0
psychonitro

reserve cable/pin disconnection

Recommended Posts

All right, did some search but couldn't find what I wanted so I start a new thread, also I don't know whether this would suit better the gear and rigging section, if so move it. Heard one rigger of another dz telling he was once repacking a friend's reserve and he found the canopy to fit very tightly into the container, so he did (luckily) a pull simulation and hell, the handle got pulled but the pilot chute didn't fire. When he opened the flap he saw just the cable had got disconnected from the pin. The pin was not bent nor got blocked into any impediment, it just got disconnected from the cable. I don't think this is a frequent issue, else we'd hear about it more often (yep what a nuclear science statement:P), but I was wondering whether it's possible to change the reserve cable/pin connection design to prevent this to happen. I also fear something similar could happen at the handle level, with the metal block at the edge of the cable getting disconnected and so the letting the handle get completly free, pulling in such a configuration would be useless, since you'd pull the handle but in no way the cable. Comments and suggestions :)

Share this post


Link to post
Share on other sites
Real Name: No name entered.
Email: No email entered.
Jump Profile
Home DZ: No home dropzone entered.
Gear
Container: No container entered.
Main Canopy: No main entered.
Reserve Canopy: No reserve entered.
AAD: No AAD entered.


It a secret.
My idea of a fair fight is clubbing baby seals

Share this post


Link to post
Share on other sites
It shouldn’t happen, but of course any component can fail.

The rigger should save the faulty ripcord and return it to the original manufacturer. I’d also recommend an email to the national skydiving organization as an advisory.

Your profile says you are in Italy. If the rig is approved for use in the United States under a TSO, the ripcord should have a marking indicating when and where it was manufactured. The TSO process allows a manufacturer to trace a defective component to a specific lot, and that allows direct follow-up with distributors and users. If it is not covered by a TSO or other quality control process, then there may be nothing much that can be done to trace the component or follow up on the specific manufacturing process.
Tom Buchanan
Instructor Emeritus
Comm Pilot MSEL,G
Author: JUMP! Skydiving Made Fun and Easy

Share this post


Link to post
Share on other sites
Thanks for providing some profile information.

As Tom said, US TSO requires the following information on the ripcord:

Quote

4.2.2 Primary Actuation Device/Ripcord: The following information shall be marked on the primary
actuation device/ripcord:
a. Part number, including dash number
b. Manufacturer’s identification
c. TSO-C23( )
d. Batch, serial number, or date of manufacture (month and year)



But as we learned with the recent Capewell pin problem, very few manufactures are complying with this requirement.

Did the cable come out of the pin or did pin break off at the shoulder?

Phree,

There a 2 different types of pins. Terminal and intermediate. The method of swaging is the same. As the name states, the terminal pin is for use on the very end of a ripcord and the intermediate is for use on ripcords with more than one pin. I have only seen the terminal pins used on some military applications.

See attachments.
My idea of a fair fight is clubbing baby seals

Share this post


Link to post
Share on other sites
Quote

There a 2 different types of pins. Terminal and intermediate. The method of swaging is the same.

There is more than one method presently being used to attach the pins. One is a crimp method and another is press/extrude method.
Quote

As the name states, the terminal pin is for use on the very end of a ripcord and the intermediate is for use on ripcords with more than one pin.

Intermediate pins are routinely used on one pin ripcords. The advantage is that when you conduct the 300lb/3 sec. pull test you can see if the cable moved. The same is true when you repack and inspect the assembly in the field.
Quote

I have only seen the terminal pins used on some military applications.

They are used in both sport and military.
Time and pressure will always show you who a person really is!

Share this post


Link to post
Share on other sites
Quote

There is more than one method presently being used to attach the pins. One is a crimp method and another is press/extrude method.



And they are both forms of cold forging by using repeated blows or pressure. In either case it causes the pin to "flow" in the cable.

Quote

Intermediate pins are routinely used on one pin ripcords. The advantage is that when you conduct the 300lb/3 sec. pull test you can see if the cable moved. The same is true when you repack and inspect the assembly in the field.



Each ripcord should have a known "finished" length, and pin spacing where needed, that takes into account amount of cable inserted into the pin, pin elongation due to swaging and that which is produced by proof loading. By measuring against this "known" you can determine if the cable has shifted.

Quote

They are used in both sport and military.



Right off hand, I can't think of any sport manufacturers that use a terminal pins. Could you help me out?

Sparky
My idea of a fair fight is clubbing baby seals

Share this post


Link to post
Share on other sites
Quote

And they are both forms of cold forging by using repeated blows or pressure. In either case it causes the pin to "flow" in the cable.

Yes, but that is not what you said before. In addition they are still two separate types of processes. There is also a ripcord made that uses a set screw.
Quote

Each ripcord should have a known "finished" length, and pin spacing where needed, that takes into account amount of cable inserted into the pin, pin elongation due to swaging and that which is produced by proof loading. By measuring against this "known" you can determine if the cable has shifted.

Not only is this not true but it should never be used. Most ripcords “finished” length has a +- variance of as much as a quarter of an inch. So unless you measured every cable to the thousand’s of an inch you would not know it there was any slippage unless you marked the cable at the pin before testing. And to be accurate you would have to take before and after measurements. Most manufactures have jigs with the +- tolerance built in and the test is a pass/fail and not a specific measurement. This is why intermediate pins are used even on one pin ripcords because you can visually see any slippage after the pull test and also in the field. How would you check a pin otherwise in the field unless you knew exactly how long that specific ripcord was?
Quote

Right off hand, I can't think of any sport manufacturers that use a terminal pins. Could you help me out?

No, because that would be listing a customer and there is that whole non-disclosure thing. But I will tell you that we made them for container manufactures in the USA that use them in sport rigs.
Time and pressure will always show you who a person really is!

Share this post


Link to post
Share on other sites
There is a 3rd method of 'swaging' the pin to the cable that may be coming on the market soon. Paratec from Germany had a sample at the
Symposium that had two dimples pressed into the pin. They said that with only one dimple there testing resulted in the cable braking before the pin slipped. This should be very interesting, seeing just how this develops.

Share this post


Link to post
Share on other sites
Quote

Yes, but that is not what you said before. In addition they are still two separate types of processes. There is also a ripcord made that uses a set screw.



The process is the same, swage. You can call it crimp, press, swage or what ever, it is cold forging using pressure instead of heat to join the two metals.

At one time pins were soldered on the cable but I have never heard of a TSO'd system using a set screw.

Quote

Not only is this not true but it should never be used.



You say you have a customer that uses a terminal pin, how do you tell if it has slipped?
Can't have it both ways.

The military use dozens of different types and lengths of ripcords that must be manufactured to the specs. on the master drawings. These drawings do not allow for a + or - anything. They have required lengths such as 42 7/16" with a pin spacing of 5 9/16". The only time I have seen + or - a quarter of an inch is on non-critical soft goods.
The company I do work for made some of the H/C systems for the space scuttle and they were only allowed + - 1/16" anywhere in the drawings. This was all fabric, with metal the tolerances are 0. If these measurements should never be used then the manufacturing method needs to be changed. Critical parts for everything from planes to medical equipment are manufactured every day to exacting standards.

Sparky
My idea of a fair fight is clubbing baby seals

Share this post


Link to post
Share on other sites
Quote


Was it an eleven cell reserve? :P:P



That's a good one:D.

In answer to mjosparky: the rigger said the cable "dislodged" from the pin, I didn't see the piece, so I can't be more accurate but he never spoke about pin breaking off, at the shoulder or elsewhere. There's a point I can't actually understand: why are reserve ripcords made this way instead of a single piece cable (without pin) like you see on main ripcords (that would be safer since not having a pin there's no risk it disconnects on pull time), there will be obviously a reason but I can't guess it, maybe is there a need for extra rigidity to close the bag because of the energy of the pilot chute spring? Or is it to prevent the loop being caught in some surface imperfection of the cable like cuts (although a normal inspection should eliminate this problem)?:S.

Share this post


Link to post
Share on other sites
Not trying to hijack the thread but how would you view a cable, intermediate, that has been set with the cable a bit to the inside of the pin. It has never been flush with the opening. I did e-mail the manufacturer but no reply so far.

Share this post


Link to post
Share on other sites
Quote


Not trying to hijack the thread but how would you view a cable, intermediate, that has been set with the cable a bit to the inside of the pin. It has never been flush with the opening. I did e-mail the manufacturer but no reply so far.



>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

That is the production standard for at least one popular manufacturer. It allows them to save time by skipping the grinding phase.

Share this post


Link to post
Share on other sites
Quote

It shouldn’t happen, but of course any component can fail.

The rigger should save the faulty ripcord and return it to the original manufacturer. I’d also recommend an email to the national skydiving organization as an advisory.

Your profile says you are in Italy. If the rig is approved for use in the United States under a TSO, the ripcord should have a marking indicating when and where it was manufactured. The TSO process allows a manufacturer to trace a defective component to a specific lot, and that allows direct follow-up with distributors and users. If it is not covered by a TSO or other quality control process, then there may be nothing much that can be done to trace the component or follow up on the specific manufacturing process.



>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

European JTSO is identical to (American ) FAA TSO.
We hope that Eastern European parachute manufacturers continue with old (Cold War) military quality control procedures.

Share this post


Link to post
Share on other sites
Quote


Not trying to hijack the thread but how would you view a cable, intermediate, that has been set with the cable a bit to the inside of the pin. It has never been flush with the opening. I did e-mail the manufacturer but no reply so far.



In PPM it calls for the cable, when an intermediate is used as terminal, to set back a specified distance. I am not at home so I can't check the figure. But you can find it in section 6-14 or 6-15 of Vol. I.

Sparky
My idea of a fair fight is clubbing baby seals

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

0