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odd bridle wear

 


mr2mk1g  (C 103449)

Mar 15, 2013, 6:20 AM
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odd bridle wear Can't Post

I was helping out my local university skydiving club last night with a packing course and found odd wear to the main bridle on one of their sets of club kit thus:

http://i16.photobucket.com/.../20130314_204101.jpg

http://i16.photobucket.com/.../20130314_204207.jpg

http://i16.photobucket.com/.../20130314_204426.jpg

Gave advice to speak with their rigger generally, about pin-entrapment about potentially getting some additional tape on the bridle near the pin to help protect them from locking off against the pin. Didn't go into Brian's bridle routing method as I don't want to confuse people new to packing but it may be something to look into in the future. At this stage there's no hole close enough to the pin for the two to become involved.

My main concern for the moment is as to how the wear is occuring. Maybe something to do with the way someone is cocking the PC? With such regular wear points it looks like it's associated with having the bridle sinched up when the PC's collapsed...

Anyone able to comment or give suggestions as to how to avoid the problem getting worse? The rig's fairly well looked after and while it's a few years old it doesn't exactly have a whole heap of jumps on it.


(This post was edited by mr2mk1g on Mar 15, 2013, 6:22 AM)


theonlyski  (D License)

Mar 15, 2013, 8:03 AM
Post #2 of 16 (1377 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

In reply to:
I was helping out my local university skydiving club last night with a packing course and found odd wear to the main bridle on one of their sets of club kit thus:

http://i16.photobucket.com/.../20130314_204101.jpg

http://i16.photobucket.com/.../20130314_204207.jpg

http://i16.photobucket.com/.../20130314_204426.jpg

Gave advice to speak with their rigger generally, about pin-entrapment about potentially getting some additional tape on the bridle near the pin to help protect them from locking off against the pin. Didn't go into Brian's bridle routing method as I don't want to confuse people new to packing but it may be something to look into in the future. At this stage there's no hole close enough to the pin for the two to become involved.

My main concern for the moment is as to how the wear is occuring. Maybe something to do with the way someone is cocking the PC? With such regular wear points it looks like it's associated with having the bridle sinched up when the PC's collapsed...

Anyone able to comment or give suggestions as to how to avoid the problem getting worse? The rig's fairly well looked after and while it's a few years old it doesn't exactly have a whole heap of jumps on it.

You're burning the bridle when you cock the pilot chute.

Lets see the inside where the canopy attaches to it.

The only rig I recall ever seeing where the bridle 'cinches' up when you cock the pilot chute is a Sigma tandem rig (can't recall if the Vectors did as well)

Usually the part that cinches up is inside the bag, connected to the canopy. Post some pictures of that.

ETA: Also, do you guys cock the PC after the canopy is in the bag? I'm thinking probably.


(This post was edited by theonlyski on Mar 15, 2013, 8:10 AM)


mr2mk1g  (C 103449)

Mar 15, 2013, 8:13 AM
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Re: [theonlyski] odd bridle wear [In reply to] Can't Post

That was my first thought - only spotted this as the group was closing up the rig for the night as I'd been working with others on another rig. I'll see if I can't take another look next week and maybe some more snaps.

It's a Wings system but I'm figuring this has to be misuse/poor packing practice by someone rather than the design. Maybe someone's been standing on the bridle when cocking the PC rather than the d-bag?


theonlyski  (D License)

Mar 15, 2013, 8:15 AM
Post #4 of 16 (1352 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

In reply to:
That was my first thought - only spotted this as the group was closing up the rig for the night as I'd been working with others on another rig. I'll see if I can't take another look next week and maybe some more snaps.

It's a Wings system but I'm figuring this has to be misuse/poor packing practice by someone rather than the design. Maybe someone's been standing on the bridle when cocking the PC rather than the d-bag?

While that's possible, I don't think it's likely. The holes are too small for me to think that. It's either happening when they cock the PC, or when the wind catches it on deployment and extends the PC more.

Either way, that part of bridle should not be cinched up. I don't recall off the top of my head what attachment system the canopy has to the bridle/dbag, but the slack from cocking the PC should come from inside there (between the bag and the canopy)


mr2mk1g  (C 103449)

Mar 15, 2013, 8:20 AM
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Re: [theonlyski] odd bridle wear [In reply to] Can't Post

In reply to:
ETA: Also, do you guys cock the PC after the canopy is in the bag? I'm thinking probably.

Not when I'm watching they don't or they get a thick ear. I'd guessed that might be part of it so reminded them of what I'd said about it in their first lesson.


theonlyski  (D License)

Mar 15, 2013, 8:25 AM
Post #6 of 16 (1334 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

In reply to:
In reply to:
ETA: Also, do you guys cock the PC after the canopy is in the bag? I'm thinking probably.

Not when I'm watching they don't or they get a thick ear. I'd guessed that might be part of it so reminded them of what I'd said about it in their first lesson.

I've seen people who cock it after they bag the canopy and tell them why that's a bad idea, but then seen people cock it before bagging it, then not checking after it's bagged.

I personally cock/check my PC at least twice. Once before bagging and once after, but I keep the bridle taught and put my foot on the bag to make sure that all of the slack is coming from the inside of the bag (between the canopy attach and the dbag).

As for the repair/replacement, I'd ask a rigger there to look at it and make their determination. If they were holes without jagged edges, depending on the locations I might be okay with it, but if they're burned and have sharp edges, you're just asking to replace your kill line soon and minas well just replace the whole thing... Unless your rigger is VERY bored and wants to fix that bridle. LaughLaugh


base283  (D 15343)

Mar 15, 2013, 1:07 PM
Post #7 of 16 (1229 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

I would venture to say that it is the collapsing mode of the PC, not the cocking. A person cocking the PC would have to really try to friction burn their way thru the bridle...
What is the keel line made of? It could be that the line was replaced with something different and has different surface texture and a higher melting point than the outer.
Take care,
space


Premier Remster  (C License)

Mar 15, 2013, 1:49 PM
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Re: [base283] odd bridle wear [In reply to] Can't Post

Quote:
I would venture to say that it is the collapsing mode of the PC, not the cocking.

I'd agree with that too... Or maybe some sort of friction while travelling with the bridle folded over...


riggerrob  (D 14840)

Mar 15, 2013, 4:09 PM
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

Odd wear pattern!!!

Are the damaged edges melted?


yoink

Mar 15, 2013, 9:27 PM
Post #10 of 16 (1123 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

Does the PC completely collapse? Might it be fluttering in flight partially collapsed?

I can only imagine that wear pattern comes from a collapsed state as the bridle is cinched. That's either in flight or packing. The latter seems unlikely to me - I just can't imagine enough friction or force being being generated in that stage to cause that sort of wear.

Having said that I'm neither a rigger nor a parachute designer. I'm prepared to add 'profoundly unimaginative' to that list too...


How many jumps on the system?


(This post was edited by yoink on Mar 15, 2013, 9:34 PM)


councilman24  (D 8631)

Mar 16, 2013, 5:10 PM
Post #11 of 16 (998 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

Is bag gromment coming up the bridle after it's cinched? That's the only thing that I can think of that could cause the wear. Either a rough spot in the gromment or just repeated bag coming up the cinched bridle.

In the old daysWink we used #8 gromments with the intention of the bag coming up the bridle and choking off the PC in order to collapse it. If this bag has a number eight gromment and/or the bag stop is missing. Something, either a french link, a solid link sewn to the bridle or a wrap of webbing sewn to the bridle, should be there to trap the bag at the top of the canopy and keep it from coming up the bridle.

Show us the bridle as it goes through the bag from the outside and the inside.


dpreguy  (D 835)

Mar 16, 2013, 7:16 PM
Post #12 of 16 (965 views)
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Re: [theonlyski] odd bridle wear [In reply to] Can't Post

I agree it is probably due to cocking while wrinkled when packing. I also agree it is likely from the PC being forcefully cocked after bagging the main.
And. I wonder if - when the wrinkles come out on deployment, is the pilot chute really fully cocked after all?

You can test this, (whether it is fully cocked) by pulling on the pilot chute after the rig is pinned. Grab it by the base of the mesh=the attachment point of the pilot chute to the bridle,(not the hacky) and carefully pull until the bridle is straight, then keep going, and extract the pin and keep gently pulling until the bridle is straight to the top of the D bag. I suspect you will find it is not fully cocked.


ChrisClark  (D 8433)

Mar 17, 2013, 4:12 PM
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

The pattern of holes is symmetrical, its looks like they will match up if bridle is folded with three holes either side. It would be interesting to check if the damage is in the area that is folded back across flap 2 when closing the container. If so then it is likely that the kill line has not been cocked well enough and the slack is taken up on deployment, the burnt area will be under pressure between flaps, stiffeners and binding tape.


NovaTTT  (D 17887)

Mar 18, 2013, 7:56 AM
Post #14 of 16 (754 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

This appears to be caused by a repeated combination of techniques:

First, the bridle is being folded on top of itself across the bag before the flaps are closed (see attached image to see how the holes match).

Next, the PC isn't getting fully cocked so when checking the PC after closing to make sure it is cocked, the kill-line is tightening under that compression and causing the friction burns.

Recommend packing with the bridle extended from the bag w/o the fold and making sure the PC is fully cocked before closing.

As well, the kill-line length should be checked.

.02

Cheers.
Attachments: Bridle Holes.jpg (179 KB)


mr2mk1g  (C 103449)

Mar 18, 2013, 9:46 AM
Post #15 of 16 (719 views)
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Re: [NovaTTT] odd bridle wear [In reply to] Can't Post

Cheers for the comments all - many theories to work on.

I think there's another packing class this thurs evening so I'll have a proper look at the rig then. Only managed a quick look last week as things were wrapping up at the time I found the damage.

Tying down one theory over another is going to be interesting as the rig is jumped by a wide number of individuals within the club. Figuring out exactly what's happening therefore can't simply be done by asking 'the guy' how he packs as it's probably quite a few people over the years, many of whom will have been shown different techniques to those which I teach.


chuckakers  (D 10855)

Mar 18, 2013, 11:35 AM
Post #16 of 16 (682 views)
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Re: [mr2mk1g] odd bridle wear [In reply to] Can't Post

Do those wear spots appear on the bridle only in certain places? If they only happen in the first couple feet coming from the attachment point, it could just be where the bridle bunches up after opening and the wear spots are where the "outside" of the folds rub against the bag fabric. The wear is only in the center because the kill line runs right there, making a thick spot in the bridle adding to the friction in that spot.



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