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#51
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Aeronca 11AC Chief Project FS
Victor Bravo wrote:
Let me get this straight... you're saying there is no one common factor in the structural inflight failure crashes of... five 601XL type aircraft ??? Jay, 601XL IS the common factor ! I can only find 2 such cases in the NTSB database - and one of those appears to have been due to over-control brought on by flight into IMC: http://www.ntsb.gov/ntsb/brief.asp?e...09X00539&key=1 http://www.ntsb.gov/ntsb/brief.asp?e...17X00209&key=1 It would be helpful if you could provide information on the other three alleged incidents. P.S. For comparison, I had no problem finding several incidents of wing failures on Van's RV models. |
#52
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Aeronca 11AC Chief Project FS
On 2008-07-29, Victor Bravo wrote:
If I left you with the opinion that I was associating the tail flexing with the wing issues I apologize. They have nothing to do with each other to my limited knowledge. Well, then, there's little point in harping on it if the subject under discussion is the cause of what appears to be in-flight structureal failure. There are only three 601XL people I know personally. The 3/4 completed Quick Build kit project with a Jabiru 3300 has been put up for sale by the builder because of the wing issues. The factory built fly-away LSA airplane has been put in the back of the hangar until this same issue is sorted out to his satisfaction. The XL that was built and flown crashed on the first flight, due to something that had nothing to do with the wing or tail. Right. Airplanes crash for lots of reasons. One of the Heintz brothers ... said that there is no one common factor among the accidents that are under investigation. Let me get this straight... you're saying there is no one common factor in the structural inflight failure crashes of... five 601XL type aircraft ??? Jay, 601XL IS the common factor ! Just like the RV is the common factor in all of the inflight failures Jim Logajan mentioned. The point is that, if there's no common factor in the 601XL crashes, then there's likely no design flaw - for if there was one, it would show up as a common factor in the crashes. Even if your scaremongering about the 601XL were on target, Scaremongering !?!? Kindly explain where you would draw the line between intelligently discussing a potential problem (that has resulted in several tragedies) and "scaremongering". Would you prefer to just not allow any discussions about a potential problem with a specific airplane? Your line right abouve, about the 601 being the common factor - even though there's no evidence, at this point, that the various crashes are in fact related by any particular cause - is scaremongering. Intelligent discussion would be about trying to figure out what the problem is, not railing that the design is unsafe without anything concrete to back it up. You sound like the people who stand out in front of a courthouse screaming "racism !" because the guy who shot four innocent people and is on trial for murder happens to be a different skin color than the people on the jury. That has nothing to do with whether he shot the people or not. Because I have the nerve to hold up an argument and make people talk about a possible design issue, does not make me a scaremonger. Sorry, but I disagree. You fail to advance any other cause that's backed up by real-world data. There have been lots of crashes in RVs, but you're not running around calling it unsafe. Ahhh... the dull yellow light of higher brain function flickers briefly... For someone who claims not to stoop to personal insult, this is awfully insulting. I do not believe there is an inherent design flaw sufficient to cause structural failure of an aircraft that is properly built, well maintained, and conservatively flown. ...and just as quickly is extinguished. ....as is this. I've looked at the available data, and come to my conclusion based on what's known and what's been disclosed. Because my conclusion is different from yours, you claim my brain isn't working. All you're doing is destroying your credibility. You come across like a salesman for a competitor, trying to destroy the market for the Zodiac, not like someone interested in improving air safety. In aviation, particularly experimental aviation, we have to be far more suspicious than complacent. We have to be utterly suspicious of everything that can affect safety, and ever vigilant. This (as well as the rest of your paragraph) is nothing more than saying that pilots have to manage risks. That's indeed inherent in aviation. Aviation is not dangerous, but it's terribly unforgiving. The pilot's defense is to assess each risk and determine whether that risk is acceptable. You say there are no common factors in the failures... which SHOULD prove that at least one of them was well built and being flown within its limits. The most recent one was a formation flight, so it can be assumed that pilot was flying in level flight and not maneuvering excessively. If you're referring to the crash on the way to Sun n Fun, that aircraft was built by the Czech Aircraft Works to European LSA standards - which include a 450 kg (990 pounds) max gross, not the 600 kg the XL was designed to. CZAW had to modify the design to make that limit reachable. We don't know just what modifications they made. Until the problem is found, I intend to maintain my aircraft to the highest standards of airworthiness possible, and fly it well within its performance envelope and my capabilities as a 225-hour, non-instrument-rated private pilot. That's all I can do. Sorry Jay, I can't let you off the hook. The "highest standards of airworthiness possible" means you would load test the wings (sandbag test) to verify structural integrity... at various torsional moments (wing twisting due to air loads). This isn't something that's done for any other production aircraft during maintenance. (Remember, mine's a factory-built SLSA, not an experimental.) Zenair has done that test, and that's good enough for me. "Within its performance envelope" means that you KNOW what the real performance envelope is. AMD tested the aircraft through a full Part 23 certification flight test program. That's defined the envelope as well as any 152. If other 601XL aircraft have failed inflight operating within or even near this envelope, it means the published envelope is really not fully proven out. ....assuming that the primary cause of the crash was a structural failure of an aircraft that had been flown within the envelope for its entire lifetime. Jim Logajan said: I can only find 2 such cases in the NTSB database - and one of those appears to have been due to over-control brought on by flight into IMC: http://www.ntsb.gov/ntsb/brief.asp?e...09X00539&key=1 http://www.ntsb.gov/ntsb/brief.asp?e...17X00209&key=1 There are at least two other fatal Zodiac crashes that come to mind and could be attributed to wing failure, though the NTSB has not yet released final reports: http://www.ntsb.gov/ntsb/brief.asp?e...15X01677&key=1 http://www.ntsb.gov/ntsb/brief.asp?e...21X00519&key=1 Changing my personalities for a moment, and assuming the role of someone less antagonistic who only wants you to be able to fly safely, About damned time. I will turn off the smart-ass switch and turn on the "help this guy live to enjoy his airplane" switch. Until a real engineer has determined the full problem and figured out a real solution, I sincerely advise you to implement a temporary set of restrictions in your flight envelope to increase your structural margins. As it happens, I already do a good number of these... Reduce your turbulent air penetration speed and VNE speed by 25% each. Va is 90 knots in the Zodiac. 75% of that is 67.5 knots...and I come over the fence on landing at 65. Vne is 140. 75% of that is 105 knots - where I normally top out at, anyway. Reduce the allowable gross weight of your airplane by 10%. The Zodiac XL's 1320 pounds max gross is a regulatory number to meet the LSA spec. The airframe was designed for a max gross of 1450 pounds. 90% of that is 1305 pounds; I meet that anyway. Reduce the maximum G loading by one or two G. Limit aerobatics to low G barrel rolls. I do not fly aerobatics, period. I'm too susceptible to motion sickness. Reduce or eliminate maneuvers that put rolling (wing twisting) loads on at the same time as G loads. Such as? Taking these precautions WILL greatly reduce the loads on your structure, until a qualified engineer figures this all out. I know how my aircraft has been flown throughout its lifetime, because I'm the only one who's flown it since it passed its flight test. You're also assuming that the Heintzes aren't qualified engineers... -- Jay Maynard, K5ZC http://www.conmicro.com http://jmaynard.livejournal.com http://www.tronguy.net Fairmont, MN (FRM) (Yes, that's me!) AMD Zodiac CH601XLi N55ZC (got it!) |
#53
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Aeronca 11AC Chief Project FS
I'm not a salesman for any of the competition, nor am I "against"
Zenair in any way shape or form, sincerely. I've owned an RV-3, which is one of the RV's that you mentioned have had wing failures. Van in one case did find that there was something that was appropriate to change (rear spar attach fitting hole edge distance problem, becoming RV-3A), and also found it appropriate to change the design later to make it more immune to hot-dogging pilots (which arguably was an operational error rather than a design flaw), becoming the RV-3B. This discussion has gotten somewhat out of hand for perhaps the wrong reason. I stand by my statement that there appears to be something in the 601XL that needs to be addressed. I have personally spoken to TWO professional crash investigators (one governmental and one engine-related) who have expressed a strong personal opinion that the XL is too lightly built. These two investigators have examined one of the non-fatal 601 crash wrecks, and both have several years of professional experience looking at why airplanes crashed. My comments about moving the tail back and forth were meant to further illustrate the notion that the CH 601 is very lightly built. I found one airplane where the amount of movement startled me, and I said something about it publicly. That should not have made you anywhere near as upset or offended as you apparently got. My apologies, I was not intending to upset you when I pointed that out. (design flaw) or if there was one, it would show up as a common factor in the crashes. There have been several inflight wing separations on a common aircraft design. There has been a letter from the factory somewhat addressing the situation as well... so Heintz understands that there is some kind of situation. Common sense AND an engineering textbook should tell you that this needs to be taken very seriously. Van took it seriously every time, made changes, and the RV's continue to be well respected designs. Heintz is a well respected designer and I strongly believe he will continue to be so. Your line right abouve, about the 601 being the common factor - (snip) - is scaremongering. Stating a fact (several inflight wing failures in one particular design) should not be scaremongering. How would you have addressed this fact without being guilty of scaremongering? If I had reported that people are putting their 601's up for sale, even though that is fact (I was told about a factory-built XL being put up for sale today, and another friend of mine has put his QB project up), it could be seen as scaremongering. But all I said was that there have been several similar inflight failures and people need to get to the bottom of this issue. I stand by that still. Intelligent discussion would be about trying to figure out what the problem is, not railing that the design is unsafe I thought I HAD been discussing the idea of figuring it out. It's hard to be open minded enough to figure it out, when people are just standing there in denial that there COULD even be a problem. Sorry, but I disagree. You fail to advance any other cause that's backed up by real-world data. The real-world data is that four or five of these airplanes have had the wings come off in flight to one degree or another. That seems to be more than enough of a cause to me. Real-world data comes in several flavors... wind tunnel tests, sandbag tests, metallurgy lab tests, and on and on. Real-world data ALSO includes field testing by non- engineers in actual flight conditions. The results from this type of non-engineer testing, which in this case has involved unfortunate tragedy, is just as valid as scientists in white lab coats running computer simulations or sandbag tests. There have been lots of crashes in RVs, but you're not running around calling it unsafe. OK, the original RV-3 design is less safe than later versions, and is shown to be fundamentally unsafe for certain aerobatic or overspeed flight conditions which have resulted in tragic crashes. The unmodified original RV-3 can only be flown safely with speed and G load restrictions compared to later models... just like I am suggesting with the 601 UNTIL the root cause of the problem is figured out. The RV-3A and RV-3B upgrades have greatly extended the safe flight envelope and provide a far greater margin of structural safety. Ahhh... the dull yellow light of higher brain function flickers briefly... For someone who claims not to stoop to personal insult, this is awfully insulting. I claim that others stooped to personal insult far earlier than I. After a few people come at me with guns blazing, I'll blaze right back. No apologies on that particular issue. I've looked at the available data, and come to my conclusion based on what's known and what's been disclosed. Because my conclusion is different from yours, you claim my brain isn't working. No, I just think you have a beautiful, fun, and flying airplane, and because of that fact you don't want to even discuss the possibility it might need another couple of pounds of metal in the wing somewhere. All you're doing is destroying your credibility. You come across like a salesman for a competitor, trying to destroy the market for the Zodiac, not like someone interested in improving air safety. I am a salesman for one old, tired, Aeronca Chief project that I want to find a good home for. That's it. I do have a Zenair project in my garage, and I do not have an RV, Savannah, Sonex, or Thorp. You are dead wrong, my only interest in (this extended offshoot of my Aeronca posting) is indeed for air safety. You see, if a structural problem with ANY small airplane causes a crash, it could have a devastating effect on my ability to fly my little antique Taylorcraft around ever again. If you're referring to the crash on the way to Sun n Fun, that aircraft was built by the Czech Aircraft Works to European LSA standards - which include a 450 kg (990 pounds) max gross, not the 600 kg the XL was designed to. CZAW had to modify the design to make that limit reachable. Well, that sure as hell sounds like something that needs to be gotten to the bottom of, now doesn't it? Some of the QB kits I'm told were built in the Czech Republic too. Some were built elsewhere. So you're telling me that SOME of the XL airplanes built for one part of the world have a lot more metal in the structure, than some OTHERS built in (or for) some other part of the world? That sure as hell needs to be part of the investigation too. We don't know just what modifications they made. You're making my point 100X better than I ever could have made it !!! This isn't something that's done for any other production aircraft during maintenance. No, they only do it after there have been a few suspicious crashes... (Remember, mine's a factory-built SLSA, not an experimental.) Zenair has done that test, and that's good enough for me. Here's where I got upset and started thinking about people's heads being in the sand. Zenair "had done that test" probably before any of the crashes, and so perhaps there is something in the real world that did not show up on the tests. You are drawing arbitrary lines between this 601XL and that 601XL, between ones built here and ones built there, between experimental and S-LSA versions, between ones painted white and ones painted blue. I believe some of each have crashed. If that is true (that some SLSA's have crashed, some homebuilts, some Euro models) then the only "common factor" in the crashes would be the basic airframe design. If only one of the sub-types were crashing (ones built in Czechoslovakia on Wednesdays with greater than 50% relative humidity and using green upholstery) then that information leads you down a different path to finding out what is going on. AMD tested the aircraft through a full Part 23 certification flight test program. That's defined the envelope as well as any 152. And if five 152's had inflight wing failures within a five year period, what do you think the NTSB and the concerned owners would do... argue about who's being polite and whose table manners need polishing? ...assuming that the primary cause of the crash was a structural failure of an aircraft that had been flown within the envelope for its entire lifetime. I don't care whether the airplanes are being flown within any arbitrary envelope, it doesn't matter at the level I am talking about. Because I'm NOT attacking Zenair, and I'm NOT suing anyone, and I'm NOT advocating the grounding of the fleet... the legal issues and operating limits are not the focus of my thinking. I am thinking that aircraft are being lost in the real-world operating environment... whether that is within or not within the airplane's POH. If all these crashes are happening outside the POH limits, then it needs to be figured out WHY five different people were flying the airplane outside these limits, and whether these limits are too easily exceeded in real- world operating conditions by average pilots. (changing my personality) About damned time. You too, if we're being honest.You're looking at me like a vicious party-pooper instead of someobody who thinks there is an issue which others are not paying enough attention to. It's not my life at stake here, Hombre, I have a Taylorcraft with a 67 year history of keeping the wings on. Va is 90 knots in the Zodiac. 75% of that is 67.5 knots...and I come over the fence on landing at 65. You come over the fence at 65 knots on an airplane with a 40 knot stall speed? would you please get your flight instructor online in this conversation? I have a few words for him/her about energy management and landing distance. I do not fly aerobatics, period. I'm too susceptible to motion sickness. OK, then that is not a factor. Reduce or eliminate maneuvers that put rolling (wing twisting) loads on at the same time as G loads. Such as? Pulling the stick back and sideways at the same time. If you want to do a tight turn then my suggestion is to roll the airplane into the turn, then wait until the rolling part is complete, put the stick back in the center, THEN pull back on the stick rather than all at once. RUMOR is that on one of the crashes the ailerons were found far away from the crash site. This brings up the POSSIBLE existence of flutter (TBD by real engineers). I humbly suggest that you check your ailerons for excess play, flexibility in the system where it is supposed to be rigid, aileron mass balance, heavy paint on the ailerons, etc. You're also assuming that the Heintzes aren't qualified engineers... Oh no not at all... Chris Heintz is one of the most highly qualified light aircraft engineers around. I don't know about anyone else in the family's qualifications one way or another. Fly extra safe Jay, I'd love to have you around for a while if for no other reason than to argue with |
#54
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Aeronca 11AC Chief Project FS
On Mon, 4 Aug 2008 14:23:16 -0700 (PDT), Victor Bravo
wrote: There have been several inflight wing separations on a common aircraft design. There has been a letter from the factory somewhat addressing the situation as well... so Heintz understands that there is some kind of situation. Common sense AND an engineering textbook should tell you that this needs to be taken very seriously. Van took it seriously every time, made changes, and the RV's continue to be well respected designs. Heintz is a well respected designer and I strongly believe he will continue to be so. From what I understand, at least one "wing related crash" was a Czech aircraft works plane. Of the other 2, one had a rear spar bolt not installed, or incorrectly installed(and fell out) Another had a hardware store bolt in a critical wing attach application. Neither of these two was a design fault - and as pointed out earlier by someone, the Czech plane is not EXACTLY a 601XL LSA plane. It was originally built to a lighter standard and may or may not have been properly modified to LSA requirements. ** Posted from http://www.teranews.com ** |
#55
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Aeronca 11AC Chief Project FS
clare at snyder dot ontario dot canada wrote:
On Mon, 4 Aug 2008 14:23:16 -0700 (PDT), Victor Bravo wrote: There have been several inflight wing separations on a common aircraft design. VB, in an earlier post I believe you specifically stated there were 5 such accidents and I asked if you had references to them as I can only find 2 such accidents in the U.S. NTSB database (I provided the NTSB database links). Again, it would be exceedingly helpful if you could direct me to either the NTSB reports I'm overlooking or press accounts of the 3 other accidents you are claiming. clare at snyder dot ontario dot canada wrote: From what I understand, at least one "wing related crash" was a Czech aircraft works plane. Of the other 2, one had a rear spar bolt not installed, or incorrectly installed(and fell out) Another had a hardware store bolt in a critical wing attach application. Clare, you are claiming 3 such accidents. Again, I only have information on 2. The NTSB said the probable cause for one of those was flight into IMC followed by control overstress, and for the other the probable cause was structural failure for reasons unknown. No mention of substandard or incorrectly installed hardware in the narratives or probable cause. In fact in the second case the wing spars remained attached to the fuselage - but the engine was heard to have been changing RPM repeatedly just prior to wing failure. So if you have references for a third such accident (e.g. foreign press reports) that would help. |
#56
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Aeronca 11AC Chief Project FS
On Tue, 05 Aug 2008 00:45:20 -0500, Jim Logajan
wrote: clare at snyder dot ontario dot canada wrote: On Mon, 4 Aug 2008 14:23:16 -0700 (PDT), Victor Bravo wrote: There have been several inflight wing separations on a common aircraft design. VB, in an earlier post I believe you specifically stated there were 5 such accidents and I asked if you had references to them as I can only find 2 such accidents in the U.S. NTSB database (I provided the NTSB database links). Again, it would be exceedingly helpful if you could direct me to either the NTSB reports I'm overlooking or press accounts of the 3 other accidents you are claiming. clare at snyder dot ontario dot canada wrote: From what I understand, at least one "wing related crash" was a Czech aircraft works plane. Of the other 2, one had a rear spar bolt not installed, or incorrectly installed(and fell out) Another had a hardware store bolt in a critical wing attach application. Clare, you are claiming 3 such accidents. Again, I only have information on 2. The NTSB said the probable cause for one of those was flight into IMC followed by control overstress, and for the other the probable cause was structural failure for reasons unknown. No mention of substandard or incorrectly installed hardware in the narratives or probable cause. In fact in the second case the wing spars remained attached to the fuselage - but the engine was heard to have been changing RPM repeatedly just prior to wing failure. So if you have references for a third such accident (e.g. foreign press reports) that would help. I don't have the info - just asked a friend who is up to date on these things. One or more may NOT have been XL models, and it is possible one of the two (bolt related) was the Czeck plane. The one that went IMS and suffered control overstress was apparently the one with the missing rear spar bolt. ** Posted from http://www.teranews.com ** |
#57
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Aeronca 11AC Chief Project FS
On Mon, 4 Aug 2008 14:23:16 -0700 (PDT), Victor Bravo wrote: Fly extra safe Jay, I'd love to have you around for a while if for no other reason than to argue with -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=- Bil, Bill, Bill. May suggest you consider a left parenthesis instead of a right parenthesis in the interest of 'truthiness'. http://en.wikipedia.org/wiki/Truthiness - Barnyard Bob - The more people I meet, the more I like my dog. |
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