acid on canopy

[flyhy 0]

Our packer discovered a few brown spots on my canopy, near the tail edge, and by slightly pushing a thumb in it ripped holes into the fabric like it was paper..
Does anyone know how to treat this? Obviously I'll need some patches over the holes but how can we get the acid out first and make sure there's no more acid anywhere else on the canopy?
I've got no idea how it got onto my canopy in the first place as the rig stays at the dz and only ever travels from the landing area to the packing mat. However it has happened before to another jumper at the dz. If anyone has an idea where it could come in contact with acid in a hangar I'd appreciate it very much!

[ZigZagMarquis 9]

Bummer.

You or your rigger could query the Poynter's manual for the subject of "Acid Mesh" or "Acid Mesh Test", but basically, I think it will boil down to having to wash / rinse the canopy, let it dry and then test to see if the acid is gone... thing I'm thinking though is whether or not the Ph test one would do if they suspected acid mesh would work on nylon? ... if it is in fact acid that damaged your canopy. It likely may not apply here, but you can do a google search on "acid mesh test"; you're looking for PIA Technical Standard 108... like I said, it may not apply, but its an interesting read. Anyway, some of the real "big rigger brains" will be along and are more knowlegeable then me.

If your rig / canopy is at the DZ all the time like you say and if this has happend on at least one other occasion to someone else, I'd be really concerned as to the source of the damage... i.e. what got spilled on the carpet that maybe you're packing on? Did battery acid leak from one of the airplanes? Is your packing area in the hangar the same place they park the airplanes over night / during the week? When you leave your rig at the DZ, is it locked up in your locker or do other's have unsupervised access to it? If something has gotten on to your main and damaged it, what about your container or reserve?? These are all questions that go through my mind... I'm sure you've thought of them too.

Good luck. We'd like to hear how this mystery turns out.

[flyhy 0]

the rig is locked up over night, the plane is parked in the same hangar and we have a battery cart in as well. But we have looked for acid spots, there's nothing on the floor and the battery cart is sealed we've just checked that. Also there's lots of tandem jumping here and the tandems would be more likely to drag their canopies over the ground through stuff but there's never been any damage on those.

cheers anyway for your advice!!
We'll give it a bath first thing, any ideas what to use as detergent to neutralize the acid that's still in the fabric?

[DeNReN 0]

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any ideas what to use as detergent to neutralize the acid that's still in the fabric?

Baking soda??

[tcnelson 1]

if you decide to wash the canopy, sodium bicarbonate (baking soda) will neutralize both acids and bases so, you could add a couple of spoons full to your wash mix. if acid has affected any other part of the canopy, a fabric pull test would tell you right away. i am not a rigger but, nylon is a polyester and polyesters are degraded on contact with both acids and bases. obviously, the more concentrated the acid or base, the worse the damage. hope this helps.

"Don't talk to me like that assface...I don't work for you yet." - Fletch
NBFT, Deseoso Rodriguez RB#1329

[azureriders 0]

Cypress batteries??

This was discussed at our DZ on saftey day. Seems that it is possible to crack the cypress housing on a rough landing. Although the case that was discussed was acid on the reserve.

If I were you I may be concerned about your other ride?

Just a thought, from a newbie

[ZigZagMarquis 9]

I'm not sure about adding anything to the water when washing and rinsing out the canopy to neautralize acid. I'm hoping one of the older more experienced master riggers that lurk the board (Councilman, masterrigger, billbooth, etc.) that have had first hand experience with the "acid mesh" problem would see this thread and give their 2 cents.

Also I'm not sure if the BROMOCRESOL GREEN SOLUTION you can get from para-gear (http://www.paragear.com/templates/base_template.asp?group=240#S7989BGS) to check the mesh for acid on affected round reserves / pilot rigs would work (would be useful) for checking for acid on a main canopy since the test involves applying the solution to the material (mesh) and it turning color if "posititve"... but I'm not sure if that would work on nylon on a main that is likely already dyed some color...

Anyway, are you sure it might not be something else besides acid? Anitfreeze? I don't think if it was something hydrocarbon-ish... e.g. fuel... it would do what you've described. Can you post pictures?? You're right, it sounds like acid is the likely culprit since it sounds like it failed the "thumb test."

[councilman24 37]

Thinking off the top of my head, but I am a an analytical chemist.

I wouldn't use bromocresol green. It needs to be rinsed off the material and would be harder to rinse of material than off mesh that you can pour water through. It may also stain the material and we don't know the effect that the test dye itself can have on canopy material or coating.

A way to test specific site is with test strips like these
http://vwrlabshop.com/product.asp_Q_pn_E_0011569
Either 0 to 12 or 2 to 9. Neutral is 7, acidic is lower, basic is higher. It's a log scale so 5 is 10 times more acidic than 6.

dampen the area with distilled water (or at least test the water to see what it starts at) and then dampen the stick with the moisture from the area. It may take a little futzin (chemistry term) around to get a good measurement. This would let you know if it truly is acidic.

Some history. The acidic mesh problem was not just related to the mesh. Two pieces of nylon, different panels of the same gore, next to the same single piece of mesh: one was bad (tore at a couple of pounds) and one was full strength. So it was not only the acidic mesh but also some property of the nylon that aided the degradation. Be aware that 0-3 CFM fabric used in reserves CAN degrade to only a few pounds without any acid attack. I have one in my basement.

The round situation was complex as to what was grounded, what AD's were changed to allow washing and return to service and what canopies were only covered by service bulletins and not AD's. Some where I have a copy of the washing procedure for both the limited approval of alternate means of compliance for the Security AD. Only FAA certified companies could perform this. National canopies never had an AD that I can remember of find but had service bulletins that described testing and IIRC washing. I couldn't find any of this on line. I have it all in my files down stairs. I won't have a chance to look any of it up until the weekend. Heading out of town tomorrow.

But remember this was designed for non zp fabric. Washing a zp canopy is going to be harder since the water can't penetrate the fabric.

I wouldn't try to use anything at first to wash the canopy. Try to hang it up by the the tail and flush it with lots and lots of water. The idea is to dilute and rinse away the contaminant, not neutralize it.

As to where it's coming from. Do you land somewhere unusual on DZ? A spot in the grass where a mower leaked something? It could be anywhere, and may or may not be visible.

Added with edit:

I went and looked up the National neutralization procedure.

National Parachute Industries, Inc.
Neutralization of Acidic Mesh Reserve Parachutes-Pilot Chutes Procedure #FM-3, June 1, 1989.

It used All Temperature Cheer, 1/2 cup in 10 gallons in a plastic tub. (The GQ Parachutes Ltd procedure in England used "Biological DAZ" detergent. Pick a similar Proctor and Gamble product. The pH of a 1% solution in water should be 10.6 per the procedure. Anything between 10 and 11 would be ok.) Work in slowly, agitate with hands after wet, let soak for 10 minutes, rinse with 10 gal clean water, repeat as necessary. Other instructions were round specific. But I would wonder if this would neutralize strong acids completely. This was intended for the relatively weakly acidic flame retardant. I'd spot rinse any known spots before soaking the canopy. Washing and rinsing of a zp canopy will be much more difficult. I think I'd work with a new plastic garbage can and lots and lots and lots of water to rinse the soap away.

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

[flyhy 0]

Cypress batteries??

but wouldn't that show up on the bottom of the reserve container? And wouldn't it affect the cypres b attery voltage or anything? I turned my cypres on this morning and it didn't show me any error code..
Well, I haven't actually checked my reserve yet, could be a good idea.. but I was assuming it had happened while the canopy was unpacked as there's little spots and not one big 1..
???

[flyhy 0]

I'm in a small town so facilities are minimal..
But I've just it pH tested and it seems to be acid as the pH level was lower than the same source water..
No, I always landed on the landing area, and as far as I know, they never mow it as the grass's struggling growing.. However we had a few vehicles on the PLA the other day that are preparing the airfield for an airshow. But I'd assume even if they're leaking, the acid would sink into the ground straight away..?

[flyhy 0]

problem no.1 : where do I get a garbage bin from..? (small town...), I've got it in the bath tub at the moment hope that's just as good.
2: what kind of soap do you recommend?

[councilman24 37]

How much lower was the pH? 5 or 6 versus 6.6 isn't very significant 2 versus 6.6 is strong battery acid type.

As to where it came from. Your going to have to talk to the other jumpers that had the problem and try to figure out what you have in common. A certain day, time, place either packing or landing and walking, etc, etc. This is as little as a very small drop of battery acid. Or it may be something completely different.

Good luck.

See additions to above post with washing procedure.

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

[councilman24 37]

See above edits for soap. Tub should be fine. Just don't want to use a metal container. Going to need to look for contamination on the lines, harness and container. If you decide to wash everything be very thorough rinsing and try to dry hardware as best as possible by hand, unless stainless. I probably be taking the reserve out and making sure what ever it was didn't penetrate through. I'd take reserve off the harness to keep possibly contaminated things separate.

Hmmm, if you landed immediately after the vehicles were on the field, or even just within a couple few days and were in that area I'd wonder. Don't know the weather there but hope it rains soon to dilute and wash away anything there.

Be conservative and be careful.

Must be a really really small town if it doesn't have a grocery store or something else that sells a plastic garbage can.

edited

time for bed here in Michigan, usa.

No more tonight.

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

[flyhy 0]

Well, the tab water I used (no destilled h2o in this area..) had a pH of 9.5, the same source water that I soaked the spot in was 8.5, so still alkaline but less then the 'pure' water..
It happened to the other jumper quite a while back so could be different reason. But then I'm not exactly sure when I got those spots on my canopy, as I could've mistaken them for dirt. They're about 3 small spots on the center cell close to the tail edge.

cheers for all your help!

[councilman24 37]

Need more investigation.

See above post, yawn.

Goodnight.

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

[riggerrob 643]

At a PIA Symposium - long, long ago and far, far away - Performance Designs showed some samples of damaged canopy fabric.
One sample was of a canopy tail damaged by insects who were trapped during the packing process and tried to chew their way out.

[flyhy 0]

Do you have any photos of that example or a web link?

[ZigZagMarquis 9]

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One sample was of a canopy tail damaged by insects who were trapped during the packing process and tried to chew their way out.

Insects... huh... saw a canopy come back with a Mojave Green (rattlesnake) in it once and a different canopy, different time with a Kangaroo Rat in it, but never insect problems... kinda makes you want to get that Blag Flag canopy sponsorship...

[azureriders 0]

Probably not the issue in your case but the way it was discused at saftey day it will not necessarilly affect your cypress powering on without any error message. We were told to inspect the cypress unit by feeling it through the lower part of the reserve trey, after a hard landing, while the main was still unpacked. Supposedly you should be able to feel any cracks that are in the unit. Of course you are right, if this was a problem with the main surely you could find sign of where the acid came through the reserve trey.

[mdrejhon 8]

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Insects... huh... saw a canopy come back with a Mojave Green (rattlesnake) in it once and a different canopy, different time with a Kangaroo Rat in it, but never insect problems... kinda makes you want to get that Blag Flag canopy sponsorship...

I almost packed a grasshopper once. Knowing that some insect bodies are acidic, is that a possibility? Especially wasps, bees, red ants, etc, squashed during packing and left to rot on the canopy for weeks between skydive weekends...

Newbie speculation of course, but is it possible?

[packerboy 3]

I know where you jump... I bet you HAVE packed more than one grasshopper.

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In matters of style, swim with the current; in matters of principle, stand like a rock. ~ Thomas Jefferson

[packerboy 3]

Whatever you do, don't send it to PD... they will cut the lines off and tell you it is not airworthy. Then not only do you have to put patches on it, you have to reline it TOO!!

Kidding of course..

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In matters of style, swim with the current; in matters of principle, stand like a rock. ~ Thomas Jefferson

[mdrejhon 8]

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I know where you jump... I bet you HAVE packed more than one grasshopper.

Probably -- without knowing it.

I probably gave at least one grasshopper a free skydive from 3000 feet pull altitude.