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Thread: Nicopress fitting failure report

  1. #21

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    "Here is one example, google the internet you won't have to go far. "
    So you googled it just now as well, so you saw the Fly-baby failure as well where it was "apparently" a tension differential that caused failure and not a bad nicopress job. I'm not saying anything other than where is the stacks of proof that properly made "at home" cables have a relatively high failure rate. I'm not buying it, I have a guage and use the parts from an aircraft supplier. I have tested mine and can say the rudder/elevator horn will fail before the cable or nicopress do. Perhaps a relatively high means there are a few reports of cable failure in experimentals and only a couple in GA? I might buy that. Just not buying into the bold lettered DON'T MAKE CABLES AT HOME THEY WILL FAIL AND KILL YOU, THINK OF THE CHILDREN!!!!!!! know what I mean.

  2. #22

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    Quote Originally Posted by Racegunz View Post
    "Here is one example, google the internet you won't have to go far. "
    So you googled it just now as well, so you saw the Fly-baby failure as well where it was "apparently" a tension differential that caused failure and not a bad nicopress job. I'm not saying anything other than where is the stacks of proof that properly made "at home" cables have a relatively high failure rate. I'm not buying it, I have a guage and use the parts from an aircraft supplier. I have tested mine and can say the rudder/elevator horn will fail before the cable or nicopress do. Perhaps a relatively high means there are a few reports of cable failure in experimentals and only a couple in GA? I might buy that. Just not buying into the bold lettered DON'T MAKE CABLES AT HOME THEY WILL FAIL AND KILL YOU, THINK OF THE CHILDREN!!!!!!! know what I mean.

    No I don't! Well, All I have to say is that speaking from years of experience making cables I know what I know. I didn't say homemade cables would fail. I merely said that using the proper tools would remove the probability of a a failure. There is nothing wrong with making homemade cables if you have acess to the proper calibrated tools and testers. I reallly don't have the time to search for stacks of proof so let's let's just say some rely on time proven quality practices and some rely on luck.

  3. #23
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    Quote Originally Posted by RV8505 View Post
    No I don't! Well, All I have to say is that speaking from years of experience making cables I know what I know. I didn't say homemade cables would fail. I merely said that using the proper tools would remove the probability of a a failure. There is nothing wrong with making homemade cables if you have acess to the proper calibrated tools and testers. I reallly don't have the time to search for stacks of proof...
    I do.

    I've got a 13-year database of homebuilt accidents (1998 through 2010, inclusive). Over that 13 years, there were two accidents (LAX99LA074 and SEA00LA128) attributed to improperly-made nicopress fittings. Two accidents out of over 2,700, in a time period where 13,000 new homebuilts were added to the rolls.

    You're absolutely right this this is a critical operation, and users should use proper tools in a proper fashion. I believe the evidence indicates that the skills required are within the capabilities of an average homebuilder.

    Fabrication of cables using nicopress fittings is an approved method for both homebuilts and certified aircraft. AC43-13 does recommend (repeat, recommend) load testing. A good idea, but I think the evidence shows most builders can make safe-enough fittings reliably.

    Ron Wanttaja

  4. #24

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    It's all in how you peel the onion Ron. I have found several accidents besides the ones you quoted using different search terms. Check the NTSB site http://www.ntsb.gov/aviationquery/index.aspx and try cable failure, Nicopress, Nicropress, Cable End, Eye End, and any other applicable search term you can think of. A cable failure is a failure regardless of homebuilt or production as I know a lot of A&P mechanics make cables improperly as well. What is an acceptable rate of failure? Even a 2 in 13,000 chance is still unacceptable. One aircraft in particular (Zenair) had about 950 hours before the nicopress failed. I don't think we could even imagine the sheer terror of a elevator cable failure. At a minimum cables should be load tested. Go down to a airport with your cables flip the Mechanic a few bucks and get them tested.
    Last edited by RV8505; 04-28-2012 at 11:00 AM.

  5. #25

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    Thanks for the voice of reason Ron. Proper tools and attention to detail, that is what the message should be, not plop down the money for it. I'd go certified if I was made of money,...... maybe.
    I'd much rather learn the proper way to build/make things, that is what made this country great, not relying on someone else's work. RV8505 I meant no disrespect, but you did bold print your post, and I thank you for putting the NTSB link there, I tried to use their database without success the other night. Let's face it flying is full of risks but the prevalent accident factors are not mechanical failures, it's pilot error. So a few more facts and a bit less drama and fear, that would be helpful.
    I got fired up and went and tested a poorly swaged cable, it does guage correct though.

    Last edited by Racegunz; 04-28-2012 at 03:07 PM. Reason: add video

  6. #26

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    "I'd much rather learn the proper way to build/make things, that is what made this country great, not relying on someone else's work." "So a few more facts and a bit less drama and fear, that would be helpful"

    What??????????????

    The backyard video really proves nothing other than you can lift the back of your truck. If you would just pick up and read the 43.13 and the NTSB data base you would see I am correct. Everything writen in the 43.13 is Factual and in there for a reason and written with blood. It recomends cable testing and I recomend it as well. Wouldn't that be part of learning things the proper way? Your truck proably weighs 5000 lbs and lastime I checked the majority of the weight is in the front. Just because you lifted half of the truck doesn't mean you lifted half of the weight. Further, what you have created is a basket hitch and each leg ( Each fitting ) is carrying half of the load lifted. So really don't you have any idea what type of load your putting on that cable. It will probably not fail but your methods are unsound. This is what a cable tester looks like http://www.atitools.com/ATICatalog20...aging_2010.pdf Page 4. I have a couple of A&P instructor friends at Vinceness University A&P school in Indianpolis that I worked with at Britt Airways if you are old enough to remember Britt. I am not sure if they have a tester or swagger but I could call them and ask if you could come over and test them on their machine if they have one.
    Last edited by RV8505; 04-29-2012 at 12:28 AM.

  7. #27

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    No it proves that even a sloppy job will sustain a continuous load more than you could hold with your control stick. I did say it wasn't scientific, didn't I? and yes the cables ends shared the load I know that. I don't have a problem with testing them witha proper tester and would love to. I put that together in a few minutes mostly to show that the ones that failed must have been a miserable job. I have a 4313 and have no problem with it, I also have confidence in my workmanship. I would love to go to your friends and test some of my cables, now that would be the most helpful thing.

  8. #28

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    I thought it was kind of a clever idea to lift a trailer attachment point w an engine lift. If these were 1/8 inch cables, the breaking strength should be about 1500 lbs in each strand.

  9. #29
    rwanttaja's Avatar
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    Quote Originally Posted by RV8505 View Post
    It's all in how you peel the onion Ron. I have found several accidents besides the ones you quoted using different search terms. Check the NTSB site http://www.ntsb.gov/aviationquery/index.aspx and try cable failure, Nicopress, Nicropress, Cable End, Eye End, and any other applicable search term you can think of.
    OK...let's do just that.

    During the period from 1/1/1970 to 4/15/2012, running the NTSB database with the "amateur-built" flag set to "Yes":

    There were six Experimental amateur-built aircraft accidents that were attributed to Nicopress failures (plus one ultralight, which are not Experimental Amateur-Built aircraft).

    There was one case where the failure was a "Nicropress" fitting (plus two ultralights).

    There were two instances where references were made to failures of a cable end. One was on a Sukhoi (not an Experimental Amateur-Built aircraft) and the other referred to a throttle cable (not a stress-bearing item).

    There was one accident (FTW01LA034) that referenced "Cable Eye". In this case, it had nothing to do with cable fabrication or cable strength.

    There was one accident (NYC00LA134) that references "Eye End." This case also did not involve cable fabrication, but improper adjustment of a turnbuckle.

    So in that forty-two year period, there were a grand total of seven Experimental Amateur-Built aircraft accidents due to the failure of "home-made" cables. That's about 0.1% of the total accidents. That's an average of one accident every six years. Heck, the incident last month was the first case since 2000.

    When you read those Nicopress-failure accidents, one thing seems to stand out: The NTSB investigator didn't have to look far to find the problem. They didn't need a testing lab to ascertain that the builder made the Nicopress fittings wrong. It was apparently visually obvious that the builder made the fittings incorrectly. In one Fly Baby accident, the sleeves had been compressed with a pair of pliers. Quoting another report (CHI83LA256): "WHEN THE PILOT/ BUILDER WAS QUESTIONED ABOUT THE INSTALLATION, HE APPARENTLY DID NOT KNOW THE PROPER INSTALLATION PROCEDURES."

    So the problems were not subtle...they probably should have been caught by a tech counselor or another builder. But too many builders don't avail themselves of EAA's services, or insist on going their own way. Four out of those seven cases occurred prior to 1985, which I think pre-dates the tech counselor program.

    Quote Originally Posted by RV8505 View Post
    A cable failure is a failure regardless of homebuilt or production as I know a lot of A&P mechanics make cables improperly as well.
    Allow me to quote your initial posting on this subject:

    Quote Originally Posted by RV8505
    As A Tech Counsler and Airline Mechanic I discourage the use of home made cables!
    Few people would consider a cable made by an A&P as a "home made cable."

    Ironically, there was one Fly Baby accident (ATL99LA092-- non-fatal, fortunately, the pilot had a chute) that happened because the builder did NOT use "home made cables."

    Quote Originally Posted by RV8505 View Post
    What is an acceptable rate of failure? Even a 2 in 13,000 chance is still unacceptable.
    Flight involves risk management, as does building or maintaining an aircraft. The question is, what do you do to minimize the risk at an acceptable cost? Two accidents out of 13,000 aircraft is a 0.016% failure rate...ridiculously low.

    That 2 out of 13,000 case was over a 13-year period. Over that same period, there were two additional cases where the builder hooked up the controls in reverse (SEA00LA107 and CHI06CA039). Does this mean we should tell people not to do "home made" control connections? Should they defer critical work like that to licensed A&P mechanics? Is that risk *truly* unacceptable?

    During the same time period, there were 96 homebuilt accidents caused by faulty fuel systems. Seems that, if a builder is going to pay to have someone check their work, it'd be a lot better if they had someone go over their fuel systems than tug on a few cables.

    Or, for that matter, maybe they should spend the money on some refresher training. As has been posted, the majority of the accidents are due to pilot error, not mechanical issues. If you want builders to spend $200 for increased safety, you get more "bang for the buck" from an hour with an instructor than a formal test to detect errors which are usually visually apparent.

    Quote Originally Posted by RV8505
    As A Tech Counsler and Airline Mechanic I discourage the use of home made cables!
    And, as a run-of-the mill EAA member, I disagree. :-)

    Ron Wanttaja

  10. #30

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    Now that's peeling the onion! Ron. seriously, thanks for taking the time to put that together. who would have guessed the fuel system would be a difficult item to do properly?? I would like to see that broken down to ,pump versus gravity fed systems, and how many were new or neglect of the system that caused failure. Well I have had a great week-end of fabric covering and stitching, so off to do more ploybrush/taping.

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