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klondike(at)megalink.net
Guest

Posted: Sat Apr 14, 2012 8:58 am Post subject: 601 down...

Paul-- please clarify---  you say 2 different things.



1)    "XL builders included a bunch of idiots

        that were causing the wings to regularly fall off".



2)     "At least  in the XL case the problems were eventually identified and

          apparently fixed with the AMD update"



Which is it???????



Your first statement was "rather harsh" considering folks died.



Fritz.



---

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psm(at)att.net
Guest

Posted: Sat Apr 14, 2012 2:41 pm Post subject: 601 down...

Hi Fritz,



Comment #1 was me "Aping" what the Heintz clan was saying for several 

years.  In effect they refused to believe there was anything wrong with 

the design and the deaths were all caused by maintenance issues (i.e. 

loose aileron cables) and similar such builder faults.  I never believed 

that.



Comment #2  Reflects my current opinion.  It also reflects the opinions 

of the engineers in the FAA Small Airplane Directorate as documented in 

their SAIB: CE-10-08 dated November 7, 2009 which effectively grounded 

the entire fleet of Zodiac XLs until they had the AMD update installed.  

I believe the designation for CH601XL and CH650 from Zenith Aircraft 

Company changes the names to CH601XLB and CH650B when the update is 

included and installed.  This update adds a considerable amount of metal 

and rivets to the wing spars and spar carry-through and also adds mass 

balancing weights to the ailerons.  Other changes are also included such 

as reinforcements for the wing attach uprights.



I was not convinced the update actually fixed the problem after reading 

the various FAA documents.  I thought the conclusion was that there 

might be a problem and the update strengthens the design which might fix 

the problem if there is one.  I was turned around on this point of view 

by a 20 minute face to face conversation with Wes Ryan (the guy whose 

name appears at the bottom of the FAA documents on this whole issue).  

He convinced me that they had indeed found serious problems with the 

design which were corrected by the update.  Apparently I was unable to 

interpret their released documents clearly.



So the bottom line, in my opinion, is that Zodiac XLs and 650s are death 

traps until the AMD update is installed.  After this installation they 

have a competent engineering design which should be considered safe.  

(Of course they are still home built and/or uncertified airplanes so 

there is a bit of danger that remains.  This is no different from any 

other kit or plans built airplane.)



I hope this helps.  Please accept my apology for unclear writing 

earlier.  I didn't mean to confuse anything or reflect negatively on 

anyone who fell victim to this problem.



Paul

Camas, WA



On 4/14/2012 9:57 AM, fritz wrote:

 	  Quote: 	
		   



 Paul-- please clarify---  you say 2 different things.



 1)    "XL builders included a bunch of idiots

        that were causing the wings to regularly fall off".



 2)     "At least  in the XL case the problems were eventually 

 identified and

          apparently fixed with the AMD update"



 Which is it???????



 Your first statement was "rather harsh" considering folks died.



 Fritz.

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pmchap(at)gmail.com
Guest

Posted: Sat Apr 14, 2012 2:41 pm Post subject: 601 down...

At 11:15 14-04-12, you wrote:

  	  Quote: 	
		  .  In the BD-5 case he refused to send out the final kit part, the engine cowl, to any of this customers because he knew many of them would get killed if they got to fly their planes.  	


 I don't want to go too far off on a tangent, but the whole story is a lot more complex (and I only know a bit). It was the whole damn engine that ended up not being available to kit customers; it wasn't some trick to avoid liability. And that aircraft was in a whole other class, a hot little plane with minimal structure around the pilot, one that would be very unforgiving if one's own engine installation didn't work out right. And hotter still if the engines actually installed weighed a lot more (in a light fuselage) than Bede had initially hoped, which usually was the case. 



 I'm sure that there were some poorly designed plans or kit built aircraft out there that never got popular, but the XL was unusual for being reasonably popular yet having catastrophic structural failures. 



 

 Peter Chapman

 Toronto, ON           601 HDS  /  912  /  C-GZDC    [quote][b]

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klondike(at)megalink.net
Guest

Posted: Sat Apr 14, 2012 3:42 pm Post subject: 601 down...

I have an idea what the updates consist of and thought these would make the 

airplane safer.



But,  what was the specific cause you talk about?   Was it one major flaw or 

was it a combination of what the updates cover.   Were any of the updates 

"just in case" ? ie aileron balance system.  Elevator travel restriction??



Does the 7 -9 degree (?) slant of the wing spar contribute to the problem vs 

being 90 degrees ??



Was the whole wing design  and the way it attached a problem?



Fritz

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psm(at)att.net
Guest

Posted: Sat Apr 14, 2012 4:37 pm Post subject: 601 down...

Hi Fritz,



I don't know the answers to all your questions.  I am a retired engineer 

but not an aviation engineer.  I made a living doing electrical 

engineering.  For specific answers I suspect you should contact the FAA 

or Zenith or Zenair.  I don't know if any of them will tell you exactly 

what the truth is for a variety of reasons.  You can't contact AMD 

because they sold out shortly after the design update was released.



I was told the FAA and NTSB guys found evidence of flutter and 

structural failure in the accident wreckage.  They could not determine 

if the flutter caused the structure failure or the structure failure 

caused the flutter.



There was no change to the elevator travel or anything else related to 

the elevator.



Many people who may not rate as experts in the Zodiac accidents claimed 

the aileron balance was very important.  It was part of the update so it 

should be installed in all XLs and 650s. It was developed by the LAA 

before the rest of the update was developed by Zenair/AMD.



Nobody I talked to said the tilted spar was related to the problems.  

This causes the wing tips to be moved forward - part of the unique 

design of the XL.  The update did not change this.



Mostly the update added lots of aluminum to the spars.  It also added 

metal and hard rivets to  the spar carry through.



Best regards,



Paul



On 4/14/2012 4:41 PM, fritz wrote:

[quote] 



 I have an idea what the updates consist of and thought these would 

 make the airplane safer.



 But,  what was the specific cause you talk about?   Was it one major 

 flaw or was it a combination of what the updates cover.   Were any of 

 the updates "just in case" ? ie aileron balance system.  Elevator 

 travel restriction??



 Does the 7 -9 degree (?) slant of the wing spar contribute to the 

 problem vs being 90 degrees ??



 Was the whole wing design  and the way it attached a problem?



 Fritz

 ---

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paulrod36(at)msn.com
Guest

Posted: Sun Apr 15, 2012 11:24 am Post subject: 601 down...

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  We seem to be missing something here. If you "slowly enter", and are in the  stall regime, buffeting and bobbing, and there is still enough elevator to  rapidly pull the stick back even further, you either have too much airspeed, or  have too much elevator displacement for a non-aerobatic airplane. A violent  pitch-down that would put you against the canopy shouldn't happen. Just my  opinion, but based on a bunch of years of flying.

  

 Paul R.

  

  

  

  

 ---

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tonyplane(at)bellsouth.ne
Guest

Posted: Sun Apr 15, 2012 2:41 pm Post subject: 601 down...

CG



Sent from my iPhone



On Apr 15, 2012, at 2:22 PM, <paulrod36(at)msn.com (paulrod36(at)msn.com)> wrote:



[quote] <?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  We seem to be missing something here. If you "slowly enter", and are in the  stall regime, buffeting and bobbing, and there is still enough elevator to  rapidly pull the stick back even further, you either have too much airspeed, or  have too much elevator displacement for a non-aerobatic airplane. A violent  pitch-down that would put you against the canopy shouldn't happen. Just my  opinion, but based on a bunch of years of flying.

  

 Paul R.

  

  

  

  

 ---

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