Heat Damage on UPT Risers

[mmundry 0]

So I was looking at my risers the other day and this is what I found. Symmetrically on the front of both front risers, there is an area about an inch long by a quarter inch wide that looks like its been slightly cauterized. Both Mel and my rigger were kinda scratching their heads over it until they thought because of how symmetrical it is, it must be the heat of the slider grommets that are basically flash melting the nylon. There was no other friction damage anywhere else on the rig.

I jump a Samurai with Germain's Vectran and Spectra combo lineset. Where the friction lines are vectran and the rest are spectra. My rigger inspected the lines very closely and cannot find any damage on them. The concerninng thing is that I jumped a loaner pair of risers after I grounded these and after about 15 jumps they are already showing the same deterioration.

Just for shitz and giggles I went back and looked at my videos of openings and the way the slider sits on the slinks before I collapse it and stow it behind my head is actually up and away from the risers. The grommets are only touching the slinks, which also show no damage. There is also zero damage on the risers where the slider sits after it is stowed.

My question is, why is there such significant damage being done on the part of the riser where the grommets only instantaneously touch while I'm stowing it, and no damage at all where the grommets actually sit for the duration of the flight?

Attached is a pic, it's kinda hard to tell because of quality but it's the shiny area in kind of a half moon shape at the bottom of the riser. These are 24in type 13 risers with Louie Loops and trulocks.

I'm getting a new set on and since we don't really know whats happening, I'm just gonna jump the new set and after every jump my rigger and I will look at them. I kinda dislike this look and see approach cause we don't really know where the damage is coming from, so anybody who has seen this before I'd appreciate some advise.

Matt

[mcordell 2]

is the damage in a location where the risers push against the riser covers as they are being forced from their closed position? If the damage isn't coming from the grommets of the slider, then perhaps it is coming from the friction against the rig upon opening. This seems very unlikely as it is such a short distance the risers actually travel where they could rub on the rig, however if your rig has stiff tuck tabs, perhaps the riser covers are being forced against the risers on opening harder than usual.

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[mmundry 0]

no, it is at the opposite end of the riser, near the dive loop. Also, we have looked over the rig and there is no damage anywhere else, so I guess that means the friction is not coming from there

[GLIDEANGLE 1]

It is not true that you must have matching wear on the container or riser covers.

I have seen a sharp edge of hot knifed cordura damage risers without any visible wear on the offending part.

I would use my fingers as well as my eyes and FEEL where the riser covers and container touch this riser.

The choices we make have consequences, for us & for others!

[LouDiamond 1]

I am thinking it is caused during the opening/extraction sequence as Mcordell mentioned above. Two ways to look for the problem.

1. Lay the packed rig on the floor, reserve side up, and pull the PC out of the BOC and walk the opening sequence of the parachute. Pay particular attention to where the risers are being extracted from the pack tray and especially the areas that have been affected. From your description and the small picture, my guess is that this is being caused as the risers are coming under tension and are being extracted from the pack tray. In short, they are rubbing on some part of your harness/container during deployment which is why you are seeing a friction burn.


2. Clean set of risers, same parachute placed in a different harness container. Jump it several times and inspect it after each jump to see if the friction burns appear. If not, switch it to your harness container and jump it, if the friction burns appear, you can safely say it is something related to your container and the risers interacting.



Is your harness container new or are you using a container that is designed for a smaller parachute?

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[irishrigger 31]

its hard to see from the pic,but i also think it might possibly be a packing issue.what way do you pack the risers into the rig? are they straight down the side or do you tuck them around the reserve tray by any chance? its a good suggestion to open it up on the ground like lou suggested,it might clear this mystery up for you.i have seen damage like this before and it came down to packing and the grommets on the slider.but as your rigger has ruled that out,i think it might be a packing issue.
do you use a packing weight to pack? or tie the risers together by any chance?
hope you get it figured out soon
blue skies
rodger

[parachutist 1]

Matt,

I had melted riser damage from an Aerodyne Vision with HMA line set. Here's the thread I posted about that with photos of damage. This was over a year ago... my solution was put the Vision in a bag & it's sitting in a closet now.
http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3346001

Chris

[timmyfitz 0]

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I jump a Samurai with Germain's Vectran and Spectra combo lineset. Where the friction lines are vectran and the rest are spectra.

Sorry for the thread drift but what are "friction lines".

[justinb138 0]

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I jump a Samurai with Germain's Vectran and Spectra combo lineset. Where the friction lines are vectran and the rest are spectra.

Sorry for the thread drift but what are "friction lines".

I'm assuming they're referring to lines that come into contact with the slider.

[timmyfitz 0]

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I jump a Samurai with Germain's Vectran and Spectra combo lineset. Where the friction lines are vectran and the rest are spectra.

Sorry for the thread drift but what are "friction lines".

I'm assuming they're referring to lines that come into contact with the slider.

I had assumed something similar. Just wanted to get mmundry take on it.

[a.n.knowen 0]

how was your last opening? a fast one? so the slider comes down very fast?

[mmundry 0]

Thanks to all for the suggestions. We will go over everything again this weekend.
@Lou: It's a TJN so max airlocked is 120, I've got a 136 in it...but it doesn't really seem like an overly tight rig. Grommets still line up.
@Irish: I try to make sure the risers are not wrapped around the reserve. Because of the thick dive loops, I stack them vertically and try to make sure they stay to the outside of the pack tray
@Parachutist: Did you go to a diff size wing afterwards? Or was it specific to the type wing not the size?
@Timmy: The friction lines are the ones that come into direct contact with the slider as it travels down the lines.
@a.n.: Openings are great on this canopy. I have yet to have anything remotely resembling a slammer

I'll throw this out there, idk if it makes a diff, but I have an mPod d-bag that I use in this rig. I don't see how it would affect the risers, but just to throw it out there. If you don't know what it is, just search it here on the forums.

[parachutist 1]

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@Parachutist: Did you go to a diff size wing afterwards? Or was it specific to the type wing not the size?

I went from the 117 Vision to a Cobalt 120 to cure it.

[fcajump 153]

Matt

I have seen a set of risers exactly as you describe, from a canopy using such a hybrid line set. I will leave it up to those more knowledgeable than I, but here is my guess...

I am reading between the lines (sorry) of several reports out using this hybrid configuration... and based both on the reports, and the set of risers I saw last week, it seems to me that the heat that would normally be dissipated into the spectra (causing the unwanted shrinkage) is being held by the slider grommet during its travel and not dissipated into the Vectran at all.

This results in the hot slider grommets coming to rest on the risers. The heat quickly dissipates into (and damages) the first area of Nylon webbing it contacts. By the time you have stowed your slider, the grommets are probably cool.

If this is correct (and I am very open to other ideas) it seems to me that having to retrim the canopy after a while is better than melting risers and risking their failure... but that's just me...

JW

PS - seems like one more reason to reline with Dacron

Always remember that some clouds are harder than others...

[Ronaldo 0]

If the slider is coming down to the risers it makes sense, specially if you consider that the canopy certainly uses stainless steel grommets (because of the Vectran lines). Steel has a higher specific heat which means it holds its temperature for a longer time. Of course only a more detailed study would be able confirm this.

Engineering Law #5: The most vital dimension on any plan drawing stands the most chance of being omitted

[AndyMan 7]

I've seen heat damage to risers caused by hot stainless slider rings rubbing against HMA.

Your damage is not consistent with the pattern that I've seen.

The heat damage I've seen gives the risers a glossy look, as the warm nylon gets polished and smoothed by the fast moving gromets.

The damage that you're showing looks more like friction than heat.

_Am

__

You put the fun in "funnel" - craichead.

[masterrigger1 2]

Matt,
Just a couple of points here:

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I jump a Samurai with Germain's Vectran and Spectra combo lineset. Where the friction lines are vectran and the rest are spectra. My rigger inspected the lines very closely and cannot find any damage on them.

I actually saw your canopy yesterday for the first time.
It is a Samurai, but it has 550 lb HMA on it, not the combo setup that you thought it had.

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My question is, why is there such significant damage being done on the part of the riser where the grommets only instantaneously touch while I'm stowing it, and no damage at all where the grommets actually sit for the duration of the flight?

I thought I had covered this question already, but will cover it again.

The grommets are at their hottest at the top of the riser, just after coming to rest there post opening.

When you start pulling them down, both the melting process (which is transferring heat from the grommet to the riser) and time of cooling result in lesser damage to the lower portion of the risers.

Heat damage is not exactly new to risers. It mostly has been noted on bigger Tandem-like canopies with soft links installed. The soft links will allow the grommets to touch the risers while setups with Rapide links will keep the slider off of the risers.

Line type plays a large role in the amount of heat generated during the opening process.

Believe it or not, Large Dacron lined canopies usually generate as much if not more heat than HMA lined canopies. This is because the line is usually larger and the canopies are typically bigger to boot.

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I'm getting a new set on and since we don't really know whats happening, I'm just gonna jump the new set and after every jump my rigger and I will look at them. I kinda dislike this look and see approach cause we don't really know where the damage is coming from, so anybody who has seen this before I'd appreciate some advise.

Unless you do something with the canopy, the results will be the same....I pretty much summed this one up in short fashion.

I also inspected the "loaner" risers on yor canopy. they are starting to show the same results....no question about it!

With the temperatures much lower now than in the middle of the Summer, you probably will see lighter damage than before.

Cheers,
MEL

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