Carabiner Fatigue : Finsterwalder & Charly (whitepaper)

Aninder: What is up everyone? Welcome back to Paragliding Atlas podcast. I am Anindar Singh and if you are new here, this is the show where we talk about all things paragliding. From gear tips to flying techniques and stories to experiences. We cover some of the most interesting and important topics that you have always wanted to know more about from the blue yonder. Today, however, I want to chat about something that is crucial for all of us who love to fly. And I'm talking about none other than our humble carabiners. You know, those small metal clips that keep us connected to our wings, which we rely on every time we take to the skies? But how much do we really know about them? Let's take a closer look

and see how we can make sure that they are safe and reliable as we practice the art of flight. So as I was designing this episode, I reached out to a trustworthy equipment manufacturer in our industry, which goes by the name of Finsterwalder and Charlie. Now, Finsterwalder and Charlie have often been known to make high quality carabiners for various applications in the sport of free flights over many years. But Thomas Finsterwalder, the owner of the company himself, could not be a part of the show due to his limited English language proficiency. However, he was kind enough to send me a research paper that he had worked upon a few years ago from which I was able to take some very key takeaways and

prepare the first of its kind solo episode for all of you out there. Now, even though I completely understand that the world of carabiner is much larger to cover in a single episode, this, however, is an attempt to cover one of the most important, yet one of the most overlooked topics of material fatigue. Today we'll try to simplify some technical concepts, share some insights from the paragliding community, discuss some practical maintenance tips, and highlight why it is so important to pay attention to these small but vital pieces of equipment. So without further ado, let's get started.

Aninder: Let's begin this episode by acknowledging that there have been some incidents in our community where carabiner failures have often led to serious accidents. While specific details are often kept confidential out of the respect for those involved, these unfortunate events serve as a stark remainder of the importance of regular equipment inspection and maintenance. And material fatigue and corrosion have often been identified as contributing factors in some of these cases. Most of the time they involve carabiners which are used beyond their recommended service life or without proper inspection and care. These incidents underscore the critical need to understand how and why carabiners fail even when they appear to be in a perfectly good condition upon visual inspection. So what exactly is material

fatigue and why is it so crucial for us as pilots? To explain this further, I would want you to imagine a paperclip, something as simple as that. And if you keep on bending a paperclip back and forth repeatedly, what really happens is that initial few times, it flexes without any problem. but over time it keeps on becoming weaker and weaker at a certain point and eventually snaps. Now this is the simplest way to visualize material fatigue. The progressive structural damage that occurs when a material is subjected to repeated stress cycles. In context of paragliding, every single launch, every single encounter of turbulence, or when we perform maneuvers, our carabiners are kind of

going through the same stress cycles. Now, applying the same analogy of paperclip, once these stress cycles keep on repeating themselves over a period of time, they tend to cause microscopic cracks in the metal. Now, I understand visualizing microscopic cracks is going to be difficult, but the problem is while individual stresses may be well within the carabiner's capacity or the rated limit, the cumulative effect over a period of time can weaken its strength significantly. And that is why understanding material fatigue and how it affects our equipment is very essential to our safety. Now, as I was going through the research paper, I thought of having some conversation with some

experienced pilots who shared their thoughts on this topic. One of the pilots mentioned in their early days they didn't really pay much attention to carabiners. They assumed, just like all of us, that as long as the equipment wasn't visibly damaged, it was fairly safe to use. And another pilot who's an acrobatic flyer pointed out that high stress maneuvers actually put a lot more additional stress on carabiners. And in fact, acro flyers make it a point to replace their carabiners more frequently than the usual cross-country flyer or the weekend flyers. And most importantly, they also try and keep a log of their flights and maneuvers to monitor the stresses placed on their equipment over a

period of time. Now these insights highlight a common realization amongst a lot of us and that is even without visible signs of wear, carabiners can fail if not properly replaced or maintained when necessary. To illustrate this further, I would like to break down a technical concept and I'll try and keep it as straightforward as possible. Let's talk about static strength. Static strength refers to the maximum load a carabiner can withstand when a force is applied in steady and slow manner. In other words, application of a constant and unchanging load. For example, if a carabiner, as they usually are, is rated at 20 kN. If you look at any of your carabiner from your equipment,

you can see it must be rated at 18 or 16 or 20 kAmp. Now, kilonewton is a unit of measurement which runs in thousands. So let's say 20 kilonewton means 2000 kilograms. And the carabiner is rated to not fail up till 2000 kilograms under static conditions. However, this varies differently in real life flying conditions when we are actually dealing with dynamic loads. And these forces vary greatly in magnitude and direction, and often suddenly at times. You know, visualize this. Think about hitting a turbulence and facing a massive collapse. And then the reopening is so violent that sometimes these forces on the carabiner can spike momentarily, exceeding the typical load limits

experiencing during the regular flight. Now going back to our paperclip analogy, bending it gently in one direction may not cause any issues. But rapidly bending it back and forth accelerates the fatigue process. So similarly, dynamic loads also contribute to the material fatigue in carabiners in a very same way. Each stress cycle, even if it's below the carabiner's maximum rating, adds up over time. And this cumulative effect can weaken the carabiner, eventually making it more susceptible to failing. Now, manufacturers of paragliding equipment such as Petzl and Edelrid provide guidelines to help keep our gear in top condition. While specifics may slightly vary depending upon the model and the equipment number you have, there are some common themes which we can focus on. Firstly, the service life is a very crucial concept. Even

though metallic equipment doesn't degrade in the same way as a fabric or a plastic in paragliding, the manufacturers recommend retiring carabiners after a certain period of time or the amount of use. And factors such as frequency of use and types of activities and environmental conditions can all influence this timeframe greatly. Secondly, regular inspections are essential. Before and after each flight we should check our carabiners for any signs of wear, deformation or corrosion or damage. There is often emphasis on proper maintenance and this basically in simpler words means cleaning the carabiner after they have been exposed to something out of the ordinary such as dirt or sand or salt water which comes down to drying them thoroughly before storage or lubricating the moving parts with

Aninder: appropriate products such as silicon based lubricants. Finally, the storage also matters up to a certain point, although this goes overall for the harnesses in general, but keeping carabiners along with the harness in a cool and dry place, away from direct sunlight, not leaving them in your car or out in the landing field for long will of course help extend the lifetime of our equipment and eventually enhance the safety in our skies while we practice the out-of-flight. Now, as we are talking about manufacturer recommendations, I would also like to bring in a detail about environmental factors and their impact on our equipment. Pilots who frequently fly in coastal areas or humid climates need to be

particularly vigilant about saltwater, as the moist air can accelerate this corrosion and even on the metals that are generally resistant to rust. So for example, if you're flying around the coast, carabiners are exposed to salty, humid air, and this can eventually lead to corrosion if not cleaned properly. So it's very important to rinse carabiners with fresh water after such flights and dry them thoroughly before storage. And same goes for sandy or dusty environments which can cause abrasion and wear and tear eventually. So overall regular cleaning helps remove small particles that might grind against the moving parts or surfaces and cause more damage to these microscopic cracks that eventually develop while we are practicing some hygiene maneuvers. Although we might not always think

about environmental factors but they do play a significant role in longevity and reliability of our equipment so being mindful of these conditions and taking appropriate care can make a big difference. Now moving on, I would like to address some common misconceptions that can often lead to complacency. The first one, which of course even I as a flyer have to go through a lot of time is that if it looks fine, it is usually safe. You know, because usually we visually inspect something in the first go and it's easy to assume if our carabiners show no visible signs of damage, they're kind of good to go. However, as talked about previously, the damage in carabiners happens at a microscopic level

and isn't always visible during visual inspection except for the usual paint job or some bit of scratches that we might be able to watch out for. Now, oftentimes I've seen, and this usually goes for people buying pre-owned equipment, that carabiners last forever if they're not involved in an accident. And needless to say, as mentioned earlier, regular stresses will accumulate over a period of time based on how much the equipment has been used by the previous owner. So carabiners do have a finite service life and using them beyond this period will increase the risk of failure greatly. Now third one and the last one is basically about steel carabiners because steel is much more durable and

resistant to wear and tear than aluminium that is more common in our industry. However, we have to understand it is not immune to material fatigue and corrosion and they also require regular inspection and maintenance just like the other aluminium or alloy carabiners that we are most commonly using in our usual equipment. Now let's get on to some actionable steps that we all can take to make sure that we keep our equipment in top shape possible. One of the simplest things that comes to my mind is aluminum carabiners have to be replaced every five years according to manufacturer's recommendation, especially if you fly frequently. And on top of that, if you engage in acro flying or perform

dynamic maneuvers such as wing overs or spiral dives, you might consider replacing them a bit more often. Thorough inspections also help a lot. Visual checks before every flight such as figuring out if the gate is opening or looking for cracks or deformation of corrosion helps a lot. However, detailed inspections periodically can take this a step further. Try taking a closer look using a magnifying glass or even better try having a professional qualified person inspect your gear. Now I can sum up this section that by incorporating these simple tips into your routine you can help ensure that your equipment remains reliable and safe and you can have the peace of mind that you want while

you take to the skies. So staying updated with latest information from manufacturers and paragliding community is vital. Because manufacturers often release safety notices or updates based on their guidelines on new research and new findings. So subscribing to their newsletters or checking their websites periodically can help keep you informed. Additionally, engaging with fellow pilots through clubs, forums or social media also allows us to share experiences and learn from each other. And remember, knowledge is a powerful tool in enhancing our safety and the safety of people around us. Now, as I plan to wrap up this episode, I would like to talk a little bit about advancement in carabiner technologies and how it looks forward in time to come. And how it looks in time to come. Oftentimes, manufacturers are always

Aninder: exploring new alloys and composite material that offer high strength to weight ratios and build resistance to fatigue. These eventually aim to produce carabiners that are lighter and yet more durable. The gate mechanisms have been there for a while and in time to come the idea is to reduce gate flutter and help minimize the risk of accidental gate openings and eventually reduce the stress on carabiners during dynamic loads. Some carabiners are also planning to bring in the visual cues of featuring wear indicators which basically will alert you when the equipment is reaching its end of its service life or needs inspection. Although still in development, there are some talks about

RFID tags or sensors into carabiners to try and track the usage and stress cycle. This technology one day could provide pilots with real-time data on their equipment and conditions. While these innovations sound really exciting, I would like to undermine that they do not replace the need for regular maintenance and responsible equipment management. So to bring it all together, here are some steps that you can take starting today. First of all, check the age and condition of your carabiners. Review your equipment. Refer to the manufacturer's guidelines for service and maintenance life. Secondly, educate yourself. Read the user manuals and safety notices from your manufacturer. Stay informed about new developments and recommendations in the paragliding community. Thirdly, implement a

maintenance routine. Make this a part of your lifestyle. Do regular inspections and try and stick to them. Try and keep a logbook of your equipment's usage and maintenance performed as well, and not just about the flying hours. And lastly, engaging with the community, sharing your experiences, participating in discussions, workshops, and webinars will help a lot. And taking these proactive steps, you not only enhance your own safety, but also contribute to the culture of responsibility and awareness in the paragliding community as a whole. So, final thoughts to wrap this up. Material fatigue in carabiners is a very crucial issue that deserves our attention. While it might seem

technical or even daunting at first, understanding the basics empowers us to make better decisions about our equipment. Remember, these little small pieces of metal are responsible for keeping us connected to our wing and keeping us safe. So respecting their limitations, maintaining them properly and replacing them when needed is the way we can entrust our lives to them in a responsible manner. And on that note, thank you so much for joining me on this journey into the world of carabiner safety. I hope you found this discussion insightful and it inspires you to take a closer look at your own gear. If you have any questions, thoughts or experiences that you'd like to

share, please feel free to reach out to me at aninder at the rate paraglidingatlas.com To spell it, I'd say it's A-N-I-N-D-E-R at the rate paraglidingatlas.com and also all my social media links are available in the show notes below. And needless to say, your insights enrich the community and help us all fly safer.