I pulled unstable on my back today and got into a massive mess of line twists. Tried to cut away but the handle wouldnt come loose no matter how hard i tried (and i tried hard). Can anyone suggest why this would happen? Had to try to untangle my main which wasnt pretty and had a pretty close call. I kind of backflipped through the risers and one got wrapped round my arm. It seems crazy that the chutes cannot take this kind of thing. I was pretty angry that I couldnt cutaway.
Re: [JayCam] Why wouldnt my cutaway cutaway?
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Can anyone suggest why this would happen?
If the risers were twisted together, then the cutaway cables were also twisted together. Without the protection of metal housings, this twisting causes the cutaway cables to be much harder to pull than normal. Also, if the cutaway cables are dirty, that can dramatically increase pull forces. Student rigs tend to be overlooked for regular, 30-day, 3-ring maint and cable cleaning.
Re: [JayCam] Why wouldnt my cutaway cutaway?
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Check the rig for "hard housings" the yellow cable that holds your 3 rings in place can get twisted up in the risers when you have line twists, this can "clamp" the yellow cables in the risers. Hard housings can prevent this.
Re: [JayCam] Why wouldnt my cutaway cutaway?
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- What did your instructors or senior dz people say about it when you described the experinece to them? (I expect they should want to look at the rig.)
- Did the cutaway cables move freely after landing, ie not dirty, bent, kinked, or anything else wrong with them?
Re: [JayCam] Why wouldnt my cutaway cutaway?
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what kind of rig was it? What size rings do the risers have? Are you sure that they are in tolerance? How long has it been since the three rings have been inspected and the cut away cable cleaned? Is there any hard channels inside the soft cable housing in the riser? Does the rig have soft or hard cutaway housings? Can you take the risers off the D-rings and attach a close up photo of the riser rings and the loop that holds them in place so that I may see their geometry? Maybe then I can give some answers rather than ask more questions. K
One more thing. When you take the risers off the rig check to see if the yellow cable has been bent by being partially sucked through the grommet on the housing. With the cutaway pillow in place on the velcro, check the cable where the cable exits the housing. If it is bent there, then the cutaway may need to be replaced Properly built risers should be able to withstand up to 600lbs of force before the yellow cable begins to suck through the grommet on the housing. At that point, cuttng away becomes impossible. If you experienced 600lbs or more then the cable will most certianly need to be replaced. If you do not believe that you reached 600lbs of force but your cabel is still bent, then you may have risers that are out of spec. If they are out of spec, they cannot be repaired. Cut the hardware off of them and and buy new risers
(This post was edited by KevinMcGuire on Jun 22, 2005, 10:42 PM)
Re: [JayCam] Why wouldnt my cutaway cutaway?
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Glad you didn't die.
Given your experience level, and some LIKELY (but not definite) interpretations and assumptions, I'd suggest the problem was probably you. Either you were pulling on something other than the handle (perhaps in addition to the handle), such as a piece of your jumpsuit, or the main lift web, or you were pulling the handle in shear mode rather than peel mode. You state that the "handle wouldn't come loose" which says to me that you never pulled on the cables, just the handle.
Don't get me wrong, I believe it is possible that there was something else wrong, but with the evidence at hand I just think the other scenarios are less likely. Dirty cables and housings can make pulls very hard also.
Re: [Hooknswoop] Why wouldnt my cutaway cutaway?
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Can anyone suggest why this would happen?
If the risers were twisted together, then the cutaway cables were also twisted together. Without the protection of metal housings, this twisting causes the cutaway cables to be much harder to pull than normal. Derek
I'd like to see evidence of this (as in test data)....
Re: [darkwing] Why wouldnt my cutaway cutaway?
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Glad you didn't die.
Given your experience level, and some LIKELY (but not definite) interpretations and assumptions, I'd suggest the problem was probably you. Either you were pulling on something other than the handle (perhaps in addition to the handle), such as a piece of your jumpsuit, or the main lift web, or you were pulling the handle in shear mode rather than peel mode. You state that the "handle wouldn't come loose" which says to me that you never pulled on the cables, just the handle.
Don't get me wrong, I believe it is possible that there was something else wrong, but with the evidence at hand I just think the other scenarios are less likely. Dirty cables and housings can make pulls very hard also.
Sorry bad choice of words. The handle DID come loose and the cutaway cables came out about 4 inches but would come no further. I DEFINATELY was pulling the pad I saw the yellow cables come out and I was trying to pull it for about 20 seconds and then again later on. It wasnt a case of getting the handle off the velcro or pulling the wrong thing.
To all the gear questions I am sorry I dont know I am but a newbie who isnt even qualified to pack yet. It isnt my rig it belongs to my drop zone so I cant take it apart and take pictures. They will be inspecting it Im sure so I will have to ask next time I am there.
Re: [RMURRAY] Why wouldnt my cutaway cutaway?
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I'd like to see evidence of this (as in test data)....
There was an article in Parachutist with test data and it is well-documented. Try it in a hanging harness. It is the reason housing inserts in risers are common today.
A search for 'Hard Cutaway' will provide some info too.
Derek
(This post was edited by Hooknswoop on Jun 23, 2005, 5:11 AM)
Re: [Hooknswoop] Why wouldnt my cutaway cutaway?
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There was an article in Parachutist with test data and it is well-documented. Try it in a hanging harness. It is the reason housing inserts in risers are common today.
I dont read Parachitist, and still remember reading a test on this, so maybe even in Skydiving or Skydive the Mag (BPA magazine) (I douobt it was Canpara). Tests with 1, 2, 3 people (again, I remember them calling it the Bloke test, as in 2 blokes hanging...) hanging off 1 set of risers in a hanging harness to simulate Gs.
Re: [JayCam] Why wouldnt my cutaway cutaway?
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Which type of canopy were you jumping? What size of canopy? What size of risers (1" or 1 23/32" wide)? Did the risers have hard inserts to protect the cables? What size of rings on the risers (mini or large)? What size of rings on the harness (mini or large)? What model of harness? Hard or soft cutaway housings on the harness? Was the cutaway handle built by the same factory as the harness? When was the last time the cables were cleaned?
Re: [Hooknswoop] Why wouldnt my cutaway cutaway?
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I'd like to see evidence of this (as in test data)....
A search for 'Hard Cutaway' will provide some info too.
Derek
searching DZ.com does not prove anything to me - I'd like to see real test data. John Sherman says they are not needed (on my racer) so I will go with what he says. This has been discussed before - I don't mean to highjack the discussion.
Re: [RMURRAY] Why wouldnt my cutaway cutaway?
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I'd like to see real test data.
Then go through old issues of parachutist and skydiving magazines.
Or do it yourself. Use your rig in a hanging harness test. Twist up the risers, get two people to hang off the harness, and use a spring scale to pull the cutaway handle. Slide some inserts into the risers and repeat.
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John Sherman says they are not needed (on my racer) so I will go with what he says.
If manufacturers were never wrong, there would be no AD's/SB's.
Re: [RMURRAY] Why wouldnt my cutaway cutaway?
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John Sherman wasn't flying the canopy I jumped several years back when I had line twists that pinned my head down to my chest. I pulled muscles cutting that one away.
Re: [RMURRAY] Why wouldnt my cutaway cutaway?
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I'd like to see evidence of this (as in test data)....
A search for 'Hard Cutaway' will provide some info too.
Derek
searching DZ.com does not prove anything to me - I'd like to see real test data. John Sherman says they are not needed (on my racer) so I will go with what he says. This has been discussed before - I don't mean to highjack the discussion.
rm
I can believe that a Racer's cables will pull out easier because they are teflon coated, everything else being equal, but unfortunately everything else is not equal. The teflon cables are not as stiff, so they get bent by the loop easier, increasing pull forces.
The thought of the cable being bent like this is not comforting.
(This post was edited by sundevil777 on Jun 23, 2005, 5:53 PM)
Re: [RMURRAY] Why wouldnt my cutaway cutaway?
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Look in the May 2003 issue of Parachutist for the breakdown.
Here is some of the info:
We demonstrated those same three combinations with me hanging normally, then with two line twists, then with two line twists at 2 Gs. We simulated 2 Gs by having a guy who weighed about the same as me hanging onto my back.
The results were amazing. When I was just hanging straight, I could cutaway with about 5-10 pounds (closer to 5) of force, regardless of the presence of cable housings.
With two line twists introduced, results went as follows: No housings: 45 pounds of force (use two hands, folks!) Plastic housings: 10 pounds Steel housings: 5-10 pounds.
With 2 line twists plus 2 Gs: No housings: Off the scale. Scale only measures to 50 lbs, but there was still room for the needle to go up above the 50 lb mark. Basically, I had the needle slammed all the way up against the top, well beyond the 50 lb mark.
Re: [hookitt] Why wouldnt my cutaway cutaway?
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John Sherman wasn't flying the canopy I jumped several years back when I had line twists that pinned my head down to my chest. I pulled muscles cutting that one away.
So what was the root cause of the problem. Was your yellow cable clean and lubricated??? I asked only because my buddies here (with highly loaded cross braced canopies) just laugh when I ask them - in fact nobody I know clean/lubs their (yellow) cable properly. The red cable may be harder to terminate and not as tough but overall I'd say it is better since you don't need to touch it. I guess I will need to test myself because no one (including JumpShack) has been able to give me proper comparative test results...
Re: [sundevil777] Why wouldnt my cutaway cutaway?
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I did'nt do it, just coppied and posted but if I remember right in that issue they did it for both sizes of rings and had charts for them all.
Yeah, I mention hard inserts to some of the people that don't get online and never travel away from my DZ and they look at me weird too. Talking to people like SkyMonkey1 who almost went in due to the risers getting twisted on his little canopy changed my mind fast and a few others.
Glad to hear you saved your own life. 
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