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Quick open poll about wing failures.

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William Dominguez

Joined: 09 Apr 2008
Posts: 118

Posted: Mon Jun 15, 2009 5:05 am Post subject: Quick open poll about wing failures.

Now that this topic have again resurfaced, lets cool down and do a little

open poll in the meanwhile. This is an open poll so every one is free to

keep their own count of the results.



Please respond to this thread with the number associated with your

response. You can optionally leave any comment if you wish.



When it comes to wing failures accidents in the Zodiacs 601XL fleet,

which of the following views best describe your own;



1) What wing failure accidents? There have not been any confirmed

wing failures, its all speculation.



2) There is no design issue with the plane, the reason for the accidents

are pilot error.



3) I don't know if there is a design issue or pilot error, I will  hold

judgment until this whole thing clarify further.



4) There must be a design flaw with the plane and Zenith  should

address it.  [quote][b]

_________________
William Dominguez
Zodiac 601XL Plans
Miami Florida
http://www.geocities.com/bill_dom

jmaynard

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

Posted: Mon Jun 15, 2009 5:20 am Post subject: Quick open poll about wing failures.

On Mon, Jun 15, 2009 at 06:02:30AM -0700, William Dominguez wrote:

 	  Quote: 	
		   When it comes to wing failures accidents in the Zodiacs 601XL fleet,

 which of the following views best describe your own;


	


 	  Quote: 	
		   3) I don't know if there is a design issue or pilot error, I will hold

 judgment until this whole thing clarify further.


	


 	  Quote: 	
		   4) There must be a design flaw with the plane and Zenith should address

 it.


	


My view is in between these two. I don't know if there is a design issue or

not, but I believe it's imperative that Zenith take every action they can to

resolve whatever issue there is in order to prevent future in-flight

breakups and rstore the reputation of the type.



Pilot error is what remains after all other causes have been ruled out. So

far, we're far from that point.

-- 

Jay Maynard, K5ZC, PP-ASEL, CFI-SP   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

tigerrick(at)mindspring.c
Guest

Posted: Mon Jun 15, 2009 5:40 am Post subject: Quick open poll about wing failures.

I wish there was a #5:



"When G loading on the airframe is exceeds design spec, the failure points are very predictable and repeatable."



That's still my belief.



Rick Lindstrom



--

Trainnut01(at)aol.com
Guest

Posted: Mon Jun 15, 2009 6:24 am Post subject: Quick open poll about wing failures.

3 An Excellent Credit Score is 750. See Yours in Just 2 Easy Steps!

  [quote][b]

d.goddard(at)ns.sympatico
Guest

Posted: Mon Jun 15, 2009 7:20 am Post subject: Quick open poll about wing failures.

I'l take #3 from the list offered but I somewhat agree with Rick here, there 

could be more choices. On the other hand the elevator stops are intended to 

remove the likelyhood of this failure mode and may be a solution. No?



It raises a question, is a design in which the design spec is easily 

exceeded by a normal or even slightly careless pilot (completely ruling out 

someone who deliberately defies the spec) a defective or poor design? I'm 

totally torn on an answer, it should be a definitive no but slight or casual 

moments of  carelessness are so common that it seems it should be within 

capabilities without immediate or long term consequences. And since this 

must affect the entire aviation fleet both certified and homebuilt, it seems 

that in most cases it's not normally an issue.



---

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Mon Jun 15, 2009 8:03 am Post subject: Re: Quick open poll about wing failures.

 	  d.goddard(at)ns.sympatico wrote: 	
		  

It raises a question, is a design in which the design spec is easily 

exceeded by a normal or even slightly careless pilot (completely ruling out 

someone who deliberately defies the spec) a defective or poor design? I'm 

totally torn on an answer, it should be a definitive no but slight or casual 

moments of  carelessness are so common that it seems it should be within 

capabilities without immediate or long term consequences. And since this 

must affect the entire aviation fleet both certified and homebuilt, it seems 

that in most cases it's not normally an issue.



--- 	




Aircraft design is a series of compromises. They were made when Boeing designed the 747 and Chris had to do it when he designed the 601XL. When the 601XL was designed it had a center stick. Maybe over control of the elevator wasn't as "easy" that way? I was butt testing my new seats this weekend after installing the ELT. I reached to the far side of the cabin to test the ELT. The stick was full forward as it will always be when not in flight. Guess what piece of the aircraft came in contact with my ample tummy as I reached across. What would have happened in flight if something had cause me to reach over there is a hurry when the stick wasn't full forward? And at 180 my stomach isn't as ample as some who fly 601s with duel sticks. What about a passenger who is clueless and pushes the stick as they are getting moving around.



I'm seriously thinking about making the right stick removable.



But as to the design sure the over-control would be less possible with a smaller elevator but then you would have pilots running out of elevator authority at low speed.

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

tonyplane(at)bellsouth.ne
Guest

Posted: Mon Jun 15, 2009 8:09 am Post subject: Quick open poll about wing failures.

I would vote for a #5.

I can still vividly recall, as I have reported before, of a Piper Tomahawk 

owner/pilot I was letting fly in my XL in very gusty conditions.

The nose pitched up on climb out, and he actually pushed the stick rapidly 

forward, putting us tight against the seat belts and into a nose low dive. 

(I think if my belt had been unbuckled, I would have gone through the 

canopy - my head was touching the canopy). I blocked and grabbed the stick, 

stated "my airplane" and "eased" the nose to level.  I often wonder had I 

not grabbed the stick if he would have just as rapidly pulled the stick back 

to raise the nose.



Tony Graziano

XL/Jab

N493TG; 501 hrs



---

rtdin

Joined: 16 Mar 2008
Posts: 46
Location: Florida panhandle

Posted: Mon Jun 15, 2009 10:08 am Post subject: Quick open poll about wing failures.

I say:

 

                                          4

 

 To blame EVERY in flight break up on pilot error is reprehensible. The general consensus that I picked up on this list is that the ULTIMATE load for this air craft should now be three G's. Even the most ardent supporters (those that vote "1") make frequent remarks such as "He did a 3 G pull up and the wing failed." Following the crowd, I suggest that the new Matronics consensus limitation (3G ultimate) be observed.

 

 That would make the new normal load = 2 G. That means that the Vn diagram must be redrawn. A new Va would result. Furthermore, tried and true flutter mitigation measures are invalid. FAR 23.629 is junk. If so, is AC 43.13b also? Bernoulli is dead. Consensus rules!  What do I know, I'm just a washed up ancient aviator that hangs out with retired aerodynamicists and old AI's? I must follow the herd. 

 

 Bob in FL

 601XL

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

Download the AOL Classifieds Toolbar for local deals at your fingertips. (http://toolbar.aol.com/aolclassifieds/download.html?ncid=emlcntusdown00000004)  [quote][b]

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Mon Jun 15, 2009 10:30 am Post subject: Re: Quick open poll about wing failures.

You act as if the cause for 58% of ALL airplane accidents isn't pilot error. Pilot error doesn't necessarily mean the pilot did something real stupid just that, for what ever reason, the allowed the aircraft to stray outside of it's design limitations. Of the in-flight break ups where the cause is known both were pilot error. One being flying the plane into bad weather the other being the French guy who did aerobatics and reset the G meter prior to the investigative team being able to check it.



For that matter it may not have even been the fault of the pilot who was flying it at the time of the accident. None of the accident aircraft were being flown by the guy that built them. SO it is  safe to assume that the plane had been flown by someone else prior. The plane could have been over stressed and damaged by a previous pilot. Just not enough to cause immediate failure.

[quote="rtdin"]I say:

 

                              ï¿½           4

 

 To blame EVERY in flight break up on pilot error is reprehensible. The general consensus that I picked up on this list is that the ULTIMATE load for this air craft should now be three G's. Even the most ardent supporters (those that vote "1") make frequent remarks such as "He did a 3 G pull up and the wing failed." Following the crowd, I suggest that the new Matronics consensus limitation (3G ultimate) be observed.

 

 That would make the new normal load = 2 G. That means that the Vn diagram must be redrawn. A new Va would result. Furthermore, tried and true flutter mitigation measures are invalid. FAR 23.629 is junk. If so, is AC 43.13b also? Bernoulli is dead. Consensus rules!  What do I know, I'm just a washed up ancient aviator that hangs out with retired aerodynamicists and old AI's? I must follow the herd. 

 

 Bob in FL

 601XL

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

Download the AOL Classifieds Toolbar for local deals at your fingertips. (http://toolbar.aol.com/aolclassifieds/download.html?ncid=emlcntusdown00000004)   	  Quote: 	
		  [b]

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

psm(at)att.net
Guest

Posted: Mon Jun 15, 2009 11:40 am Post subject: Quick open poll about wing failures.

I am stuck between 4 and 5.



I am convinced there is a design problem.  That is the only possible 

explanation for such a large number of in-flight structure failures - 

many with experienced pilots flying straight and level and relatively 

slowly too.  However, there is absolutely no clue to the actual 

problem so there is no way Zenith or anyone else can fix it right now.



I am beginning to consider the idea that the problem is not a simple 

design problem. Rather, it might be a design feature intentionally 

built into the plane.  I refer to the very light elevator/pitch 

response.  This was intentionally done to allow for great control all 

the way down to stall speed.  Unfortunately, it might also mean the 

plane is susceptible to rapid pilot (or panicked passenger) stick 

inputs at higher speeds that could instantly overload the structure.



With all the testing that has been done, I am sure there is not a 

simple design problem here.  It is not an oversight or arithmetic 

mistake.  I think the accident numbers are alarmingly high, but not 

so high that they point to a real risk for normal flight under normal 

conditions.



Paul

XL grounded





At 06:02 AM 6/15/2009, you wrote:

 	  Quote: 	
		  4) There must be a design flaw with the plane and Zenith should

address it.

n801bh(at)netzero.com
Guest

Posted: Mon Jun 15, 2009 2:29 pm Post subject: Quick open poll about wing failures.

I am a 3 but..... The Yuba City incident has me still wondering on how it transpired. And the one headed to Sun and Fun is baffling too.  One thing to remember is the GVT is computer modeling, not real flight testing so the potential for a false negative still exists. 

do not archive

Ben Haas

N801BH

www.haaspowerair.com



--------

n801bh(at)netzero.com
Guest

Posted: Mon Jun 15, 2009 2:34 pm Post subject: Quick open poll about wing failures.

If you were at or below VA who cares, The plane "should" stall first before it can destroy itself..  

do not archive



Ben Haas

N801BH

www.haaspowerair.com



--------

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Mon Jun 15, 2009 2:49 pm Post subject: Quick open poll about wing failures.

I have to assume you're joking. I've pulled four Gs in mine at gross  

weight during phase 1 testing with no problem at all. The Zodiac will  

not shed its wings at three Gs unless you've got it grossly  

overloaded. or didn't bother to install the wing bolts.



On Jun 15, 2009, at 1:56 PM, MaxNr(at)aol.com wrote:



 	  Quote: 	
		   I say:



                                   4



 To blame EVERY in flight break up on pilot error is reprehensible.  

 The general consensus that I picked up on this list is that the  

 ULTIMATE load for this air craft should now be three G's. Even the  

 most ardent supporters (those that vote "1") make frequent remarks  

 such as "He did a 3 G pull up and the wing failed." Following the  

 crowd, I suggest that the new Matronics consensus limitation (3G  

 ultimate) be observed.



 That would make the new normal load = 2 G. That means that the Vn  

 diagram must be redrawn. A new Va would result. Furthermore, tried  

 and true flutter mitigation measures are invalid. FAR 23.629 is  

 junk. If so, is AC 43.13b also? Bernoulli is dead. Consensus rules!   

 What do I know, I'm just a washed up ancient aviator that hangs out  

 with retired aerodynamicists and old AI's? I must follow the herd.




	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

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

William Dominguez

Joined: 09 Apr 2008
Posts: 118

Posted: Mon Jun 15, 2009 3:50 pm Post subject: Quick open poll about wing failures.

How uncomfortable does 4 G feel? 



I have experienced some Gs to the point where I have felt a little dizzy for the few seconds it lasted but I didn't have a G meter to get an idea how much it was. I'm curious as to how it feel as it gets close to the airframe limit.



William Dominguez

Zodiac 601XL Plans

Miami Florida

http://www.geocities.com/bill_dom 



--- On Mon, 6/15/09, Bryan Martin <bryanmmartin(at)comcast.net> wrote:

 	  Quote: 	
		  

From: Bryan Martin <bryanmmartin(at)comcast.net>

Subject: Re: Re: Quick open poll about wing failures.

To: zenith-list(at)matronics.com

Date: Monday, June 15, 2009, 6:46 PM



--> Zenith-List message posted by: Bryan Martin <[url=/mc/compose?to=bryanmmartin(at)comcast.net]bryanmmartin(at)comcast.net[/url]>



I have to assume you're joking. I've pulled four Gs in mine at gross weight during phase 1 testing with no problem at all. The Zodiac will not shed its wings at three Gs unless you've got it grossly overloaded. or didn't bother to install the wing bolts.



On Jun 15, 2009, at 1:56 PM, [url=/mc/compose?to=MaxNr(at)aol.com]MaxNr(at)aol.com[/url] wrote:



 	  Quote: 	
		   I say:

 

                                   4

 

 To blame EVERY in flight break up on pilot error is reprehensible. The general consensus that I picked up on this list is that the ULTIMATE load for this air craft should now be three G's. Even the most ardent supporters (those that vote "1") make frequent remarks  such as "He did a 3 G pull up and the wing failed." Following the crowd, I suggest that the new Matronics consensus limitation (3G ultimate) be observed.

 

 That would make the new normal load = 2 G. That means that the Vn diagram must be redrawn. A new Va would result. Furthermore, tried and true flutter mitigation measures are invalid. FAR 23.629 is junk. If so, is AC 43.13b also? Bernoulli is dead. Consensus rules!  What do I know, I'm just a washed up ancient aviator that hangs out with retired aerodynamicists and old AI's? I must follow the herd.

 


	


--Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

========================http========================http://www.matronics.com/contributio==============





	
  [quote][b]

_________________
William Dominguez
Zodiac 601XL Plans
Miami Florida
http://www.geocities.com/bill_dom

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Mon Jun 15, 2009 7:12 pm Post subject: Quick open poll about wing failures.

It's tolerable but not very pleasant. It really puts you into the seat  

cushions. The semi-reclined seating of the Zodiac probably makes it  

more tolerable than what you'd experience in a Cessna. I only tried it  

a couple of times just to verify the flight envelope.



It just occurred to me to wonder if that has anything to do with some  

of these accidents. A pilot might pull more Gs than he thinks he is  

because it doesn't feel as high if he's not used to pulling Gs in a  

Zenith.



On Jun 15, 2009, at 7:41 PM, William Dominguez wrote:



 	  Quote: 	
		   How uncomfortable does 4 G feel?



 I have experienced some Gs to the point where I have felt a little  

 dizzy for the few seconds it lasted but I didn't have a G meter to  

 get an idea how much it was. I'm curious as to how it feel as it  

 gets close to the airframe limit.




	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

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

paulrod36(at)msn.com
Guest

Posted: Mon Jun 15, 2009 7:34 pm Post subject: Quick open poll about wing failures.

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Gig, I would love to be able to interview "the French guy" in detail, I  think he has a wealth of information that we could all benefit from. Bureaucracy  being what it is, I bet he dare not open his mouth. However, if any of our  French friends knows him, it would be great if they wrote a FICTITIOUS chapter  to an aviation novel, depicting an imaginary flier who lost both wings,  "theorizing" how the hero got into the hypothetical situation.  The hero of  the Fictional story would rightfully own the title of "Lucky Pierre".

     Entendez, nous amis Zenithoises? (Poor French, I  know)

  

 Paul R.

 [quote]   ---

Scotsman

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

Posted: Tue Jun 16, 2009 1:32 am Post subject: Re: Quick open poll about wing failures.

A four for me.



Bryan you may have a valid point...the reclined lazyboy seating arrangement is likely to reduce the perception/physiology of g loading on the occupant in the same manner that an F16's seat is reclined to ultimately increase the pilot's g tolerance.  This may cause certain people to exceed limitations based on their perception of g loading norms in other aircraft.



While it may be a contributing factor I think that there is something else at play with specific reference to the crashes in which the pilot was not doing anything particularly dumb at the time (such as showboating or flying into thunderstorms etc).



I have started building again on the assumption that any changes will be able to be retrofitted and that it appears at last proper testing is being undertaken.  While we may have concerns about certain aspects of the the design you can't fault Chris for making an easy to build nice little aircraft.



Cheers

James

_________________
Cell +27 83 675 0815

reinkings(at)comcast.net
Guest

Posted: Tue Jun 16, 2009 10:07 pm Post subject: Quick open poll about wing failures.

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