Acid Mesh

[John_snurkowski 0]

Looking for an old rigger's advice. 

Someone just dropped off Security Pilot Emergency rig and asked me to tell them whether or not it's airworthy. (It likely is not.) But the parachute is from the '70s and as far as any records I have seen on it, has not been tested for acidity. 

 

Can someone tell me how I am supposed to conduct that test, and possibly the list of serial numbers (which I'm told are out there) which Security said are subject to the acid mesh pandemic?

[mark 107]

70's is before acid mesh was a problem.  Does the canopy even have mesh?

--Mark

[JerryBaumchen 1,434]

21 minutes ago, mark said:

70's is before acid mesh was a problem.  Does the canopy even have mesh?

--Mark

Hi Mark,

Yup, it would probably be just Security's 26 ft LoPo canopy.  That was not a subject of the AD.  

Jerry Baumchen

[skydiverek 63]

 

What exactly was a problem? What is 'acid mesh' ?

[kleggo 145]

A non-riggers recollection = Some round canopy's drive slot mesh was not properly cleaned / treated during manufacturing which led to a low ph condition on the surface of the mesh = acid mesh.

When the mesh is folded and packed against the canopy's nylon panels, they could become discolored and otherwise damaged, (think failure during deployment due to weakend fabric).

 

How'd I do Jerry?

 

Cheers

 

 

 

[JerryBaumchen 1,434]

14 minutes ago, kleggo said:

A non-riggers recollection = Some round canopy's drive slot mesh was not properly cleaned / treated during manufacturing which led to a low ph condition on the surface of the mesh = acid mesh.

When the mesh is folded and packed against the canopy's nylon panels, they could become discolored and otherwise damaged, (think failure during deployment due to weakend fabric).

 

How'd I do Jerry?

 

Cheers

 

 

 

Hi Kleggo,

Pretty good, if I do say so myself.

Re:  Some round canopy's drive slot mesh was not properly cleaned / treated during manufacturing which led to a low ph condition on the surface of the mesh = acid mesh.

It wasn't that it was not properly cleaned.  It was that the mesh mfrs added a non-flammable 'coating' to the mesh.  The mesh still met the Mil Spec req'ments.  But, this 'coating' is what caused the interaction with the nylon fabric in the canopies; resulting in strength failure.

They added the 'coating' so the non-flammable mesh could be used in things like tents, etc.

The parachute mfr's did not know about the coating, so they used the mesh without concern.

Anyway, that's my story & I'm sticking with it.

Jerry Baumchen

 

[chuckakers 426]

19 minutes ago, kleggo said:

A non-riggers recollection = Some round canopy's drive slot mesh was not properly cleaned / treated during manufacturing which led to a low ph condition on the surface of the mesh = acid mesh.

When the mesh is folded and packed against the canopy's nylon panels, they could become discolored and otherwise damaged, (think failure during deployment due to weakend fabric).

 

How'd I do Jerry?

 

Cheers

 

 

 

That's about it. Mike Smith from the old Spaceland Parachute Center discovered it while packing his girlfriend's reserve. The fabric tested fine during a repack, then 120 days later during another repack he pull tested it again and the fabric fell apart like wet paper. It was determined that the contaminated mesh having contact with the F111 fabric degraded it severely. No one ever figured out how the fabric could test perfectly fine for a long time, then suddenly fall apart in the course of one repack cycle.

The fix was an acid test followed by a specific washing method if it was positive.

[John_snurkowski 0]

1 hour ago, JerryBaumchen said:

Hi Mark,

Yup, it would probably be just Security's 26 ft LoPo canopy.  That was not a subject of the AD.  

Jerry Baumchen

It was '78 26' lopo. thanks for the response. crisis averted. 

[jimjumper 25]

I have a National 28' Phantom packed in a Warp 3 container that was subject to the recall. Since I retired it after 2 recalls and 1 modification it was a favorite to give to give to rigger candidates. 

[riggerrob 643]

To further complicate the issue, only certain batches of acidic mesh reacted with certain batches of F-111 fabric. Note that several other fabric mills sold fabric similar to F-111. Finally, it required a specific combination of heat and humidity for the the two types of fabric to interact and deteriorate the canopy fabric. Only Strong Enterprises and Free-Flight stuck with MIL-SPEC fabric and mesh. Round canopies from all other manufacturers are suspect. The FAA, GQ Security, National, Pioneer, etc. issued Service Bulletins to get their customers back in the air, but that was only a short-term goal. By 1990, square reserve manufacturers had caught up with demand and sold plenty of replacement reserves. Sales of round reserves plummeted during the late 1980s. By 1990, square reserve manufacturers had caught up with demand and by 1990 something like 80 or 90 percent of new containers were sold with square reserves.

While I may have tested a thousand-ish round reserves with bromocreasol green and tensile tested them too, I no longer have the tools or the desire to ever test another round reserve built during the mid-1980s. If anyone brings me a 1980s vintage round canopy, I point them towards the museum.

[JerryBaumchen 1,434]

1 hour ago, riggerrob said:

To further complicate the issue, only certain batches of acidic mesh reacted with certain batches of F-111 fabric. Note that several other fabric mills sold fabric similar to F-111. Finally, it required a specific combination of heat and humidity for the the two types of fabric to interact and deteriorate the canopy fabric. Only Strong Enterprises and Free-Flight stuck with MIL-SPEC fabric and mesh. Round canopies from all other manufacturers are suspect. The FAA, GQ Security, National, Pioneer, etc. issued Service Bulletins to get their customers back in the air, but that was only a short-term goal. By 1990, square reserve manufacturers had caught up with demand and sold plenty of replacement reserves. Sales of round reserves plummeted during the late 1980s. By 1990, square reserve manufacturers had caught up with demand and by 1990 something like 80 or 90 percent of new containers were sold with square reserves.

While I may have tested a thousand-ish round reserves with bromocreasol green and tensile tested them too, I no longer have the tools or the desire to ever test another round reserve built during the mid-1980s. If anyone brings me a 1980s vintage round canopy, I point them towards the museum.

Hi Rob,

Re:  Only Strong Enterprises and Free-Flight stuck with MIL-SPEC fabric and mesh.

From what I learned back then, all of the mesh met the Mil-Spec req'ments.  

The problem was that the Mil-Spec did not consider/address that the materials might be treated with this 'non-flammable' coating.

Not all of the mesh used had this coating.

Jerry Baumchen

[jimjumper 25]

A bit off the topic Rob, but in the small world we live in, you were the one who performed the first two modifications on the Phantom that I have. The diaper was changed from a single stow to a double stow, and then later, after Scott Wakefield blew up a 28' Phantom at terminal, you also did the service bulletin adding a Kevlar reinforcement to the lower lateral band. That's when you were working for Manley at Cal City. I took the canopy with me to Misawa Japan and discovered from Parachutist that it had been recalled for acid mesh. I surrendered and replaced with a square reserve.

[councilman24 37]

It also was not just the mesh as Rob mentioned.  I had a Pioneer with two panels on one gore next to one larger piece of mesh. So two pieces of white fabric next to one piece of mesh.  Had seen identical conditions since sewn together.  One panel full strength, one completely degraded. The two panels might have come from different lots, batches, rolls etc. but had been sewn next to each other.  We gave Invista, maker of nylon filament, samples of bad fabric.  IF they discovered the issue they never told the industry.  I did several high tech spectroscopic analysis on the bad versus good nylon. I couldn't identify the difference.

To the OP, I pack a lot of old stuff but I would not pack an old Securty LoPo  in a pilot rig.

[piisfish 140]

A pre-acid mesh era parachute probably deserves a display in a museum more than an AIR before potential use. 

[ikenever 1]

If I'm not mistaking... This issue started with the SAC (Security Aero Conical) reserve in the 80's and then prompted an AD for other canopies as well like the National Phantom reserve series.

 I owned and Bromo/pull tested quite a few of both brands and found non to have acid mesh.

[fcajump 164]

On 7/26/2022 at 11:56 AM, ikenever said:

If I'm not mistaking... This issue started with the SAC (Security Aero Conical) reserve in the 80's and then prompted an AD for other canopies as well like the National Phantom reserve series.

 I owned and Bromo/pull tested quite a few of both brands and found non to have acid mesh.

Friend came out of retirement a few years back and took his closet-queen to an older rigger who tested the SAC reserve.  Told my friend he needed a new reserve.  Friend said "why??  its been well cared for..."  Rigger picked up the skirt and easily ripped it to the apex.  Friend (very fit Marine BTW) looked him dead in the eye and said... "so, what reserve would you recommend?" 

(I said he was a Marine... not stupid... he knew a life-saving demonstration when he saw it...)

JW

 

[ikenever 1]

Not all SAC reserve canopies had mesh treated with process chemicals containing acid. Some did, some did not. This was determined with using the bromo alkali test and pull test using a scale with special vise clamps designed for the test.

I find it hard to believe that the (older) rigger did not use the above test as recommended by the manufacturer prior to ripping it from skirt to apex first with his/her bare hands. Or did you leave that part out?

BJ Alexander (old rigger)

[fcajump 164]

On 8/11/2022 at 7:53 PM, ikenever said:

Not all SAC reserve canopies had mesh treated with process chemicals containing acid. Some did, some did not. This was determined with using the bromo alkali test and pull test using a scale with special vise clamps designed for the test.

I find it hard to believe that the (older) rigger did not use the above test as recommended by the manufacturer prior to ripping it from skirt to apex first with his/her bare hands. Or did you leave that part out?

BJ Alexander (old rigger)

(heard 2nd hand)
My assumption was that prior to calling my friend in, he had either did the bromo test, and/or tensile test.  IIRC the rigger was trained ~1999 by DeWolf and would have included full training on the SAC issue (while they predated 1999, they were still common enough to walk in with older/closet gear).

DeWolf kept a hot one around to give his class the briefing and chance to test a known bad one.

JW

 

 

[ikenever 1]

Good information.

[JerryBaumchen 1,434]

On 11/12/2021 at 6:27 AM, John_snurkowski said:

Looking for an old rigger's advice. 

Someone just dropped off Security Pilot Emergency rig and asked me to tell them whether or not it's airworthy. (It likely is not.) But the parachute is from the '70s and as far as any records I have seen on it, has not been tested for acidity. 

 

Can someone tell me how I am supposed to conduct that test, and possibly the list of serial numbers (which I'm told are out there) which Security said are subject to the acid mesh pandemic?

Hi John,

Since I was the second person in the US to obtain the FAA approval for the testing of SAC canopies, I will offer some thoughts.

1.  To do the testing, one had to develop & submit to the FAA for approval, an Alternate Means of Compliance ( or words very similar to that ).

2.  While each procedure submitted could be different, almost everyone followed the same procedures.  These were testing for acidity; then, if that was OK, tensile testing of the fabric, usually using some clamps and a device to measure the loads.

3.  If the canopy passed all of the testing, then the approval holder could mark the canopy with some info that it was OK for further service.

Security was out of business when the acid mesh problem surfaced.  So you could not go to them to see what canopies were effected.

The FAA issued an AD that listed the effected canopies.

No one could legally do the testing & re-certification without an FAA approved procedure.

If you have any additional questions, just post them; I'll try to respond if it is something that I have knowledge of.

Jerry Baumchen

PS)  I'm an old rigger.

 

Edited August 22, 2022 by JerryBaumchen

[ikenever 1]

Good to see you're still at it Jerry!