Does safety tie add 9 lbs to the reserve pin pull ?

[erdnarob 1]

A discussion with a rigger friend of mine prompted me to publish this post.
As a rigger, we test the reserve pin minimum sliding force and it has to be between 5 and 22 lbs. However this test is done before installing the seal and safety tie. The safety tie red thread being rated at a MBS of 4.5 lbs, it seems that it adds 2 x 4.5 lbs = 9 lbs to the reserve pin minimum sliding force when installed since a safety tie is a loop with two strands.
I would like to have a sincere discussion about the above affirmation being true or not.
If it is true, in a case of the test showing 22 lbs, the additional force of 9 lbs would make a final force of 31 lbs (22 + 9 =31 lbs). Comments please.

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

[airtwardo 7]

good question...on the fish scale what does the loop actually break at?

~ If you choke a Smurf, what color does it turn? ~

[Scrumpot 1]

Short answer - No.

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I would like to have a sincere discussion about the above affirmation being true or not.

Okay - but just remember - you ASKED for it!
For the longer read, a rather lengthy discussion on just specifically this topic/question was once had in here before, that I just happened to recall - which you can see in essence, started in this thread (pun only slightly intended ):

HERE

I also recall someone posting somewhere too, an alternate (endorsed by either Canadian or EU somewhere) thread routing method, that in essence assures a nearly ZERO added pull/break force when it is employed too - but I cannot seem to find that particular one right away. I'll post that up later if I happen to also find that too.

EDITED TO ADD: FOUND IT! ...BPA Reserve Sealing Method Document

coitus non circum - Moab Stone

[mjosparky 4]

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it seems that it adds 2 x 4.5 lbs = 9 lbs to

Unless you can get each leg of the loop to be exactly the same length, almost impossible, you are only loading one leg at a time. Once you have the pin moving the force to keep it moving is less so the total will probably never exceed 22 lb.

Sparky

My idea of a fair fight is clubbing baby seals

[billvon 3,111]

You could probably rig a test to ensure that all the forces add and that the extraction force does indeed increase by up to 9lbs. In actual usage, force peaks when the pin just begins to move (i.e. overcomes the stiction between the pin and the loop) and then drops as the pin starts to slide. The load from the seal thread occurs after this point, so it in effect does not increase maximum pull force.

[mjosparky 4]

Is there an echo in here?

Sparky

My idea of a fair fight is clubbing baby seals

[erdnarob 1]

Since the sealing includes a safety tie red loop fixed at the top but able to slide and adjust at the bottom under the pin, the two strands will be at the same length. Just slide the pin slightly up and you will see. OTOH Murphy's law makes it possible to have no slack at all in the loop especially if the sealing has been made with the pin too far, tested and adjusted so that there is no slack. What I am trying to do here is the worst case scenario where the resistance of the safety tie would add to the sliding force of the pin making possibly the rig illegal. As I mentioned it in a related other post, in the actual reserve activation, the 2-3 inches slack near the ripcord handle will allow the all ripcord and the arm pulling to get enough momentum to overcome the extra force. The reason of that post is to check if container manufacturers have thought about this possibility.

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

[councilman24 37]

The current TSO standard requires no more than 22 lbs WITH THE SEAL IN PLACE. TSO C23b was NMT 22 lbs WITHOUT THE SEAL. I don't remember which TSO C23c was without looking and it's too late to look.

Of course TSO test rigs don't necessarily represent common, overstuffed skydiver rigs.

A the BPA method violates a basic principle of not putting a needle in a packed reserve container. Yes you can do it safely if you pay attention but I hate to start telling a newbie rigger that it's EVER okay.

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

[mjosparky 4]

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TSO C23c was without looking and it's too late to look

TSO-C23c also calls for the rig to be sealed.

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A the BPA method violates a basic principle of not putting a needle in a packed reserve container.

Just ask Patrick De Gayardon. RIP

Sparky

Some rigs back in the day and a few military rigs I have worked with tie off the seal like this.


http://i397.photobucket.com/albums/pp55/mjosparky/Skydiving/IMG.jpg

My idea of a fair fight is clubbing baby seals

[piisfish 140]

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A the BPA method violates a basic principle of not putting a needle in a packed reserve container.

Just ask Patrick De Gayardon. RIP

de Gayardon stuck a needle in his packed main, not reserve...

The principle remains the same

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[mark 107]

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The current TSO standard requires no more than 22 lbs WITH THE SEAL IN PLACE. TSO C23b was NMT 22 lbs WITHOUT THE SEAL. I don't remember which TSO C23c was without looking and it's too late to look.

Not exactly.

AS8015B 4.3.2.1 requires a representative group of users to pull a sealed ripcord without difficulty, but does not specify the maximum force required. ( :) - I just noticed that the person who numbered these sections had a sense of humor.)

AS8015B 4.3.2.4 requires a maximum of 22 pounds of force to pull the ripcord, but doesn't specify the seal.

If it is not hard to pull the sealed ripcord, even if it requires more than 22 pounds of force, the system meets the standard. AS8015A has essentially the same requirements. NAS-804 doesn't mention seals at all.

Mark

[councilman24 37]

Your right Mark. I was having trouble opening up a copy of TSO standards and my memory failed.

I think I was actually using a memory of a comment from someone and not my reading it.


BUT!!!!!!!!!

PIA TS135 DOES require the seal in place and maximum pull force of NMT 22lbs.

4.3.3 HUMAN FACTORS AND ACTUATION FORCE TESTS:
An anthropometrically diverse group of individuals (consisting of a representative group of no less than 3 males and 3 females) from the intended user group shall be employed for all human factors tests in 4.3.3. All individuals shall be able to operate the subject device without any undue difficulty. Table 2 lists the required test conditions and number of tests for each particular component. Additional information for the component tests is listed below.

TESTS: Under normal design operating conditions, all devices tested under this paragraph shall result in a positive and quick operation of the device within the following load range applied to the handle:

(a) a load applied at the handle of not less than 5 lbf (22.2 N), applied in the direction giving the lowest pull force,
(b) a load applied at the handle of not more than 22 lbf (97.9 N), applied in the direction of normal design operation,
(c) for chest type parachute assemblies, the maximum pull force shall be 15 lbf (66.7 N),
(d) the primary actuation device shall be tested in accordance with Table 2,
(e) the emergency/reserve drogue release (if used) shall be tested in accordance with Table 2.

NOTE: For these tests, the primary actuation device (ripcord or equivalent) shall be equipped with a tamper-indicating device (i.e. seal thread or equivalent) of the same type that will be required for production articles in service.
http://www.pia.com/piapubs/TSDocuments/TS-135v1.4.pdf

Bold highlight added by me.

I think I actually questioned this and someone told me the AS8015b already required it. Obviously that statement is not accurate. It may be tha who ever made that statement has been interpreting it that way. And I don't have a clue who that was in a PCSC meeting.

One more thing to discuss in St. Louis.

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

[riggerrob 643]

Also think about wear and tear on that flimsy - 8.5 pound MBS cotton thread.
It usually breaks in less than 180 days on student rigs. That too often leads to jump-masters roaring around - in a panic - trying to find a rigger to re-seal an "illegal reserve."

Far simpler to follow CSPA practice and not seal school rigs.
I usually install two seals on (two-pin) tandem reserves, knowing that one seal would break long before 180 days.

[mjosparky 4]

Mark,

Both are listed under 4.3 “Qualification Tests”. 4.3.2.1 and 4.3.2.1.1 detail how the tests shall be conducted and 4.3.2.4 gives the performance standard they must meet.

Sparky

My idea of a fair fight is clubbing baby seals

[theonlyski 8]

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I usually install two seals on (two-pin) tandem reserves, knowing that one seal would break long before 180 days.

Adding 17 lbs to the pull force?

"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

[riggerrob 643]

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I usually install two seals on (two-pin) tandem reserves, knowing that one seal would break long before 180 days.

Adding 17 lbs to the pull force?

.......................................................................

Like I said, the flimsy cotton thread usually breaks long before 180 days.