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LAA Testing

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yak52

Joined: 25 Oct 2007
Posts: 50

Posted: Tue Jul 21, 2009 3:42 pm Post subject: LAA Testing

What we are seeing in the British "testing" is the final step in the execution of a self fullfilling prophecy. I contacted the engineer with the LAA to suggest that the test envelope be tried on the airplane without the "modifications" designed by CH. Then to do the testing again on the airplane after the "modifications"  were done and compare the results. This would seem to be a logical regimen. I was informed that the LAA would not do that as they fully accepted the premise that flutter would occur with "slack"  aileron cables and it would be unnecessary to do "before" testing. They also acccepted the premise that a structural strengthening of the center spar carry through would be necessary although they had no evidence or engineering study for that premise.  Now they have done the after "test" without any baseline or before tests to compare it with and will declare the modifications a success and require the kit be installed in order fly the airplane in the UK.  The "flutter" people will pat themselves on the back and declare themselves superior. Everyone else will face the prospect of doing the modifications;  and no one will know anymore about what really caused the accidents than before. In case you don't realize it, this is not a success in any form except that now some people can feel confident in building and flying their airplane, at least until the next time someone pulls 6 plus g's. 

  [quote][b]

Larry Webber

Joined: 05 Jun 2008
Posts: 63
Location: West Kingston Rhode Island

Posted: Tue Jul 21, 2009 4:12 pm Post subject: LAA Testing

Well said Roger   more BS will follow from "the renegade group"



 Larry



  



  Date: Tue C 21 Jul 2009 19:41:27 -0400

Subject: LAA Testing

From: n601ap(at)gmail.com

To: zenith-list(at)matronics.com



 What we are seeing in the British "testing" is the final step in the execution of a self fullfilling prophecy. I contacted the engineer with the LAA to suggest that the test envelope be tried on the airplane without the "modifications" designed by CH. Then to do the testing again on the airplane after the "modifications"  were done and compare the results. This would seem to be a logical regimen. I was informed that the LAA would not do that as they fully accepted the premise that flutter would occur with "slack"  aileron cables and it would be unnecessary to do "before" testing. They also acccepted the premise that a structural strengthening of the center spar carry through would be necessary although they had no evidence or engineering study for that premise.  Now they have done the after "test" without any baseline or before tests to compare it with and will declare the modifications a success and require the kit be installed in order fly the airplane in the UK.  The "flutter" people will pat themselves on the back and declare themselves superior. Everyone else will face the prospect of doing the modifications;  and no one will know anymore about what really caused the accidents than before. In case you don't realize it C this is not a success in any form except that now some people can feel confident in building and flying their airplane C at least until the next time someone pulls 6 plus g's. 

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Doug.Norman(at)sportaviat
Guest

Posted: Tue Jul 21, 2009 5:22 pm Post subject: LAA Testing

Roger,  

   

You have it exactly right, well said. In fact the short summary we see on the LAA web site is rather equivocal about what they’ve done, what they’ve tested, and how really establishes goodness. I’m sure it’s a fine set of tests… it’s just that we have no idea what it proves. Perhaps only that they have not broken the airplane with their modifications. “…These tests have been conducted at various aileron cable tensions and the instrumentation is showing excellent damping of the wing vibratory responses even at cable tensions well below the manufacturers recommended settings. ...” As you point out, there’s an assumption of a ‘wing vibratory response’ to which there is no evidence. In fact, just the opposite when factoring the German testing and analysis. Talk about constructing a straw man to be knocked down!   

   

BTW: what has struck me lately is that Part 23 does not require mass-balanced ailerons (we hear many who demand this as the only answer to a (apparently imagined) problem). Consider the Alarus (yes, also a CH design). It is a Part 23 certified airplane, and I don’t believe it has mass-balanced ailerons.   

   

It’s all quite fascinating.    

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of roger lambert

 Sent: Tuesday, July 21, 2009 7:41 PM

 To: zenith-list(at)matronics.com

 Subject: LAA Testing  

  

     

What we are seeing in the British "testing" is the final step in the execution of a self fullfilling prophecy. I contacted the engineer with the LAA to suggest that the test envelope be tried on the airplane without the "modifications" designed by CH. Then to do the testing again on the airplane after the "modifications"  were done and compare the results. This would seem to be a logical regimen. I was informed that the LAA would not do that as they fully accepted the premise that flutter would occur with "slack"  aileron cables and it would be unnecessary to do "before" testing. They also acccepted the premise that a structural strengthening of the center spar carry through would be necessary although they had no evidence or engineering study for that premise.  Now they have done the after "test" without any baseline or before tests to compare it with and will declare the modifications a success and require the kit be installed in order fly the airplane in the UK.  The "flutter" people will pat themselves on the back and declare themselves superior. Everyone else will face the prospect of doing the modifications;  and no one will know anymore about what really caused the accidents than before. In case you don't realize it, this is not a success in any form except that now some people can feel confident in building and flying their airplane, at least until the next time someone pulls 6 plus g's.   

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rtdin

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

Posted: Tue Jul 21, 2009 10:29 pm Post subject: LAA Testing

Hi Roger. 

 Glad to see that you are still active in the search for answers to the unfortunate accidents that involved in flight breakups of CH 601XLs. I recall the msgs that we exchanged while you were trying to get your mind around one of the fatalities. I sent you copies of that NTSB docket. I cited portions of their report to bring you back to the facts as reported as you explored so many blind alleys. I stopped trying when you set your mind on theories that were not supported by NTSB findings. 

 

 I find comfort that the LAA and its engineers are conducting the tests with Heintz designed modifications. Glad to see that you are offering assistance. Please fill us in your qualifications. Engineering experience, pilot ratings, hours etc. I have searched the various dockets and reports and I have not yet found any instances of the improper pilot techniques that you report. Especially, pulling six Gs. Please cite those instances from the reports. I have only found reports of in flight breakups that happened in the enroute/cruise phase of flight or in the traffic pattern. I did find a report from France that reported a "rumor" that the pilot sometimes pulled almost three G. This has resulted in some of the most avid supporters seriously recommending three G as the new ultimate limit. I've seen a few remarks such as "If he does a 3 G pull up, the wing will fail." With friends like this....... The LAA is beefing up the center spar. Silly LAA.

 

 I forwarded to you, part of one report that the NTSB said that while established in cruise for ten minutes after t.o., the front hor. stabilizer brackets first failed downward, causing a 200 ft climb, then the h.s. popped up causing a severe nose tuck that destroyed the ship. You favored pilot error. This could have been caused because an inspection point (cracking, after 100 to 300 hours in svc.) in this area was first reported by CH in the Zenair Association Newsletters. See ZN 150 (Sept-Oct, 2005) pg.2 for details. Then another pilot reported in ZN 155 (July-Aug, 2006) pg. 8 finding these cracks on his bird. I don't know. What do you think? I wasn't there.

 

 Don't worry about me pulling all those Gs. My wife holds me down to 2 G. If she is sitting next to me it is further reduced to one G.

 

 Bob Dingley

 CH601XL plans 6-6791

 (Holding at the wings)  Do not archive

 

 

  

 

 

 

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

Dell Deals: Treat yourself to a sweet155x1201715982/aol?redir=http:%2F%2Faltfarm.mediaplex.com%2Fad%2Fck%2F12309%2D81939%2D1629%2D6)  [quote][b]

BobCollins

Joined: 12 Aug 2008
Posts: 19
Location: Sunnyvale CA USA

Posted: Wed Jul 22, 2009 12:39 am Post subject: LAA Testing

Bob,

I would then assume that if your wife is sitting next to you, then you 

and her are not flying. Please remember that _any_ (non-inverted) turn 

causes a g-force greater than one.



Bob Collins

Sunnyvale CA USA

MaxNr(at)aol.com wrote:



<snip>

 	  Quote: 	
		   Don't worry about me pulling all those Gs. My wife holds me down to 2 

 G. If she is sitting next to me it is further reduced to one G.



 Bob Dingley

 CH601XL plans 6-6791

 (Holding at the wings)  Do not archive

yak52

Joined: 25 Oct 2007
Posts: 50

Posted: Wed Jul 22, 2009 4:35 am Post subject: LAA Testing

In a recent posting:

  

       Hi Roger. 

      

       " I stopped trying when you set your mind on theories that 

      were not supported by NTSB findings. "

  

        Those findings by the NTSB were that there was no evidence of oscillatory damage or metal fatigue. All damage was consistent with overstress. Please explain how   

        these new modifications would have prevented any of the accidents in the reports you cited.

      

      I did attend the last two Zenith events at Sebring and Sun and Fun. The g figures were supplied by Zenith who particiapted in the NTSB study and had actual   

        engineering   studies done to determine the number of g's necessary to do the damage done in the accidents.      

      

       " I forwarded to you, part of one report that the NTSB said that while 

      established in cruise for ten minutes after t.o., the front hor. stabilizer 

      brackets first failed downward, causing a 200 ft climb, then the h.s. popped up      

       causing a severe nose tuck that destroyed the ship." 

  

  

 You favored pilot error. 

      This could have been caused because an inspection point (cracking, after 100 

      to 300 hours in svc.) in this area was first reported by CH in the Zenair 

      Association Newsletters. See ZN 150 (Sept-Oct, 2005) pg.2 for details. Then 

       another pilot reported in ZN 155 (July-Aug, 2006) pg. 8 finding these cracks 

      on his bird. I don't know. What do you think? I wasn't there.

      

      Don't worry about me pulling all those Gs. My wife holds me down to 2 G. If 

       she is sitting next to me it is further reduced to one G.

      



  [quote][b]

yak52

Joined: 25 Oct 2007
Posts: 50

Posted: Wed Jul 22, 2009 5:11 am Post subject: LAA Testing

To complete my earlier post:

  

 In a recent posting:

 

      Hi Roger. 

      

      " I stopped trying when you set your mind on theories that 

      were not supported by NTSB findings. "

 

       Those findings by the NTSB were that there was no evidence of oscillatory damage or metal fatigue. All damage was consistent with overstress. Please explain  

         how  these new modifications would have prevented any of the accidents in the reports you cited.

      

      I did attend the last two Zenith events at Sebring and Sun and Fun. The g figures were supplied by Zenith who participated in the NTSB study and had actual   

       engineering   studies done to determine the number of g's necessary to do the damage done in the accident.      

      

      " I forwarded to you, part of one report that the NTSB said that while 

       established in cruise for ten minutes after t.o., the front hor. stabilizer 

      brackets first failed downward, causing a 200 ft climb, then the h.s. popped up      

      causing a severe nose tuck that destroyed the ship." 

   

       Please explain how the modifications being tested would have prevented this accident. Please explain  how an airplane flying in level flight causes both horizontal  

        stabilizer   attachments  to break simultaneously and the stabilizer then fails downward. Please explain how the airplane, while in level flight, loses an aileron that circles

        over the airplane to strike the newly failed horizontal stabilizer on the opposite side of the airplane? 

    

             

      "Don't worry about me pulling all those Gs. My wife holds me down to 2 G. If 

      she is sitting next to me it is further reduced to one G."

  

        I'm sure you realize that you experience 1 g while just standing(sitting in your case) on the earth.

  

        Once again, I just wish the LAA testing actually would have gone toward determining the cause of actual accidents, not just creating a false sense of security through a

         faulty test regimen. 

         

  

  

  

  

 

      

  [quote][b]

dougsire

Joined: 10 Jan 2006
Posts: 37

Posted: Wed Jul 22, 2009 6:38 am Post subject: Re: LAA Testing

Roger,



Do you have a copy of the NTSB Materials Laboratory Report 07-095 dated 9/19/07 regarding the Yuba City crash?   One can't hope to understand what might have happened without really digesting this.

_________________
Doug Sire 601XL
Do Not Archive

yak52

Joined: 25 Oct 2007
Posts: 50

Posted: Wed Jul 22, 2009 8:36 am Post subject: LAA Testing

"Roger,



Do you have a copy of the NTSB Materials Laboratory Report 07-095 dated 9/19/07

regarding the Yuba City crash?   One can't hope to understand what might have

happened without really digesting this."

 

--------



  No, I don't have a copy of the NTSB metallurgy report. All I have is the full narrative, which I believe must be based in part on that report.  Please post that part of the report where the cause of the accident is stated. Not the result, but the cause.

 

  

  

 I don't want to understand what might have been  the cause . We have all heard endless speculation. I want to know what the cause was  within reasonable engineering probability and certainty. Unless one has the cause of an accident within some reasonable degree of engineering probability, then any changes to the airframe are being based on guesswork. Its analogous to taking your car to the shop- the mechanic only listens to your description of the problem  and making no investigation himself, changes a part. He then sends you on your way to be a tester for his actions in parts replacement. If it works, fine: if it doesn't you're the one alongside the road. You won't know until its too late. The same thing is being done to this airframe. Thinking that making these modifications is the cure only puts you in the spot of the car owner. Hopefully, the pilots are now aware of the V speeds, sensitive elevator and cable tension characteristics of this airplane and will fly the airplane accordingly, making the modifications only redundant. The only thing we know is that these modifications will get the LAA  of Zenith's back and put the airplanes back in the air. The true effect of the modifications is unknown because the LAA refused to do before and after testing. 

  [quote][b]

tigerrick(at)mindspring.c
Guest

Posted: Wed Jul 22, 2009 9:05 am Post subject: LAA Testing

Well put, Roger.



Thanks.



Rick Lindstrom

ZenVair N42KP



do not archive



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