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Freeflaw

Cypress washer rips

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On my seventh reserve pack job I managed to rip a cypress washer from hole to hole. I was closing the bottom flap (last flap) of my wings container with a very short closing loop when I suddenly felt the tension slowly melt away. It was not the sudden breaking that you feel when loop rips but a very gradual decline in closing loop tension. When I opened the container I found a sliced washer. The washer had not been visibly damaged and had been used for the last three pack jobs on this container. Pretty weird.

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I pull a loop, make a new one using the washer from another used loop and then throw the used one into the box for the washer to be used next time. I haven't but a new one in service in years. I've never seen any deformation and I've never seen any corrosion.
I'm old for my age.
Terry Urban
D-8631
FAA DPRE

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I am aware of at least two smilie discs that have done the same thing here in Australia. I believe there was a recall of a certain number of discs. I will try and find the advisory but from memory there was a difference in the 'shine' of the discs.
I like my canopy...


...it lets me down.

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Just damn, we've had a few of these too over the past year. I keep meaning to send a note to Airtec...glad to hear Terry has...I'll need to follow-up as well.

All of the times it has happened here is when we are pre-stretching the loop before putting it in the rig. I think we still have the discs at the shop...will have to dig them out.

Mike
ChutingStar.com

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After seeing the damaged Cypres washer picture, I would say that it is not a question of new, old or corroded washer. I think it's a missing heat treatment problem. Any parachute rig piece of hardware would be put out of shape without the appropriate heat treatment. Could this washer by any chance have two holes drilled too close ? Personally it's a big surprise and I never had that problem with the rigs I have packed including the Wings systems.
However, I am now using more and more the Vigil washer which is made of stainless steel. It has only one hole and 2 clefts on the sides. See the picture.
Learn from others mistakes, you will never live long enough to make them all.

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Quote


I think it's a missing heat treatment problem. Any parachute rig piece of hardware would be put out of shape without the appropriate heat treatment. Could this washer by any chance have two holes drilled too close ?



The washers look to be "cold stamped" probably in a two stage die.

My guess is stress fractures resulting from a dull die punch in the first stage. (which punches the holes).


Cheers,
MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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If what you say is correct ie. (holes done with a die), the hole chamfer or bevelled edge should remove the possible fractures. It would be interesting using a microscope to see the damaged washers and look for micro cracks. Also how do you explain that most of the washers are OK ? The very small number of failures has suggested me that those faulty washers have missed the heat treatment. Speculations here.
But wait a minute, I just have tried a Cypres washer with a file strike and I can see it is made of ordinary soft steel. OTOH the visible remainder of the burr around the washer shows that the washers are stamped at least for the round shape. Mystery ???:$

Learn from others mistakes, you will never live long enough to make them all.

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Hi Andre',

Quote

Mystery ???



Failure analysis can be a lot of fun or it can be very frustrating. :o

It is very possible ( and there are only about 159 possibilities :P ) that AirTec has the parts/washers built by some 3rd party and the supplier changed something w/o telling anyone.

It has happened many, many times.

Been there, done that.

JerryBaumchen

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If what you say is correct ie. (holes done with a die), the hole chamfer or bevelled edge should remove the possible fractures.


If it was going to be heat treated, yes.
Sharp corners and heat treating do not mix.

The holes look to be punched as the surrounding metal is raised.
If you look closely you can see a "mound" around the holes.

The force of a dull punch can tear the metal alot like cookie dough tears.

The way I would inspect it would be UT.(Ultrasonic Testing)
Or I would float a pancake probe (Eddy Current Testing) over it.

This is my "real" job field. Nondestructive Testing(NDE) in the Nuclear Industry.

Cheers,
MEL
Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

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