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Yesterday a buddy of mine had his brake line snap at the deep break setting during a 3 second slider down jump.
It's a 310, the red Dacron broke not the white brake setting.
Everything was routed correctly and he only has 8 jumps on this canopy.

What would cause this ? Is it possible his canopy has a bad batch of Dacron and should be relined?

Straight cut on the white line will cause higher damage on the brakeline.
But after only 8 jumps?

I assume you have already contacted the manufacturer? Keep us posted what comes from there, sounds like a very bizarre thing given that there was no unusual action (salt water / barb wire / sharp rock / etc landings) during the previous 8 jumps

one water landing in still waters, no salt.

I will keep this post updated with reports back from the manufacturer

Dyed dacron can do some funny things at totally random times. Something to do with the dying process makes it less reliable than the good old white stuff. Notice how no one pushes black line sets any more.

That's interesting to know, but surely they adjust the breaking strength accordingly?
We have been in contact with the manufacturers and have given as much information as possible. I will update the forum with the findings when I hear back from them.

Nope. It seems to be pretty random but most likely apparent early on in a canopies life. I once seen a brake line stretch over 2 inches in a single jump. Confused the shit outta me when I tried to pack it.
Not saying that this is what caused your failure but I bet it's probably close. Alternatively whoever bartacked the brake line could have totally hacked up the line with the sewing machine, but I doubt that woulda made it through QC.

I inspected the canopy fully when it arrived and I checked all the attachment points, cascades and bartacks thoroughly. I didn't notice any fraying at all and the line seemed as new to me.

I'm not a rigger so I may have missed something.

Hey Dan, I had the same thing happen to me on a new canopy as well. If I remember correctly, it had maybe 10 jumps on it. Did a 5sec slider off jump and both lines broke. I had replacements sent and since changing them have now done a few hundred on that canopy with no issues

Did you also replace the Centre C and D lines? I was thinking it may be a bad batch and all the red lines may be weak.

No, just the brake lines

Brake lines are also under a lot more load on opening than just about any other line on the canopy (bar the center A+B). Center C and D lines will take no where nere the same load and shouldn't be a problem.

Didn't know that either,

I assumed that because they are not load bearing lines, they don't carry much of the jumpers weight on opening.

This exact mal happened to me on a solid 4sec SD delay off 500ft guyed A. Better to take it lower for more room between the wires. I threw the good toggle (prob should have kept it ) and just landed w/o incident on rears.

Vented Troll, about 80 jumps. My issue was the loop on risers were made of spectra line not dacron. I took it to PeteS for repair and he replaced with dacron, no issues after that even on deep delays.

I'm actually not sure what the set loop of my buddy's risers have but it's very stiff and hard, could be 500lb dacron but it doesn't feel soft like dacron, the manufacturers asked about that so it must be a contributing factor.

He kept the one toggle and had a soft stand up landing, with one toggle and one riser.

Excellent.

Never toss the second toggle. 1 toggle and 1 rear riser is so much easier to control and flare.

center C and D's are made of 525lb dacron, while lower brake lines are made of 900lb dacron (unless its a light/ultralight canopy) so they come off different rolls and cannot be same batch.

there has been a apex bulletin in 2008 regarding excessive linestrecht on their canopies with black lines, but i didnt hear of reduced strenght because of this before.

i think spectra is used on most new rigs (at least apex and adrenalin use that stuff i think). ive seen some quite thin spectra (i suppose, had just a quick look) on apex risers recently, the last one i got from adrenalin (already 4 years ago) had rather thick (1500lbs i think) spectra loops, the ones i got from morpheus had rather thick material that doesnt feel like spectra or dacron but maybe its just another conditioning...
i think they use spectra because its way more abrasion resistant and take a lot more beating than dacron, and its way easier to replace the lower brake lines when worn than the loops on the risers. i replace my lower break lines approximately every 100 jumps, on my slider down rig due to the brake setting splice is getting fucked, on my slider up rig because of abrasion.

a good solution for this issue would be using a slider for delays longer than 3s

im looking forward on an update what the manufacturer has to say about it, also what the bar tack looks like... (can you post another highres picture with the bartack of the broken line?)

Ya that is kind of weird . It's the outside Red sheathing & not the Gut .
But If it was a hot knife sharp edge on the eyelet that is Fid . it would cut & wear from the inside & not the sheathing .
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[Fledgling]
..." I once seen a brake line stretch over 2 inches in a single jump. Confused the shit outta me when I tried to pack it ".
.
Might not have been pre-stretched .
I was taught & always told when you unroll ' New ' Break-Line . Before installation & all the measuring of the length, cutting & break-setting for eyelet .
Always stretch-out the break line & put it under some ( Pre Load ) pull weight . & let it sit & stretch for some time before putting on your canopy .
New Break Line will stretch inches in length . & a Pre-Streatching under a load for a time keeps the Break Line more uniform length when it's under opening shocks on the 1st few canopy openings .
.

At Ray, His canopy is a BJ310, I think it's 900lb Dacron all around if I'm not mistaken, so chances are that it is from the same roll.

It ripped through 3-4 stitches and the line was definitely pre-tensioned, I watched him pack it.

The manufacturers have been great with lots of feedback and have already said they will send out replacement brake line-set. we are waiting on their final findings, but I can understand that it's hard to assess what has happened without the gear to look at.

I too remember the Apex bulletin but did not mention it as it is not just an Apex problem. I have seen this problem on multiple canopies from 3 different manufacturers. It is a problem resulting from the dying process no matter the colour, and I wouldn't be surprised if all the manufacturers used the same supplier for their dacron.
Reduced strength? What do you call it then when a line is able to stretch inches in a single jump? If it is possible for it to be stretched that much it is easily capable of snapping too.

I know that any type of line should be loaded to like 15lbs before measuring. Never heard of manufacturers excessively loading line for a period of time to pre-stretch it though.
I remember being told back when the dyed dacron started stretching that Apex were testing each new roll of line for excessive stretch before using it on line sets. This isn't to say they were following your suggested method.Do you know if manufacturers do this?

If you hadn't said this the picture does suggest that it maybe wasn't pre-tensioned after he set his brakes.

"a good solution for this issue would be using a slider for delays longer than 3s"....

I agree with this however I absolutly hate SU openings in the 3-5sec range.....that "soft, mushy, feeling". And as I said my particular jump was a guyed A and opening lower was "safer" (landing area was HUGE open field, very little objects to hit)

FWIW: my loops on risers were very, very thin spectra line. Not sure if they were original or a replacment as I bought the rig used. The rigger agreed this thinner line acted as a "knifes edge" while under the loading process. I mention this to OP just as a possibility of something that could have been the issue with his friend's incident.

I have seen a few snapped Break Lines before on Slider-down jumps . But the only thing that was the culprit was not proper routing, loop-ring-toggle .
& you say everything was routed right on the toggle stow . So It is all guessing after that .

But PIC.
shows the point of line break @ one of the biggest stress points on opening shock & that's the Break setting position .
So that say's a lot .
.

How heavy is the jumper? Can you put up a picture of the opposite brake line to see what that looks like? Look for any fraying around the bartack above the break, might show evidence of a bad needle causing damage.

A quick failure like this has a reason, we just need to find it.

The jumper is 90kg's (200lbs), so he is on a light wind loading for his canopy size. On opening his right shoulder was dipped but the left line snapped.

I can assure you the other brake line looks to be 100% new condition as well as the other stitching on the offending line. I don't have a picture, but I see absolutely no sign of wear, fraying or damaged fibres of the line.

Update

The batch of Dacron passed both production quality control standards and internal QC checks at the manufacturer and had a breaking strength of 1142.28 lbs tensile. There are a multitude of factors that can lead to a break line snap, from an excessive delay, dying process, damage caused during bar tack, the materials used, packing methods, etc...

In this case it is not possible to tell the exact cause of the failure, it seems to be one of those 1 in a million accidents.

The manufacturers have sent out replacement lines and have been very good at relaying communication to us throughout the process.
They responded in a timely manner, but I have taken long to post an update

Have fun and Play safe,

Well duh

4 and 5 secs is totally overdelaying for SD
Manufacturers recommend maximum 2 sec for vented and 3 for unvented.

Anything longer than that, and you greatly increase risk of not only line damage, but canopy damage, container failure or other malfunctions. Not to mention spine compression trauma

I thought this was pretty obvious stuff guys.

A bad batch of 900 (lower control lines) wouldn't effect the center C and D lines, which are made of 400/525/600 depending on the manufacturer. The C/D lines and the lower control lines have to come from different batches because they are made from different line.