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#41
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"Dave Nadler \"YO\"" wrote in message .. .
"I assume the technique is similar for all German designed gliders." Very bad assumption. Not even the same for all products from each mfg. Could you please explain some of the different spar construction methods used by the different German manufacturers? Which ones use a spar which is constructed outside of the wing assembly process? |
#42
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At 14:12 19 September 2003, Nick Hill wrote:
John Galloway wrote: At 22:48 18 September 2003, Slingsby wrote: The price of these costly toys may indeed go up but something bad has just happened to the value of Shemp Hirth products. snip... Firstly, only spars built at the Czech factory were built incorrectly using an simple error in the technique which has been identified and we can be pretty sure it has been eliminated. Secondly, therefore, the bulk of the German built SH fleet are unnaffected and I think the glider buying public are informed enough to be able to figure that out. Thirdly, all the SH gliders that could possible be affected (i.e. Discus and Duo with Czech wings) have been or will be inspected and, if necessary, repaired and brought up to full airworthiness. Maybe a better statement is the reputatation of Schempp Hirth products and procedures. It is fine to say the Czech built ones are at fault but you buy them from Schempp Hirth who therefore carry the responsibility for the production and quality control. Nick Hill Better than this. When our club ordered its Discus B they specifically asked for a German built glider and payed more for the privilege, they were told that 'some components would come from the Czech republic in accordance with normal manufacturing' it turns out that 'some components' are the sodding wings, the glider was grounded (during a competition!) and the club is still losing revenue. |
#43
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Earlier, Slingsby wrote:
I assume the technique is similar for all German designed gliders." And Dave Nadler replied: Very bad assumption... And Slingsby responded: Could you please explain some of the different spar construction methods used by the different German manufacturers? Which ones use a spar which is constructed outside of the wing assembly process? To which I say: Slingsby, I think you kind of slipped a groove back there. You started off by talking about "German designed gliders," but after Dave responded you changed the topic to German manufactured gliders. Design and manufacture are two different things. A survey of the Akaflieg Web pages might show a couple of examples of German designs with the characteristics you are talking about. What then? Bob K. |
#44
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"John Galloway" wrote... Thirdly, all the SH gliders that could possible be affected (i.e. Discus and Duo with Czech wings) have been or will be inspected and, if necessary, repaired and brought up to full airworthiness. I believe some recent Ventus 2 wings were also constructed in the Czech factory, I would hope they have plans to inspect those, as well. I am, by the way, very much impressed with the way Schemmp-Hirth notified and provided support to those of us with Duos, whether or not the glider was still in warranty. It was a class act, and I wouldn't hesitate to buy another SH glider. Marc |
#45
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At 17:42 19 September 2003, Marc Ramsey wrote:
I believe some recent Ventus 2 wings were also constructed in the Czech factory, I would hope they have plans to inspect those, as well. Marc, Agreed. However, according to what we were told the construction technique error on the Duos, at least, was so simple and specific that they might be able to positively identify some Czech spars that are not under suspicion. IMHO it would be in Schempp-Hirth's best interests to publish a full account of the production problem, the rationale behind the inspection and repair procedure, and the actions taken to ensure future quality standards. John Galloway |
#46
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John Galloway wrote in message ...
At 22:48 18 September 2003, Slingsby wrote: The price of these costly toys may indeed go up but something bad has just happened to the value of Shemp Hirth products. This is unlikely to happen as glider buyers and sellers are not fools. Buyers are unlikey to avoid gliders that are perfectly airworthy and sellers are unlikely to give them away. If they aren'r aware already bofore long they will be that: The opinion that "Safety doesn't sell" which is discussed on the DG website might provide an argument to your statement that buyers and sellers are not fools. The concept of a Czech manufactured Duo Discus or Discus being "perfectly airworthy" is in the eye of the beholder. As I ponder whether or not to buy a used Discus, which is the better log book entry, "AD complied with and no voids in the wing spars were found," or "AD complied with and a sufficient amount glue was squirted into the wing spar so that they can never fall apart. Wings are now perfectly airworthy." Firstly, only spars built at the Czech factory were built incorrectly using an simple error in the technique which has been identified and we can be pretty sure it has been eliminated. Right, a "simple error in the technique" lead to wings breaking off in normal flight. We can be "pretty sure" it has been eliminated because we sent our best German craftsmen to the Czech factory to, once again, show them how to spread glue on a spar cap. The problem is eliminated, Murphys Law will not rear its ugly head around here again. Secondly, therefore, the bulk of the German built SH fleet are unnaffected and I think the glider buying public are informed enough to be able to figure that out. The glider buying public will also be informed whenever a Shemp-Hirth glider breaks apart in flight. Thirdly, all the SH gliders that could possible be affected (i.e. Discus and Duo with Czech wings) have been or will be inspected and, if necessary, repaired and brought up to full airworthiness. Right, and the German built gliders couldn't possibly be affected because none of them have broken apart, yet. Until then, they are fully airworthy. As an inspected Duo owner I have made it my business to be certain in my own mind that an inspected or repaired glider will be at full design spar strength - for example that there have been no post manufacturing new delaminations in the Czech wings, that wings that pass the visual inspection actually are strong. I have no particular sentimental attachment to Schemmp-Hirth and no business relationship with them. Like most affected owners I was pretty upset but now I know the facts I feel no need to be concerned about the strength or value of our Duo. I have also just ordered a new Schempp-Hirth glider. Lastly, there is no reason to think that the cost of new gliders will go up. There is nothing wrong in principle with the way that they are built - as long as they are built as intended. John Galloway They weren't built as intended, and the blind method of assembling the spar as the wing is being assembled is wrong in principle. You should be pretty upset, THEY DIDN'T GLUE THE SPAR TOGETHER. Not just one, THEY DIDN'T GLUE THE SPAR TOGETHER ON A WHOLE BUNCH OF WINGS. Oops!!! But hey, "now I know the facts I feel no need to be concerned about the strength or value of our Duo. I have also just ordered a new Shemp-Hirth glider" Nice sales pitch, how much are you asking for your Duo? |
#47
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At 22:06 19 September 2003, Slingsby wrote:
John Galloway wrote in message news:... At 22:48 18 September 2003, Slingsby wrote: The price of these costly toys may indeed go up but something bad has just happened to the value of Shemp Hirth products. This is unlikely to happen as glider buyers and sellers are not fools. Buyers are unlikey to avoid gliders that are perfectly airworthy and sellers are unlikely to give them away. If they aren'r aware already bofore long they will be that: The opinion that 'Safety doesn't sell' which is discussed on the DG website might provide an argument to your statement that buyers and sellers are not fools. The concept of a Czech manufactured Duo Discus or Discus being 'perfectly airworthy' is in the eye of the beholder. As I ponder whether or not to buy a used Discus, which is the better log book entry, 'AD complied with and no voids in the wing spars were found,' or 'AD complied with and a sufficient amount glue was squirted into the wing spar so that they can never fall apart. Wings are now perfectly airworthy.' That's not the full repair . I agree that I would prefer one that didn't need a repair - but mainly because it didn't have holes cut in the wing skins to do the work. I was also very pleased that ours were OK. The airworthiness of passed or repaired wings is not in the eye of the beholder - unless you have some technical information to show otherwise - or perhaps you think the factory, the LBA and the local airworthiness organisations are incompetent or part of a conspiracy? Firstly, only spars built at the Czech factory were built incorrectly using an simple error in the technique which has been identified and we can be pretty sure it has been eliminated. Right, a 'simple error in the technique' lead to wings breaking off in normal flight. We can be 'pretty sure' it has been eliminated because we sent our best German craftsmen to the Czech factory to, once again, show them how to spread glue on a spar cap. The problem is eliminated, Murphys Law will not rear its ugly head around here again. I am not sure what point is being made in the above. As far as I am aware Murphy's Law is spread evenly throughout human activity. I thought that's what it was about. And are you suggesting that retraining cannot possibly correct a production error? Secondly, therefore, the bulk of the German built SH fleet are unnaffected and I think the glider buying public are informed enough to be able to figure that out. The glider buying public will also be informed whenever a Shemp-Hirth glider breaks apart in flight. How could it be otherwise? Thirdly, all the SH gliders that could possible be affected (i.e. Discus and Duo with Czech wings) have been or will be inspected and, if necessary, repaired and brought up to full airworthiness. Right, and the German built gliders couldn't possibly be affected because none of them have broken apart, yet. Until then, they are fully airworthy. Are you accusing Schemmp-Hirth of lying when they say that only Czech wings were built by the faulty technique? Or are you suggesting that properly built spars are not airworthy? If so back it up - and remember that this is a public forum. As an inspected Duo owner I have made it my business to be certain in my own mind that an inspected or repaired glider will be at full design spar strength - for example that there have been no post manufacturing new delaminations in the Czech wings, that wings that pass the visual inspection actually are strong. I have no particular sentimental attachment to Schemmp-Hirth and no business relationship with them. Like most affected owners I was pretty upset but now I know the facts I feel no need to be concerned about the strength or value of our Duo. I have also just ordered a new Schempp-Hirth glider. Lastly, there is no reason to think that the cost of new gliders will go up. There is nothing wrong in principle with the way that they are built - as long as they are built as intended. John Galloway They weren't built as intended, and the blind method of assembling the spar as the wing is being assembled is wrong in principle. You should be pretty upset, THEY DIDN'T GLUE THE SPAR TOGETHER. Not just one, THEY DIDN'T GLUE THE SPAR TOGETHER ON A WHOLE BUNCH OF WINGS. Oops!!! This is simply stating what we already know. That is the starting point of the whole problem. Things have moved on from there and the wings are being checked and repaired if needed. It is self evident that this is the biggest manufacturing error in modern gliding history but it is being sorted - not without a lot of inconvenience and irritation for the owners but it is happening. As regards the 'blind' construction method for the spars - if you have knowledge to suggest that passed or repaired Czech wings, or German built wings, or any SH wings built from now on are not airworthy please state it. This is, as you are shouting out, a pretty serious matter and would benefit from information rather than assertion or insinuation. 'now I know the facts I feel no need to be concerned about the strength or value of our Duo. I have also just ordered a new Shemp-Hirth glider' Nice sales pitch, how much are you asking for your Duo? It would not have been proper for me not to have declared my relevant interests in this matter and why it has been important to me to be sure of the situation. Weather permitting, tomorrow (like all the other inspected owners) I will be betting my life that our Duo spar is sound and then, in the future, I will also be betting a bigger chunk of the value of my house than I like to think about that the next glider will also be sound. Our confidence in the structural integrity of a composite aircraft comes from our confidence in the integrity of of the constructor. That isn't a complete defence against a mistake being made and when it does we then have to judge whether the constructor has shown the integrity to learn from the problem, make good the consequences of it, make sure it can't happen again, and then extend the audit process to prevent other types of error occuring in the future. Your feelings about this problem are much milder than mine were a few weeks ago. As far as I was concerned I had to get all the facts I could and then judge whether (as said before) I was being told the truth or whether several agencies were being simultaneously incompetent and/or dishonest because that would be the only other logical conclusion. John Galloway |
#48
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That's not the full repair . I agree that I would
prefer one that didn't need a repair - but mainly because it didn't have holes cut in the wing skins to do the work. I was also very pleased that ours were OK. I might prefer one which did need a repair as I suspect that finding a void, poking a wire into it to find a much larger hidden air pocket will trigger a much more detailed inspection of the spar cap than just using a video. That would lead to a very thorough filling of the voids. Limiting the inspection to a video of the rear of the upper spar cap won't find hidden air pockets. This may all be changing with Discus CS. I also wonder if an ultrasonic inspection could be done which could map the spar cap to shear web interface. The airworthiness of passed or repaired wings is not in the eye of the beholder - unless you have some technical information to show otherwise - or perhaps you think the factory, the LBA and the local airworthiness organisations are incompetent or part of a conspiracy? The perceived airworthiness of a wing is very much in the eye of the beholder. Whether a glider flys regularly or sits in a box for several seasons because the owner can't sell it and is too nervous to fly it is based more on perception of safety than actual safety. Some pilots stop flying after a bout with rough air. I'm not charging incompetence or conspiracy but in an earlier posting I mentioned Deming and my belief that there is a process problem which is more serious than just the Czech factory and Schemp-Hirth. The process problem has more to do with how the wing and spar are designed and assembled and whether the construction method leads to tightly consistant results every single time or variability in results. Variability leads to failure. Not knowing if you always get the right amount of glue on the spar joint is a process which is out of control. German craftsmen may decrease the variability and Czech employees may increase the variability but it is the process which needs to be changed. Firstly, only spars built at the Czech factory were built incorrectly using an simple error in the technique which has been identified and we can be pretty sure it has been eliminated. Right, a 'simple error in the technique' lead to wingsbreaking off in normal flight. We can be 'pretty sure' it has been eliminated because we sent our best German craftsmen to the Czech factory to, once again, show them how to spread glue on a spar cap. The problem is eliminated, Murphys Law will not rear its ugly head around here again. I am not sure what point is being made in the above. As far as I am aware Murphy's Law is spread evenly throughout human activity. I thought that's what it was about. And are you suggesting that retraining cannot possibly correct a production error? Process again. Murphy's Law should serve as a constant reminder to look for areas where it can occur and minimize its ability to occur. It's not entirely random. If applying adhesive to 30 feet of a spar cap and web is part and parcel of a process which simultaneously applies glue to several hundred feet of rib and wing edges and if it is possible to miss a few spots every 20 or so wings then there will always be spar caps which are not completely glued together. Retraining might minimize the occurence but it probably won't eliminate it. |
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