Static line failure?

[mircan 0]

What is the possibility of scenario like this:
- Static line with nylon coated cable,
- after some wear and tear nylon gets cracked,
- on jump, the center of the line (wire) is pulled, but nylon coating which is cracked stays in the loop making a total mal.
Is this likely to happen?
Provided that there is poor gear check and maintenance.

dudeist skydiver #42

[Andrewwhyte 1]

What is more likely is that the cracked sheath causes a hang up and a jumper in tow.

[mircan 0]

But if not (no jumper in tow)?
Did it happen to anyone?

dudeist skydiver #42

[councilman24 37]

Main ripcords used to use the same or similar cable coated with clear plastic, not sure it's nylon. Also there was is cable coated with black plastic.

I seem to remember the clear coating coming off and causing a total. Don't remember if it was static line or ripcord. Ripcord I think. A static line as to either be direct bag or have a PC assist device per FAR's. This would help open a static line rig.

Don't have a clue if I'm really remembering this or making it up.

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

[rlucus 0]

As the pilot chute is also connected to the static line (a 6-8 inch length of Velcro) I doubt if this would be strong enough to over come the nylon coating...

A more like point of failure is the whole cable separating from the static line. Both would cause a total main malfunction but not a jumper a jumper-in-tow

Both would require massive negligence on gear maintenance. But the student would pull the reserve or (hopefully) be saved by the AAD.

[captain_stan 0]

Quote

As the pilot chute is also connected to the static line (a 6-8 inch length of Velcro) I doubt if this would be strong enough to over come the nylon coating...

Not when the direct-bag system is used. With DB, the end of the SL is connected to the main D-bag. If the plastic coating was shed and left in the loop, the weight of the jumper falling away from the AC may be enough to pull the grommets past the plastic sheath stuck in the loop--helluva snatch force goin' on there.

[captain_stan 0]

Quote

What is more likely is that the cracked sheath causes a hang up and a jumper in tow.

Makes sense to me. It's hard to imagine the entire coating sliding off the end. I'm inclined to think it would flake off in smaller chunks and that someone would notice the damage. And if not, the jumper in tow would indeed result.

[billvon 3,008]

> If the plastic coating was shed and left in the loop, the weight of the
>jumper falling away from the AC may be enough to pull the grommets past
>the plastic sheath stuck in the loop . . .

This is not unique to direct bag. Most PCA systems use a pin connected directly to the static line as well - thus the student's entire weight will act on the pin/loop.

[captain_stan 0]

An FAA-compilant PCA device may release with as little as 28 lbs. tension. The few types that I have rigged would permit the device to snake past the flaps and leave the PC inside a locked container once the tension is overcome. This release tension combinded with the PC spring pressure may or may not be enough to pull/push the flaps open, but is certainly less than the snatch force generated by the full weight of a jumper reaching the end of the SL that is connected directly to the bag without a release device.

[billvon 3,008]

>An FAA-compilant PCA device may release with as little as 28 lbs. tension.

The PCA can be just a piece of velcro - but the pin/line on the end of the SL (that holds thecontainer closed) is attached directly to the SL. Once you hit the end of the SL, if the pin will not release, one of three things will happen:

1) The closing loop/flap will fail and the main will open. (most likely)

2) The SL will fail and the jumper will fall away with a closed container (unlikely.)

3) Nothing will fail and you will have a student in tow, suspended by his closing loop (very unlikely.)

[captain_stan 0]

Quote

The PCA can be just a piece of velcro - but the pin/line on the end of the SL (that holds thecontainer closed) is attached directly to the SL. Once you hit the end of the SL, if the pin will not release, one of three things will happen:

1) The closing loop/flap will fail and the main will open. (most likely)

2) The SL will fail and the jumper will fall away with a closed container (unlikely.)

3) Nothing will fail and you will have a student in tow, suspended by his closing loop (very unlikely.)

All true, of course. My comments relate to the OP's question regarding the plastic part of a damaged cable being lodged in a closing loop, a different scenario than you describe. I'm not interested enough in any of this to go off-topic.

[mjosparky 4]

If you can imagine it, it can happen and probably already has.

Sparky

My idea of a fair fight is clubbing baby seals

[sberkovitz 0]

#3 did indeed occur.

It was the force of the reserve opening that eventually ripped the grommet out and freed the jumper.

http://www.skydivingmovies.com/ver2/pafiledb.php?action=file&id=7624&string=static%20line%20hangup

-Steven

[jerolim 7]

OMG, student not puting hands on his head, and afer 8 seconds opening reserve, after getting hand singnal to wait!
Glad that they are all ok!
We have 2 snap off cutters on jump plane, but I'll buy one more hook knife after seeing this video

[RiggerLee 61]

As to the history of clear coated cable. They used to build cutaway cables from something simular. Didn't they have issues with cracking in cold weather? Did just have snag incedents or did they actualy strip sections?

Lee

Lee
lee@velocitysportswear.com
www.velocitysportswear.com