Seatbelts for a chest strap?

[hackish 8]

This rig was grounded but I still wanted to post up photos of the work for discussion.

I don't have a problem with the strength of the webbing used. The width seems inapropriate for the friction adapter and it doesn't lock properly on the slippery polyester webbing.

Photos attached. Sorry for the quality they were shot with my blackberry.

-Michael

[AndyMan 7]

Neat! The workmanship looks great except for the material choice - the person who did the work clearly knew something about harness sewing, again - except for how to choose appropriate materials. How odd!

_Am

__

You put the fun in "funnel" - craichead.

[riggerrob 558]

African engineering at its finest!

[JerryBaumchen 1,048]

Hi Michael,

Go to some 3rd world countries, you will see a lot worse than that.

JerryBaumchen

[JohnRich 4]

Re: 2nd photo: IMG00047.jpg

Are rows of bar tacks the appropriate way to stitch that webbing? It seems that this method puts all the force on the 1st bar tack, thereby concentrating the force there, creating more likelihood of a failure at that point. I'm under the impression that the better stitching method is a three-point or a diamond stitch, to spread the force out over more surface area. I am not a rigger...

[pchapman 261]

Hey John,
It is one thing to discuss bar tacks vs. cross stitch patterns (diamond or W patterns). That's an interesting enough question, considering that bar tacks are often used for somewhat load bearing applications -- like line attachments tapes (other than ParaFlite), or climbing harnesses.

But in this case, we're not even talking about bar tacks, but multiple rows of straight stitches.

Poynter didn't explain much relevant about the theory of stitch patterns other than to say , "Never sew a straight line back and forth in an attempt to duplicate a bar tack. This just perforates the material."

So the stitching in that chest strap may be doubted more than your words suggested...


(To clarify the photos: I assume they are showing that new chest strap is just sewn onto the stub of the old strap?)

[rapaz 0]

Ooohhh Jerry !!!, 3rd world countrys ??, where you live? on the 1st world ??, OOuuuoooo, Im very impress, 1st world people made also a bunch of bad and crapy stuff.

[airtwardo 6]

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Ooohhh Jerry !!!, 3rd world countrys ??, where you live? on the 1st world ??, OOuuuoooo, Im very impress, 1st world people made also a bunch of bad and crapy stuff.

Yeah but we in the 1st world don't actually JUMP it, we just sell it to 3rd world-ers...


Oh....and:

It's 'countries' & 'crappy' & 'impressed', where did ya go to school a thatch hut?

~ If you choke a Smurf, what color does it turn? ~

[lilchief 0]

What do you want to accomplish by doing this?

Does it have any properties that Type 8 or 17 doesn't have?

"Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been and there you long to return." - Da Vinci
www.lilchief.no

[JerryBaumchen 1,048]

Hi rapaz,

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3rd world countrys ??,

I was trying to convey some information &, hopefully, not making a negative comment.

Guess it did not work.

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where you live?

Look at 'my' profile, it is there for anyone to see.

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1st world people made also a bunch of bad and crapy stuff.

Have I ever said or implied that they do not?

If you really have something to say, then say it. Negative comments like yours do not mean very much to me.

YMMV

JerryBaumchen

[hackish 8]

Quote

What do you want to accomplish by doing this?

Does it have any properties that Type 8 or 17 doesn't have?

If my ticket allowed me to do a repair like this it sure wouldn't be done like that! It surprises me that any rigger would do that.

Properties that type 8 and 17 lack:
a) ultra-slippery property - allows the webbing to glide through the friction adapter both ways oh so easily.

b) extra wide property - Standard width of the webbing should be 1 23/32 so. More is better right? You get an extra 5/16" of adapter bar impeding webbing to make chest strap removal a zip.

c) extra strong property - 1500lb stronger than the 4000lb capacity of most chest straps. More than the friction adapter that holds it on...

All joking aside this was found on a rig that was going to be jumped. I hope some educational feedback and discussion comes from the photos.

-Michael

[hackish 8]

Quote

(To clarify the photos: I assume they are showing that new chest strap is just sewn onto the stub of the old strap?)

No, actually the photo was shot to foster the type of discussion that has occurred. I felt that it was improperly stitched but lacked the expertise to confirm this. It's outside the privileges of my ticket but if I were able to do this repair I think it would be best to unstitch it from the harness and replace it completely.

-Michael

[pchapman 261]

Hi Hackish,

Somehow we talked past each other. I do see that you're posting it to get a discussion going. (And that you aren't the one who sewed this up!)

I was just trying to understand whether the chest strap was simply added on to a stub of the old strap -- I think a closer look at the photos does show this to be the case. Looks like harness stitching? Still, the orientation is frowned on.

The slipperiness issue is interesting, and we don't have easy to find standards on that as far as I know.

A complete replacement of the original chest strap in its original configuration gets complex, as on that rig the stitching through the original chest strap at the MLW is also part of the main 3 ring / harness junction stitching.

[Hellis 0]

d) Seatbelts stretch ~50% when they are used.

I dont think there will be enough force to make it stretch but, it can

[timmyfitz 0]

Quote

Ooohhh Jerry !!!, 3rd world countrys ??, where you live? on the 1st world ??, OOuuuoooo, Im very impress, 1st world people made also a bunch of bad and crapy stuff.

Could someone translate this into english please?

[airtwardo 6]

I'm not a rigger, but have related question~

Some time ago I brought a rig to a master rigger for a repack.

He noticed a mark on the chest strap where the hardware had scuffed the material, this mark was a result of very sharp teeth on the friction bar and happened on the very first jump I made on the rig, new from the factory.

I saw the mark, called the manufacturer and was told if it wasn't actually cut, to simply buff the sharp ends off the teeth and get on with my life, which I did...so ten years later the rigger in question took it upon himself to sew ANOTHER piece of webbing over the original one...

Aside from doing 'imo major' work not asked for, is it 'okay' to make a 'repair' of that nature in that way?

It was stiff and hard to get through the hardware, but seemed to work okay.

~ If you choke a Smurf, what color does it turn? ~

[riggerrob 558]

to answer pchapman and airtwardo ...

The best repairs are close copies of factory stitch patterns, materials, etc.

IOW a proper repair is indistinguishable from factory work, at arm's length.


Rob Warner
FAA Master Rigger
CSPA Rigger Examiner

[riggerrob 558]

It was improperly stitched.

A proper repair would look like a new chest strap installed by Jump Shack with all new webbing and new 6-cord sewn with the factory stitch pattern.

The repair in question does not use 6-cord, nor does it use the factory stitch pattern (4 point WW).

Nor does it use factory-spec materials.

Ergo, it is an illegal repair.

The only saving grace is that chest straps are rarely subjected to loads heavy enough to break their 500 pound buckles.

In conclusion: Sandy Reid said: "If you don't understand something, copy it exactly."