pchapman 279 #1 November 2, 2009 Anyone got photos of lines that broke in some way due to wear, with background info? I think there needs to be a thread on this! We always hear about replacing lines before they get too worn, but it is rare to learn much about what the limits are. One hears about line breaks, but at least for me, it is rare to actually see them, so there's no way to learn what is too worn. (Maybe it is different on a big turbine DZ full of competitive swoopers.) I'll start off with this case: Photos 1 & 2: Broken brake line. Supposed to be 500 HMA, same as the rest of the lines. (That's what I was told.) Broke at 396 jumps. (The jumper was fine because he had planed out on rears and just tried to finish the end of the flare with toggles, while skimming feet right on the ground. So when he sharply applied brakes and the line broke, he just skidded in on his feet and ass and one hand, without even tipping over.) First pic shows the line, second shows the line vs. the unbroken brake line. The break was somewhat below the brake-set cat eye, actually a bit below (and not _at_) where the fingertrap ends for the brake set loop. The brake lines in general don't look so bad, but are "somewhat fuzzy" in that area. They look better from a distance than when close up! Quote Share this post Link to post Share on other sites
lilchief 1 #2 November 2, 2009 We had an incident this summer where a skydiver tried a Velo 84. It may be debated whether it was mostly the hard opening, or wear. If you don't find my post relevant to this thread, let me know by PM, and I'll delete it. All the information I've got is here, so I can't elaborate more, I'm sorry. Line set var original PD 500lb HMA lineset with standard slider, assembled here in Norway by a Master Rigger. According to the incident report the canopy has more then 1000 jumps on it and 200 on the lineset. I spoke with the owner, and he couldn't specify it any narrower then "more then 1000 jumps" on the canopy. The picture named "Unknown located cut" I don't recall where on the canopy it was, but it was on one of the left side lines. I'm throwing it in just in case it might give you some extra info, even though I doubt it. The jumper who was jumping and packing it, had some 40+ jumps on the canopy before the hard opening. The person has been in the sport for a long time and has over 1400 jumps. The jumper is also a lightweight person at about 130lb. This ended up in a spinning mess and the skydiver cut away. If someone would like to have any the of the photos in full size jpeg, let me know. They're about 3mb each in that case. "Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been and there you long to return." - Da Vinci www.lilchief.no Quote Share this post Link to post Share on other sites
Fledgling 0 #3 November 3, 2009 QuoteOne hears about line breaks, but at least for me, it is rare to actually see them, so there's no way to learn what is too worn. Check out PD's website. There is a great article pertaining exactly to this and is at least one way to learn what is too worn. Quote Supposed to be 500 HMA, same as the rest of the lines. (That's what I was told.) I have always been creeped out by using HMA brake lines so I always switch mine to 1000lb vectran. But that is just to make feel good. QuoteBroke at 396 jumps. I believe this to be far too many jumps on a HMA brake line. After all it is suggested to change the entire line set at 500 jumps. So I swap mine out at 250 jumps. For $20 you can't go wrong. QuoteThe break was somewhat below the brake-set cat eye, actually a bit below (and not _at_) where the fingertrap ends for the brake set loop. I would almost bet that this would be directly related to the pilots flying style. Depending on how deep in brakes he usually flies would dictate where the guide ring would wear on the line the most. QuoteThe brake lines in general don't look so bad, but are "somewhat fuzzy" in that area. They look better from a distance than when close up! I call BS on that. For HMA lines they look terrible. That much wear may be acceptable on thicker lines but not on HMA. Again, check out the article regarding HMA lines on PD's website. Quote Share this post Link to post Share on other sites
Cloudi 0 #4 November 3, 2009 Quote I call BS on that. For HMA lines they look terrible. I second that. Judging from the pics, those lines have been ready to break for awhile. Quote Again, check out the article regarding HMA lines on PD's website. HMA FAQ I know someone who helped write that... Kim Watch as I attempt, with no slight of hand, to apply logic and reason. Quote Share this post Link to post Share on other sites
pchapman 279 #5 November 3, 2009 Thanks for the HMA link Cloudi. "Generally" the lines are fuzzy, but not terribly so, and actually seem to fit into the "some wear" category rather than the "should replace" category of that HMA article. But more specifically, yes, there are issues: those lines are critical brake lines, they are HMA, they were pretty low strength to begin with (for brake lines), and one particular area (where the break was) looks more fuzzy -- and it is the worst part that needs to be looked at. Quote Share this post Link to post Share on other sites
Fledgling 0 #6 November 3, 2009 Quote"Generally" the lines are fuzzy, but not terribly so, and actually seem to fit into the "some wear" category rather than the "should replace" category of that HMA article. It appears to me that those lines fit squarely into the should replace category. QuoteBut more specifically, yes, there are issues: those lines are critical brake lines they are HMA, they were pretty low strength to begin with (for brake lines), It is not about them being low strength as they are not low strength lines! You have to start thinking about it as % of wear. If the lines were vectran they would have probably been fine. But as HMA lines are already so thin to start with, that amount of wear as a percentage of the line thickness is much greater and therefore more critical. Quote Share this post Link to post Share on other sites
RMURRAY 1 #7 November 4, 2009 when HMA first came out I think I had MEL put dacron (not the huge stuff) on for the lower control lines. what are advantages and disadvantages of this. Quote Share this post Link to post Share on other sites
Fledgling 0 #8 November 4, 2009 I doubt PD would recommend putting dacron anywhere near a velocity :-) Dacron will not be as dimensionally stable as vectran or HMA for one thing. I prefer to use Vectran for my brake lines. Thicker and longer lasting than HMA and shows wear better but still just as stable as the HMA. Quote Share this post Link to post Share on other sites
masterrigger1 2 #9 November 4, 2009 Quote Dacron will not be as dimensionally stable as vectran or HMA for one thing. I prefer to use Vectran for my brake lines. Thicker and longer lasting than HMA and shows wear better but still just as stable as the HMA. Actually, lower contol lines made from Dacron will stay pretty much at the nominal dimension. 525 lb Dacron is actually the line of choice in my shop for longevity. Is is about the same size as 1050 Vectran, last longer, and slows down the openings more so that Vectran or Technora. BS, MELSkyworks Parachute Service, LLC www.Skyworksparachuteservice.com Quote Share this post Link to post Share on other sites
Fledgling 0 #10 November 4, 2009 QuoteQuote Dacron will not be as dimensionally stable as vectran or HMA for one thing. I prefer to use Vectran for my brake lines. Thicker and longer lasting than HMA and shows wear better but still just as stable as the HMA. Actually, lower contol lines made from Dacron will stay pretty much at the nominal dimension. 525 lb Dacron is actually the line of choice in my shop for longevity. Is is about the same size as 1050 Vectran, last longer, and slows down the openings more so that Vectran or Technora. Well then, I guess I stand corrected. Quote Share this post Link to post Share on other sites