The rest of the lines are within tolerance, and the canopy fabric passes porosity. You have the manual and a line-tension board.
1. Is the replacement line acceptable? Explain how material, diameter, and trim affect the decision.
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The replacement line is not acceptable simply because its diameter matches. Line material affects stretch, strength, creep, and shrinkage under load; a different material can change trim in flight even if it measures close on the board. The measured 0.25-inch difference is twice the manual plus-or-minus 0.125-inch tolerance, so the canopy is out of trim. Trimming the long line is not a fix: it changes the attachment geometry and does not correct the material mismatch. The correct action is to install the manufacturer-approved line for that canopy and recheck trim at the specified tension; if a matching line cannot be obtained, replace the line set. Return the canopy to service only when all lines are within tolerance and of approved material.
2. How should you handle the burred connector link, and why is filing a poor choice?
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Replace the connector link with an approved link of the correct type and size. A sharp burr can cut the suspension line or riser under load, and it can also damage the mating link. Filing the burr is a poor choice because it can remove plating, create a stress riser, and leave a sharp edge; a load-bearing connector is not a field-filing project. Inspect the line and riser for abrasion, replace any damaged components, and confirm the link gate operates and is properly seated. Document the replacement.