Are "good" pins good enough?

[riggerrob 643]

I have seen MIL SPEC pins bent bad enough to prevent pulling the ripcord.
The first was on a Stylemaster main that got jammed under the instrument panel of a Cessna. After three tries, the jumper pulled his reserve.

I came close to suffering the same problem once during a tandem. We were doing a poised exit from a Cessna when the student tried to stand up on the step. He jammed the reserve container against the underside of the wing and bent a reserve pin 45 degrees. That was the last time I eve4r did a poised exit.

[df8m1 24]

riggerrob

I have seen MIL SPEC pins bent bad enough to prevent pulling the ripcord.
The first was on a Stylemaster main that got jammed under the instrument panel of a Cessna. After three tries, the jumper pulled his reserve.

I came close to suffering the same problem once during a tandem. We were doing a poised exit from a Cessna when the student tried to stand up on the step. He jammed the reserve container against the underside of the wing and bent a reserve pin 45 degrees. That was the last time I eve4r did a poised exit.

There seems to be two camps in regards to pins. One camp swears that pins don't bend, or at least not bad enough to matter, and the other camp says they have seen or had pins bend so bad they would have been a fatality if the jumper needed to use the reserve.

I was just talking with an associate the other day about Tandem pins. My area is dominated by Sigmas so I don't have any first hand experience with any other Tandem containers. To anyone that has experience with pins bending on Tandems, any information about what caused it to bend would be helpful. Please feel free to PM me or the OP if anyone does not want to go on the record.

The really scary thing to me about something happening to a tandem reserve system is that there is someone on the front that has no clue in reality all the things that can go wrong, and signs up based on "good times and high fives". I have the up most respect for Tandem Masters (from my era) / Instructors who do everything in their power, which includes sacrificing themselves, to protect the passenger when things go wrong.

One of the tests will be to simulate what happened to you, so the more information we can get to use to duplicate the conditions the better.

[riggerrob 643]

Not much to be gained from simulating conditions that bent my reserve pin. We understood that malfunction mode 30 years ago.
Solutions are also well known. Two solutions immediately come to mind. The first is reducing snag hazards in jump planes. I had that conversation with a DZO last week. He was grumbling about scuffed main pin covers on his Sigmas. I pointed out the different door frames on his access as. His Cessna 182 had a smooth door frame, while his Cessna 205 had some rough edges on its door frame. I suggested that his best solution was to get a sheet-metal worker to install a copy the 182's door frame in his 205.
The second solution is better pin covers. Since my incident, Atom, Eclipse, Next, Plexus, Racer, Sigma and Strong have introduced better pin covers.

[df8m1 24]

riggerrob

Not much to be gained from simulating conditions that bent my reserve pin. We understood that malfunction mode 30 years ago.
Solutions are also well known. Two solutions immediately come to mind. The first is reducing snag hazards in jump planes. I had that conversation with a DZO last week. He was grumbling about scuffed main pin covers on his Sigmas. I pointed out the different door frames on his access as. His Cessna 182 had a smooth door frame, while his Cessna 205 had some rough edges on its door frame. I suggested that his best solution was to get a sheet-metal worker to install a copy the 182's door frame in his 205.
The second solution is better pin covers. Since my incident, Atom, Eclipse, Next, Plexus, Racer, Sigma and Strong have introduced better pin covers.

I want to see how much it takes to bend a pin through the flap. Two schools of thought on this one.... One is to make changes to reduce the situations that can result in bending a pin, (which is good to do, but still leaves a pin that can be bent), the other is to address the pins ability to bend in the first place. When employed together, the two approaches provide the best protection.

Don't get me wrong, improving the flap makes sense and is a good thing to do, but the term "band-aid" comes to mind. Again it comes down to the opinion of if the pin should bend easily or not in the first place.

Additionally, testing can provide some idea of what it takes to bend a pin with the improved flaps. I think it would be nice to be able to compare what it takes to bend a pin with the old flaps, to what it takes with the new flaps.

Again, I am hoping the results will be fantastic, and it will be good to know how good our gear protects us, just like how we want to know how our cars protect us.

[riggerrob 643]

When I bent that reserve pin, I was jumping an early Strong Dual Hawk tandem. The reserve pin cover is only a couple of layers of Cordura wrapped around a layer of ballistic cloth. Since that rig preceded tuck-tabs, suspect that the pin cover had blown open and the bare pin was rubbing directly on the door handle.
Since the early 1980s successive waves of canopy formation and sit-flying jumpers have forced manufacturers to re-think pin covers several times. Modern pin covers with their MDS stiffeners and multiple tuck-tabs are much less likely open pre-maturely.

[df8m1 24]

riggerrob

When I bent that reserve pin, I was jumping an early Strong Dual Hawk tandem. The reserve pin cover is only a couple of layers of Cordura wrapped around a layer of ballistic cloth. Since that rig preceded tuck-tabs, suspect that the pin cover had blown open and the bare pin was rubbing directly on the door handle.
Since the early 1980s successive waves of canopy formation and sit-flying jumpers have forced manufacturers to re-think pin covers several times. Modern pin covers with their MDS stiffeners and multiple tuck-tabs are much less likely open pre-maturely.

Gotcha... thanks for the specifics in your case.

How old do you think the oldest gear still being jumped is? I still have my first rig, and one of its smaller brothers (both Infinities) and they are about 17 years old I would guess. My Vector is probably about 6 ish. I wish I could make one rig from the best features of the two lol...

My main interest is in current equipment, but how does one define "current"?

[riggerrob 643]

The last majo0r revolution in skydiving gear was about 25 years ago. Around 1990, we saw the introduction of: collapsible pilot-chutes, ZP fabric, zero stretch suspension lines, canopies that could be loaded more than 1 pound per square foot, BOC deployment, hip rings, RSLs, electronic AADs, etc. All the major bugs (mini 3-Rings) had been worked out by 1998, so the only major development left was refining containers to make them "free-fly friendly" and that occurred by the turn of the century.
I explained this and more to my last rigging course and they all wrote "I will not repack gear more than 20 years old." Their answer was simplistic, but I could respect it, so they all passed that question.
If a rig has been jumped for 20 years straight, it is probably worn out by now.
OTOH I have a Talon that was made in 1996 and has less than a thousand jumps on it. During that same period I made more than 3,000 tandems and wore out a bunch of tandem gear.
Strong says to retire their tandem harnesses after 18 years and reserve canopies after 22 years. If a tandem main lasts more than 8 years, you are in the wrong business!
Hah!
Hah!
Now several manufacturers say not to repack their gear after 15 or 20 years.
When I worked in Southern California, most lofts refused to repack anything more than 20 or 25 years old, because nylon wore out so quickly in the desert.
I recently told a local jumper to consider retiring his 19-year-old Infinity because it is frayed on multiple corners and I have already sewn a few patches on it. If he brings me a new Infinity, I will cheerfully pack his new reserve.

I cannot give you an exact answer. Instead, I will refer you to the judgment of your local rigger.

[mcordell 2]

I own and jump a 29 year old vector with the original main from the same year. Probably has 150 jumps on it all together. Reserve is also from 86. They are out there. I have no problem packing any gear that is airworthy. A lot of riggers won't but I still can't figure out a good reason for that. anyone with older gear that can't find a rigger can send it to me. I will gladly I spectacular it and pack it if it is still good.

www.facebook.com/FlintHillsRigging

[sundevil777 102]

JohnSherman

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Reserve pins have to be soft metal because that allows the shank to be swaged onto the steel cable, where under great pressure the metal flows into the fibers of the cable for a tight grip. So I guess the trick is to have a pin hard enough not to bend, and at the same time, soft enough to be swaged. If you had a hardened steel pin, then you've got to figure out a new way to attach the pin to the cable...

Ripcord pins are made from .188 dia 302SS Cond A (303 is also allowed but I don't use it) they are then rotary swaged to a diameter of .094 using the rotary Swag process of cold forming as you can't harden SS with Heat treat. The overall length of the blade is dictated by the end user but is usually 1.25 inches. Column strength of the blade is tested by inserting it into an .096 dia hole one half inch deep and applying an 8 pound weight to the end. The results is checked in a go-no go gage of .104 dia to the full depth and the pin must fall out without friction after insertion.
This process and design was originally for a pin and metal cone thru a 9/16 and 7/16 grommet situation. The amount of allowable bend was critical as the thru hole in the cone was about a half inch deep/thick.
Today we use 1/4 inch grommets with a cloth loop. A far less critical arrangement.
Yes, the pin can bend in that configuration but it is usually from dropping or throwing the rig down or against something as the rig is compressed when it hits something and this causes the rest of the rig to want to expand causing a great load on the loop and subsequently on the pin causing a bent pin. The good news is that is can still be pulled even with a bend.
The Military still uses this pin on their center pull chest reserve with cloth loops and even with the rough treatment they get have had no problem.
Larger diameter pins would cause a harder pull with the same loop load. Additionally, the shank and cable would also have to be enlarged to obtain the necessary strength as the blade would still have to be cold formed to make it hard enough.
The thicker pins used on some assemblies have no greater column strength as they are not cold formed from a larger diameter. Don't let size fool you.

Column strength? That sounds like buckling to me, and that is not the type of stress to which the pin is subjected. Still haven't had a reply to the challenge of his assertion cold forming is better than the 8x greater strength from the beginning diameter.

Here's another account of a slight bend being very bad:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4715831#4715831

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In one such case that I saw, rigger 1 repacked a small Racer, then rigger 2 "helped out his friend" by tightening the closing loop down. He was "being safe" since an exposed PC was a snag hazard.

When rigger 3 received it they noticed that the pins were slightly bent. They did a pull test, but their scale only went to 50 pounds. The handle was eventually pulled by two people working together. Best guess was that it required 75-80 pounds of pull to get the bent pins to release.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[df8m1 24]

I took the opportunity and went to Parachute Lab's seminar on pins. As an accomplished machinist and a former certified welder, I was surprised to hear some of the statements that Nancy made during the seminar. I will not attempt to repeat them as I did not write them down or have her on video, so I can not quote her properly, but anyone who was at the same seminar (the first one) I’m sure knows what I am talking about.

Nancy did give us two new pins to use in our comparison tests, which was nice of her. I want to get some Capewell pins as well to compare.

I have some cleaning up to do from preparations for the show, as well as some follow up work to do, but I will start designing the test rig and the process to load and measure the forces of interest on each pin.

I might even make a pin of my own to see how it does in comparison for grins…

The goal of this series of tests is to gather real data and publish it, so when the subject comes up, people can reference real numbers instead of opinions or claimed results of tests that were never made public.

I will test standard diameter pins as well as larger diameter pins and compare the pull forces to provide some real data on that subject as well.

I want to have something by mid summer…