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Kevin Bonds

Joined: 09 Jan 2006
Posts: 171
Location: Nashville, Tn

Posted: Tue Mar 11, 2008 1:35 pm Post subject: accident

I noticed that the L angle, where the nose ribs attach, are still 

attached to the spar, but the ribs are not.



Kevin Bonds



Iberplanes IGL wrote:

 	  Quote: 	
		   This is a link to the video  of the accident. When this articule was 

 published they suspected an engine failure.

  

 At the end of the video you can see the nose wheel.

  

  http://www.elmundo.es/elmundo/2008/02/05/barcelona/1202234945.html

_________________
KevinBonds
Nashville, TN
Plans-building Zenith CH601XL w/Corvair Power
http://home.comcast.net/~kevinbonds

stshuck2(at)yahoo.com
Guest

Posted: Tue Mar 11, 2008 1:43 pm Post subject: accident

Wish I spoke and understood Spanish..

  



Iberplanes IGL <iberplanes(at)gmail.com> wrote:

  [quote]        This is a link to the video  of the accident. When this articule was published they suspected an engine failure. 

   

  At the end of the video you can see the nose wheel. 

   

   http://www.elmundo.es/elmundo/2008/02/05/barcelona/1202234945.html

   

  Alberto Martin

Iberplanes IGL 

http://www.iberplanes.es

Igualada - Barcelona - España



   

  [quote]  ---

swater6

Joined: 16 Dec 2006
Posts: 52
Location: Minnesota-KMIC/KANE

Posted: Tue Mar 11, 2008 2:30 pm Post subject: Re: Accident

Kevin,

I meant to paraphrase the content of the NTSB report in my description of each accident.  Sorry if it looks as though I was stating a conclusion, I only meant to describe each in a few words based on the content of the NTSB report. 



Also agreed that we can all give opinions and guesses as we do think these things and wonder.  I do get worried when I hear folks talk about modifying a design based on these discussions and sometimes it gets a little out of control.   



Scott



[quote="Kevin Bonds"]Scott,



You state conclusions about these accidents. But the FAA reports do not 

do so. So you are  making conjectures and assumptions to some extent.

_________________
601 XL kit N596SW reserved
Tail, control surfaces and both wings complete. Now working on fuselage

www.scottwaters.com

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Tue Mar 11, 2008 3:59 pm Post subject: Re: Accident

I agree. The wings are plenty strong in static load. Dynamically, I'm not so sure. Extra ribs provide extra torsional stability and strength, as well as actually making the wings stronger in a pure positive or negative load. Shorter segments to transmit the same load across equals less leverage to crumple the skins, particularly in compression. Think of a 5' fishing pole with only one eye at the very end of the pole. Now think of the same pole with an eye every 6 inches. Much stronger under load.



I would guess that if you could stand next to that inverted Zenith wing when it was being static tested, and just touched it, it would hobble and bobble all over the place, possibly even notice a bit of a "slow motion flutter".



 	  n85ae wrote: 	
		  Actually when I think about the way the zenith wings are designed it

seems obvious with just a pure positive or negative loading that the

wing is plenty strong. However if for some reason you could get it to

twist I can imagine how it could collapse and fold back quite easily.



Like somebody said this is nothing but pure speculation anyway.



Jeff

 	  ashontz wrote: 	
		  I'm starting to think the main culprit here, if there is in fact wing folding incidents not due to pulling to hard on the elevator, is torsional strength of the wing and under certain conditions turns into abrupt wing flutter. I'm even inclined to think that the slight forward sweep really doesn't have much to do with it, although it's not helping, but is not the main culprit. Consider every time a true straight wing plane is slipped, well, right there you have forward sweep on ne wing. Any time the ball is not perfectly centered, again, one wing or the other is experiencing forward sweep.



I think one condition that could lead to a wing folding in the XL would be, deploy flaps, then turn, then either drop the nose or raise the nose. Say it's a left turn. More than likely the ball will not be perfectly centered, and due to adverse yaw, now the left wing will be even more 'forward swept'. So now we've got a wing in preloaded in maximum torsion, flap down, aileron up, possibly wing even more forward swept due to adverse yaw, and you either drop the nose or rais the nose somewhat abruptly adding to or descreasing the torsional spiring loading of the wing. If the wing is not reinforced enough it starts to go into aero-elastic flutter, which if the rivets aren't good, we've already got a forward canted spar, and you have a wing locker giving even less buckling resistance to the main spar between rib 4 and 5, well, that might not be too fun to experience. But it all starts with torsional resistance.

ggower_99(at)yahoo.com
Guest

Posted: Tue Mar 11, 2008 4:18 pm Post subject: Accident

Is like  putting a Hummer  and a  Tracker   side by side...   

   

  Here the  C 152 and C 172 can hardly climb,  heavyly overbuilt and expensive to fly...  

  As women say around here (for everything they dont like) "I will rather die, than buy one  of those"  

   

  Saludos

  Gary Gower

  I think we needed now a little of humor...  Too many "experts" around here 

  Do not archive.



ella <rhodes1(at)copper.net> wrote:

  [quote]--> Zenith-List message posted by: "ella" 



Hi

Your numbers may be close. If there has been 5 wing failures in a certain 

model aircraft I would say there has to be a reason why

I have just started my rudder  and I am concerned. I can't remember 

any wing failures in Cessna 172 or 150 but I could wrong

--

Jaybannist(at)cs.com
Guest

Posted: Tue Mar 11, 2008 4:48 pm Post subject: Accident

Or like a Ford Mustang beside a Ford Model A.



Jay in Dallas

Do not atchive

Gary Gower <ggower_99(at)yahoo.com> wrote:



[quote]Is like  putting a Hummer  and a  Tracker   side by side...   

   

  Here the  C 152 and C 172 can hardly climb,  heavyly overbuilt and expensive to fly...  

  As women say around here (for everything they dont like) "I will rather die, than buy one  of those"  

   

  Saludos

  Gary Gower

  I think we needed now a little of humor...  Too many "experts" around here 

  Do not archive.



ella <rhodes1(at)copper.net> wrote:

  



Hi

Your numbers may be close. If there has been 5 wing failures in a certain 

model aircraft I would say there has to be a reason why

I have just started my rudder and I am concerned. I can't remember 

any wing failures in Cessna 172 or 150 but I could wrong

--

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Tue Mar 11, 2008 5:00 pm Post subject: Re: Accident

A rib weighs about 8 ounces, I don't know if it even weighs that much, so ten extra ribs in the two wings is what, 5 pounds?



[quote="ggower_99(at)yahoo.com"]Is like  putting a Hummer  and a  Tracker   side by side...   

   

  Here the  C 152 and C 172 can hardly climb,  heavyly overbuilt and expensive to fly...  

  As women say around here (for everything they dont like) "I will rather die, than buy one  of those"  

   

  Saludos

  Gary Gower

  I think we needed now a little of humor...  Too many "experts" around here 

  Do not archive.



ella <rhodes1> wrote:

   	  Quote: 	
		  --> Zenith-List message posted by: "ella" 



Hi

Your numbers may be close. If there has been 5 wing failures in a certain 

model aircraft I would say there has to be a reason why

I have just started my rudder  and I am concerned. I can't remember 

any wing failures in Cessna 172 or 150 but I could wrong

--

Kevin Bonds

Joined: 09 Jan 2006
Posts: 171
Location: Nashville, Tn

Posted: Tue Mar 11, 2008 5:15 pm Post subject: Accident

I understand. It just illustrates a key point. The whole problem is, we 

never get enough info from those friggin reports. They only seem to give 

enough info to get the imagination going. I wish we had some sort of 

investigative team, from the homebuilt community, that could get access 

to investigate these accidents and provide more info than the NTSB is 

willing to--in the interest of safety.



Kevin



swater6 wrote:

 	  Quote: 	
		   



 Kevin,

 I meant to paraphrase the content of the NTSB report in my description of each accident.  Sorry if it looks as though I was stating a conclusion, I only meant to describe each in a few words based on the

_________________
KevinBonds
Nashville, TN
Plans-building Zenith CH601XL w/Corvair Power
http://home.comcast.net/~kevinbonds

Jaybannist(at)cs.com
Guest

Posted: Tue Mar 11, 2008 5:27 pm Post subject: Accident

This a question to all you folks who are so skeptical of the design and safety of the Zodiac CH 601XL:



WHY IN THE WORLD ARE YOU BUILDING ONE???



Jay in Dallas 601XL N2630J "Lil Bruiser"

Do not archive

cndmovn(at)gmail.com
Guest

Posted: Tue Mar 11, 2008 5:49 pm Post subject: Accident

Well said!   There are sooooo many "arm chair engineers" who have all the solutions....extra ribs, no long range tanks, BRS, no wing lockers....



Planes crash all the time.  It is a fact.   If you look at the published stats, design failure accounts for very few of the causes of crashes.  Usually it is the pilot error or weather related. 

 

I am tired of all of the pretend engineers.  If you are an aerospace engineer, then you have the qualifications to post about the design.  If not, you need to proceed your post with "I have no qualifications to make this recommendation but you guys should listen to me....."

 

I have a great deal of faith in Chris Hintz and his abilities.  I think before everyone posts, they need to ask themselves...what are my qualifications to question the design"



Flame off.



 On Tue, Mar 11, 2008 at 9:22 PM,  <Jaybannist(at)cs.com (Jaybannist(at)cs.com)> wrote:

 	  Quote: 	
		   --> Zenith-List message posted by: Jaybannist(at)cs.com (Jaybannist(at)cs.com)

 

 This a question to all you folks who are so skeptical of the design and safety of the Zodiac CH 601XL:

 

 WHY IN THE WORLD ARE YOU BUILDING ONE???

 

 Jay in Dallas 601XL N2630J "Lil Bruiser"

 Do not archive

 

 

 

 

 	


-- 

Paul Riedlinger

cndmovn(at)gmail.com (cndmovn(at)gmail.com)  [quote][b]

craig(at)craigandjean.com
Guest

Posted: Tue Mar 11, 2008 6:06 pm Post subject: Accident

 	  Quote: 	
		   WHY IN THE WORLD ARE YOU BUILDING ONE???

 
	


   

I was going to name my XL “Plane Ugly”. Now I’m leaning towards “Deathtrap” (very big smile).  

-- Craig  

Do not archive  

   

  [quote] [b]

skyguynca

Joined: 05 Jun 2006
Posts: 128

Posted: Tue Mar 11, 2008 6:31 pm Post subject: Accident

Paul, there really are sooooo many arm chair  engineers with solutions. Your right and I agree I believe Chris Henitz is a  great designer. Other designers have missed things and miscalculated so lets not  forget we are all human and he could have made a error. Me I look at the fact of  so many XL accidents versus very few HD and HDS accidents, maybe a flaw creeped  in on the new design?

 [quote]   ---

jmaynard

Joined: 27 Feb 2008
Posts: 394
Location: Fairmont, MN (FRM)

Posted: Tue Mar 11, 2008 8:24 pm Post subject: Accident

On Tue, Mar 11, 2008 at 09:46:41PM -0400, Paul Riedlinger wrote:

 	  Quote: 	
		   I have a great deal of faith in Chris Hintz and his abilities.  I think

 before everyone posts, they need to ask themselves...what are my

 qualifications to question the design"


	


Not all of us are builders.



My concern is simple: Am I about to spend $130K on an aircraft with a design

flaw that makes the wings fall off? I'm nearly 100% certain that answer is

no, but I'd feel better if that little bit of doubt were removed.

-- 

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 (getting ready to order)

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

mwtucker

Joined: 11 Mar 2008
Posts: 16
Location: Charlotte, NC area

Posted: Tue Mar 11, 2008 9:55 pm Post subject: Re: Accident

It is easy to try and second-guess a design based on some supposed â€œfactsâ€ from media stories and â€œeyewitnessesâ€.  Yes, itâ€™s true that most of us are not aeronautical engineersâ€¦  But I think that it is constructive to discuss the accidents, keeping in mind that we may not know all the facts.  That said, it does seem that we may want to make note of the fact that wing structural failure seems to be coming up as a common thread.  Has wing structural failure been mentioned in relation to accidents of other aircraft (even certified designs)?  We all know that flight into thunderstorms and/or loss of control can over-stress the airframe and result in failureâ€¦.



But I must admit that I am a bit concerned about the â€œsupposedâ€ in-flight structural failures on the 601XL.  I know that Chris Heintz did a re-evaluation of the wing structure and loading after two supposed in-flight wing failure accident reports.  But these were static load tests and would not expose any dynamic problems related to flutter or torsional deflections that may lead to wing failure.



I have attended the rudder workshop at Zenith and am getting pretty close to making the commitment to go with a 601XL.  I plan to ask them at Sun-n-Fun about the wing â€œissueâ€, although I would imagine that they will not tell me anything that I donâ€™t already know.  Again, we donâ€™t want to jump to conclusions.  I could wait and go with a Vans S-12 or a RANS 19â€¦  But those are new designs and could also have â€œdesignâ€ problems.  In fact, one of the reasons I was looking at the 601 XL is that the designer is well-known and respected and the design has been flying for awhileâ€¦.



Does anyone know if there are any similar â€œstructural failuresâ€ on other AB aircraft?  Again, we are assuming that there was, in fact a structural wing failure.  I guess that we donâ€™t really know for sure.



What type of flight testing has the 601XL design been through?  Are there any flight test requirements that subject the airframe to the limits of the loading?  I think the plane is rated to +/- 6 G?  Does flight testing require that to be demonstrated?



As to Jayâ€™s comment â€œwhy are we building the 601XLs in light of the alleged in-flight structural failures?â€  I imagine that most people who are in the process of building a 601XL started their kits before they were aware of the several accidents in question.



Some responses on the forum are suggesting that the aircraft will be fine as long as it is flown properlyâ€¦  In a 172, I once ran into clear-air turbulence over the mountains of Pennsylvania and it scared me to death.  There was nothing I could do to prevent that incident.  Can the 601XL survive an upset like that?



Let me close in saying that we donâ€™t really know for sure about the â€œpotentialâ€ structural failures.  Itâ€™s possible that they could all be explained by airframe failure due to loss of control by the pilot (e.g. birdstrike, flight into storm, accidental rapid movement of the controls, etc.).



Thanks, Mike

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Wed Mar 12, 2008 3:31 am Post subject: Re: Accident

Because I was 40% through it before all this came to light. Did you want to refund my money for me and do all the work on a 601HD to get me back to where I am on this project?

 	  Jaybannist(at)cs.com wrote: 	
		  This a question to all you folks who are so skeptical of the design and safety of the Zodiac CH 601XL:



WHY IN THE WORLD ARE YOU BUILDING ONE???



Jay in Dallas 601XL N2630J "Lil Bruiser"

Do not archive

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Wed Mar 12, 2008 3:33 am Post subject: Re: Accident

Funny isn't it. They're the Nation Transportation SAFETY Board and you can't get any safety clarity out of them. Typical gummint agency. Useless.



 	  Kevin Bonds wrote: 	
		  I understand. It just illustrates a key point. The whole problem is, we 

never get enough info from those friggin reports. They only seem to give 

enough info to get the imagination going. I wish we had some sort of 

investigative team, from the homebuilt community, that could get access 

to investigate these accidents and provide more info than the NTSB is 

willing to--in the interest of safety.



Kevin



swater6 wrote:

 	  Quote: 	
		   



 Kevin,

 I meant to paraphrase the content of the NTSB report in my description of each accident.  Sorry if it looks as though I was stating a conclusion, I only meant to describe each in a few words based on the

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Wed Mar 12, 2008 3:37 am Post subject: Re: Accident

Plenty of structural analysis courses in engineering school.



Ever hear of John Hombolt? He's the lowly low level engineer that came up with the concept of Lunar Orbit Rendevous. He had to break ranks and risk getting fired to get a plausible idea some facetime to see the Apollo missions be successful at landing on the moon rather than having a preposterous Atlas sized rocket land backwards on the moon.



[quote="cndmovn(at)gmail.com"]Well said!   There are sooooo many "arm chair engineers" who have all the solutions....extra ribs, no long range tanks, BRS, no wing lockers....



Planes crash all the time.  It is a fact.   If you look at the published stats, design failure accounts for very few of the causes of crashes.  Usually it is the pilot error or weather related. 

 

I am tired of all of the pretend engineers.  If you are an aerospace engineer, then you have the qualifications to post about the design.  If not, you need to proceed your post with "I have no qualifications to make this recommendation but you guys should listen to me....."

 

I have a great deal of faith in Chris Hintz and his abilities.  I think before everyone posts, they need to ask themselves...what are my qualifications to question the design"



Flame off.



 On Tue, Mar 11, 2008 at 9:22 PM,  <Jaybannist> wrote:

 	  Quote: 	
		   --> Zenith-List message posted by: Jaybannist(at)cs.com (Jaybannist(at)cs.com)

 

 This a question to all you folks who are so skeptical of the design and safety of the Zodiac CH 601XL:

 

 WHY IN THE WORLD ARE YOU BUILDING ONE???

 

 Jay in Dallas 601XL N2630J "Lil Bruiser"

 Do not archive

 

 

 

 

 	


-- 

Paul Riedlinger

cndmovn(at)gmail.com (cndmovn(at)gmail.com)   	  Quote: 	
		  [b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Wed Mar 12, 2008 3:39 am Post subject: Re: Accident

Exactly. Plus, we've already speculated he didn't do the ful design himself. Sometimes success leads to hubris, leads to laziness, leads to failure.

[quote="skyguynca"]Paul, there really are sooooo many arm chair  engineers with solutions. Your right and I agree I believe Chris Henitz is a  great designer. Other designers have missed things and miscalculated so lets not  forget we are all human and he could have made a error. Me I look at the fact of  so many XL accidents versus very few HD and HDS accidents, maybe a flaw creeped  in on the new design?

  	  Quote: 	
		     ---

barcusc(at)comcast.net
Guest

Posted: Wed Mar 12, 2008 5:02 am Post subject: Accident

Jay,

  

 WHY IN THE WORLD ARE YOU BUILDING  ONE???



  

 Because I bought the kit before these problem came  to light.I searched the FAA archives before the purchase and didn't see of  anything of concern. Before I go any further, I  know the risk involved with building and flying, I am willing to accept  reasonable risks. However, when a few failures happen  in a relatively short period of time showing  a possibility of  a trend I think one  should seek information. The reason for speculation is the fact we  will not get any information from the FAA or Zenith anytime soon, that causes  those of us that want to know to pursue as much information as possible. That  said: I do not believe they have the facts yet, at the same time, if  they have suspicions they are not going to share that with us either, we are on  our own. In my case, I have a dream of offering the chance for my  family ( Probably 6 or 7 will be interested) to learn to fly at a very young age  paying for nothing but fuel. It is one thing to put my life on the line, it is  quite another when it comes to my adult Sons, Daughter and  Grandchildren. I still believe the 601 XL is a well designed  aircraft, but that doesn't mean I will stick my head in the sand  and ignore this. There have been a lot of designs over the years, certified and  experimental, where problems began show up sometime after several have been  flying for a while. Right now, I am debating whether or not to add a BRS System.  I spoke with them on Monday, that will cost $4350.00 including shipping that  does not include the required components to attach to parachute. Then there is a  weight penalty of 35 pounds and a loss of a portion of the baggage compartment,  that is a lot to consider, especially if it turns out to be for nothing. I have  no intention of putting my project on hold, but if someone comes up with a way  to strengthen the wing in the meantime, you can bet I will do it.

  

 Opinion given with all due  respect. 

  

 DO NOT ARCHIVE

  

 Clyde Barcus

601 XL, Continental  Powered

 ---

bill_dom(at)yahoo.com
Guest

Posted: Wed Mar 12, 2008 5:24 am Post subject: Accident

I made the decision to build the XL before all of this incidents occurred. I haven't regret my decision and I continue building because I think that if there is a flaw in the design, it will be discovered and a solution will be published before I finish my plane. 



IMHO, this discussions are an important part of the process of discovering whether or not there is a flaw.



William Dominguez

Zodiac 601XL Plans

Miami Florida

http://www.geocities.com/bill_dom



Jaybannist(at)cs.com wrote:[quote] --> Zenith-List message posted by: Jaybannist(at)cs.com



This a question to all you folks who are so skeptical of the design and safety of the Zodiac CH 601XL:



WHY IN THE WORLD ARE YOU BUILDING ONE???



Jay in Dallas 601XL N2630J "Lil Bruiser"

Do not archive  [quote][b]

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