Do Reserve Canopies lose TSO rating with age

[dgw 8]

I thought this was a worrying concept. Of course, the whole idea of idea of expecting a brand new umbrella to withstand a major hurricane is a worying concept, albeit for different reasons.

Apologies, I don't know how to make it blue.

http://www.bpa.org.uk/forms/council/Riggers%20Minutes%20-%201%20June%202006.doc

"John Harding had also included information and statistics on tests carried out by a number of organizations regarding the handling of parachute material vs porosity. The results from these organizations show that there was a marked increase in the porosity of the fabric due to handling, and this is mainly during the packing process.

They also concluded that parachutes that undergo such a porosity increase might not pass TSO tests. John had also included information of countries that have adopted a one-year re-pack cycle and a list of manufactures who have endorsed 1 year repack cycles on their equipment where regulations allow."

[billvon 3,076]

There is no question that a canopy that has been handled enough experiences a significant increase in permeability, and certainly any nylon canopy that sees a lot of UV exposure will be degraded to the point where it is no longer strong enough to handle a hard deployment. In most cases it is the rigger that makes the call as to whether or not the reserve is still airworthy.

PD handles this issue by requiring a factory inspection after 40 repacks or 25 deployments.

The issue of prolonging canopy life by reducing the number of annual inspections required (from 3 to 2 or 1) is certainly a valid issue. There are other issues which work against that, such as timely retirement of older designs that are no longer up to industry standards. (The canopy may not change, but industry standards sure do as we gain experience in canopy design and maintenance.)

[BIGUN 1,422]

And, your thoughts on water degrading the material would be of interest.

Nobody has time to listen; because they're desperately chasing the need of being heard.

[rigger_john 0]

  Quote

Apologies, I don't know how to make it blue.

http://www.bpa.org.uk/forms/council/Riggers%20Minutes%20-%201%20June%202006.doc

Regards John Harding

_________________________________________

Nullius in Verba

• Quote

[DJL 235]

I don't know if the language of it is "losing the TSO" but I just retired a reserve that was showing signs of its age. The fabric was losing it elasticity so we put her down, ripped the orange label off of it and wrote "unairworthy" across a portion of it.

"I encourage all awesome dangerous behavior." - Jeffro Fincher

[dgw 8]

Thanks for the feedback.

The text in the BPA document is suitably vague. I would infer from PD's inspection requirements that any given PD reserve could be expected to meet the TSO requirements after 40 repacks (or handlings).

However, the BPA document *appears* to infer that degrading of the reserve fabric could occur sooner. In the UK, 40 repacks (with no deployments) is at least 20 years in service. It seems that technology advances may provide a 'natural buffer' to use of reserves of this age. Having said that, I have an old Swift 5-cell reserve manufatured WAY back in the day (not in a serviceable rig) that, until now, I would have happilly used (subject to inspection), on the basis that it is 'tried and tested' technology.

In relation to the uprating of standards, it follows that gear which is entirely acceptable today will, in time, slip below the 'bar', regardless of wear and tear on gear. I, like all non-visionaries, struggle to envisage any major changes in current gear design that would intrinsically improve safety, and dislkie the ideas that current gear, with acceptable risk to me today, will be 'dangerous' in a decade. Having said that, I've got an old Pioneer H/C which is masterclass willies material. It made me think that the 'old school' were a little cavalier...

[marinho 0]

  Quote

I don't know if the language of it is "losing the TSO" but I just retired a reserve that was showing signs of its age. The fabric was losing it elasticity so we put her down, ripped the orange label off of it and wrote "unairworthy" across a portion of it.

I think you're going on the right direction! TSO is lost when the FAA revokes it! A canopy can become unairworthy when a rigger or the manufacturer think it is not safe to be recertified!
Cheers,

Gus Marinho

[dgw 8]

Hi,

I don't want to labour (labor) a point, but I would say a TSO is lost when a component can no longer meet its TSO requirements. A TSO is not like an MOT ( A carworthiness criteria that states whether a car is roadworthy on the day of test). A TSO is, if I understand it correctly, a quality assurance standard expected to apply to a component for the duration of its use. Notwithstanding this, I would be happy to accept a Riggers view on airworthiness.

[potvinj 0]

This is a topic that has frustrated me for many years.

Yes, I can see that porosity increases with the number of (tight) pack jobs. It is the conclusion that "...with greater porosity the parachute may no longer meet the TSO req's..." that bothers me.

Where's the data for this assertion? I have never
seen any. Here's what I would like to see:

1) By exactly how much is the fabric permeability
increasing? 5%?10%?50%100%?

2) Has anybody tried to do a complete
TSO test program with a
many-times repacked parachute system? and
if so, did the chute take too
long to inflate (thus failing the TSO)?
As far as I know, no such tests have been performed. (Please prove me wrong)

If there is no such data, why is the industry so
quick to retire old gear?

JP

[dgw 8]

I am a schmoe in the world of parachutes, and my opinion should be treated with schmoeination.

In relation to point 1, I think that this would be valuable information.

With regard to point 2, I can't prove anything about testing. I am a schmoe.

I think the valuable point is that there doesn't seem to be any real (or *firm*) ownership of the product suitabilty after it's bought. Maybe a best before date?....

[billvon 3,076]

>Where's the data for this assertion?

I don't think anyone is saying that old gear is no longer legal. I think the issue is that, after gear experiences enough wear, it may no longer pass the original tests it was certified to. I think most riggers out there have, at some point, seen gear that was so worn that it was no longer safe to use. (note that those two statements are similar to each other but are _not_ identical, since riggers do not typically do TSO-level testing on the gear they maintain.)

>By exactly how much is the fabric permeability
>increasing? 5%?10%?50%100%?

I don't think you can come up with one hard number. Precision did a study in 2002 that stated:

"A study was recently accomplished where 10 different fabric samples
were handled 16 times using methods typical of the packing of a parachute. Four
samples were from a well-known company that no longer manufactures fabric, but
is commonly seen in parachutes manufactured several years ago. The samples were
in new condition and had minimal handling. The other six samples were
representative of more modern 0-3 cfm fabric commonly used at this time. Among
Precision's conclusions were:
After testing, the fabric had porosity increases ranging from approximately
four-fold to slightly over twelve-fold compared to before testing. The fabric
of newer design has generally better porosity characteristics, in that the
fabric starts at lower porosity before handling, and does not degrade to as
high a porosity as the fabric of older design. The porosity increases seen in
these tests were representative of porosity increases seen on actual parachutes
in service. The porosity increases seen on actual parachutes are due to the
handling of the parachutes, mainly during the packing process. Parachutes that
undergo such a porosity increase may not pass the TSO tests under which the
parachute was originally certified."


>2) Has anybody tried to do a complete TSO test program with
>a many-times repacked parachute system? and if so, did the chute
>take too long to inflate (thus failing the TSO)?

Good question. I know Precision did testing with very long term pack jobs (well over a year) and they still seemed to deploy well, but I don't know if it was a controlled test. Also keep in mind that the time a parachute takes to inflate is just one of the many factors in TSO testing.

Edited to add - here's one such study by PD:

"Performance Designs conducted a study of porosity of 18 reserve parachutes they
manufactured between April 1990 and May of 1998. The parachutes ranged in size
from 126 square feet to 218 square feet. After measuring the porosity on all
the canopies, the company selected one large and one small parachute that had
the highest porosity. These two parachutes were then packed and deployed from
reserve containers after an intentional cutaway in the same manner as is done
for TSO testing. The result was a noticeable increase in the time and distance
required for both parachutes to open, and a very noticeable increase in the
skill required to land the smaller parachute softly. The parachutes had been
packed 10 and 14 times respectively, and both had only been deployed once
before. While both parachutes performed reasonably well at this stage,
considering the amount of handling they have had in that number of repacks,
they are still far from the porosity level that they will attain after many
more such pack jobs. Like any ram air manufactured using similar fabric, these
parachutes may degrade to a condition where they may not pass TSO tests. They
will certainly degrade to a point that the landing characteristics will not be
acceptable to their owners or to the standards of the manufacturer, even if
they do pass the TSO tests for landing performance."


>If there is no such data, why is the industry so quick to retire old gear?

Well, there are many ways that gear can become non-airworthy. A PD reserve is required to be sent back after 40 repacks or 25 jumps; they may inspect it and decide it is no longer airworthy. Other reserves have life/packing limits, but are harder to maintain since they do not have those handy "check boxes." Many riggers are equipped to do pull tests and porosity tests; if they fail these tests, the canopy may be considered non-airworthy, even if the TSO tests are not repeated.

In addition, sometimes old gear simply is not up to the standards of newer gear. Take the Raven reserves. Larger Raven reserves work pretty well, but modern reserves are loaded to far higher levels than the (Super) Raven was designed for. This can lead to stalls (and often injuries) when small Ravens are used for larger jumpers. In such a case, it might be wise to retire the smaller Raven reserve and switch to a larger Raven or a smaller PD reserve (which does better at higher loadings.) This would be a case where the canopy itself may still meet its original specifications, but has been "superceded" by new technology.

[potvinj 0]

Ah, some data at last! Thank you very much!

The Precision study is indeed informative. I guess my next question is this:
is the increased porosity seen all over the canopy? or is it most likely
at some special locations on the canopy (caused by the way reserves are packed)?

The PD study adds data also - but here too I have questions:

>These two parachutes were then packed and deployed from
>reserve containers after an intentional cutaway in the same manner as is done
>for TSO testing. The result was a noticeable increase in the time and distance
>required for both parachutes to open...

Do you happen to know how much opening time was involved? With TSO C-23d
the maximum opening time is 3 sec (excluding deployment - see paragraph
4.3.6 in SAE AS8015 Rev B)). Were
the opening times "noticably" greater than 3 seconds? how much?
Perhaps someone from PD could chime in.

So indeed increased porosity
"may" invalidate the TSO-status of a particular parachute.
Is the "may" underlining the fact that not all reserves with over 40 repacks
will fail the test? What is the likelyhood of this?
We cant say since it appears that PD has done two tests only (but "thank you PD" for those!).
Will we retire perfectly good reserves by grounding them after a set number of repacks?

To me (as a rigger) the issue of airworthiness is all about individual parachutes
meeting the TSO requirements. If indeed the increase in porosity due to repack
is a problem, then so be it - and I shall certainly ground the parachute.

Concerning:

>In addition, sometimes old gear simply is not up to the standards of newer gear.
and:
>They will certainly degrade to a point that the landing characteristics will not be
>acceptable to their owners or to the standards of the manufacturer, even if
>they do pass the TSO tests for landing performance."

Althoutgh I aggree with the fact that more modern designs land better that older designs
(factory-fresh or many-times repacked) it seems that the decision-making involved
in the grounding of parachutes is going beyond meeting the TSO requirements. I surely dont
agree with that. If indeed landing performance has become
a determining factor in deciding to ground an emergency parachute, then what should we do
(as riggers) with customers who have gained a significant amount of weight since purchasing
their emergency chutes, but not enough to invalidate the TSO? we all know that their "landing
characteristics will not be acceptable to their owners ", even with factory-fresh reserves.
So, should I ground the rig? I think not (but a stern warning shall be issued).

The debate goes on.

[steve1 5]

I know this is a rigger's call. There is such a big variation in the knowlege base that individual riggers have, that I wonder how many beginning riggers can safely decide what is air worthy and what isn't. I was a licensed rigger many years ago, and I had almost zero training in this. Yet I was packing reserves for folks.

I suspect that riggers today probably have better training than I did, but I still wonder how many riggers out there are rigging by the seat of their pants. I have nothing but respect for a Master rigger. Many senior riggers have a ton of practical experience also. But some do not. Some riggers probably get a reserve and pack it up with little more than a quick visual check. Sure they are liable if it blows up, but that is little consolation if I am the one who is dead.

I'd like to shop around and get the best rigger for my money to pack my reserves, but often times I have a really hard time even finding a rigger. Is it any wonder they are hard to find. With all the liability issues involved now days, I wonder why anyone would want a rigger's license. There is a ton of stuff one needs to know to become a proficient rigger. Just because someone has a license, may not mean a whole lot. Just some food for thought. Maybe this is my own personal twisted view of things. Set me straight if I am wrong!...Steve1

[riggerrob 643]

I'd like to shop around and get the best rigger for my money to pack my reserves, but often times I have a really hard time even finding a rigger. Is it any wonder they are hard to find. With all the liability issues involved now days, I wonder why anyone would want a rigger's license. There is a ton of stuff one needs to know to become a proficient rigger. Just because someone has a license, may not mean a whole lot. Just some food for thought. Maybe this is my own personal twisted view of things. Set me straight if I am wrong!...Steve1

[dgw 8]

Does anybody know what aspect of the 'handling' causes the change in porosity?

If, for example, the aspect of 'handling' that causes the damage was sweat, would wearing a pair of latex (or other non-porous material) gloves during repacks reduce the degradation of the material?

[riggermick 7]

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Does anybody know what aspect of the 'handling' causes the change in porosity?

If, for example, the aspect of 'handling' that causes the damage was sweat, would wearing a pair of latex (or other non-porous material) gloves during repacks reduce the degradation of the material?

Just touching it(any flexable fabric) with "somthing" changes the poroseity. Fabric makeup is (in the parachute industry and others) essentially the compactivness (?) of the weave/ knit with adjuncts and it's relation to outside forces. Special coatings are just that, coatings. They are not part of the molecular makeup of the material itself, they instead bind the fabric fibers closer together forming a more resistant (air tight) surface. Some fibers are more prone to compact tightly together due to their molecular make up than others but are ultimatly swayed by outside forces. Even with coatings to "glue" the indididual fiber strands together in a consistent "mash" they will all fail eventually after being touched by somthing (due to yarn seperation), all the "glue" does is hold them together for longer periods of time before they eventually break down and let the fiber bundles gravitate to their natural state. Thus causing seperation of said fiber bundles, whereby holes appear (read: higher porosity (air discharge)). Long before I started skydiving I was involved with the textile industry and the concept of weave seperation was/ is Textile looming/ knitting 101.

Hope this helps grasp the concept.


Mick.

[billvon 3,076]

>would wearing a pair of latex (or other non-porous material) gloves during
>repacks reduce the degradation of the material?

Folding and friction seem to be the biggest culprit. I recall a study that looked at the best surfaces to pack reserves on (based purely on canopy wear) and they found painted concrete to be the least damaging - and some types of carpeting to be the most damaging.