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rbe21716(at)bigpond.net.a
Guest

Posted: Sat Dec 20, 2008 5:16 am Post subject: 601 problems

Well Hi all I wish every one a merry  Christmas 

  

 I would like to make a few observations  

  

 1/

 OK lack of communication that's a problem  ??? 

 Chris and the boys need to let us know  more

  

 2/

  if there isn't any problems come out and tell  the customers  that have spent there savings on there kits and that would  be the end of the story for me

  

 3/

 if there is a problem tell us so we can fix  it

 when its all said and done I want is to be  able to put one of my children in the seat next to me and feel safe doing  so 

  

 4/

   so at the end of the day all I want is a yes  or no either way I will be able to fix the problems  and be happy  doing so 

  

  

      

 

   [quote][b]

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Sat Dec 20, 2008 11:31 am Post subject: 601 problems

First of all, this list is not an official outlet for news and  

information from Zenith Aircraft, so any information you get from  

Zenith on this list will probably be second hand. The official outlets  

for information from Zenith are the newsletter and the Zenith website.  

Through these official channels, some information has been reported  

about these accidents. Zenith is actively participating with the NTSB  

and FAA in the investigation of these accidents. Unfortunately, since  

two of these accidents are still under investigation here in the U.  

S., the information that can be released is limited.



One thing that has been stated is that no common link has been found  

in these accidents that would point to a design flaw. They have also  

stated that flutter is suspected in some of the accidents. A big  

problem with determining the cause of these accidents is that there  

are many different ways an airplane structure can be made to fail and  

it's not easy to figure out what exactly happened when all you have to  

go on is a pile of wreckage. You have to sort out the damage that  

happened on impact from the damage that happened before impact.



Most of the accidents occurred with the airplane loaded near or above  

gross weight with two people aboard, two accidents occurred with one  

person aboard.



As I recall, two of the accidents that happened in Europe (Spain and  

France) were linked to structural overload due to pilot error in the  

official accident investigations. The pilots apparently pulled up hard  

from shallow dives. This is not from first hand knowledge on my part  

so it could be in error.



The accident in England that was apparently cited in the Dutch  

grounding was not a 601XL, it was a 601UL. It was also reported as  

structural overload due to pilot error. The pilot reportedly made a  

hard pull up to avoid power lines after making a high speed pass.



The Canadian, Texas accident occurred after a sport pilot took off  

into a low ceiling with heavy rain and lightning in the vicinity. It  

was also linked to pilot error in the NTSB report. The National  

Transportation Safety Board determines the probable cause(s) of this  

accident as follows: "The pilot's improper pre-flight planning and  

decision to depart into deteriorating weather conditions, which  

resulted in a loss of control and subsequent in-flight break up." NTSB  

Identification: DFW07LA102, Aircraft: Walker Zenith Zodiac 601 XL,  

registration: N10028



So about half of the reported accidents have been somehow linked to  

pilot error.



The Oakdale, California accident occurred on the first flight by the  

new owner after buying the airplane from the original builder. It was  

also the first flight after a major modification was made to the  

airplane. A co-pilot brake system was installed requiring removal and  

reinstallation of the control sticks and rudder bars. A post crash  

fire destroyed much of the wreckage and no definite cause was found  

for the crash. If you can believe the eye witness reports though,  

flutter is a good possibility here. NTSB Identification: LAX07FA026,  

Aircraft: Hooker Zodiac 601XL, registration: N105RH



The NTSB report of the Yuba City accident contains a great deal of  

information. This accident appears to be very different from most of  

the others in that the airplane broke up into several major pieces in  

the air which then impacted separately over a large area on the  

ground. Based on the description of the wreckage, it appears that the  

airplane failed from a negative G overload. The reported radar  

tracking seems to confirm this. Within a half minute or so the plane  

went from level flight to a 700 ft/min climb to 2000 ft/min descent.  

This accident is still under investigation.  NTSB Identification:  

LAX07FA026, Aircraft: Aircraft Mfg & Dev. Co. (AMD) CH601XL SLSA,  

registration: N158MD.



The Polk City accident aircraft had one person aboard but may have  

been heavily loaded because he was on a long cross country trip to the  

Sun'N'Fun air show, the report doesn't mention weight and balance  

data. It's still under investigation. NTSB Identification: NYC08FA158,  

Aircraft: Chech Aircraft Works SPOL SRO CH 601 XL RTF, registration:  

N357DT.



In my opinion, most of the accidents have been strongly linked to  

abrupt maneuvers or loss of control. As far as I can tell, only the  

Polk City, Oakdale and Netherlands accidents haven't yet been strongly  

linked to a possible reason for failure.



On Dec 20, 2008, at 8:15 AM, Russell Bell wrote:



 	  Quote: 	
		   Well Hi all I wish every one a merry Christmas



 I would like to make a few observations



 1/

 OK lack of communication that's a problem ???

 Chris and the boys need to let us know more



 2/

  if there isn't any problems come out and tell the customers  that  

 have spent there savings on there kits and that would be the end of  

 the story for me



 3/

 if there is a problem tell us so we can fix it

 when its all said and done I want is to be able to put one of my  

 children in the seat next to me and feel safe doing so



 4/

   so at the end of the day all I want is a yes or no either way I  

 will be able to fix the problems  and be happy doing so


	




-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

aerobat

Joined: 07 Nov 2008
Posts: 21
Location: UK

Posted: Sat Dec 20, 2008 11:34 am Post subject: Re: 601 problems

I think that deep down, as much as we love our XLs a lot of us feel there is a problem. 

Wings should not fall off aeroplanes, there must be many other types out there with incorrect cable tensions flying without dropping out of the sky.

Rumour has it that the UK LAA have voiced their concern to the designer who appears to deny any problem.

Unfortunately if something is not done history points to another XL wing failing in flight.

Last edited by aerobat on Sat Dec 20, 2008 1:17 pm; edited 1 time in total

jaybannist(at)cs.com
Guest

Posted: Sat Dec 20, 2008 11:50 am Post subject: 601 problems

aerobat (whoever you are),

 

 Where do you get this "we" stuff?  "We" don't all know there is a problem with the XL.  Maybe there is a problem with some of the XL pilots, but "we" are not all in agreement with you. 

 

 And please rumor out of any serious discussion of the XL.

 

 Jay in Dallas

 Do not archive

 

   

 

   

 

 --

aerobat

Joined: 07 Nov 2008
Posts: 21
Location: UK

Posted: Sat Dec 20, 2008 1:00 pm Post subject: Re: 601 problems

Apologies if I've touched a raw nerve, you may have 100 percent confidence in your XL but a lot of owners that I've talked to do not.

Heatonhe36(at)msn.com
Guest

Posted: Sat Dec 20, 2008 1:26 pm Post subject: 601 problems

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Mr. Aerobat,

  

 Are you, by any chance, familiar with the Bradley Aerobat?  No  insinuations...Just curious.

  

 Regards,

 Herb

 601XL from plans

  

 ---

aerobat

Joined: 07 Nov 2008
Posts: 21
Location: UK

Posted: Sat Dec 20, 2008 2:12 pm Post subject: Re: 601 problems

Sorry, no connection whatsoever.

Scotsman

Joined: 27 Aug 2007
Posts: 89
Location: Johannesburg, South Africa

Posted: Tue Dec 23, 2008 9:36 am Post subject: Re: 601 problems

While I don't necessarily agree with everything that Aerobat (regardless of his/her motives) has to say his/her comment "there must be many other types out there with incorrect cable tensions flying without dropping out of the sky" seems to bear some merit.



If cable tension was the single problem causing catastrophic failure then you would expect to see this alleged aileron flutter resulting in structural failure across numerous other types (both Zenith designs and other designs).  Since I do not observe this I consider that maybe the XL is particularly susceptible to a failure mode resultant from aileron flutter.



Furthermore, the potential for the wing folding incidents being exacerbated or caused by overloading thus should not be unique to the XL as many aircraft are often overloaded yet this does not appear to commonly lead to catastrophic failure.



Does anyone agree with the above thinking?

James Roberts



BTW - Yes I do own a XL kit which I am in the process of building (although currently stopped awaiting clarity on the matter) and this can be seen on the South African distributors website.

_________________
Cell +27 83 675 0815

larry(at)macsmachine.com
Guest

Posted: Tue Dec 23, 2008 2:18 pm Post subject: 601 problems

James,

I'd think if cable tension could become harmonic with the ailerons at a 

lesser tension than specified, the logical thing to do would be to place 

guides half or third the distance between ends to  keep

the cables from becoming a player in the harmonic situation. I don't use 

more than 25 lbs on any of my cables, but then it's a HDS and the 

conditions are slightly different.

Seriously doubt cable tension has anything to do with inducing or 

enlarging the frequency of wing flutter, even in the XL, but there's 

nothing wrong with being on the safe side.



Larry McFarland 601HDS at www.macsmachine.com



Scotsman wrote:

 	  Quote: 	
		   



 While I don't necessarily agree with everything that Aerobat (regardless of his/her motives) has to say his/her comment "there must be many other types out there with incorrect cable tensions flying without dropping out of the sky" seems to bear some merit.



 If cable tension was the single problem causing catastrophic failure then you would expect to see this alleged aileron flutter resulting in structural failure across numerous other types (both Zenith designs and other designs).  Since I do not observe this I consider that maybe the XL is particularly susceptible to a failure mode resultant from aileron flutter.



 Furthermore, the potential for the wing folding incidents being exacerbated or caused by overloading thus should not be unique to the XL as many aircraft are often overloaded yet this does not appear to commonly lead to catastrophic failure.



 Does anyone agree with the above thinking?

 James Roberts



 BTW - Yes I do own a XL kit which I am in the process of building (although currently stopped awaiting clarity on the matter) and this can be seen on the South African distributors website.



 --------

 Cell   +27 83 675 0815





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 20779#220779

planecrazydld(at)yahoo.co
Guest

Posted: Tue Dec 23, 2008 3:57 pm Post subject: 601 problems

...I keep mentioning the forward swept wing design - because it is real.



David L. Downey

  Harleysville (SE) PA, USA



  

--- On Tue, 12/23/08, LarryMcFarland <larry(at)macsmachine.com> wrote:

[quote]From: LarryMcFarland <larry(at)macsmachine.com>

Subject: Re: Re: 601 problems

To: zenith601-list(at)matronics.com

Date: Tuesday, December 23, 2008, 5:17 PM



[quote]--> Zenith601-List message posted by: LarryMcFarland

<larry(at)macsmachine.com>



James,

I'd think if cable tension could become harmonic with the ailerons at a 

lesser tension than specified, the logical thing to do would be to place 

guides half or third the distance between ends to   keep

the cables from becoming a player in the harmonic situation. I don't use 

more than 25 lbs on any of my cables, but then it's a HDS and the 

conditions are slightly different.

Seriously doubt cable tension has anything to do with inducing or 

enlarging the frequency of wing flutter, even in the XL, but there's 

nothing wrong with being on the safe side.



Larry McFarland 601HDS at www.macsmachine.com



Scotsman wrote:

 	  Quote: 	
		   --> Zenith601-List message posted by: "Scotsman"

<james.roberts(at)computershare.co.za>
	


 	  Quote: 	
		  

 While I don't necessarily agree with everything that Aerobat

(regardless of his/her motives) has to say his/her comment "there must be
	


many other types out there with incorrect cable tensions flying without dropping

out of the sky" seems to bear some merit.

 	  Quote: 	
		  

 If cable tension was the single problem causing catastrophic failure then

you would expect to see this  alleged aileron flutter resulting in structural
	


failure across numerous other types (both Zenith designs and other designs). 

Since I do not observe this I consider that maybe the XL is particularly

susceptible to a failure mode resultant from aileron flutter.

 	  Quote: 	
		  

 Furthermore, the potential for the wing folding incidents being

exacerbated or caused by overloading thus should not be unique to the XL as many
	


aircraft are often overloaded yet this does not appear to commonly lead to

catastrophic failure.

 	  Quote: 	
		  

 Does anyone agree with the above thinking?

 James Roberts



 BTW - Yes I do own a XL kit which I am in the process of building

(although currently stopped awaiting clarity on the matter) and this can be seen
	


on the South African distributors website.

[quote]

 --------

 Cell   +27 83 675 0815





 Read this topic online         [quote][b]

rans6andrew

Joined: 23 Nov 2008
Posts: 16
Location: Berks, UK

Posted: Tue Dec 23, 2008 4:03 pm Post subject: Re: 601 problems

I had been thinking along the same lines as Scotsman (who is from South Africa, apparently) and then I came around to comparing accident types and rates with other Zenair(ith) designs.



I don't know how many 601XLs there are out there or indeed how many 601HDs there are or 601ULs there are.  In the UK we currently have 20 XLs on the register, 28 ULs , 17 HD and 10 HDS  models.  So less than 30 % of the fleet is XL types.



Is this typical of the ratio in the world as a whole?



If it is, assuming that the same sort of people buy/build ULs, HDs, HDSs and XL varients, assuming that the same spread of pilot abilities, the same ratio of aerobatic wannabees buy each model and the same spread of builder competences we should be hearing about 3 times as many in flight break ups of the non XL types as XL types.



We don't.



In the UK we have had only one aircraft break up in flight, a UL, when it was observed to be beating up an airstrip and pulling up to avoid overhead power lines, with two people and significant fuel on board.  The investigation suggested that the pilot was in the habit of this type of flying and the airframe was overstressed on this or on a previous occasion leading to the failure.  This is the only non XL 601 in flight break up I have heard about.



Where are the others?



This line of thinking tells me that either I have missed something significant or that there is something peculiar to the XL.

Please correct me if there is a fatal flaw in my reasoning.



Oh, and feel free to flame me 'cos it seems to be par for the course if you post from the UK!

Andrew - in the UK and building a 601UL.

_________________
A good way through building a 601UL with 912UL.
Still flying Rans S6 with 503.

psm(at)att.net
Guest

Posted: Tue Dec 23, 2008 4:21 pm Post subject: 601 problems

Hi Andrew,



I think your reasoning is sound - at least to a point.  It also seems 

to me that there is something about the XL that makes it more 

susceptible to in flight structure failures.  I feel the number of 

failures is too high to be just random chance, but too low to 

indicate a simple design flaw.



While the various Zodiac models seem to be very similar there are a 

number of very significant differences between the XL and the other 

models.  The wings are much thinner, tapered and have a  single long 

main spar.  The other ones have much fatter constant chord wings with 

shorter spars.  The fuselage is a foot longer.  The interface between 

the wings and fuselage is completely different.  To make matters more 

interesting, I suspect the XL is considerably faster than the other 

models.  (I don't know this for sure because there doesn't seem to be 

reliable data about the speeds the builder community has achieved 

with any of the models.  This is compounded by the wide variety of 

power plants used.)



I feel there is a definite weakness in the XL structure that shows up 

extremely rarely.  If only the rocket scientists who analyze the 

failed structures could work their magic I feel this weakness would 

be found and corrected.  For now, I believe all we can do is wait for 

the experts to do their thing.



(No flame intended).



Paul

Camas, WA

do not archive

At 04:03 PM 12/23/2008, you wrote:



 	  Quote: 	
		  This line of thinking tells me that either I have missed something 

significant or that there is something peculiar to the XL.

jmaynard

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

Posted: Wed Dec 24, 2008 6:44 am Post subject: 601 problems

On Tue, Dec 23, 2008 at 04:03:09PM -0800, rans6andrew wrote:

 	  Quote: 	
		   Oh, and feel free to flame me 'cos it seems to be par for the course if

 you post from the UK!


	


It hasnothing to do with posting fromt he UK, and everything to do with

anonymously making nasty comments about the Zodiac.

-- 

Jay Maynard, K5ZC, PP-ASEL           http://www.conmicro.com

http://jmaynard.livejournal.com       http://www.tronguy.net

Fairmont, MN (KFRM)                        (Yes, that's me!)

AMD Zodiac CH601XLi N55ZC http://www.tronguy.net/N55ZC.shtml

_________________
Jay Maynard, K5ZC
AMD Zodiac XLi N55ZC

Scotsman

Joined: 27 Aug 2007
Posts: 89
Location: Johannesburg, South Africa

Posted: Wed Dec 24, 2008 7:29 am Post subject: Re: 601 problems

Yes I am currently based in South Africa for about the last seven years but originally from Scotland.



"It also seems to me that there is something about the XL that makes it more susceptible to in flight structure failures. I feel the number of 

failures is too high to be just random chance, but too low to 

indicate a simple design flaw"



I am glad that I am not the only person who feels this way and I believe that the above quote summarised it nicely.  To expand upon it I feel that aileron cable tension alone would be too "simple" a problem to be the only root cause of the in flight break ups otherwise similar numbers of failures would be observed in other types of aircraft.  



I sincerely hope that, collectively, the issue is resolved asap as I am feeling a bit miff at the moment with an expensive paperweight in my garage that I don't know whether or not to continue with (not forgetting the large financial outlay for the kit).  



I understand the frustrations of the UK guys as I am currently visiting family in the UK and was at a local airfield where one other builder has also left his project pending an outcome (in the same hangar another completed XL also sits grounded)...sad really.

James Roberts

_________________
Cell +27 83 675 0815

Iberplanes

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

Posted: Wed Dec 24, 2008 7:39 am Post subject: 601 problems

same here (Spain) , but the right place to make comments such as  the one made by our friend from the UK is the ZBAG yahoo group. 



http://groups.yahoo.com/group/ZBAG/

 

Hope to see you there !! 



Bye. 

Alberto Martin

www.iberplanes.es

Igualada - Barcelona - Spain



----------------------------------------------

Zodiac 601 XL Builder

 Serial: 6-7011



Tail Kit: Finished

Wings: Not Started

Fuselage: Ordered

Engine: Jabiru 3300

  [quote][b]

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

paulrod36(at)msn.com
Guest

Posted: Wed Dec 24, 2008 12:45 pm Post subject: 601 problems

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  You're not the only one..I've been putting the wings in place as a rough  draft to figure out where the holes for cables, fuel lines and wires go, and  once I get the temporary pins in, I see forward sweep. Not a whole lot, but it's  there, and it's driving me nuts. With what we know about the spars and  carry-through all being individually mated during manufacture, my original  skepticism about sweep has turned to wonderment and consternation. If I pivot  the wings back to the neutral position, I'm putting a load on the  spar-to-carry-through joint, where ideally there shouldn't be any. Anybody got  any ideas on this?

  

 Paul Rodriguez

 [quote]   ---

ter_turn(at)yahoo.com
Guest

Posted: Wed Dec 24, 2008 1:49 pm Post subject: 601 problems

Wow, I thought a while back the discussion was about back sweep!!!



Do not archive



Terry Turnquist



paulrod36(at)msn.com wrote:[quote]      <?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  You're not the only one..I've been putting the wings in place as a rough  draft to figure out where the holes for cables, fuel lines and wires go, and  once I get the temporary pins in, I see forward sweep. Not a whole lot, but it's  there, and it's driving me nuts. With what we know about the spars and  carry-through all being individually mated during manufacture, my original  skepticism about sweep has turned to wonderment and consternation. If I pivot  the wings  back to the neutral position, I'm putting a load on the  spar-to-carry-through joint, where ideally there shouldn't be any. Anybody got  any ideas on this?

  

 Paul Rodriguez

 [quote]   ---

geather

Joined: 06 Feb 2008
Posts: 23
Location: Mt Hutton Australia

Posted: Wed Dec 24, 2008 1:50 pm Post subject: 601 problems

Paul  

   

Doesn’t wing sweep depend on the angle of the front spar? If you make the front spar vertical (by lifting the front wheel) then the sweep magically “disappears”!! – see pics  

   

ge  

   

   

         

  

From: owner-zenith601-list-server(at)matronics.com [mailto:owner-zenith601-list-server(at)matronics.com] On Behalf Of paulrod36(at)msn.com

 Sent: 25 December, 2008 7:45 AM

 To: zenith601-list(at)matronics.com

 Subject: Re: Re: 601 problems  

  

       

You're not the only one..I've been putting the wings in place as a rough draft to figure out where the holes for cables, fuel lines and wires go, and once I get the temporary pins in, I see forward sweep. Not a whole lot, but it's there, and it's driving me nuts. With what we know about the spars and carry-through all being individually mated during manufacture, my original skepticism about sweep has turned to wonderment and consternation. If I pivot the wings back to the neutral position, I'm putting a load on the spar-to-carry-through joint, where ideally there shouldn't be any. Anybody got any ideas on this?  

    

   

    

Paul Rodriguez  

  [quote]    

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_________________
ge

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Dec 24, 2008 3:57 pm Post subject: 601 problems

The forward sweep is an artifact of the 3 degree forward tilt of the  

spar and the wing dihedral. If you raise the nose until the spar is  

vertical you will see no forward sweep. During final assembly, the  

entire spar web should be on the same plane with no bend in it.



On Dec 24, 2008, at 3:45 PM, <paulrod36(at)msn.com> <paulrod36(at)msn.com>  

wrote:



 	  Quote: 	
		   You're not the only one..I've been putting the wings in place as a  

 rough draft to figure out where the holes for cables, fuel lines and  

 wires go, and once I get the temporary pins in, I see forward sweep.  

 Not a whole lot, but it's there, and it's driving me nuts. With what  

 we know about the spars and carry-through all being individually  

 mated during manufacture, my original skepticism about sweep has  

 turned to wonderment and consternation. If I pivot the wings back to  

 the neutral position, I'm putting a load on the spar-to-carry- 

 through joint, where ideally there shouldn't be any. Anybody got any  

 ideas on this?




	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

planecrazydld(at)yahoo.co
Guest

Posted: Wed Dec 24, 2008 5:47 pm Post subject: 601 problems

nothing easy or simple.



David L. Downey

  Harleysville (SE) PA, USA



  

--- On Wed, 12/24/08, paulrod36(at)msn.com <paulrod36(at)msn.com> wrote:

[quote]From: paulrod36(at)msn.com <paulrod36(at)msn.com>

Subject: Re: Re: 601 problems

To: zenith601-list(at)matronics.com

Date: Wednesday, December 24, 2008, 3:45 PM



       You're not the only one..I've been putting the wings in place as a rough  draft to figure out where the holes for cables, fuel lines and wires go, and  once I get the temporary pins in, I see forward sweep. Not a whole lot, but it's  there, and it's driving me nuts. With what we know about the spars and  carry-through all being individually mated during manufacture, my original  skepticism about sweep has turned to wonderment and consternation. If I pivot  the wings back to the neutral position, I'm putting a load on the  spar-to-carry-through joint, where ideally there shouldn't be any. Anybody got  any ideas on this?

  

 Paul Rodriguez

 [quote]   ---

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