Does F-111 typ material age even though not being used?

[anj4de 0]

Hello all

I had an interesting discussion with a master rigger here in Germany yesterday...about the age limits on parachutes in general. To be more precise...about the question if an unused but old canopy (MC-4 from 1988, brand new in bag still) would still be considered new...or at least usable. His opinion is that a canopy that old, even though properly stored, would not be good any more and should not be brought into circulation and hence would not get his airworthiness certificate . The MC-4 I just mentioned as an example since it seems like there are quite a few NOS ones floating around right now. The discussion mainly stayed in the F-111 type arena...(MC-4, MC1-1C/D, SF-10A, Paracommander etc...) ZP was not really spoken about. So now here my question to the broader forum; Is this true for an unused, sealed, stored away in the dark canopy and how does simply time (not saying UV rays, salt water, usage, etc...) really affect nylon canopy material?
Going forward, is this also true/untrue for ZP?
What makes me wonder in relation to this is that the German Army regulation for parachutes strictly follows the DOM date...over x years old goes into the bin, that is also done with fabric roles, lines, etc...where as the US Army parachutes for example always carry two dates, the DOM and the PIS (put in service) date which makes me believe that pure shelf aging can't be that dramatic...but I am by no means an expert in fabric nor a rigger.

thanks
Uwe

PS: my second SF-10A has a DOM 06/03 and a PIS of 07/09! That's six years in the closet...

For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return.

-Leonardo da Vinci

[pchapman 279]

It's a complex situation and most of us just don't have data, if we don't have access to military reports etc. I myself have just scratched the surface of it all.

Clearly some military practices are conservative and equipment is just tossed without spending the time & money to test each set of gear extensively.

Nylon does degrade over time though - more on that after.

There's also the problem of how strong equipment needs to be, and how things are certified. If a harness is certified to 5000 lbs, does that mean it should be condemned if it tests to 4900? Or is the thought of age and wear built into the initial calculations on how strong a harness should be? Typical certification standards specify initial values but not what kind of safety factors are built in. (Other than say testing to X % extra weight and speed.)

So even if we know that something lost 10% of its strength, we don't know if that is acceptable.

Reserves are of course tested brand new, and fabric isn't excessively strong to begin with, so there there will be more concern over even small amounts of strength loss. E.g., say we have a one size fits all 40 lb test for old rounds, but one is looking at an older canopy that used fabric that was only a 42 lb spec to begin with instead of a 45 lb spec. Is it really a non-destructive test even on new fabric, with non-professional test methods? Is the test fair for the older style fabric? And what if older canopies could take a 35 lb test only, just how bad is that?

Even in aircraft there aren't clear standards on how strong is strong enough. You can operate a 1946 light aircraft with wooden spars, or a WWII fighter. While you have to inspect for spar corrosion or cracks, it is legal to fly them, even if everyone would agree that flying them hard, right up to their certification limits of strength, might not be the best thing.

Since I don't have a coherent overall theory on the whole issue, I'll just throw in a few odds and ends:

1. From some web site on textile chemistry by the American Chemical Society:

Quote

Hammond's work is focused on the chemistry of polymers from which synthetic fibers are made. He is involved in understanding the complex chemistry surrounding the degradation of nylon so that he can find ways to inhibit its occurrence. Hammond explains, "If the nylon is not properly stabilized with additives to minimize the thermal, photo, and oxidative degradation, the strength of that product will decrease over time, and it will not function properly." This is especially important for the nylon fiber used in parachutes.

2. Attachment 1 is from a 1968 US Army Technical Report 68-45-CM on nylon aging. It notes how their parachute fabric improved in 1963 due to new heat and light resistant nylon, and suggests that the nylon continued to be improved. So the inherent quality varies with age of manufacture too.

3. In the same paper, small strength losses were seen over time, along with an increased dispersion of strength within a large sample. But the evidence was messy and can't be summed up easily.

4. Attachment 2 is from a circa 1994 paper on "Storage Life of Parachutes" by a US lab associated with the military (Sandia Labs). It concludes that strength losses in 25-30 year old parachutes are very low based on previous research, and they found no real strength loss in one particular 29 year old canopy. Yet some strength loss was seen in some cases so as usual the paper calls for further research.

[airtwardo 7]

It concludes that strength losses in 25-30 year old parachutes are very low based on previous research, and they found no real strength loss in one particular 29 year old canopy.

Quote

...that study also brings into question the 'actual' motivation for the 20 year 'shit-can the reserve' thing going on these days.

I have an old rig with a 270 sqft F1-11 main, the reserve is the exact same parachute except for the free-bag and the suspension lines.

The main has 1000 jumps on it, packed in every imaginable environment and it still opens great, flies well and I can 99.5% of the time land it standing up...

WHY is the reserve~ that has never been deployed, which has been packed carefully maybe 30 times in a relatively clean environment...junk?

$eem$ kinda weird to me.

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

[likestojump 3]

Quote

It concludes that strength losses in 25-30 year old parachutes are very low based on previous research, and they found no real strength loss in one particular 29 year old canopy.

Quote

...that study also brings into question the 'actual' motivation for the 20 year 'shit-can the reserve' thing going on these days.

I have an old rig with a 270 sqft F1-11 main, the reserve is the exact same parachute except for the free-bag and the suspension lines.

The main has 1000 jumps on it, packed in every imaginable environment and it still opens great, flies well and I can 99.5% of the time land it standing up...

WHY is the reserve~ that has never been deployed, which has been packed carefully maybe 30 times in a relatively clean environment...junk?

$eem$ kinda weird to me.

I am of the same opinion. It drives me up the wall, and to this date I am yet to hear a reasonable answer as to what happens from 19 years and 364 days to 20 years of age.
Not to mention that the fabric is made long before the parachute is stamped with the DOM


$safety $tandard$ I suppose....

[riggerrob 643]

"

Quote

... Not to mention that the fabric is made long before the parachute is stamped with the DOM
...

"

...........................................................................

Trivial pint, but materials as supposed to pass MIL SPEC and PIA SPECS the day they pass final inspection at the canopy factory. Materials degrade at a very slow rate when properly stored and manufactured.

Teh real danger here is skydivers jumping obsolete equipment.

For example, the young jumpers used to think I was grumpy old bastard when I discouraged them from buying tiny, old Raven reserves. They naively believed that if they could load modern ZP main canopies at 1.5 or even 2.0 pounds per square foot, that they should also be able to load old Ravens that heavily.
They did not understand that Ravens were never designed to be loaded at 2.0.
They continued to ignore me until one of them broke a lot of bones stalling a tiny Raven (loaded around 1.6 pounds per square foot).
The next week, sales of second-hand, tiny, Ravens dropped faster than a head-downer!

[AndyMan 7]

I'm a bit curious why there's a tendency to overthink this.

Riggers have the tools and ability to inspect parachutes. One of the tools riggers use is a pull-test, the procedure is common and well known. It's also reliable when done correctly.

I happily inspect and reserves that I'm familiar with - this includes some from the late 80's and early 90's such as the Swift Plus.

_Am

__

You put the fun in "funnel" - craichead.

[Deyan 36]

Quote

Riggers have the tools and ability to inspect parachutes. One of the tools riggers use is a pull-test, the procedure is common and well known. It's also reliable when done correctly.

True.

But how many riggers have the tools to measure the permeability of the fabric?

"My belief is that once the doctor whacks you on the butt, all guarantees are off" Jerry Baumchen

[anj4de 0]

Quote

It concludes that strength losses in 25-30 year old parachutes are very low based on previous research, and they found no real strength loss in one particular 29 year old canopy.

Quote

...that study also brings into question the 'actual' motivation for the 20 year 'shit-can the reserve' thing going on these days.

I have an old rig with a 270 sqft F1-11 main, the reserve is the exact same parachute except for the free-bag and the suspension lines.

The main has 1000 jumps on it, packed in every imaginable environment and it still opens great, flies well and I can 99.5% of the time land it standing up...

WHY is the reserve~ that has never been deployed, which has been packed carefully maybe 30 times in a relatively clean environment...junk?

$eem$ kinda weird to me.

I guess in your case you could at least make the reserve your "new" main and look for a newer dated reserve...

For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return.

-Leonardo da Vinci

[councilman24 37]

Those dollar signs may be my entire financial future if I get sued.

Life limits based on time are arbitrary, of course. I don't as a general rule support absolute life limits. But, I have no way to test the strength of a harness. Neither does anyone else as far as I know. We have to go on our experience and comfort. I can pull test some fabric. But some canopies I can't because it's expressly forbidden to put a clamp on them. I also can't test one hundred percent of the fabric, the tapes, the thread, and we don't have guidelines on the lines.

BTW I'm one of the few people that have found a ram air main that had fabric that tore at 2 or 3 pounds, much like the bad SAC's. I tested the area because it felt different. It felt different because it was in contact with the coated fabric of the free bag. I had tested many reserves that felt the same because of the coating. Only one has failed catastrophically. BUT, this area was limited to about 2 square feet. Out of 170.

Using a time guideline as a rigger has helped get some of the obsolete gear out of the air. (Like a safety flyer). It's tougher now when some of the gear that is 20 years old is still available new. When is old gear too old? We pretty much have to guess.

What's the difference between your main and your reserve? Your reserve is your LAST CHANCE TO LIVE. I have to look at every canopy and every harness knowing that if they don't work or do fail you may die. It's hard to see some damage on rescue and climbing ropes. But it's not worth the risk to keep old or stressed ropes in service.

All of us that are riggers have handled 20 year old reserves that feel like new but also 20 year old reserves that are as limp as a wet paper towel. They are obviously different than new. Does it matter? I don't know.

Of course there are riggers who will pack anything, no matter how old, obsolete, or inappropriate for the jumper.

So what do we do? As per the law riggers have to follow the manual. In the absence or life limits we have to do what we think is best for our clients and for ourselves. At the end you can be your own rigger and do what the hell you want.

As an aside TSO C23e, that was withdrawn, required some information in the users manual about life limit. It didn't say one had to be set. But some statement had to be made. The draft of TSO C23f, currently in comment review prior to issuance removed that requirement. It may or may not be there when it's published.

As to the OP's canopy? I'd put it in the air as a main. If it was a reserve? Who knows. Ask me when it's in may hands.

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

[likestojump 3]

I agree.

I also tend to think mandating a 20 year life limit is silly. Worse of all convincing your customers that 20 years is an industry RULE is plain fraud.

I like having the ability to say Yes or No based on my Inspection.

[airtwardo 7]

I guess in your case you could at least make the reserve your "new" main and look for a newer dated reserve...

[masterrigger1 2]

Quote

Riggers have the tools and ability to inspect parachutes. One of the tools riggers use is a pull-test, the procedure is common and well known. It's also reliable when done correctly.

The pull test is also a Destructive Test rather than the claimed Non-Destructive test by PIA.
This is one correction that we are putting in the new rigger handbook BTW.

Also, if you conduct or perform a pull test on certain canopies in the field, that test will void the TSO on that canopy.

Cheers,
MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[JerryBaumchen 1,446]

Hi Terry,

Quote

I have no way to test the strength of a harness. Neither does anyone else as far as I know.

PD does have a drop test tower that could be used to test a harness.

And that was an excellent writeup with some good thoughts.

JerryBaumchen

PS) Your hot cutter will got out in a day or so; IMO that thing is way too heavy for production use. It weighs 2 lbs compared to 2 oz for my HK-60.

http://www.hsgmusa.com/Products/hsg-0-heat-cutter.asp

http://products.mmnewman.com/item/heavy-duty-hot-knife-and-tips/heavy-duty-hot-knife/hk-60?

[councilman24 37]

PD does have a tower. But I don't. The comment referred to a field test similar to TS-108.

Besides, how long would we argue about the force to use to test a harness without damaging it. Some think TS-108 damages canopy fabric unacceptably. And canopy fabric is an individual component, not an assembly with stitches and various loading methods.

From another thread I wondered about your webbing junction pull testing. Did you do that or have it done? If you had it done I'm curious about the cost. I've always wanted to be able to pull test to 10000lbs. Not only for skydiving but for climbing/rescue.

Your hot knife works as well as mine? If so I may have to get one of them. The others I have don't cut as well. And I like being able to turn it on with the trigger and be ready in 10 sec. Mine would build up your forearm also.

At least you got to try it.
No great rush to get it back.

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

[Trae 1]

in reply to "The pull test is also a Destructive Test rather than the claimed Non-Destructive test by PIA. "
....................................

On my reserve there is a small stain on the F111 .
My rigger does a thumb test on every repack.
It looks like he's trying to push his thumb through the fabric.
I'm wondering if the F111 will eventually be destroyed by his testing it all the time.
It has passed so far but is his (somewhatbrutal) testing making it weaker each time?

[riggerrob 643]

Remind him to trim his thumbnail before testing your canopy.

[riggerrob 643]

Pull-testing once IAW PIA standard usually leaves minor weave separations. No big deal, as long as mark the test are to discourage other riggers from repeatedly pull-testing the exact same are.

I have only ever seen one PD reserve damaged during a proper pull test, circa 1999. I suspect that the new FAA Senior Rigger had done a second pull-test exactly on top of an older pull-test, because the previous rigger was too lazy to mark his work.

[masterrigger1 2]

Quote

Pull-testing once IAW PIA standard usually leaves minor weave separations. No big deal, as long as mark the test are to discourage other riggers from repeatedly pull-testing the exact same are.

I consider it a big deal!
But you have to remember that I am probably the only rigger on this website that is also certified in methods of non-destructive testing.

You might want to ask PD how many reserves have had panels split after a reserve deployment that started in the area of a pull test.....

I know of two.

The next question is how many reserves (barring Phantoms) have actually failed from weak fabric during a deployment?

I do not know of any!

TS-108 is label a non-destructive test when in actuallity is a destructive test....Google is your friend here.
Anytime the positive result is failure or destruction, it is considered a destructive test.

Terry hit the nail on the head about one thing. If you suspect fabric to be "different", you need to test it.
But here is what I do differently:

I install a 8"x8" patch over the area of interest. I then use the removed material and pull test that.

The difference is that if it fails and is a positive test result; i just patched a bad canopy. No big deal.

If the test is negative and the material is considered good, I did not possibly damage a otherwise perfectly good canopy!


MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[pchapman 279]

Whoah.
You're getting at the issue of a "non-destructive test" in a general sense, and "Non-Destructive Test (NDT)" in a technical engineering sense.

So we can have different levels of testing:

1) tests that are non-destructive, even to items that are tested "bad" (weak, damaged, out of spec, whatever). (e.g., the ultrasound, magnetic particles, x-ray, or whatever doesn't cause damage in any case). You're making the point that that's true NDT.

But there's also:

2) tests that are non-destructive when the parts are OK. So you can do a 100% sample and not destroy every item that comes off the production line. However, for a bad part, one either:

2a) destroys the whole item (e.g, the cable failed the tensile test, it broke)
or
2b) destroys only the section of the item being tested. So it isn't destructive to the whole item, just the section being tested, so that one can theoretically save the production item by fixing the section that failed. (e.g., ripped canopy panel, or other localized damage to the tested item)

I'm not sure we can use the term "destructive testing" either. I may be wrong, but that is normally defined as testing something to its breaking point. For us, that would be ripping every spot on a canopy we test, and recording the breaking strength.

So we need terminology for something in between.

Then we can better argue about whether TS-108 is a Locally-Non-Destructive-To-Good-Items-But-Locally-Destructive-To-Failed-Items-Test.

(Note: I have no certifications in any of NDT, DT, or LNDTGIBLDTFIT.)


P.S. That's interesting about actually seeing reserves fail at pull test locations.

[masterrigger1 2]

Quote

Whoah.
You're getting at the issue of a "non-destructive test" in a general sense, and "Non-Destructive Test (NDT)" in a technical engineering sense.

So we can have different levels of testing:

1) tests that are non-destructive, even to items that are tested "bad" (weak, damaged, out of spec, whatever). (e.g., the ultrasound, magnetic particles, x-ray, or whatever doesn't cause damage in any case). You're making the point that that's true NDT.

But there's also:

2) tests that are non-destructive when the parts are OK. So you can do a 100% sample and not destroy every item that comes off the production line. However, for a bad part, one either:

2a) destroys the whole item (e.g, the cable failed the tensile test, it broke)
or
2b) destroys only the section of the item being tested. So it isn't destructive to the whole item, just the section being tested, so that one can theoretically save the production item by fixing the section that failed. (e.g., ripped canopy panel, or other localized damage to the tested item)

I'm not sure we can use the term "destructive testing" either. I may be wrong, but that is normally defined as testing something to its breaking point. For us, that would be ripping every spot on a canopy we test, and recording the breaking strength.

So we need terminology for something in between.

Then we can better argue about whether TS-108 is a Locally-Non-Destructive-To-Good-Items-But-Locally-Destructive-To-Failed-Items-Test.

Peter,
It is pretty simple. TS-108 is tesing for destruction.
That is the positive result of that test.Period.

The part that most do not understand is terms like "elastic", "plastic" and "yield".

A non-destructive test does not alter the material in ANY manner.
In the case of TS-108, weave separation is an alteration of that material

To take it further, I believe that some fabric will enter into the plastic stage even at 30 lbs of test strength. But it it may not enter the yield stage of destruction at that point and time, just to the edge of it......

Cheers,
MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com