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XL wing fold in flight

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kitfoxuk(at)btinternet.co
Guest

Posted: Sat Oct 25, 2008 1:39 pm Post subject: XL wing fold in flight

Hi XL owners/operators

 This is my first posting, as iam consideringbuying an XL (already built)

  

 I have heard that 7 Zodiacs have had the wings fold in flight due to structual failure, maybe inside or outside the flight envelope. The lastest happen in Holland in the last week, with unfortunately 2 killed. Zodiacs are grounded in Holland at the moment

  

 Can anyone shed any light on this issue, and should i be concerned in purchasing an XL? I am an experienced pilot of 20 years, and fly straight and level, generally in crusing mode

  

 thanks in advance

 roger 

 [quote][b]

swater6

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

Posted: Sat Oct 25, 2008 3:38 pm Post subject: Re: XL wing fold in flight

Roger,

You've just opened Pandora's box.  Who knows what responses will follow and you'll see many varied opinions.  Since the NTSB reports are not final for the two recent LSA accidents, you'll have to guess like the rest of us.



Here is some simple advice. Pretend you're about to go on a flight and you're looking at the weather.  Take in all of the information you can find and YOU determine if what you see falls within your personal minimums. 



Your minimums will be different than others. Not wrong, just different.  



Best of luck.

Scott

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

www.scottwaters.com

tigerrick(at)mindspring.c
Guest

Posted: Sat Oct 25, 2008 7:32 pm Post subject: XL wing fold in flight

Hi, Roger.



If you search the archives, I'm sure you'll have no trouble finding all sorts of posts containing everything from informed opinion to wild speculation. As you probably already know, a group recently splintered off to form its own investigative list and solicited funds to perform an independent stress analysis of the wing, spar, and fuselage attach points. Haven't yet heard anything concrete from their findings.



If you scratch a bit below the "7 crashed 601s involving wing folding / failure," you'll find that the accidents in question don't (yet) have an obvious failure mode that ties them all together. It's most likely true that wing failure at the rear spar attach point is the ultimate catastrophic failure point after several suspect things happen to the airframe first. So far, the list seems to include accumulated airframe stress from unauthorized aerobatics, exceeding airframe design limits, sudden and excessive down elevator deflection, airframes constructed with lighter or inferior materials to meet non-U.S. standards for the desired category, runaway control surface flutter, and fretting from loose spar attach bolts. Those are just the ones I can recall off of the top of my head.



I do know that when I fly my own 601, these crashes lurk in the back of my mind at all times. On the other hand, I know my 601's airframe has made several long cross-country trips, one coast-to-coast, through all sorts of weather and turbulence and it still shows no signs anywhere of any accumulated stress risers or cracks, fretting, part deformation, flutter, or any other airframe anamoly. And I do check it carefully.



I also speak with the Heintz's on a semi-regular basis about this topic. They've been working diligently with the NTSB to come up with a common causal factor, so far without finding one. In this case, no news is actually good news. The 601 design has flown many tens of thousands of hours over the years, and so far, no single weak point has been fingered as the instigator in the 7 crashes. And my insurance for my 601 is only about $800 per year, so the underwriters still appear to have confidence in the design.



Frankly, there are quite a few people who are really spooked by these crashes, to the point of being afraid to fly in them anymore. There are a ton of 601s for sale, no doubt this fear has something to do with it. But the more I fly my own, the more confidence I have in it. However, I do a very thorough preflight, I don't get horsey on the controls, and I stay alert for anything that might fortell any sort of impending airframe failure.



And then I go fly and enjoy the heck out of it.



Rick Lindstrom

N42KP / ZenVair 601XL



--

chris Sinfield

Joined: 28 Nov 2006
Posts: 270
Location: Sydney Australia

Posted: Sun Oct 26, 2008 2:46 am Post subject: Re: XL wing fold in flight

You know

yesterday I flew in a mates Zodiac XL to get some practice before I flew my own. I did circuits, Stalls and cruised around for 1.5 hours with 2 people and full fuel. It was great. It sat on 110 knots would go to 120/ 130 KIAS easily in the cruse with the Jab3300.  No Flutter he now has 80 hours on his and is going away next weekend on his second major X country. He is very happy and So am I. Its a great 2 seater local and X country plane.



So far this week In Australia I have seen a Cessna, a Piper and a Robin all crash but no XL. Not to say it cant.

Chris.

GBzodiflyer

Joined: 22 Apr 2008
Posts: 7

Posted: Sun Oct 26, 2008 11:03 am Post subject: Re: XL wing fold in flight

Hi Roger,

good to see something from another interested party here in blighty .

I have around 500 hrs in 601 variants , 125 in my current home built 601xl, and as a uk laa inspector have overseen a good many.

I have to agree with the other guys replying to your question , they really are the gentlemans arm chair , i have the tail wheel version . i can only give it the thumbs up .

 As for the wing folding !!!!!!!.

its always there in the back of my mind , and it probably is the rear spar attach , i give mine a real good check over before and after flight, but all we can do is wait and see ? . personally i would like to see some more testing by CH , manufactured on the ground , trying to simulate what could be happening , with the resultant wing fold. i just hope that now the 650 is in production this on going problem dosent get put to the bottom of the pile . 

ps give me a call .



Gary   G-CECZ

austria

Joined: 09 Feb 2007
Posts: 7

Posted: Mon Oct 27, 2008 5:15 am Post subject: Re: XL wing fold in flight

Hello,

have a look on this page: http://www.geocities.com/mgd3/flying/flutter

The damage is like the same on the attached photo from a 601XL accident.



austria

zodiac file 030.jpg

Description:

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152.16 KB

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832 Time(s)

fderfler(at)gmail.com
Guest

Posted: Mon Oct 27, 2008 6:05 am Post subject: XL Wing Fold in Flight

Gary ... in Blighty.. a question for you.  You said, "...probably is the rear spar attach

, i give mine a real good check over before and after flight."

  

 How do you check it?  One puzzling thing about this broohaha is that no one has ever mentioned finding a crack, a wiggle, a squeak, on the ground.  If there was one clue found before or after floight then there would be none of this endless/useless speculation.  How would you check?   

   

 Frank Derfler

 Islamorada, Florida  

-- 

Twitter! Follow me at http://Twitter.com/Fderfler



See my new Novel, "A Glint in Time" at http://GreatGuyBooks.com. 

 

See my discussion of  All the Guy Toys that aren't (clearly) illegal or (blatantly) immoral at http://mostlyflying.com  



Anybody who READS (anybody out there?) See www.greatguybooks.com

 

  [quote][b]

jaybannist(at)cs.com
Guest

Posted: Mon Oct 27, 2008 6:20 am Post subject: XL Wing Fold in Flight

Frank,

 

 On my airplane, I torqued the attach bolts and put a spot of paint at the base of the nut.  Flaps down, I can check to see that the nut hasn't moved during pre-flight inspection.

 

 Jay in Dallas

 

   

 

   

 

 --

brianrobertwood(at)gmail.
Guest

Posted: Tue Oct 28, 2008 2:02 am Post subject: XL wing fold in flight

Here is a link to a you-tube video of a Zodiac XL 601 in Brazil that has  

aileron balance weights installed. I am not endorsing nor condemning the  

installation, I am not qualified to pass judgement, just for your  

information.



http://www.youtube.com/watch?v=q_D4bt0guvM&feature=related



Brian in Brazil



Em Mon, 27 Oct 2008 11:15:40 -0200, austria <kleinsaft(at)hotmail.com>  

escreveu:



 	  Quote: 	
		   



 Hello,

 have a look on this page: http://www.geocities.com/mgd3/flying/flutter

 The damage is like the same on the attached photo from a 601XL accident.



 austria





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 10488#210488





 Attachments:



 http://forums.matronics.com//files/zodiac_file_030_399.jpg




	


-- 

Usando o revolucionário cliente de e-mail do Opera:  

http://www.opera.com/mail/

willemdelange

Joined: 28 Oct 2008
Posts: 4

Posted: Tue Oct 28, 2008 7:11 am Post subject: Re: XL wing fold in flight

Supersedure:

Not applicable

Subject:

ZODIAC CH 601 XL (MICROLIGHTS OR HOMEBUILT AIRCRAFT) - GROUNDING

Applicability:

All Zodiac CH 601 XL (Micro Light or Homebuilt Aircraft)

Reason:

On the 14th of September 2008 a fatal accident occurred with a Micro Light Aircraft, Type Zodiac CH 601 XL. There are indications that break-up of the wing structure was the cause of the accident. Based on the preliminary findings of the accident investigation of the Dutch Safety Board, the Civil Aviation Authority of the Netherlands declares the aircraft not airworthy until further notice.

Effective date:

24 October 2008

Mandatory Actions and Compliance Times:

From the effective date of this AD, the aircraft is grounded and shall not be flown until appropriate action has been agreed in order to return the aircraft to airworthiness.

Reference Publication(s):

None

Remarks

_________________
Willem de Lange
CH601XL owner

willemdelange

Joined: 28 Oct 2008
Posts: 4

Posted: Tue Oct 28, 2008 8:16 am Post subject: Re: XL wing fold in flight

Quick and dirty translation with help of google

Willem, the Netherlands

Nederlands  Â» Engels  translate 

FACTUAL INFORMATION 

Proceedings of the flight 

The PH-4B6, a micro-light plane aero (MLA) of the brand and type Zenair Zodiac CH601 XL, take off from the airport Midden Meer (North-Holland).September 14, 2008 around 12:30 On board were two people: the owner / pilot and a passenger. 

After the take-off from run-way -05 the aircraft flew in a northeasterly direction north-east. At the height of the village Kreileroord a left turn of around 270 degrees was made which made the plane flew south to Medemblik. Above Medemblik a  360 turn was made. The height during this stage of the flight ranged between 1100 and 1300 ft. From the Medemblik the PH-4B6  flew to Hoorn. The plane then flew on to the  Lake of  Hoorn. The plane flew at an altitude of about 1000 ft. There were witnesses on the ground seeing that the right wing folded up and that the  plane crashed  in the water of the Marker Lake around 12:47. The two occupants did not survive the crash. 

RESEARCH 

A researcher of the research board has been  on the spot and after the saving of the wreck did an initial investigation. At a later time an extensive technical research was conducted with the help of a ground engineer. Later a part of the main spar of the right wing and the rear spar has been removed. Also the GPS unit and the speedometer where removed for further examination. The flight data mentioned in this report are drawn from the GPS unit. Through the Aviation Police witness statements were obtained. 

The PH-4B6 is a Zenair Zodiac CH601 XL. In 2000 this aircraft has been developed in the United States (U.S.) from earlier versions of the Zodiac CH601. The CH601 XL can be delivered as a "kit" in which the owner assembles the prefabricated parts or as  "ready to fly" where the aircraft has been  fully assembled and delivered by the manufacturer. In the U.S., this type of aircraft is accepted under the category "Light Sport Aircraft". One of the consequences is that the aircraft is not certified according to international airworthiness requirements. The manufacturer declares that the design meets the requirements for this category of aircraft and that the device is manufactured in accordance with an approved method. The maximum take-off mass of this aircraft in the U.S. is 595 kg. 

The same type of plane is built under license from the beginning of 2005 until the end of 2006 in the Czech Republic, in particular for the European market. To meet the criteria for European "Micro Light Airplane" (MLA) in the Czech Republic  a number of modifications where made to the model to the meet the requirement of a maximum take-off mass of 450 kg. The accidents PH-4B6 is a Czech Republic model. 

The model fabricated in the Czech Republic is tested by the "Deutsche Aeroclub" which resulted in  a so-called "GerÃ¤tekennblatt" was issued which stated that the German plane meets the airworthiness requirements for MLA's . In the Netherlands, among others this "GerÃ¤tekennblatt" is used by the Traffic and Water Management Inspectorate (IVW) to issue a "special airworthiness certificate" . 

The same type of aircraft can also be registered as a "home built" aircraft in the Dutch aircraft register. In that case, the aircraft meets the requirements of amateur aircraft construction standards. The statutory requirement of a maximum take-off mass of 450 kg it expires. 

The preliminary investigation shows the following: 

â€¢ 

In the Dutch aircraft registry offers 12 aircraft of the type which registered CH601 XL 8 as MLA and 4 are home built.  In addition, we have 15 registered aircraft of the type CH601 HD, HDS and UL. These are other versions of the type CH601. 

â€¢ 

The PH-4B6 aircraft had a valid "special certificate of airworthiness." 

â€¢ 

A calculation shows that the mass of the airplane at the start probably at or slightly above the maximum allowable off mass of 450 kg. 

â€¢ 

After reading from the GPS unit showed that the aircraft has made no extreme movements and just before the time of the accident a straight flight at about 1000 ft exported. 

â€¢ 

The right wing moved up during the flight and folded back with the top of the wing folded on  the top of the fuselage behind the canopy. 

â€¢ 

The right wing is not broken. 

â€¢ 

The upper reinforcement of the main spar of the right wing is kinked and twisted, just before the wing-fuselage attachment. 

â€¢ 

The bottom reinforcement of the main beam of the right wing is twisted, just before the wing-fuselage confirmation. 

â€¢ 

The acting load factor of the wings was far below the permissible load factor. 

â€¢ 

Data from the Royal Netherlands Meteorological Institute show that the wind at 1000 ft from the direction of 070 Â° blew with a force of 11 knots. The visibility was more than 10 kilometers and there was no turbulence. 

â€¢ 

From 2006 until today there have been at least seven accidents worldwide with Zenair Zodiac CH601 where one or both wings have collapsed due to overloading. These accidents have occurred in the United States, Britain and Spain. The investigation into this accident has not (yet) pointed to a single cause for the collapse of the wings. 

â€¢ 

A comprehensive examination design drawings of the U.S. draft has shown that the outcome of the strength calculations by the designer was probably too optimistic. 

PRELIMINARY CONCLUSION 

The study by the Research Council for Security to the cause of this accident is not yet completed. Nevertheless, the Council decided, in view of the seven similar incidents elsewhere in the world and pending the final results of his research, in this interim report all directly and indirectly involved must seriously warn against the obvious risks in the use of this type plane.

_________________
Willem de Lange
CH601XL owner

craig(at)craigandjean.com
Guest

Posted: Tue Oct 28, 2008 11:17 am Post subject: XL wing fold in flight

Key point is this:



"A comprehensive examination design drawings of the U.S. draft has shown that the outcome of the strength calculations by the designer was probably too optimistic."



How do we reconcile this with the actual load testing (which was said to have been conducted by an independent outside engineer)?



http://www.zenithair.com/zodiac/6-photo-testing.html



-- Craig



--

"z 601"(at)anem
Guest

Posted: Tue Oct 28, 2008 11:48 am Post subject: XL wing fold in flight

On Tuesday 28 October 2008 14:17, Craig Payne wrote:

 	  Quote: 	
		   

 <craig(at)craigandjean.com>



 Key point is this:



 "A comprehensive examination design drawings of the U.S. draft has shown

 that the outcome of the strength calculations by the designer was probably

 too optimistic."



 How do we reconcile this with the actual load testing (which was said to

 have been conducted by an independent outside engineer)?


	


Assuming there is a problem, the difference may lie in how the testing was 

done. The load testing I saw posted on the Zenith site appears to have been 

static, rather than dynamic, testing.

-- 

==============================================

Those who can, do. Those who can't, sue.

=================================================

               Jim B. Belcher

    BS, MS Physics, math, Computer Science

                  A&P/IA

           Instrument Rated Pilot

     General Radio Telephone Certificate

=================================================

tigerrick(at)mindspring.c
Guest

Posted: Tue Oct 28, 2008 11:51 am Post subject: XL wing fold in flight

If I didn't misread the translated accident report, it states that the accident aircraft "is a Czech Republic model."



I'm wondering how the construction differed to allow adequate useful load with the 450 kg weight limitation, especially  in the area of the rear spar fuselage attachment.



Rick



--

ch701builder(at)yahoo.com
Guest

Posted: Tue Oct 28, 2008 12:19 pm Post subject: XL wing fold in flight

Also, the link show not only static testing, but, for negative G's and not positive.

Also, wasn't there a mention about having to do design change to meet the European "Micro Light Airplane" MLA 450kg (992lbs) weight limit.



Keith

CH701 - scratch

do not archive

************************************************************************

From: Jim Belcher <z 601(at)anemicaardvark.com>

To: zenith601-list(at)matronics.com

Sent: Tuesday, October 28, 2008  1:49:27 PM

Subject: Re: Re: XL wing fold in flight



 --> Zenith601-List message posted by: Jim Belcher <"z 601"(at)anemicaardvark.com>



On Tuesday 28 October 2008 14:17, Craig Payne wrote:

 	  Quote: 	
		   --> Zenith601-List message posted by: "Craig Payne"

 <craig(at)craigandjean.com (craig(at)craigandjean.com)>



 Key point is this:



 "A comprehensive examination design drawings of the U.S. draft has shown

 that the outcome of the strength calculations by the designer was probably

 too optimistic."



 How do we reconcile this with the actual load testing (which was said to

 have been conducted by an independent outside engineer)?


	


Assuming there is a problem, the difference may lie in how the testing was 

done. The load testing I saw posted on the Zenith site appears to have been 

static, rather than dynamic, testing.

--           [quote][b]

z601(at)anemicaardvark.co
Guest

Posted: Tue Oct 28, 2008 12:48 pm Post subject: XL wing fold in flight

On Tuesday 28 October 2008 15:19, Keith Ashcraft wrote:

 	  Quote: 	
		   Also, the link show not only static testing, but, for negative G's and not

 positive. Also, wasn't there a mention about having to do design change to

 meet the European "Micro Light Airplane" MLA 450kg (992lbs) weight limit.


	


If I correctly understand, the weight limit in Europe is a part of their 

rules, and does not necessarily indicate a structural problem with the 

aircraft as it was designed for the U.S.



I believe the aircraft structure was changed somewhat to meet those standards. 

Thus, I am of the belief that we may need to sort the crashes into two piles: 

those of aircraft built to US standards, and those built to European 

standards.



In his July, 2007 letter, Chris Heintz stated:



"To 'certify' the CH601XL in the LSA category, a complete stress analysis was 

performed and confirmed for the positive loads be (sic) static tests. No 

permanent deformations were found at limit loads (i.e. +4 'g') and no 

failures at ultimate loads (i.e. +6 'g').  The bending deformations were in 

accordance with the analysis and the torsional deformations were barely 

measurable, removing the possibility wing or tail flutter."



While I find myself wondering how this proves the aircraft is not subject to 

flutter, since it is a static test, he does say the tests were performed at 

positive loads.



In March of this year, Heintz further stated:



"Among the aircraft that have experienced an in-flight break-up, all appear to 

have been subjected to severe structural loads that are consistend with 

"over-controlling" the aircraft. More specifically, and based on the 

(limited) information I have, most accidents linked with a break-up suggest 

excessive negative G forces caused, in whole or in part, by extreme elevator 

input from the pilot and/or occupant of the aircraft..."



Obviously, this doesn't include the most recent accidents. I suspect his mod 

to limit rudder travel was intended to make it more difficult to overcontrol 

the aircraft. It does suggest that the aircraft may  not like negative G 

loads.



There are videos of pilots performing acrobatics in the aircraft, making me 

wonder how widespread this practice may be. 

-- 

==============================================

Those who can, do. Those who can't, sue.

=================================================

               Jim B. Belcher

    BS, MS Physics, math, Computer Science

                  A&P/IA

           Instrument Rated Pilot

     General Radio Telephone Certificate

=================================================

willemdelange

Joined: 28 Oct 2008
Posts: 4

Posted: Thu Oct 30, 2008 3:28 am Post subject: Re: XL wing fold in flight

keith, the european design is not really different from the US version, the wing construction and the fuselage is the same. Just the main landing gear is of composite and the wheels some lighter.  This is because the empty weight must be around 290 kg to meet the European regulations. The lower MTOW is just a matter of regulation.

Other European changes are in details in the canopy, instrument panel and firewall forward.



The 650 has the same wing design as the XL so I expect here the same problems.



Willem



The Netherlands.

_________________
Willem de Lange
CH601XL owner

maarten versteeg

Joined: 15 May 2007
Posts: 37
Location: San Antonio

Posted: Thu Oct 30, 2008 4:37 am Post subject: XL wing fold in flight

Hello All,



As a native Dutch speaker living in Texas I looked at the original text:

 	  Quote: 	
		   Uit een globaal onderzoek van de onderwerptekeningen van het 

 Amerikaanseontwerp is naar

 voren gekomen dat de uitkomst van de sterkteberekeningen door de 

 ontwerper wellicht te

 optimistisch was.

and the word 'globaal' does not equate in a 'comprehensive', as in 
	


covering completely or

based on a full grasp, (of the) investigation. It could actually  be 

translated as 'cursory', as in

quick initial examination of the plans, suggesting that a more complete 

investigation is going

to follow.

This just to make sure that the intend of the message is not lost in 

translation. Clearly this

doesn't say anything about the conclusion which may or may not be valid.



Regards,

    Maarten Versteeg



plans build 601XL, about to finish the second wing



 	  Quote: 	
		   Time: 12:48:42 PM PST US From: Jim Belcher <"z 

 601"(at)anemicaardvark.com> Subject: Re: Re: XL wing fold 

 in flight On Tuesday 28 October 2008 14:17, Craig Payne wrote:

> > <craig(at)craigandjean.com>

> >

> > Key point is this:

> >

> > "A comprehensive examination design drawings of the U.S. draft has shown

> > that the outcome of the strength calculations by the designer was probably

> > too optimistic."

> >

> > How do we reconcile this with the actual load testing (which was said to

> > have been conducted by an independent outside engineer)?

>     



 Assuming there is a problem, the difference may lie in how the testing was 

 done. The load testing I saw posted on the Zenith site appears to have been 

 static, rather than dynamic, testing.

 -- ============================================= Those who can, do. 

 Those who can't, sue. ================================================

Those who can do, Those who can't simulate

_________________
Maarten Versteeg
601XL scratch building wings

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