Swap before it breaks

June 8, 2020

A series of (rare) carabiner breaks draws attention to a topic that has received too little attention: aluminum carabiners should be replaced regularly. A carabiner from the Italian manufacturer Camp (for Woody Valley). The beginning of a crack is shown in the bend at the bottom right. The carabiner of the same type opposite in the harness was already broken at this point. // Source: Slovenian police In spring 2020, an aluminum carabiner for his Woody Valley harness broke at a pilot in Slovenia. Technical investigations (pdf) showed that it was a permanent vibration break (material fatigue). In Slovenia, therefore, a safety notice was even issued for this type of carabiner. However, there had already been documented incidents in which such carabiners broke in previous years. The development is very well summarized in the blog "Paragliding-Karabiner" by the Frenchman Eric Ferlay, who recently published a safety note there (also in English). Aluminum carabiners from the Italian manufacturer Camp, which produces and brands such models in a very similar design not only for Woody Valley, but also for other harness manufacturers, became noticeable due to breaks. One might think that such carabiners should generally be removed from the market because of possible construction defects. But that's a little too simple. Because that would mean suppressing the fundamental problem behind it. All aluminum carabiners with a snap opening on the side are more susceptible to permanent vibrations due to the material. For this reason, for example, the operating instructions for the harnesses from Woody Valley also recommend that the carabiners be replaced every two (!) Years. In all of the above cases where there was a break, this timeframe was clearly exceeded. It is also a responsibility of the pilot: if you want to fly with light aluminum carabiners because of the weight saving and are not just a casual flyer (just a few flight hours), you should take the replacement intervals recommended by the manufacturer seriously. In addition, "chipped" aluminum carabiners, no matter what their age, should no longer be used. If you want to dig deeper into the topic, you can read on now. Below I present a text on the same topic that I published in DHV Info 197 in 2015. I updated the dates in it: From the meaning of the carabiner exchange carabiners have a limited useful life. Depending on the design, manufacturers recommend an exchange after two to eight years. Pilots should stick to it. Every pilot uses them, but very few people think about them: the carabiners. As a rule, you will find an installed pair on every newly purchased harness and will also use it for convenience. But after two years of flight experience at the latest, you should waste a few thoughts on the carabiners. After all, you hang your life on the piece of metal. And even if the breaking loads according to the specifications go far beyond your own weight limits, you have to be aware of one thing: carabiners age and should be replaced at certain intervals to be on the safe side. It was almost 20 years ago that a series of carabiner breaks caused a stir in the paragliding scene. At that time, the German Hang Glider Association (DHV) initiated safety investigations and came to the conclusion that there was a significantly increased risk of breakage only for a certain type of carabiner. It was a special version of the Parafly Automatic harness carabiner from AustriAlpin, namely those that were finished with a shiny and particularly hard chrome surface. Small cracks in this finish could continue particularly quickly in the load-bearing aluminum body. Carabiners of this type were then "grounded" by means of a safety message, withdrawn from the market and no longer allowed to be used. Back then, the DHV's analyzes revealed other insights that have remained valid until today. Among other things, it was shown that many types of carabiners, which are opened and closed with a snap mechanism, do not achieve complete traction during flight. In order for the snapper to be opened easily, it needs a certain amount of play. Only with a higher weight load does the carabiner bend so far that the closed snapper itself can act as a load-bearing element. In normal flight, especially for lightweight pilots, there is typically a little bit of play. In fact, it is nothing more than flying with a fully open carabiner. Accordingly, the metal is not only subjected to tensile, but also bending forces. This can lead to so-called stress cracks that slowly eat into the material until the metal suddenly breaks. The loads that a carabiner has to endure change constantly during flight, which leads to small vibrations. A snap-lock carabiner bends slightly in thermal flight up to 25 times per second and then resets itself. Measurements have shown that. These permanent vibrations tire the metal over time. For safety reasons, it is therefore advisable to adhere to the replacement intervals recommended by the manufacturers. Each manufacturer provides different information for its karabiner types, depending on what material they are made of, what material thickness and forging shape they have and how the adhesion is achieved. The recommended replacement intervals are typically two to three years or 500 flight hours for snap-action carabiners made of aluminum and five years or 1500 flight hours for those made of steel. Pinlock carabiners are also made of aluminum, but their design makes them non-positive. The manufacturer therefore recommends a service life of up to eight years. // Source: Finsterwalder-Charly Specially shaped aluminum carabiners made from Titanal - an alloy in which cracks spread somewhat less quickly than with the Zicral alloy commonly used for carabiners - also have a recommended service life of five years. The non-positive Pin-Lock carabiner from Finsterwalder Charly is even eight years old. The pin lock does not have a snapper, but a sliding steel pin as a closure and load-bearing element. In addition to the pure counting of the carabiner years of use, pilots should of course also rely on their common sense. Even carabiners that are only slightly bent open - recognizable by the fact that the snap lock is slightly jammed or that screw locks cannot simply be turned with two fingers - should be replaced immediately. One should also regularly pay attention to the external condition of the carabiners. Aluminum is a relatively soft material. If it hits stones or rattles along something hard, quirks quickly appear. They can be the starting point for deeper, invisible cracks. Especially when such cracks or quirks become visible on the curved corners of the carabiners, it is time to buy new carabiners - even if the service life recommended by the manufacturer has not yet been reached.

This article has been translated for your convenience and was originally written in alemán.