Friction adapter safety issues?

[tfg30 0]

I'm not sure if I just have a wild imagination, am paranoid, or am just a downright nervous skydiver when under canopy, but are there any safety issues with leg straps with friction adapters?

Sometimes I look down at my legs under canopy and wonder if they could ever fail and let go, allowing me to fall out of the harness?

Maybe I just don't understand the physics behind them, but as a relatively new skydiver, I get nervous when I think about the possibilities. It's actually at the point where it affects my ability to concentrate when under canopy.

Any comments? (Other than "quit skydiving") :P

(Pic attached in case it's not clear what I'm talking about)

[mcordell 2]

Rigs have been made with friction adapters for the chest strap and leg straps for years and years. There are thousands upon thousands of rigs with them. Any mechanical component can fail but the more weight you put on a friction adapter, the harder it grips and holds. You would be amazed by the amount of force you put on your harness during opening, especially a hard opening. If they hold during opening you can pretty well bet they will hold during your decent under canopy. You can get b12 snaps but they are adjustable too so if you are worried about the harness slipping that won't help unless you have the harness tacked once it's adjusted.

Just relax and enjoy the view. The friction adapter is much less scary than the fact you are hanging below tissue thin nylon and string.

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[JerryBaumchen 1,048]

Hi tfg,

Quote

It's actually at the point where it affects my ability to concentrate when under canopy.

I would be far more worried about other parts of your parachute system.

Over the years I have tested a fair amount of various pieces of parachute hardware, webbings, and stitch patterns.

My experience tells me that the most likely first point of failure will be the stitching. Well, actually it will be you that fails.

Last year I did some testing and found that a B-12 snap ( rated at 2,500 lbs ) still held ( with no noticeable deformation ) at over 5,000 lbs of load.

Just something to think about,

Jerry Baumchen

PS) Edit to add: About 40 yrs ago I got a letter from Jim Rueter, V-P at Pioneer at the time, telling me that the typical "L" bar connector link, while rated at 3,000 lbs, was good for over 10,000 lbs before it would fail.

Just adding to the knowledge base.

[RiggerLee 61]

Actually it's not a trivial question. We have been plagued with problems with friction adapters for years. There have been problems both with slippage and damage to the webbing from the adapters. A lot of the problems come down to compatibility. The standard 22040 is a very old design that actually predates modern nylon webbing. They had to build special weaves of the nylon webbing to try to make the adapter hold and avoid slipping. And we don't even use that. It was never mint to hold on type 8 or even 7 webbing. But never the less we continue to insist on using these light weight materials. Then people decide that every thing has to be made from stainless and there are problems with slipping because the coefficient of friction is different or there is damage to the webbing from the radiuses or sharpness of the hardware. Or the hardware is just flat wrong with pieces assembled up side down. Then we try to reinvent the wheel with brand new designs. Some times the slip and some times they cut into the webbing damaging it on opening.

Slippage is a real problem and a danger. It can come from ether the reasons above or just from the geometry of how it fits you and how it loads. It's enough of a danger that there are rules about how the leg straps are sewn. Note the heavy stitching in the roll in the end. What that basically means is that at some point it killed the hell out of some body. The rules requiring that all leg straps must ether be rolled and sewn with 5 cord or split and sewn is so old that I don't know the story behind it but you can bet it was written on some ones tomb stone.

And if you're a nervous nelly than stay the hell out of the Rigging forum. The people here will actually answer your questions rather then blow smoke up your ass. It will not do any thing good for your confidence. It's like I always tell people, if you want to feel safe, stay the hell out of the loft. Do not hang out with the riggers. Especially when they are drinking beer.

Lee

Lee
[email protected]
www.velocitysportswear.com

[monkycndo 0]

I think the question by the OP is a good one because someone wants to know about their gear. That is so refreshing in this day and age of getting an A license and using packers from there on.

Lee, with an answer like yours, we now might have one less jumper in the sport.

Yes, there have been problems with slippage. Answer me this. How many jumpers do you know of that have died/been injured due to friction adapter/harness failure?

To the OP, keep on asking questions. The more you know about your gear, the more you will trust it. And, you will know when to take it to your rigger and say, "This doesn't look right."

50 donations so far. Give it a try.

You know you want to spank it
Jump an Infinity

[pchapman 261]

To the OP, I'lll try to summarize a complex situation without going all RiggerLee on you:

Basically if you're not having a problem, you don't have a problem.

If you're worried about them breaking, don't. They're good for thousands of pounds.

If you are having a slippage problem, get it looked at. Usually any slippage is just when the harness is looser, eg, sitting on the plane. Not fun to open up with a leg strap a few inches loose. But you do check your straps before exit, right? Slippage has happened occasionally. Tends to involve certain adapters and certain leg strap types. So most rigs don't have a problem at all, but a few do, and that can be taken care of. (Occasionally dirty leg straps can get a bit slick and contribute.) It isn't a random out of the blue problem. Make sure you know how to tuck the leg strap ends away in keepers and/or under the leg strap covers to keep them in place when not loaded.

It is very rare for any slippage to happen under load. Usually only a few inches at most. Not good for reaching toggles etc or loading the canopy evenly, but usually not a cause of any real accident. (And one can usually tighten up under canopy if needed.) People have fixed such problems with an extra layer of webbing on the leg straps. Or I fixed the problem for one guy with gaffers tape on the hardware to make it less slick.

Remember that the leg straps have fold backs at the loose end, which are designed so that the leg strap can never slide out (but can only be removed if carefully unthreaded).

Other than that, conquering fears is part of skydiving.

[RiggerLee 61]

As I said, I actually don't know the original story. I would be very curious to hear it if one of the old timers recalls. It's such an old rule that it's got to be a very old story.

I've never heard of some one falling out from this particular problem. But I have seen webbing slip all the way to the stop. If it had not been rolled and sewn they would have been dead.

As to harness failures... Let's see. How about the Racer that blew a chest strap. That was a fatality wasn't it? Didn't he tumble out of the harness. And then there was the upper junction on that Russian rig that blew to hell. Major structural failure. I don't recall, was that a fatality? And just recently there was that base rig with integral risers that blew the upper junction. Still relevant since it was for all intents and purposes the same as your reserve risers. And I've personally seen total failures of the lower junction where it sheared the entire lower half of the stitch pattern. I've seen several of those actually but by luck all of the total failures were on rigs with wrap around harnesses with redundant stitching. By luck we caught all the plug ins before the failures were catastrophic. But I always heard about a European fatality on ether a vector or a talon but I was never able to nail the story down. But that was about the time that Booth changed his harness design in the middle of the Vector 2 to make it wrap around the inner layer of type 8 ... So yah, shit does break from time to time. Not a lot but it's worth acknowledging. And every one should know about the danger of leg straps. I've caught rigs where some rigger want to be decides to get smart and shorten his leg straps and resew them with E thread. Or how about the Pilot that decides to just cut the ends off so the excess wont flap around. Seen that too.

I'm all in favor of learning, but I'm serious about a D license requirement to hang in the loft after the beer light. And students should just flat out be banned. It's important for student retention. If something needs to be fixed the instructor should take it in there. No students any where near the loft!

Lee

Lee
[email protected]
www.velocitysportswear.com

[councilman24 36]

Look close at the photo in the OP. That's hardware I'm not familiar with. And if.you squint real hard it might be assembled with the.bar upside down. Looks kind of thin.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[mcordell 2]

that looks like a stock photo

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[tfg30 0]

Alright, thanks for all the responses, even the scary ones from RiggerLee (jokes )

Basically what I'm taking from this is that gear failure happens, but in terms of leg straps, it's really not all that common?

As for the photo in my original post, it was just a stock photo that I found on Google to show what I was referring to; I'm not sure it's even from a skydiving rig. My main question was whether or not these adapters fail, particularly when under pressure (ie after deployment under canopy, or during high G load turns when I feel my ass and legs pressing hard into the leg straps).

[councilman24 36]

didn't get that it was a stock photo that's not a skydiving piece of hardware. You wanted to see something that makes you worry I look up at the suspension lines that you're hanging from. I am worried about the harness specially whenever whenever I look up at the suspension lines I think I'm hanging from those?
don't worry about the harness specially the hardware but could just pay attention to your learning and your performance.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[mark 102]

councilman24

didn't get that it was a stock photo that's not a skydiving piece of hardware.

It is a DJ Associates SSA, stainless steel friction adapter intended for use on skydiving equipment.

Not a stock photo: https://www.miragesys.com/products/mirage-g4/leg-strap-friction-adaptors/

Mark

[BIGUN 1,053]

I only ever used stainless steel adapters and at 6'6" 240 pounds did not have any issues over the 18 years I was diving.

Nobody has time to listen; because they're desperately chasing the need of being heard.

[erdnarob 1]

In order to increase the friction to avoid slippage, put beewax on your webbing at least near the adaptors. I hope that your adjustable straps are all made with a sewn folded ending

Learn from others mistakes, you will never live long enough to make them all.

[JerryBaumchen 1,048]

Hi Mark,

Quote

DJ Associates SSA, stainless steel friction adapter

https://www.miragesys.com/products/mirage-g4/leg-strap-friction-adaptors/

http://catalog.dj-associates.com/item/stainless-steel-hardware/stainless-steel-quick-fit-adapter/dj-ssa?

Looks like a typo on the Mirage website. They are calling it a DJ-55A and DJ says it is a DJ-SSA.

Jerry Baumchen

[riggerrob 558]

...

Jerry Baumchen

PS) Edit to add: About 40 yrs ago I got a letter from Jim Rueter, V-P at Pioneer at the time, telling me that the typical "L" bar connector link, while rated at 3,000 lbs, was good for over 10,000 lbs before it would fail.

Just adding to the knowledge base.

..................................................................................

Agreed Jerry,

I suspect that 3,000 pound Minimum Breaking Strength is based on a "worst direction" loading.

I can cite plenty of types of hardware that will hold much heavier loads than their published MBS. For example, if you can hold a light-weight, cold-stamped steel chest strap buckle perfectly on the webbing, it will hold a 2,000 pound load, but only 500 pounds if end-loaded, so it is only rated for 500 pounds.

[riggerrob 558]

That leg-strap friction-adapter is rated for a Minimum Breaking Strength of 2,500 pounds, 10 to 20 times your weight. Before you break that hardware, you will need to open HARD, assymetrically, so that you put the entire opening shock on one leg strap. An opening that hard will dis-locate your hip and probably break your femur (the largest bone in your skeleton). You will be glad the opening knocked you unconscious!
IOW Parachute harnesses are built stronger than humans.

Time currently wasted worrying about hardware would be better spent learning how to pack neatly, so that you never suffer a hard opening.

If you are still worried about slippage ... that is a legitimate fear. However, at the first sign of slippage or fraying, you should take you r harness to your local rigger. The fix is easy, simply sew another layer of webbing over top of the existing leg strap. Aerodyne published that fix so long ago that I forget the date ... jut know that I have sewn that "fix" onto leg-straps made by: Aerodyne, Flying High, Relative Workshop, Strong Enterprises, Sun Path, etc.