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Guest leoibb
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hello just wondering is there a difference in the quality of caribener from different manufacturers i was told today that the austri pin caribs i have a prone to cracking and breaks? it concerened me infact it stoped me from flying this eve so am just wondering is there any truth in what was said? if so i want to change them but which is the best?

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In order to calculate whether a karabiner is sufficiently fatigue endurable or not, every pilot should ascertain the loading (Fk) necessary to ensure that the play in the karabiner catch fastener completely disappears. This point of actuation by gravity can differ widely even within one model of karabiner. For example the point of actuation (Fk) for the Austrialpin Parafly karabiner was measured to be between 15,5 kg and 147 kg .

Particularly vulnerable are those karabiners by which the actuation by gravity occurs with a loading (Fk) that is greater than the value for the oscillation strength Fou (reduced by 20%) of the karabiner with the catch open (in other words Fk larger than Fk erf).

If you follow the link below you will see that Australpin alluminium carabiners have the lowest oscillation strength of the most popular makes, They also have a wide variation in load-lock weights, so cannot be relied on. You can check yours to make sure thay are OK.

Also some australpin carabiners that had a shiny "bright chrome" finish were suspected of being weakened by the finish and were subject to a BHPA safety notice,

Some time later caribiners, generally, were questioned concerning inflight fatigue stress at the bottom corner because the gate was not supporting the load. This has led to some testing and the publishing of a simple test of the carabiner which is to load it progressively and find the load at which the gate cannot be opened when loaded. This applies to all snap gate carabiners not just austalpin.

See here for details

Assuming your Australpins are ally and not brigh chrome your load lock weight should be 21kg or less. If more or you do have chrome ones then bin them (actually cut them in half so they cant recirculate.) If yours are steel the loadlock weight should be 50kg or less.

I replaced all my aluminium carabiners with steel ones about three years ago when all this came up, although the above applies equally to steel, except steel takes longer to fatigue. Carabiners need to be rechecked, periodically, for load locking.

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The Parafly steel are fine but if you want ally then yes the supair twist locks have the best Fou. They still need to be checked as described. If found to be Fk gretaer than Fou-20% they go back to the shop as "un-fit for purpose" but quality control has got tighter since the dhv notice so that shouldnt happen.

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The best kind are the pin-lock type, as there is no gate movement to allow stress fracturing.

Charly make both pin locks and the quick out type that are good if you need to release under load.

Francis, your statement about testing a carabiner by seeing if it will release when under load is not nescessarily good advice. All it does is indicate that the 'biner has flexed to the point where all gate play has been taken up. If you had a very strong 'biner that had sufficient strength to keep flex within the stress limits but not take up all the play in the gate, then by your check, would fail un-necessarily. Also, a 'biner could pass your test whilst still flexing beyond it's stress limit. For this reason, I don't think the test of opening under load is a particularly useful. (Unless you are thinking from a safety point of view, where the ability to open a carabiner in flight might be seen as a bad idea).

Seems like I'm always trying to contradict you at the moment Francis, and it's not intentional. I think we both just have strong ideas. Creating a debate is almost as important as being right, so I don't mind being shown to be wrong :)

All the best

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Its not "my" advice Phil but the advice of both the DNV and the BHJPA. It is my understanding of heir advice that if you can open the carabiner when it is loaded with your weight it is in danger of flexing to fatigue failure. If as you say the biner has sufficient "open" strength to cope with that flexing without fatigue then I dont disagree with your argument in principle. Find me that carabiner and lets test it. Until then I will rely on the advice (my interpretation of it, of course) that is issued by my association's flight and safety council and by the DHV who have load tested all the different makes of carabiner before issuing the safety notice.

Caveat Emptor.

I have absolutely no problem with you arguing the point as it sharpens us both to cut through to the underlying truths.

Please continue to be analytical and critical. :D

Charly Pin locks have their own issues e.g an extra check to ensure full insertion and locking. But they do have the advantage of eliminating oscillation fatigue. Quick outs need careful maintenance to ensure grit does not wear them prematurely and I always insert the dog with the pins depressed rather than snapping it in to reduce component wear. They are not so easily fitted and are matched pairs so a wing is wedded to a harness making wing swapping more work. (as I understand it) :wink:

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the ones i have is the steel ones but i bought some new ones didnt know what sort they were as i got them off the walkerjet site well they arrived eactly the same make and everything as the ones i got lol but i been lookin and i dont think it was refering to the steel ones lol ohh well i got another set of caribs now lol

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