Pull tests (tensile tests) on old main canopies

[pchapman 279]

What are the opinions on doing pull tests on old main canopies, in particular, what force to use?

As a rigger, I've done the test with the regular reserve pull test clamps, to 30 lbs. This is for pre-purchase inspections, and is not normally done at reserve repack time.

30 lbs is used for square reserves, so it is natural to apply it to mains, for lack of better data.

Yet anecdotally I heard that PD prefers to test to only 20 lbs on used demo equipment, as the 30 will too easily rip seemingly airworthy canopies. Fiction or not?

The aft center top skin gets beaten up over time on propacked ZP canopies, and may be the canopy's weakest area.
I did rip one canopy in that area, that was said to have over 1000 jumps on it. That's a lot, but nowhere near what really high # of jump canopies have.

(When doing a pull test for a customer getting an inspection of a canopy they wish to buy from a 3rd party, one had better be clear on who is on the hook if the canopy does rip!)

Would those canopies have survived that long, had that topskin area been tested?

Ripping a canopy with 800 jumps might be wasting a still usable canopy. On the other hand, people have flown canopies until they've blown up on opening. Whether that's a good or bad thing depends on the perspective.

So I'm interested in hearing what other riggers do.

I am leaning towards a relaxed standard of 20 lbs on an area like the aft center top skin, but ONLY IF the owner concurs and is made aware of any wear in that area which may increase the chance of failure.

Peter Chapman

[mjosparky 4]

I do not pull test main canopies.
Sparky

My idea of a fair fight is clubbing baby seals

[chutingstar 1]

Before relining our SET 400 mains for the 3rd time, we pull tested the fabric to 20 pounds to see if it was even worth it, per a recommendation from Strong. Most failed horribly (about 10-12 pounds).

I don't pull test mains on a regular basis, but in certain instances (such as before dumping a bunch of money on a 2nd/3rd reline or other expensive/extensive repairs), I will test to 20 pounds.

So take all that for whatever it's worth...

Mike

ChutingStar.com

[mjosparky 4]

Quote

Before relining our SET 400 mains for the 3rd time, we pull tested the fabric to 20 pounds to see if it was even worth it, per a recommendation from Strong. Most failed horribly (about 10-12 pounds).

I don't pull test mains on a regular basis, but in certain instances (such as before dumping a bunch of money on a 2nd/3rd reline or other expensive/extensive repairs), I will test to 20 pounds.

So take all that for whatever it's worth...

Mike

That sounds reasonable.

My idea of a fair fight is clubbing baby seals

[riggerrob 643]

Yup!
20 pounds sounds reasonable.
However, I would only pull-test a faded, frayed and filthy main canopy that I had already concluded was near the end of its life. Pull-testing merely provides numbers to back up my opinion.

On a side note, I have only torn 3 round reserves while pull-testing them (as per PIA procedures). The first two were faded, frayed and filthy military-surplus reserves that were almost as old as me. They failed at less than 20 pounds.

The third torn reserve was built by a long-deceased Southern California manufacturer. At arm's length, it was obvious that the canopy was built from two different bolts of fabric. One panel looked like regular LoPo fabric, but the other panel had a peculiar coating that I could not identify. The LoPo fabric easily exceeded a 40 pound pull-test, but the unidentified fabric failed at 25 pounds.

[councilman24 37]

I've torn one Pioneer round, examined a weak security, and torn one Ram-Air reserve at about 8 pounds. The real "acid mesh" bad ones are scary. Two bias panels, the same color, next to one piece of mesh. One bad (2 or 3 pounds tensile strength) and one normal. And both looked and felt normal.

The ram air is scary and is still being investigated, but the manufacturer is no longer in business. It was either 1989 or 92 (don't remember without looking) Laser. There are other circumstances that make this unusual but AFAIK the reserve wasn't mistreated. I don't know it's history prior to about 1997.

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

[riggermick 7]

Quote

Yup!
20 pounds sounds reasonable.
However, I would only pull-test a faded, frayed and filthy main canopy that I had already concluded was near the end of its life. Pull-testing merely provides numbers to back up my opinion.

On a side note, I have only torn 3 round reserves while pull-testing them (as per PIA procedures). The first two were faded, frayed and filthy military-surplus reserves that were almost as old as me. They failed at less than 20 pounds.

The third torn reserve was built by a long-deceased Southern California manufacturer. At arm's length, it was obvious that the canopy was built from two different bolts of fabric. One panel looked like regular LoPo fabric, but the other panel had a peculiar coating that I could not identify. The LoPo fabric easily exceeded a 40 pound pull-test, but the unidentified fabric failed at 25 pounds.

Rob,

Do you remember the Safety Flier we tore apart at Ron Horescrofts loft in Elsinore back around 92 or 93? If memory serves it failed under minimal pressure even though it looked normal.

Mick.

[nitrochute 2]

heres one for you.years ago (1977) a local jumper bought a26 navy conical from a navy jumper who had been using it for a main. he then had a master rigger (with a shaky background) install it as a reserve in his sst.. master riogger never pull tested or anything to ensure the canopy was safe. it was broght to me when the pack job expired. i took it to the loft at para flite(i worked there at the time) and prceeded to destroy the canopy with apull of less than 6 pounds. first panel i pullede ripped. in all the canopy had 28 seperate panels that failed EASILY. i condemmed it on the spot and informed my customer .he was in shock. at his exit weight of 225 he would have died .