Brake line attachement failure

[Treejumps 0]

Some nice Friday afternoon swooping started out well. but on my third jump I opened into a nice spin. Corrected hard with opposite rear riser and checked the brakes, both were still set, A quick check revealed no broken lines, but there in the left brake cascade was the culrpit, the little piece of tape used to attach the inner most brake line (along with the line) was wrapped around the other lines and locked under the cascade. Cya.

A close inspection revealed that there was no tear and that over time the bar tack had simply been wiggled loose one stich at a time. The other inboard was the same and halfway unraveled. I guess the angle they are pulled at made this possible as bartacks on other high load lines were fine. A little sewing in the morning and the swoop will be on again, but be sure to check these attachments on higher jump number canopies.

This was a VX 120 with 1100 to 1300 jumps on it and otherwise in excellent condition.

Cya.

[mjosparky 4]

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This was a VX 120 with 1100 to 1300 jumps on it and otherwise in excellent condition.

This canopy has 1100/1300 jumps and has never had a line replacement? A good habit to get into is go over your main at least every 30 days. And take your time to check everything.

Sparky

My idea of a fair fight is clubbing baby seals

[darkwing 5]

Generally speaking, the inboard steering line gets a lot more load that the other steering lines. I am surprised about the gradual unstitching of both attachments.

-- Jeff
My Skydiving History

[Hooknswoop 19]

I think he means a line attachment point pulled off the canopy because the force isn't 90-degrees to the bar-tack.

Derek

[Treejumps 0]

Correct. The lines are fine with only 300 or so on the set. I check all of the bartacks and more than half were coming loose, so I just reinforced them. Oddly enough the A line attachements were mostly good, probably because they are pulled more closely to 90 degrees. The outboard lines were the least affected.

I think that this problem would be limited primarily to heavy jumpers (250+ out the door) at very high wing loadings. Something for the husky swooper to look at.

Cya.

[riggermick 7]

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Correct. The lines are fine with only 300 or so on the set. I check all of the bartacks and more than half were coming loose,


Questions: What type of bar tacker was used to reattach the line set? Was it a center start/ stop? Was it a 42 stitch? Were the thread tails scissor cut or hot seared? Did the stitch width allow for any thread to interlock on the very edge or even off the edge of the lines?

Each and every one of these points either individually or collectively can cause a bartack to fail under repeated loading.

Also double-check the thread to verify if it is indeed "e" thread.

Just food for thought.

Mick.


Oh, just for clarification;

The left hand side start stop bar tack when loaded at odd angles has been known to unravel, this is one the reasons many canopy mfg's use center start/ stop tackers.

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