RIGGER ERROR - LIFE SAVING ISSUE

[potvinj 0]

Thanks for recalling those passages from Poynter's manuals. They sure do point to something that is rarely mentioned.

The way I understand this age/wear debate is that fabric on reserves can be damaged in two ways mainly:

- application of stress on the fabric during packing

- continuous changes over time, of nylon chemistry even in ideal storage conditions.

Concerning the latter there are reports out there that show how nylon degrades over the years, under all sorts of storage humidty and temperature considtions (PM me if you want copies). They seem to point to a reduction of about 10 -30% of actual breaking strength over a period of about 20yrs. Now, as actual breaking strength (of a given batch of fabric) is typically higher than the rated (or required) breaking strength, such degradation can still yield strong enough cloth as examplified in P2.
Unfortunately, the results of these studies are hard to compare since the experimental conditions (and fabric and nylon types) are different - so their use to riggers and manufacturers is rather limited. But as you said, at least old canopies were built like tanks so that a "little" aging should not affect the rated/required strength. Heck, I have several 40yr-old USAF C-9 canopies in my basement that have survived repeated 40lbs tests!

It seems that the stresses applied during packing is what concerns PD and others the most. I can see this at least with tight rigs, where some areas of the canopy get really stretched - to levels high enough to affect the permeability of the fabric. As related by billvon in a previous thread, PD and Precision (?) have performed experiments showing this. That said, one would conclude that canopies packed in "looser" rigs would not be as susceptible, which would jive with the findings of other manufacturers that show little permeability changes.

So I would agree that the issue of retirement age should be left to each manufacturer to determine. After all,

- different type of parachutes are used differently

- the manufacturer should have a good idea of the ways the equipement is used.

[potvinj 0]

Another thing about the chemical change of fabric over the years. Someone from the industry should chime in on this but I have read somewhere that different batches of nylon fabric come with different actual breaking strengths (but same rated breaking strength), so thread degradation would be different with each batch.

That would mean that individual canopies would perform differently, say over a 20- 50yrs stretch, with regards to meeting TSO-mandated strength requirements.

Yes?

[stratostar 5]

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I have several 40yr-old USAF C-9 canopies in my basement that have survived repeated 40lbs tests!

I have four 44 year old (1962) paracomanders that survived live "test drops" a couple times a year, they always work too. With that said you all will be the second ones to learn if a conopy blows up's.

you can't pay for kids schoolin' with love of skydiving! ~ Airtwardo

[drjump 0]

Canopy Strength? What ever happened to the old fashioned thumb/knuckle test? If the fabric tears it is NOT airworthy! If it doesn't tear pack it and jump it. Nuff said.

[stratostar 5]

Well yea I did that test when we first got them and put the rig's together, BUT I'm not going tell the " live test dummy's" that cuz that would take away part of the fun of scaring the shit of of um.

you can't pay for kids schoolin' with love of skydiving! ~ Airtwardo

[JerryBaumchen 1,050]

Hi Strato,

The first ParaCommanders hit the market in late Spring-early Summer of '64.

Just so you will know,

JerryBaumchen

[stratostar 5]

Hey I'm not in the loft and I'm going by memory and with 22 paracomanders of all colors and DOM's it get's a little tough at this age (as you know) to remember all the DOM's we have, however I assure you we have a number of early 60's PC's, two of them are in the team RWB colors and I have been told they are U.S. team canopies, they have the white apex in them made out of ripstop not tafata, but IDK if that is true. Anyway so that makes them 42 yrs old then as these two are the ones I remember being very early in the 60's and they don't blow up on deployment, yet.

I have been trying to get more detailed photos of the whole collection together,but it taking me sometime to do as I have not been to the dz much this year due to travels.

you can't pay for kids schoolin' with love of skydiving! ~ Airtwardo

[slotperfect 7]

Let's get the thread back on topic please

Arrive Safely

John

[jheadley 0]

FWIW, I'm a relatively new jumper and new rigger and I had no problem doing an I&R on a 21 year old Raven II and certifying it as airworthy.

[deathtrap 0]

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It seems that the stresses applied during packing is what concerns PD and others the most. I can see this at least with tight rigs, where some areas of the canopy get really stretched - to levels high enough to affect the permeability of the fabric. As related by billvon in a previous thread, PD and Precision (?) have performed experiments showing this. That said, one would conclude that canopies packed in "looser" rigs would not be as susceptible, which would jive with the findings of other manufacturers that show little permeability changes.

I've been trying to wrap my head around this concept, but maybe you can explain it a little better. How exactly does compressing a packjob (generally from outside a bag or container) stretch the canopy fabric?

I always thought the majority of fabric wear from packing came from the salt and oils transferred from the packer's skin/sweat.

[stratostar 5]

Gee, John I thought talking about packing and using 20 & 30 & 40 plus year old canopies main & reserves and harness & container systems was right on topic with this thread, if you see in the post your talking about I said the use of those parachutes that "they have NOT blown up YET!" and these rigs are used "regularly" each year.

If I was an out of line, sorry. I'll go ahead and shut up about our large collection of old rig's we jump, now.

you can't pay for kids schoolin' with love of skydiving! ~ Airtwardo

[potvinj 0]

Hummm...I see your point. But then, if the sweat was really a factor, should'nt we see drastic fabric aging in most old parachute equipment? As far as I know, not all equipment shows that. But obviously, that should be a factor to consider.

As for "stressing the fabric" - I guess that could come from using strong packing clips, or putting a canopy in an undersized deploy bag, thumb-testing, or any other general "canopy handling" strategies that would cause thread displacement - and hence porosity changes.

It seems to me that just handling the fabric should'nt really cause such thread displacement but thats my understanding of what I have read elsewhere (mostly statements of fact, but no numbers from actual measurements I might add).

[RiggerLee 61]

There is wear during packing. The millatary did a study of packing surfaces. Every thing from grass to concreat, wood, blue tarps, etc. I don't remember where to find it and exactly what they were measuring, probably perosity. Oddly what they found to be the best surface was concreat. Smooth painted concreat like a really nice hanger floor. They could sweep it very clean and they were not getting damage from the fibors of the carpet picking the fabric of the canopy. One of the worst was a blue tarp. It was ok when it was new but as soom as it wore the little fibors would become very abrasive.
In any case the point is that there is a fair bit of wear even just from packing over time. The two real questions are does this actually effect the porfomance, the answer being diffrent for diffrent canopies, and is there some wild card out there that might destroy the structural integraty.

Lee

Lee

Lee
[email protected]
www.velocitysportswear.com

[ronny2 0]

It was the Belgian Parachute School who did this test on canopy's, I was involved in it and we did a siminar on the PIA symposium.
The test was to see the increase of porosity on several canopy's thinking that the number or kind of jumps was the factor. We see this was not the case but the surface where we packed and the number of pack-jobs let the porosity increase.
We have reserves of 10 years old, never jumped only repacked every 120 days, the porosity was rised to an average of 9 cfm. This is high for a canopy that never jump as you know new fabric (F111) have an average between 0 and 3 cfm. We see a lot of hot-spots on the left side of the canopy because we did side packing. Also the middle cell have a huge cfm factor because of the use of a molar strap.
We can only conclude that the handling and packing surface increase the porosity of the canopy. The lifetime for a reserve canopy in the Belgian Army is 12 year, in the civilian is 20 year. Most reserve canopy's are made of F111 fabric and we know that a high porosity can effect the opening of the canopy this is something we don't want on a reserve canopy.

[potvinj 0]

Thanks for the data.

Here's a link to an old thread that discussed other experiments that manufacturers have done. See entry by billvon, dated Sep 28, 2006.

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2456291;search_string=potvinj;#2456291

Edited by slotperfect to make the link clicky!

[deathtrap 0]

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Hummm...I see your point. But then, if the sweat was really a factor, should'nt we see drastic fabric aging in most old parachute equipment? As far as I know, not all equipment shows that. But obviously, that should be a factor to consider.

Have you ever seen a main that has several hundred jumps on it, where the center cell top skin trailing edge is discolored heavilly? All of that is due to a sweaty arm being run up the skin to squeeze the air out. I know PD has patched MANY canopies in that area, and not just due to the little holes that often pop up from the grommets pinching the fabric. Generally, the other cells are just fine.

[RIGGER 0]

What kind of inspection & tests you do to insure that ?

21 years old F-111 canopy based on 120 days cycle & maybe some more for deployments have about 60 or maybe more I&R, how do you know the porosity level, the fabric strength or it the reserve still meets the TSO spec. as a reserve parachute ?

Saying that you have no problems sounds "great" but you need a technical base for that.

As a young rigger think twice on that.

Comments ?

Be Safe !!!

[bodypilot90 0]

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2456291;search_string=potvinj;#2456291

made it clicky

[bodypilot90 0]

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21 years old F-111 canopy based on 120 days cycle & maybe some more for deployments have about 60 or maybe more I&R, how do you know the porosity level, the fabric strength or it the reserve still meets the TSO spec. as a reserve parachute ?

What about reserve that old that has had 10 repacks. You are trying to cause someone to ground good gear. I have a problem with that. Gear must be looked at on a case by case basis not thrown out on a whim because the people who make it want to limit their liability.

SIDE NOTE: if we had yearly I&Rs 20 year old gear would just need to be checked if it was a pd reserve. 6 months is a step in the right direction.

[RIGGER 0]

Well, I'm not forcing to ground any system, I'm just saying that myself & other riggers & some mfg. fills the same, no. of repacks versa age it is a point but the main point that there is a STOP point, why 20 & not 25 or other no. ? it is also good to consider that there are countries that put a life limit, same the military & there is a reason for that as well.

Liability is not a bad word & should be in consideration as well.

We saw nylon fabric that failed at low forces even was well handled & in service.

It will not make a difference which brand/mfg. it is.

Maybe some mfg. are moving for service life limits for liability reasons Technical/todays freefall speeds BUT maybe others does not agree from
$$$ reasons who knows, some says the porosity go higher with time & handling & other say it goes higher to a point & then got stable, I heard that too.

I would say it should be a kind of worldwide spec. on that to eliminate the case that you can jump a 25 years old system in the USA & can not jump it in other countries.

There are no parachutes for ever !!!

Be Safe !!!

[Capricorn1 0]

Manufactures are in the business of sell gear last I checked. There are not in the business of seeking truth, scientists do that.

19 year old, 11 months, and 29 days reserve perfectly good. 20 year old and one millisecond old same reserve grounded for life.

Same deal with the Cypres. 12 years +/- 3 months all good, 12 years and 4 months, time for the junk yard.

If manufactures want to sell more gear they should probably invest more money into R&D instead of selling fear that your reserve might explode just because it's 20+ year old. And there are plenty of 20+ year old canopies that fly just as well as brand spanking new ones, and sometimes better.

Got to love it, really.

[potvinj 0]

From the info that has been submitted in this discussion I can see that fabric aging and wear
are pretty much dependent on the history and type of each individual rig:

- A skydiver's reserve repacked 3 times/year over twenty years (with the rig jumped 10 months/year) will age a lot faster than a pilot's rig that is repacked twice a year, used in the cockpit 4 months/year and stored in ideal conditions over the same two decades.

- For reasons that have to do with descent and flying performance, I can see the aging issue for rounds being different from that of squares.

- And the material used to make each rig also has an effect.

I think that we should NOT have a blanket age limit for all equipment (even though some contries have done it), less we want to throw away perfectly good equipment. I say: leave it to the individual manufacturer to set their own retirement policy .

[phoenixlpr 0]

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Manufactures are in the business of sell gear last I checked. There are not in the business of seeking truth, scientists do that.

19 year old, 11 months, and 29 days reserve perfectly good. 20 year old and one millisecond old same reserve grounded for life.

Same deal with the Cypres. 12 years +/- 3 months all good, 12 years and 4 months, time for the junk yard.

Try not to forget that you are talking about life saving devices. The line should be drawn somewhere.

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If manufactures want to sell more gear they should probably invest more money into R&D instead of selling fear that your reserve might explode just because it's 20+ year old. And there are plenty of 20+ year old canopies that fly just as well as brand spanking new ones, and sometimes better.

Notice that you are using consumer stuff, I guess you would not pay the price of the longer lasting stuff...

[deathtrap 0]

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If manufactures want to sell more gear they should probably invest more money into R&D instead of selling fear that your reserve might explode just because it's 20+ year old....

I don't see any manufacturers in here selling fear, there are plenty of skydivers and riggers that do that juuust fine. But when you come up with an accurate, non destructive way to test for UV degredation, be sure to share it with the group, OK?

[Capricorn1 0]

Are we talking about main or reserve here?

How much UV exposure does an average reserve get in 20 years? If I had to take a guess it would be that the UV exposure is going to be non-significant when it comes to fabric strength.

Well you don't buy the PC example, maybe taffeta is much more durable than f-111 so here is another one. We have a Raven 4 that is 22 years old, it has more than 1500 jumps, some fresh water landings, and it's still being used as a main occasionally. It does not blow up on opening and lands just fine if not over-loaded.

Are you telling me if the same canopy being used let's say 10 times as a reserve only would just be un-airworthy? I cannot see how 10 jumps, 3 packs a year, and a few minutes of direct sun exposure are more detrimental than 1500+ jumps, 1500+ packs, water landings, and about 100 hours of sun exposure. Buy hey there is a possibility for everything in this world. Maybe PD puts subatomical time bombs embedded in the fabric so at 20 years the whole canopy self destroys.

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don't see any manufacturers in here selling fear, there are plenty of skydivers and riggers that do that juuust fine

Yes I agree and this thread is a clear example.