Cypress washer rips

[councilman24 36]

Go to www.cypres-usa.com/CYPRES_disc_update.pdf

No heat treating. The story is explained. Should be only 400 'weak' discs out and about.

If you find one DING DING DING DING !!!!!!!!!

YOU WIN





NOTHING!

Thanks to Cliff for getting this to me.

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

[NovaTTT 1]

Thanks for posting, Terry.

"Even in a world where perfection is unattainable, there's still a difference between excellence and mediocrity." Gary73

[masterrigger1 2]

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No heat treating.

I didn't think so.

The stronger,harder material makes sense with regards to stress fractures from manufacturing.

BUT, if it is really harder, stronger material WITHOUT stress fractures, the yield should be higher.

MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[riggerpaul 1]

www.cypres-usa.com/CYPRES_disc_update.pdf

[divegoddess 0]

yup Mike-Looking at your photo- our loft had a brand new wings container that did exactly the same thing.
Interesting to hear that others have run across this as well.

[hackish 8]

I did some testing on the cypres material and found that it broke at somewhere around 360-375 lbs. Although my testing was looking into some reports of bending reserve pins I broke many closing loops without destroying a single cypres washer. I still have the washers used and I could try a die penetrant test to look for cracking. I scratched "X" on them so they would never be put in service but I don't think it would really impact a cracking test.

For what it's worth they're made of aluminum, not steel. There is a hardening process for aluminum and even the age of some alloys will have an impact on their hardness.

I'm going off memory here but I seem to recall that you can naturally age something to about a T5 temper (6xxx series AL). I'm sure a few of the engineering types could produce a table of how long they have to age but a month or so can have a significant impact.

One thing that would worry me is a washer that has partially yielded during packing and thus has sharp edges. They could in theory then cause the reserve loop to fail at some later time.

-Michael

[Unstable 8]

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I'm going off memory here but I seem to recall that you can naturally age something to about a T5 temper (6xxx series AL). I'm sure a few of the engineering types could produce a table of how long they have to age but a month or so can have a significant impact.

I'll put on my Engineering Hat here, but this is shooting from memory... I have a big Processing book here that has those charts somewhere, and IIRC, in Aluminium with that hardening process, the outer 3 layers oxidize to respective amounts and you do see hydrogen brittling ~ a slow process that will in fact very slowly weaken them.... I need to find that chart, but I think we are talking decades for a truly significant difference.

=========Shaun ==========

[hackish 8]

I asked a friend who worked as a metalurgist for Boeing and he said that they go so far as to refrigerate annealed parts so they do not naturally harden.

If you start with a piece of 6061 in O (annealed) condition it will naturally age as far as T51. Most of the 6061 I buy is already T6 but after I weld it it's stuck at best at T5. I wasn't able to figure out how long it takes to naturally age it but I vaguely recall it's a month or so.

Depending on what the washers are made from it could also work harden. For example stamping them out and forming them before deburring would definitely impact hardness.

-Michael

[koppel 3]

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One thing that would worry me is a washer that has partially yielded during packing and thus has sharp edges. They could in theory then cause the reserve loop to fail at some later time.

I have been thinking the same thing. I tried to raise the issue with our Federation here in Australia only to be told it wan't a big enough deal to be worth talking about?

I disagree.

I have not been provided with any information yet that has eased my concerns about that situation arising.

Why did it take so long for Airtec to advise people of this? The letters that they have posted on SSK and Airtec websites were only posted within the last week!

I like my canopy...


...it lets me down.

[hackish 8]

Realistically there are well over a 1/2 million cypres washers out there and only a few have failed in this way. I'm not saying it's right but they are still well produced and have proven to be reliable. As long as the rigger doesn't crank the @#$@# out of it they'll probably be OK.

Having said that, any reliable way we could test washers to weed out the bad ones? Probably not but definitely a very good idea to closely inspect your washer before re-installing it. Also don't use an excessive amount of force as a replacement for effective packing skill.

-Michael

[JerryBaumchen 1,048]

Hi Michael,

You have played around with some pull forces testing.

Quote

rigger doesn't crank the @#$@# out of it

and

Quote

an excessive amount of force

So could you give us your thoughts on what this might be?

JerryBaumchen

[koppel 3]

Quote

Realistically there are well over a 1/2 million cypres washers out there and only a few have failed in this wa

realistically there a a couple less than 400 that are by Airtec's own admission (if a year late) a problem. They say that they should fail during the closing of a rig, they do not say what pressures are required to cause this to happen. Yes I have posed the question. I have not had answer to my last three emails with questions to Airtec. By Comparison when I sent an email to Vigil asking for answers on a comparison tho their cutter vs the Argus cutter which is the same style and grounded here in Australia I got a long well thought out reply inside of a week. Mind you I got a quick email within 2 days telling me they were going to reply.

Quote

As long as the rigger doesn't crank the @#$@# out of it they'll probably be OK.

hmmmm most of my reserves come in around 18lbs-20lbs pressure on the pin. So I would say that during closing I might reach as high as 25 when I am 'cranking the @#$@#' out of it... Would you call that a lot? Too much for these discs that are affected? Enough to ensure that an effected disc would fail or could it conceivably tear just enough to create a sharp edge that may cause a loop to fail as someone is climbing out of the plane and bends some loading the loop a little more than previously...

Can someone please show me an example of a good disc and a bad disc? what exactly are we looking for?

In Australia I have been informed that 'it does not require urgent attention'

I disagree.

I like my canopy...


...it lets me down.

[masterrigger1 2]

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As long as the rigger doesn't crank the @#$@# out of it they'll probably be OK.

--------------------------------------------------------------------------------


hmmmm most of my reserves come in around 18lbs-20lbs pressure on the pin. So I would say that during closing I might reach as high as 25 when I am 'cranking the @#$@#' out of it... Would you call that a lot? Too much for these discs that are affected? Enough to ensure that an effected disc would fail or could it conceivably tear just enough to create a sharp edge that may cause a loop to fail as someone is climbing out of the plane and bends some loading the loop a little more than previously...

Exactly my thoughts.

I spoke with Mike G. a couple of days ago.
He informed me that he had around 4 to fracture and they all were during pre-tensioning.

What bothers me is the slight amount of tension needed to yield those washers vs the amount of pressure applied closing the container.

It would seem that the washers that yielded @ pre-tension had a stress fracture(s) from manufacturing BEFORE the pre-tensioning.
If that is true, then it is entirely possible to have washers in service with stress fractures not as severe as the ones that yielded @ pre-tension.

Installing washers with possible cracks in them IMHO, is not packing something that is legally airworthy.


Now that this issue has been brought public, it would seem that USPA, APF, etc would respond in a more positive manner.

My recommendation to Airtec would be to enlarge the washer by at least 1/8" and also add 1/16" to the hole spacing.

This would do two things.

1. Make the washer stronger than even the original.

2. It would provide a means to easily identify the "new" washer.

Quote

In Australia I have been informed that 'it does not require urgent attention'

I disagree.

You, me, and a lot of other riggers here in the States!

BS,
MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[pchapman 261]

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hmmmm most of my reserves come in around 18lbs-20lbs pressure on the pin. So I would say that during closing I might reach as high as 25 when I am 'cranking the @#$@#' out of it...

Um, that's the pressure to PULL OUT the pin.
The pressure ON the pin is going to be some multiple higher. Five times? Ten times? Who knows without tests.

It doesn't change the arguments about the discs though.

[koppel 3]

you are probably right by the look of it. I can't say that this sort of maths is a strong point for me.

anyone work it out for us?

I like my canopy...


...it lets me down.

[hackish 8]

How much force is too much force? Tough to quantify that, but it could be calculated if you know the length of lever and diameter of your leverage device. Personally I find that cranking a tight one slowly will give you enough closing loop to pin it without having to crank too hard. When "this loop is going to snap" is going through your mind then you're probably cranking too hard.

Altering the diameter and hole spacing on the washers may not achieve the desired effect. It would really depend on whether the aluminum is "tearing" or if the bridge is bending out before failure. If it is tearing then I think the material hardness is the only solution. In the newyear when I'm back to work I might have some fun with softer aluminum samples to see if I can encourage them to "tear".

Vigil's stainless washer is going to be a lot more expensive to produce but should not suffer from this same problem given that SS is a _lot_ stronger than AL. I have not personally tested any of them. Maybe I will stop by and see if I can get some samples before I go home.

-Michael

[erdnarob 1]

Thanks Peter to mention that. Obviously, the force to get the pin moving or sliding is way different than the force held by the pin from the loop. Using my positive leverage tool to close the reserve and applying force with a scale on the lateral rod used as a lever.
Here is the result I got :
type : Cypres closing loop braid : new single braid
date: July 2008
86.5 / 7 = 12.36 (lever ratio)
15 lbs x 12.36 = 185.4 lbs (breaking strenght for one braid) 15 lbs is the force read from the scale applied on the lever.

In an actual loop there is two braids which makes a theoretical breaking strenght of 2 x 185.4 = 370.8 lbs

Note 1: I would say that when closing a one pin reserve the force applied on the loop is between 150 and 250 lbs
Note 2: The size of the grommet used with the loop at the bottom of the reserve container is influencing the possible bending of the washer. Bigger is the grommet hole (size), more leverage is applied on the washer between where it is in contact with the grommet (on the side) and the hole in the middle.
Note 3: The problem of the washer bending is totally unacceptable, no matter the percentage of faulty grommets is. If the grommet bending can cause a premature reserve activation, it is a major issue. Manufacturers have to test the resistance of those grommets with their own rig, just like every reserve rip cord has to be tested for 3 seconds at 300 lbs.

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