Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Accident
Goto page Previous 1, 2, 3, 4, 5, 6, 7, 8 Next

Matronics Email Lists Forum Index -> Zenith-List

View previous topic :: View next topic

Author Message

MHerder

Joined: 11 Feb 2008
Posts: 143
Location: Fort Worth TX

Posted: Tue Mar 11, 2008 6:17 am Post subject: Re: Accident

Disclaimer:  The information contained below is filled with my own personal assumptions, many of which may not be correct (I am only trying to use my best logic)  I do not wish to be involved in a flaming session since this is a very touchy subject for those of us (myself included) who truly take pride in their project and enjoy every second of working on their project and have invested a large amount of time and money.  I am only trying to ask some questions and get others opinions as to whether or not my assumptions are logical or reasonable.



Does anyone know if the incident in Spain and Australia involved the UL version of the XL, or the UL version of the HD.  Zenair apparently manufactures the "ultralight" version for the euro market ( I don't know what is required in Australia).  As a builder I am deeply concerned, my condolences go out to the families effected.  



The reason I ask is that the UL version is about 200 or so pounds less (gross weight).  I look at the structure of my aircraft under construction and wonder where the hell I could take out such a significant amount of weight without making sacrifices somewhere.  (Lighter landing gear seems to be the largest component)



I DO NOT believe that Zenith is marketing and selling a dangerous design.  Someone once pointed out that all of the significant fly in the XL frequently, which I think is a very valid point. 



However, I was more easily able to dismiss the first two or so incidents.  This latest series is especially bothersome.



My searches find 2 down in Cali with apparent wing failures, 1 down in Canadian TX.  All of the three point to wing failures, add 2 to it and it brings us up to 5 Zodiac XL's with apparent wing failures.  In an approximately 2 or so year span.  How many Zodiac XL's are flying?  FAA (which only shows registrations for US owned) shows about 225 or so.  If we assume ( and this is a giant assumption) that the US market represents 60-70% of all Zodiac flying Zodiac XL's to about 3-400 FLYING Zodiac XL's.  Can someone please substantiate or reject these approximations?  I don't even consider the HD in these numbers because the wing is an entirely different spar design (we are talking about wing failures not rudder failures) If it were rudder failures I would consider their flying numbers in my figures since they both use the same rudder. 



What is the average number of hours on each Zodiac XL at this point in time?  My guess would be about 150-200.  (This is only my wild guess). 



So is it safe to say that there is 1 wing failure per 15000 hrs flown in a Zodiac XL?  If you fly in a Zodiac for 500 hrs do you have an 3.3% chance of experiencing a wing failure?  



Guys I'm just trying to rattle around some numbers, I think my numbers are conservative.  (More zodiacs than there actually are flying, more hours on each than there actually are etc.)  



I feel confident that if there is a design flaw Zenith will address the issue appropriately, hopefully the wreckage is in such condition that it can yield better information than the other wrecks that were inconclusive due to post crash fire.  Hopefully the landing in the ocean in relatively shallow waters will allow for a more conclusive investigation.  My thoughts and prayers go out to the families.  



If only one good thing comes of this accident, please let it be that IF there is a design issue, that it can be addressed.

_________________
Zodiac 601 HD
Jabiru 3300
Wood Sensinich 64x47
Finally Flying

johnd(at)data-tech.com
Guest

Posted: Tue Mar 11, 2008 6:43 am Post subject: Accident

Hi Michael,



As a 601XL builder I too am concerned but would like to add a couple of 

data points to this discussion:



1. The accident in Canadian, TX looks like it involved thunderstorms and 

I've read lots of cases of certified aircraft with wings coming off in 

such cases. So I'm not sure we can really point to an unexpected wing 

failure in this case.



2. The recent Australian case hasn't been show to have been caused by a 

wing failure. I think folks are jumping the gun on this one. What 

strikes me as odd is that they have found pieces of the canopy over land 

which would seem indicate that the canopy was damaged early in the 

accident. The wing apparently wasn't found with this debris. I wonder 

about a bird strike in this one...It will be interesting to see what 

they find when they locate the plane. Apparently thats supposed to 

happen later this week when the bad weather they are having subsides...

John Davis

Burnsville, NC 28714

601XL - Jab 3300



MHerder wrote:

 	  Quote: 	
		   



 Disclaimer:  The information contained below is filled with my own personal assumptions, many of which may not be correct (I am only trying to use my best logic)  I do not wish to be involved in a flaming session since this is a very touchy subject for those of us (myself included) who truly take pride in their project and enjoy every second of working on their project and have invested a large amount of time and money.  I am only trying to ask some questions and get others opinions as to whether or not my assumptions are logical or reasonable.



 Does anyone know if the incident in Spain and Australia involved the UL version of the XL, or the UL version of the HD.  Zenair apparently manufactures the "ultralight" version for the euro market ( I don't know what is required in Australia).  As a builder I am deeply concerned, my condolences go out to the families effected.  



 The reason I ask is that the UL version is about 200 or so pounds less (gross weight).  I look at the structure of my aircraft under construction and wonder where the hell I could take out such a significant amount of weight without making sacrifices somewhere.  (Lighter landing gear seems to be the largest component)



 I DO NOT believe that Zenith is marketing and selling a dangerous design.  Someone once pointed out that all of the significant fly in the XL frequently, which I think is a very valid point. 



 However, I was more easily able to dismiss the first two or so incidents.  This latest series is especially bothersome.



 My searches find 2 down in Cali with apparent wing failures, 1 down in Canadian TX.  All of the three point to wing failures, add 2 to it and it brings us up to 5 Zodiac XL's with apparent wing failures.  In an approximately 2 or so year span.  How many Zodiac XL's are flying?  FAA (which only shows registrations for US owned) shows about 225 or so.  If we assume ( and this is a giant assumption) that the US market represents 60-70% of all Zodiac flying Zodiac XL's to about 3-400 FLYING Zodiac XL's.  Can someone please substantiate or reject these approximations?  I don't even consider the HD in these numbers because the wing is an entirely different spar design (we are talking about wing failures not rudder failures) If it were rudder failures I would consider their flying numbers in my figures since they both use the same rudder. 



 What is the average number of hours on each Zodiac XL at this point in time?  My guess would be about 150-200.  (This is only my wild guess). 



 So is it safe to say that there is 1 wing failure per 15000 hrs flown in a Zodiac XL?  If you fly in a Zodiac for 500 hrs do you have an 3.3% chance of experiencing a wing failure?  



 Guys I'm just trying to rattle around some numbers, I think my numbers are conservative.  (More zodiacs than there actually are flying, more hours on each than there actually are etc.)  



 I feel confident that if there is a design flaw Zenith will address the issue appropriately, hopefully the wreckage is in such condition that it can yield better information than the other wrecks that were inconclusive due to post crash fire.  Hopefully the landing in the ocean in relatively shallow waters will allow for a more conclusive investigation.  My thoughts and prayers go out to the families.  



 If only one good thing comes of this accident, please let it be that IF there is a design issue, that it can be addressed.



 --------

 One Rivet at a Time!





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=168995#168995

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Tue Mar 11, 2008 7:00 am Post subject: Re: Accident

I'm going to install a BRS chute for sure.



 	  nyterminat(at)aol.com wrote: 	
		  Andy, What no BRS chute????????????????

   	  Quote: 	
		   	  Quote: 	
		  --> Zenith-List message posted by: "ashontz" <ashontz>



Regardless, I'm adding extra ribs, going with the 12 gallon tanks instead of the 

15, no wing-locker, and some sort of overridable system that limits control 

surface/stick travel at and above manuevering speed.

Kevin Bonds wrote:

	
	


 

 

 --

Tim Juhl

Joined: 21 Mar 2006
Posts: 488
Location: "Thumb" of Michigan

Posted: Tue Mar 11, 2008 7:02 am Post subject: Re: Accident

Regarding the article that Joe shared with us about the Australian crash, a bird strike was the first thought that came to my mind when I heard of pieces of the canopy ending up on shore, far from where the plane went in.  At the altitude the plane was at if the pilot took a bird in the face he might not have had much time to react and could easily have lost control.



We had an incident at our local airport where a Beech Sundowner being flown by a student with his instructor hit a bird (maybe Canada Goose) on final approach at night.  He was going about 80 mph when he experienced an impact that slewed the plane around.  He later said he thought he'd hit a skydiver.  Upon landing a hole was found in wing skin just outboard of the fuel tank from the leading edge to the spar and beyond.  It was big enough to stuff a frozen turkey into.  The way the skin was peeled you would have thought he'd taken an artillery round.  The insurance company decided to replace rather than repair the wing.



A bird strike may not be responsible for the tragedy in Australia but it points out that we all need to be especially vigilant when flying in areas frequented by large fowl.  I don't have a picture of the damaged wing but here is a shot of what a bird did to a Cherokee windshield.



Tim (who lives near a major migratory bird route)

birdstrike.jpg

Description:

Filesize:

65.87 KB

Viewed:

721 Time(s)

_________________
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Almost done! It'll fly in spring!

MHerder

Joined: 11 Feb 2008
Posts: 143
Location: Fort Worth TX

Posted: Tue Mar 11, 2008 7:40 am Post subject: Re: Accident

John,



Regarding Note 1.  I concur, (this incident seems to have the most plausible explanation, simply flying in adverse conditions).  However, you mention that "a lot of cases" of wing failures can be found in certified aircraft.  I was quite surprised to find how few there really were.  Perhaps my search parameters could be tight but when searching key words like wing failure, in flight break up etc not too many come up.



Note 2



Yes a bird strike is certainly a possibility, Mythbusters has some dramatic showing videos that show the potential damage from a bird strike.   A million things COULD have happened, but there appears to be a common thread in witness descriptions.  Yes, I agree I wouldn't bet two cents on a witnesses ability to truly give the type of information necessary to actually find cause.  However, all of the accounts seem to be consistent.  Loud bang, wing fold, spiral to ground.



 	  johnd(at)data-tech.com wrote: 	
		  Hi Michael,



As a 601XL builder I too am concerned but would like to add a couple of 

data points to this discussion:



1. The accident in Canadian, TX looks like it involved thunderstorms and 

I've read lots of cases of certified aircraft with wings coming off in 

such cases. So I'm not sure we can really point to an unexpected wing 

failure in this case.



2. The recent Australian case hasn't been show to have been caused by a 

wing failure. I think folks are jumping the gun on this one. What 

strikes me as odd is that they have found pieces of the canopy over land 

which would seem indicate that the canopy was damaged early in the 

accident. The wing apparently wasn't found with this debris. I wonder 

about a bird strike in this one...It will be interesting to see what 

they find when they locate the plane. Apparently thats supposed to 

happen later this week when the bad weather they are having subsides...

John Davis

Burnsville, NC 28714

601XL - Jab 3300



MHerder wrote:

 	  Quote: 	
		   



 Disclaimer:  The information contained below is filled with my own personal assumptions, many of which may not be correct (I am only trying to use my best logic)  I do not wish to be involved in a flaming session since this is a very touchy subject for those of us (myself included) who truly take pride in their project and enjoy every second of working on their project and have invested a large amount of time and money.  I am only trying to ask some questions and get others opinions as to whether or not my assumptions are logical or reasonable.



 Does anyone know if the incident in Spain and Australia involved the UL version of the XL, or the UL version of the HD.  Zenair apparently manufactures the "ultralight" version for the euro market ( I don't know what is required in Australia).  As a builder I am deeply concerned, my condolences go out to the families effected.  



 The reason I ask is that the UL version is about 200 or so pounds less (gross weight).  I look at the structure of my aircraft under construction and wonder where the hell I could take out such a significant amount of weight without making sacrifices somewhere.  (Lighter landing gear seems to be the largest component)



 I DO NOT believe that Zenith is marketing and selling a dangerous design.  Someone once pointed out that all of the significant fly in the XL frequently, which I think is a very valid point. 



 However, I was more easily able to dismiss the first two or so incidents.  This latest series is especially bothersome.



 My searches find 2 down in Cali with apparent wing failures, 1 down in Canadian TX.  All of the three point to wing failures, add 2 to it and it brings us up to 5 Zodiac XL's with apparent wing failures.  In an approximately 2 or so year span.  How many Zodiac XL's are flying?  FAA (which only shows registrations for US owned) shows about 225 or so.  If we assume ( and this is a giant assumption) that the US market represents 60-70% of all Zodiac flying Zodiac XL's to about 3-400 FLYING Zodiac XL's.  Can someone please substantiate or reject these approximations?  I don't even consider the HD in these numbers because the wing is an entirely different spar design (we are talking about wing failures not rudder failures) If it were rudder failures I would consider their flying numbers in my figures since they both use the same rudder. 



 What is the average number of hours on each Zodiac XL at this point in time?  My guess would be about 150-200.  (This is only my wild guess). 



 So is it safe to say that there is 1 wing failure per 15000 hrs flown in a Zodiac XL?  If you fly in a Zodiac for 500 hrs do you have an 3.3% chance of experiencing a wing failure?  



 Guys I'm just trying to rattle around some numbers, I think my numbers are conservative.  (More zodiacs than there actually are flying, more hours on each than there actually are etc.)  



 I feel confident that if there is a design flaw Zenith will address the issue appropriately, hopefully the wreckage is in such condition that it can yield better information than the other wrecks that were inconclusive due to post crash fire.  Hopefully the landing in the ocean in relatively shallow waters will allow for a more conclusive investigation.  My thoughts and prayers go out to the families.  



 If only one good thing comes of this accident, please let it be that IF there is a design issue, that it can be addressed.



 --------

 One Rivet at a Time!





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=168995#168995

_________________
Zodiac 601 HD
Jabiru 3300
Wood Sensinich 64x47
Finally Flying

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Tue Mar 11, 2008 7:50 am Post subject: Re: Accident

Considering it's an eye-witness account, can they really be sure they saw the explosion first. Most people I know who are not pilots don't watch planes overhead like pilots do. They'd only look up if something odd happened, like they heard a loud bang that actually occured 2.5 seconds beforehand, then they look up and see a plane with it's wing folded up, therefore, to the unwashed masses that means, loud bang, THEN wing fold.



 	  MHerder wrote: 	
		  John,



Regarding Note 1.  I concur, (this incident seems to have the most plausible explanation, simply flying in adverse conditions).  However, you mention that "a lot of cases" of wing failures can be found in certified aircraft.  I was quite surprised to find how few there really were.  Perhaps my search parameters could be tight but when searching key words like wing failure, in flight break up etc not too many come up.



Note 2



Yes a bird strike is certainly a possibility, Mythbusters has some dramatic showing videos that show the potential damage from a bird strike.   A million things COULD have happened, but there appears to be a common thread in witness descriptions.  Yes, I agree I wouldn't bet two cents on a witnesses ability to truly give the type of information necessary to actually find cause.  However, all of the accounts seem to be consistent.  Loud bang, wing fold, spiral to ground.



 	  johnd(at)data-tech.com wrote: 	
		  Hi Michael,



As a 601XL builder I too am concerned but would like to add a couple of 

data points to this discussion:



1. The accident in Canadian, TX looks like it involved thunderstorms and 

I've read lots of cases of certified aircraft with wings coming off in 

such cases. So I'm not sure we can really point to an unexpected wing 

failure in this case.



2. The recent Australian case hasn't been show to have been caused by a 

wing failure. I think folks are jumping the gun on this one. What 

strikes me as odd is that they have found pieces of the canopy over land 

which would seem indicate that the canopy was damaged early in the 

accident. The wing apparently wasn't found with this debris. I wonder 

about a bird strike in this one...It will be interesting to see what 

they find when they locate the plane. Apparently thats supposed to 

happen later this week when the bad weather they are having subsides...

John Davis

Burnsville, NC 28714

601XL - Jab 3300



MHerder wrote:

 	  Quote: 	
		   



 Disclaimer:  The information contained below is filled with my own personal assumptions, many of which may not be correct (I am only trying to use my best logic)  I do not wish to be involved in a flaming session since this is a very touchy subject for those of us (myself included) who truly take pride in their project and enjoy every second of working on their project and have invested a large amount of time and money.  I am only trying to ask some questions and get others opinions as to whether or not my assumptions are logical or reasonable.



 Does anyone know if the incident in Spain and Australia involved the UL version of the XL, or the UL version of the HD.  Zenair apparently manufactures the "ultralight" version for the euro market ( I don't know what is required in Australia).  As a builder I am deeply concerned, my condolences go out to the families effected.  



 The reason I ask is that the UL version is about 200 or so pounds less (gross weight).  I look at the structure of my aircraft under construction and wonder where the hell I could take out such a significant amount of weight without making sacrifices somewhere.  (Lighter landing gear seems to be the largest component)



 I DO NOT believe that Zenith is marketing and selling a dangerous design.  Someone once pointed out that all of the significant fly in the XL frequently, which I think is a very valid point. 



 However, I was more easily able to dismiss the first two or so incidents.  This latest series is especially bothersome.



 My searches find 2 down in Cali with apparent wing failures, 1 down in Canadian TX.  All of the three point to wing failures, add 2 to it and it brings us up to 5 Zodiac XL's with apparent wing failures.  In an approximately 2 or so year span.  How many Zodiac XL's are flying?  FAA (which only shows registrations for US owned) shows about 225 or so.  If we assume ( and this is a giant assumption) that the US market represents 60-70% of all Zodiac flying Zodiac XL's to about 3-400 FLYING Zodiac XL's.  Can someone please substantiate or reject these approximations?  I don't even consider the HD in these numbers because the wing is an entirely different spar design (we are talking about wing failures not rudder failures) If it were rudder failures I would consider their flying numbers in my figures since they both use the same rudder. 



 What is the average number of hours on each Zodiac XL at this point in time?  My guess would be about 150-200.  (This is only my wild guess). 



 So is it safe to say that there is 1 wing failure per 15000 hrs flown in a Zodiac XL?  If you fly in a Zodiac for 500 hrs do you have an 3.3% chance of experiencing a wing failure?  



 Guys I'm just trying to rattle around some numbers, I think my numbers are conservative.  (More zodiacs than there actually are flying, more hours on each than there actually are etc.)  



 I feel confident that if there is a design flaw Zenith will address the issue appropriately, hopefully the wreckage is in such condition that it can yield better information than the other wrecks that were inconclusive due to post crash fire.  Hopefully the landing in the ocean in relatively shallow waters will allow for a more conclusive investigation.  My thoughts and prayers go out to the families.  



 If only one good thing comes of this accident, please let it be that IF there is a design issue, that it can be addressed.



 --------

 One Rivet at a Time!





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=168995#168995

darrellhaas(at)gmail.com
Guest

Posted: Tue Mar 11, 2008 9:17 am Post subject: accident

It looked like that to me also. And the trim for the canopy was up.

Darrell

do not archive



On 3/11/08, alex trent <atrent8(at)cogeco.ca> wrote:

 	  Quote: 	
		   



  Looking at the photo, at this link, it appears that both wings are still attached???????????



  Time: 01:47:19 PM PST US

  From: William Dominguez <bill_dom(at)yahoo.com>

  Subject: Re: Re: Accident in Spain was a Zodiac 601XL and there is

  a picture.



  I found this from from the accident page of ultraligero.net, the entry is at the

  bottom:



  http://www.ultraligero.net/Accidentes/08.htm

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Tue Mar 11, 2008 9:17 am Post subject: Re: Accident

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.

Last edited by ashontz on Tue Mar 11, 2008 9:33 am; edited 1 time in total

rhodes1

Joined: 15 Feb 2008
Posts: 20
Location: Us

Posted: Tue Mar 11, 2008 9:18 am Post subject: Accident

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

--

Iberplanes

Joined: 10 Dec 2007
Posts: 174
Location: Igualada - Barcelona - Spain

Posted: Tue Mar 11, 2008 9:50 am Post subject: accident

Absolutely right, both wings were attached. Apparently they went beyond VNE. 

Still waiting the final report. The canopy was found 150 mts away from the 

plane, in the middle of a town.



Many witness said they´ve heard and explosion (probably the canopy) followed 

by a plane falling on an spiral. (Sorry, my English in this case sucks)



---

_________________
Alberto Martin
601 XL - Jabiru 3300
http://www.iberplanes.es
Igualada - Barcelona - Spain

johnd(at)data-tech.com
Guest

Posted: Tue Mar 11, 2008 10:02 am Post subject: Accident

Hi,



Here's a C150 that lost both its wings last year in Virginia : 

http://ntsb.gov/ntsb/brief.asp?ev_id 060917X01355&key=1.



Scott Crossfields  Cessna 210 also experienced an in flight breakup due 

to WX: http://ntsb.gov/ntsb/brief.asp?ev_id 060501X00494&key=1



and a 172 in GA that brokeup: 

http://ntsb.gov/ntsb/brief.asp?ev_id 030325X00386&key=1



And there are more if you look at the ntsb.gov database. I know its easy 

to get all hyped up with conjecture about these accidents but its 

important to stick with the facts that we have as well. Certificated 

aircraft do have accidents involving in-flight breakups, some due to 

pilot's overstressing the airframe, weather induced failures, shear 

stupidity on the pilots part, etc.



I do wish we really had some facts in the 601XL cases so we could put 

this whole issue to rest one way or the other.



John

ella wrote:

[quote] 



 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

 --

rpf(at)wi.rr.com
Guest

Posted: Tue Mar 11, 2008 10:05 am Post subject: accident

There are two photos in that attachment.  This first one is not a 601xl, the 

airfoil is much thinner than an XL.



Randy

---

bill_dom(at)yahoo.com
Guest

Posted: Tue Mar 11, 2008 10:25 am Post subject: accident

It looks like the plane is resting on the left side of the fuselage with both wings folded up in relation to the plane. The leading edge skin seem to be missing from the most part exposing the main spar. Strangely enough, the stabilizer an elevator can be seen intact in a vertical position in the background. The front wheel is pointing to the left side.



Something to keep in mind about this accident is that some of the news that cover it didn't mention a wing failure but an engine failure as the cause.



William Dominguez

Zodiac 601XL Plans

Miami Florida

http://www.geocities.com/bill_dom



Darrell Haas <darrellhaas(at)gmail.com> wrote:[quote] --> Zenith-List message posted by: "Darrell Haas" 



It looked like that to me also. And the trim for the canopy was up.

Darrell

do not [quote][b]

swater6

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

Posted: Tue Mar 11, 2008 10:49 am Post subject: Re: Accident

OK, I hate these accident discussions because they are full of conjecture, assumptions, false information and all sorts of wild guesses from people who know little or nothing. The more we talk about "what-ifs' and possible design flaws the more scared we get and scared is not good.  



We are pilots and we should mitigate risk to the best of our ability and accept the rest or don't fly.  So, as builders we do the same.  I mitigated risk by choosing an airframe and engine design with many examples flying from a designer and company with excellent history. I accept the other risks that I cannot control.



Now, hearing about accidents makes us take notice.  We should take notice so that we can learn from them if possible.  Clearly, it seems unusually to hear more than one structural failure and we want to know if it was the pilot or the design.  Personally, I haven't seen enough evidence to make me scrap my 75% completed airplane. But, for those of you that are new or just forgot, below are the facts from the FAA and NTSB databases. You can look them up if you want.



As of today, there are 239 registered 601 XL's in the United States. 

-51 are made by AMD

-3 are made by CAW

-185 are amateur built 



In the last 2 years, there have been 5 (FIVE) fatal accidents:

11/2/07- 1st flight AB-Exp. on take-off rolled left into terrain. 

5/2/07-In flight break-up. AB-Exp 1 year sport pilot flew into IMC in heavy rain and possible convective activity (ie thundersorm)

11/11/06- CAW SLW- Fuel exhaustion (empty tanks) flew into trees

11/4/06-AMD In flight break-up. 

2/8/06-AB-Exp first flight by new owner and CFI. NTSB probable cause: Structural failure of wing for unknown reasons. (This is the accident that prompted the additional wing testing for positive G's and the letter from Chris Hientz warning pilots of abrupt full elevator deflection) 



Now, my advise to myself until I know more is to realize this:  The XL flies about as fast as the 172 I fly and weighs half as much.  It is a "light" sport plane and when I fly it, I will fly it carefully and well within the normal envelope.  I'll put gas in it, I won't fly into thunderstorms, I will get transition training and I will maintain it to the highest standards. 



That's it, my lunch hour is over....carry on......

Scott 



PS, I don't know how many RV's there are registered but 27 fatal accidents in the same period with one wing falure...

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

www.scottwaters.com

n85ae

Joined: 14 Mar 2007
Posts: 403

Posted: Tue Mar 11, 2008 12:08 pm Post subject: Re: Accident

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.

Larry Hursh

Joined: 16 Feb 2008
Posts: 125
Location: Edwardsburg, MI (near Elkhart, IN)

Posted: Tue Mar 11, 2008 12:12 pm Post subject: Accident

Thanks Scott for the snap back to reality.  It DOES tend to work on one's brain when you hear so much gloom and doom.  Flight IS inherently dangerous.  So is crossing the street and driving a car or riding in one.  I for one take a lot of what I read as simply "information".  If I didn't, I would be staying home an awfully lot.......and selling my XL immediately, then going back to bed so I don't risk hurting myself by going up and down my stairs to work on the Zodiac.

   

  Thanks for the reality check - I think we all needed it.

   

  Larry H



swater6 <waters.scott(at)comcast.net> wrote:

  [quote]--> Zenith-List message posted by: "swater6" 



OK, I hate these accident discussions because they are full of conjecture, assumptions, false  information and all sorts of wild guesses from people who know little or nothing. The more we talk about "what-ifs' and possible design flaws the more scared we get and scared is not good. 



We are pilots and we should mitigate risk to the best of our ability and accept the rest or don't fly. So, as builders we do the same. I mitigated risk by choosing an airframe and engine design with many examples flying from a designer and company with excellent history. I accept the other risks that I cannot control.



Now, hearing about accidents makes us take notice. We should take notice so that we can learn from them if possible. Clearly, it seems unusually to hear more than one structural failure and we want to know if it was the pilot or the design. Personally, I haven't seen enough evidence to make me scrap my 75% completed airplane. But, for those of you that are new or just forgot, below are the facts from the FAA and NTSB databases. You can look them up if you  want.



As of today, there are 239 registered 601 XL's in the United States. 

-51 are made by AMD

-3 are made by CAW

-185 are amateur built 



In the last 2 years, there have been 5 (FIVE) fatal accidents:

11/2/07- 1st flight AB-Exp. on take-off rolled left into terrain. 

5/2/07-In flight break-up. AB-Exp 1 year sport pilot flew into IMC in heavy rain and possible convective activity (ie thundersorm)

11/11/06- CAW SLW- Fuel exhaustion (empty tanks) flew into trees

11/4/06-AMD In flight break-up. 

2/8/06-AB-Exp first flight by new owner and CFI. NTSB probable cause: Structural failure of wing for unknown reasons. (This is the accident that prompted the additional wing testing for positive G's and the letter from Chris Hientz warning pilots of abrupt full elevator deflection) 



Now, my advise to myself until I know more is to realize this: The XL flies about as fast as the 172 I fly and weighs half as much. It is a "light" sport plane      [quote][b]

_________________
Larry Hursh (N650LM Reserved)

"One rivet at a time......one day at a time.."

CH650 (Converted from CH601XL)
1/2 done with fuselage
will be Corvair Powered

Larry Hursh

Joined: 16 Feb 2008
Posts: 125
Location: Edwardsburg, MI (near Elkhart, IN)

Posted: Tue Mar 11, 2008 12:18 pm Post subject: accident

If it was an engine failure, the plane wouldn't be plunging to the ground nose down unless the pilot lost all his airspeed and stalled it out.  My question is, if there was a strike on the canopy and its destroyed, how does that change the characteristics of the airfoil and its ability to provide lift?  Is there such a thing as a stronger, more durable canopy available than what is provided in the kit??  If so, I would be very interested in purchasing one of them.

   

  Things to ponder

  Larry H



William Dominguez <bill_dom(at)yahoo.com> wrote:

  [quote]It looks like the plane is resting on the left side of the fuselage with both wings folded up in relation to the plane. The leading edge skin seem to be missing from the most part exposing the main spar. Strangely enough, the stabilizer an elevator [quote][b]

_________________
Larry Hursh (N650LM Reserved)

"One rivet at a time......one day at a time.."

CH650 (Converted from CH601XL)
1/2 done with fuselage
will be Corvair Powered

Kevin Bonds

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

Posted: Tue Mar 11, 2008 12:49 pm Post subject: Accident

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. So 

far, the "wild guesses" that have been made, have been made without 

stating them as facts. I think everyone is prefacing there opinions as 

such. The point of my last email, was to present an argument against 

armchair engineering. There is going to be some misstatements and 

misunderstandings. I think that is par for the course. But at this 

point, I don't think we should avoid the discussion entirely.



I'm ashamed to say that I have been inclined, in the past, to let 

misstatements, on this list, go unchecked, just because I didn't want to 

be the one to open the flood gates. This is bad on my part. I'm never 

sure when to comment and when not too. Someone always seems to complain 

when you do, but sometimes its necessary.



Kevin Bonds



swater6 wrote:

 	  Quote: 	
		   



 OK, I hate these accident discussions because they are full of conjecture, assumptions, false information and all sorts of wild guesses from people who know little or nothing. The more we talk about

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

Iberplanes

Joined: 10 Dec 2007
Posts: 174
Location: Igualada - Barcelona - Spain

Posted: Tue Mar 11, 2008 12:49 pm Post subject: accident

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]   ---

_________________
Alberto Martin
601 XL - Jabiru 3300
http://www.iberplanes.es
Igualada - Barcelona - Spain

Iberplanes

Joined: 10 Dec 2007
Posts: 174
Location: Igualada - Barcelona - Spain

Posted: Tue Mar 11, 2008 12:56 pm Post subject: Accident

Videos. 

  

  

 http://www.atlas-news.com/videos/streaming/adsl/nacional/2008/02/06/video_23021.shtml

  

 http://www.youtube.com/watch?v=E_FItiO6Xxc&feature=user

  

  

  

 Alberto Martin

Iberplanes IGL 

http://www.iberplanes.es

Igualada -  Barcelona - España



   [quote][b]

_________________
Alberto Martin
601 XL - Jabiru 3300
http://www.iberplanes.es
Igualada - Barcelona - Spain

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith-List	All times are GMT - 8 Hours Goto page Previous 1, 2, 3, 4, 5, 6, 7, 8 Next
Page 2 of 8

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum