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Putting Flutter Issue to Bed
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wjones(at)brazoriainet.co
Guest

Posted: Tue Jun 02, 2009 4:00 pm Post subject: Putting Flutter Issue to Bed

As far as taking everything the NTSB says as golden one must also realize 

that several members of the board are political appointments .

Wade  Jones  South East Texas



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tigerrick(at)mindspring.c
Guest

Posted: Tue Jun 02, 2009 5:47 pm Post subject: Putting Flutter Issue to Bed

Hi, Gig.



I just can't stand it any longer. As much as I try not to get down in the mud here, there comes a point when I just can't let this stuff go by without comment.



Several posters here have decided that, despite the positive results of the GVT and the lack of any single causal factor in the six 601 series crashes worldwide, that there still remains a "problem" with the design. Even though these guys fully admit they don't have any personal expertise in aircraft design, they still insist on offering "solutions" such as aileron mass balancing and changing the dynamics of the control system! What chutzpah.



Their continued insistance of an inherent design flaw in the 601 does very real damage, to which these guys seem oblivious. All of us who have invested our hard earned money and time in Chris Heintz's design now are faced with significant loss in the values of our aircraft, are now questioned about our sanity in flying the airplanes by those who simply don't know any better, and an undeserved shadow has been placed on all Zenith Aircraft designs as well.



Here's what I now know:



Flutter is NOT an issue IF aileron cable tensions are maintained to spec. They even showed no negative traits down to 10 pounds (less than HALF of what's specifiedby the factory).



The 601XL has stiff ailerons but a very sensitive elevator. You need an effective elevator at the 601's low rotation and landing speeds, but it could rip the wings off if suddenly deflected downward to it's original limit at high cruise airspeeds. So the factory recommended that it be limited to 15 degrees of down deflection.



So the bottom line is that maintaining aileron cable tension, installing the down stop, and flying with a light touch on the elevator should allow us all to enjoy this design without irrational fear. Is this so much to ask? I don't make a habit of riding my motorcycle into solid walls either, even though I'm given every opportunity to do so. Does this mean there's an inherent flaw with my bike?



The 601 is MOST DEFINITELY NOT a Cessna 172! Any ham fisted pilot can fly a 172, and will usually get to their destination without harm no matter how rough they are with the yoke. (I used to own a Skyhawk, and I was bored to tears after the novelty of being airborne wore off.) The 601 handles much better, and is very responsive to the pilot's control inputs. It teaches you to fly with a light, firm touch, and rewards you by becoming an extension of yourself. But it is NOT way, way overbuilt like a Cessna or Piper or  Beech or Mooney or Grumman! It is, by design, much lighter and needs to be flown with respect for what the designer intended. To do otherwise is just asking for it. And to insist that these flying characteristics are indicative of some kind of "problem" or "flaw" is tantamount to admitting that, instead of being pilots, we're really only glorified passengers incapable of anything beyond a minimal level of flying skill.



I've never seen such chest-thumping mule-headedness, in spite of growing evidence to the contrary. I can only conclude that, in spite of its low cost, simple construction, precise and easy handling, that the 601 really isn't for everybody. Some really would be much better served by a Skyhawk or Cherokee.



Rick Lindstrom

Zenvair N42KP



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Juan Vega Jr

Joined: 13 Jan 2009
Posts: 157

Posted: Tue Jun 02, 2009 6:34 pm Post subject: Putting Flutter Issue to Bed

Jay 

i guess my point is, we are all pilots.  Not car driverss or sled drivers, or surfers, but pilots, who choose to fly a vehicle that goes 150-160 mph.  there are 2000 of these zodiacs flying.  the plane is well designed, but the pilots are the last ones blamed not for just pilot skills but for pilot "in command", meaning, that we as the ones at the control are the owners of our fate. 



we built the plane, we test flew it. we chose to be in that little bubble canopy buzzing around.  We are accountable for our own actions.  You cannot engineer every single variable of risk out of the whole event. impossible.  the experts came back and stated clearly not a design issue.  Grounding the plane is to ground oneself, and your discomfort in assuming responsibilty for yourself and that as a pilot "in command" it is completly up to us.  You will pull the card that an AMD plane crashed.  So what!  SO did an Airbus yesterday due to electrical issues or Godforbid! It crashed for a reason we will never know!.  Regardless of the design or the experts building it,  there is still risk.  the odds on a larger aircraft ae more in the favor of more odds of human design flaw or build error,  1000s of people and 50,000 plus hours of build time in one plane.    Pull my head out of the sand?  That happened the day I built it and signed the papers saying " you built it, you, are Pilot in Command, Zenith Desinged it, But I built it!   Whose head is in the sand?



Politically there will be some BS design adjustment recommendation. 

 Then probably in time, there may be God forbid, another crash. What then? keep blaming the design?,  how about starting to look at the builder or the flyer for once!  

Does that sound like head in the sand?



Juan



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Gig Giacona

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

Posted: Tue Jun 02, 2009 6:59 pm Post subject: Re: Putting Flutter Issue to Bed

Juan, interesting that you mentioned the Air France crash. I was just watching the Weatherer Channel before heading off to bed and they had an airline pilot saying, "If you exceed the design of any plane you will rip the wings off of it."

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

d.goddard(at)ns.sympatico
Guest

Posted: Wed Jun 03, 2009 2:03 am Post subject: Putting Flutter Issue to Bed

Hello Rick.  I simply don't understand the anger here. There are 

owner/pilots who are wondering why this design has had a number of failures 

above the norm. The previous designs from CH did not have this issue so it 

appears that something is different. It's a fair question. I think that if 

you fly carefully and maintain it well there is not likely to be a problem, 

but I don't know that. Neither do I know that there is a problem, or what it 

might be. Please don't bring up the money you have spent and are trying to 

protect, in light of the loss of life, it's beyond crass. Finally, you are 

not a 601 XL, do not take questions and statements about it personally.



Here's what we all know:

Some XL's have experienced fatal airframe failures, cause unknown. (despite 

claims by some that it is pilot incompetence).

The CH200, CH601HD/S, and other CH designs have not had this issue, despite 

similar designs and the fact that they are flown by similar pilots

Tests have shown that flutter is not a likely cause, and the design has been 

changed to negate the possibilty of excessive -G forces.



That about all we actually know, anything else is supposition.

It is my hope that it was a fluke, and the issue will not repeat itself but 

will fade into memory. It's happened before.



I would like to advocate for calm about the issue, anger and name calling 

will simply back people into defensive positions from which rational 

discussion will be unlikely.



Fly safe. Do not Archive.



 	  Quote: 	
		   

 <tigerrick(at)mindspring.com>



 Hi, Gig.



 I just can't stand it any longer. As much as I try not to get down in the 

 mud here, there comes a point when I just can't let this stuff go by 

 without comment.



 Several posters here have decided that, despite the positive results of 

 the GVT and the lack of any single causal factor in the six 601 series 

 crashes worldwide, that there still remains a "problem" with the design. 

 Even though these guys fully admit they don't have any personal expertise 

 in aircraft design, they still insist on offering "solutions" such as 

 aileron mass balancing and changing the dynamics of the control system! 

 What chutzpah.



 Their continued insistance of an inherent design flaw in the 601 does very 

 real damage, to which these guys seem oblivious. All of us who have 

 invested our hard earned money and time in Chris Heintz's design now are 

 faced with significant loss in the values of our aircraft, are now 

 questioned about our sanity in flying the airplanes by those who simply 

 don't know any better, and an undeserved shadow has been placed on all 

 Zenith Aircraft designs as well.



 Here's what I now know:

jaybannist(at)cs.com
Guest

Posted: Wed Jun 03, 2009 4:41 am Post subject: Putting Flutter Issue to Bed

--

planes_by_ken(at)bellsout
Guest

Posted: Wed Jun 03, 2009 4:42 am Post subject: Putting Flutter Issue to Bed

2 Cessna Skycatcher prototypes have spun in.  So much for certified 

manufactures knowing what they are doing.

The NTSB has been recommending inerting the fuel tanks in airliners 

since flight 800 or before.  They are finally doing it.  Cost impact 

trumped safety.  NTSB can only recommend changes, not require them.  In 

a lot of incidents the cause is never determined.  We will never know 

for sure.

Ken Lilja

Gig Giacona

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

Posted: Wed Jun 03, 2009 5:41 am Post subject: Re: Putting Flutter Issue to Bed

 	  d.goddard(at)ns.sympatico wrote: 	
		  (despite 

claims by some that it is pilot incompetence).

	




Pilot error does not necessarily = pilot incompetence. 58% of accidents are pilot error that doesn't mean they were all incompetent pilots.



As I mentioned before none of the accident aircraft that are in question were being flown by a builder who flew the plane through Phase 1 testing. That is statistically significant because this is an aircraft where the majority of flying example were kit built aircraft flown by the people that built them and flew the phase 1 program.



Further in the 2 in flight break-up accidents where we DO know or are at least pretty sure of the cause they were both pilot error.



1 The low time LSA pilot that took off into bad weather.

2. The French pilot that was doing aerobatics and survived due to having a BRS. That guy even reset his G meter before the investigators got there.

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

hansriet

Joined: 09 Feb 2007
Posts: 93

Posted: Wed Jun 03, 2009 5:49 am Post subject: Re: Putting Flutter Issue to Bed

[quote="d.goddard(at)ns.sympatico"]Please don't bring up the money you have spent and are trying to 

protect, in light of the loss of life, it's beyond crass. 

[/quote]



I wholeheartedly agree. Stop bringing finances up to try to silence the people that would like to find an answer to the unexplained crashes. Frankly I'm shocked that not everybody wants to know the cause(s) of the accidents.

steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Wed Jun 03, 2009 5:55 am Post subject: Re: Putting Flutter Issue to Bed

Before anyone gets too far in adding springs and weights to your control stick, consider what most other designs have used in the past to increase the pitch force gradient; an anti-servo trim tab. There is no need to reinvent the wheel if you are really concerned with this particular flying characteristic of the xl. Consider what would happen if a spring broke and suddenly your stick is quickly launched to full deflection. When you set out to fix something, you want to be pretty sure that you're not creating an entirely different and potentially more serious problem. In any event, I think pilot education and training is the key in this case.

tigerrick(at)mindspring.c
Guest

Posted: Wed Jun 03, 2009 6:44 am Post subject: Putting Flutter Issue to Bed

Hans, Dave.



This is unbelievable.



If either of you remember any of my previous posts on this subject, I've expressed that the loss of life in any aviation accident, especially among our Zenith family, affects all of us and hits home hard. And I've also said (multiple times) that as a 601 builder/pilot, I sure as hell want to know if there's any inherent flaw that would jeopardize me or any of my loved ones who fly with me.



Dave, you caution against name calling, yet find my inclusion of the very real financial damage to both 601 owners and the manufacturer "beyond crass". (Huh? What's up with that?) The negative financial impact of undue public speculation not supported by the facts, especially in light of the GVT and Zenith's recommendations (supported by the FAA, even) is very real. I mentioned it because it does continuing damage to the 601 community. How is my bringing it up meant to silence anybody?



Yes, the 601 has had a rash of accidents atypical of other Zenith designs. We know this. And there was a rush to find a smoking gun before all the facts were in, often leading to irresponsible speculation, demands that Zenith "do something", and even proposed airframe modifications made by people unqualified to do so. And it goes on. For some reason, the very valid suggestion that additional model specific pilot training might help gets dismissed.



I can only conclude that there are some here who WANT to find a fatal flaw with the design. For what reason(s), I do not know.



Rick Lindstrom

N42KP



--

d.goddard(at)ns.sympatico
Guest

Posted: Wed Jun 03, 2009 9:39 am Post subject: Putting Flutter Issue to Bed

I've not been in contact with any Zbag members and  I can't speak about their motives, but I'm not convinced that bashing  Zeniths was one of them. As far as I know they all own XL's. As I recall before  the name calling and such started their objective was to have the airframe  analysed/tested because Zenith was not interested in doing it. I think they  should be satisfied that the testing has now been done. As far as  the other arguments, Zenith is at fault etc. I haven't seen those arguments  made, but if they were, I would likely disagree. 

  

 My advocacy for calm rational thought about all of  this is not directed solely at those who are angry at ZBAG, it's directed at bad  behaviour on both sides. There is no proof that there is a major flaw in the XL  design. Or that there is not. I think the testing was a prudent and good thing  to do, and ZBAG may have helped in getting it done. There is credit and blame to  go to both sides. If the accidents stop, so will the discussion for the most  part. Indeed I thought it had died out until whoever started this thread decided  to have one more swipe at the other side. 

 [quote]   ---

d.goddard(at)ns.sympatico
Guest

Posted: Wed Jun 03, 2009 9:39 am Post subject: Putting Flutter Issue to Bed

I didn't know that Ken, did Cessna address the issue?



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d.goddard(at)ns.sympatico
Guest

Posted: Wed Jun 03, 2009 9:55 am Post subject: Putting Flutter Issue to Bed

No question that pilot error causes accidents, but unknown remains unknown, 

we can't simply assign it to pilot error no matter how convenient that would 

be. And we should have to assume that similar pilots flying other CH designs 

would make on average the same number of errors per 100 flights and that 

does not seem reflected in the results. The numbers as they stand right now 

would appear to indicate that there is something about this aircraft that is 

different from the others.



---

d.goddard(at)ns.sympatico
Guest

Posted: Wed Jun 03, 2009 10:31 am Post subject: Putting Flutter Issue to Bed

Hello Rick, Please accept that it a description of an action and not of you, 

certainly not name calling. Yes, I am totally unconcerned about any 

potential loss resulting from a bad reputation related to this aircraft and 

I would never bring up money in a situation that has cost someone their 

life. I am very concerned for the people who for reasons unknown have had 

accidents in them, and I probably would applaud any efforts to keep any 

further accidents from happening.  I would however not have supported any 

attempt to ground them without substantial proof that they are flawed. 

Training is everything, but you have to know that a particular flight 

characteristic exists before you can train for it and there are those here 

who would not have these issues discussed at all. So, a vocal minority from 

both sides ruining it for everyone! Wow, first time that's happened!



---

Gig Giacona

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

Posted: Wed Jun 03, 2009 10:37 am Post subject: Re: Putting Flutter Issue to Bed

d.goddard,



First Skycatcher info: http://www.avweb.com/cgi-bin/texis/scripts/avweb-search/search.html?query=Skycatcher



Second, Head over to ZBAG and look around you will see a bunch of guys that won't take "yes" for an answer unless the question is "Is there a design problem?" They went out and hired a expert and paid good money for him. When he came back with a "No" answer they found some guy who says he is a Zenith builder and an expert and he ran computer simulations and said "Yes" there is a flutter problem. Simulations that did not have GVT tests as a basis I might add. (Note: this is the data they sent to the NTSB but refuse to release to the other builders) So they pitched and moaned for GVT to be done. Zenair did them and the answer was "No" and the bitching and moaning continues. Just is the last day or so there is a thread over at ZBAG with the theory that the HS is to small. A thread complete with ideas on making the HS larger. Here's a link go check them out for yourself. If after reading it you don't understand that it is not only what is said here but what is going on over there that upsets some of let me know.



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



Third, the 601XL is a different airplane with different handling characteristics than previous CH designs. Is it easier because of those characteristics for a pilot to rip the wings off? Maybe. It certainly would explain things. Is there a issue with increasing G force causing decreasing elevator feedback? I don't know. I asked one of this list's members that owns a flying factory version in which he just got his CFI-LS rating that question and haven't seen an answer yet.

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

Juan Vega Jr

Joined: 13 Jan 2009
Posts: 157

Posted: Wed Jun 03, 2009 11:12 am Post subject: Putting Flutter Issue to Bed

Dave, you are wrong. 

Factor out pilot error on each accident,  and the accident rate falls well within norms for GA E-AB.



Juan



--

tigerrick(at)mindspring.c
Guest

Posted: Wed Jun 03, 2009 11:22 am Post subject: Putting Flutter Issue to Bed

Hi, Dave. Forgive me for being "crass" again, but as someone who works closely at times with LSA and kit aircraft manufacturers, I AM concerned about any undeserved loss of reputation that can hinder their ability to remain viable. Without the manufacturer, ongoing support and resolution of issues such as these becomes much more difficult. And we all suffer as a result.



True, the devaluation of the individual aircraft is a very small factor when compared to the tragic loss of life, but it remains an issue nonetheless to those who have invested their hard earned time and money. Whether or not there is loss of life in no way changes their situations, which appears undeserved given the latest data. At some point we have to consider ALL of the unintended consequences of knee jerk speculation, and keep them in mind when contemplating our positions and actions.



You recently commented in a previous post that Zenith did nothing when these crashes began. This is also a common misconception. Zenith was prohibited from releasing any preliminary crash findings prior to the NTSB's findings, but they had people on the ground with the NTSB assisting with the investigations. The lack of instant info from Zenith infuriated some here, and ZBAG was created out of the desire that something be done NOW, appropriate or not.



I only posted here because of all of the misconceptions and half-truths still flying around, even after the GVT results were released. Those who disagreed with the premise that the airframe is flawed in some terrible way were told that they had their heads in the sand or were in denial. On the surface, the 601 appears to have a higher than usual accident rate based on six crashes. But if you go through each accident, one by one, a clearer picture emerges strongly suggesting the airplane is indeed safe IF properly built and maintained, and the pilot understands the operating limitations. The recent testing also pointed out that flap stops, likely to have been left off some airframes, are needed to insure rigidity in the flap system. This is a good thing.



Sure, I'd like my 601 to be able to withstand the most severe weather and extreme control inputs, but this expectation isn't rational given what the airplane is, and isn't.



Rick



--

d.goddard(at)ns.sympatico
Guest

Posted: Wed Jun 03, 2009 11:38 am Post subject: Putting Flutter Issue to Bed

Glad to see that Cessna is actively and aggressively testing their design, 

hope it works out.



I was unable to read ZBAG's discussion without creating a Yahoo account, 

they don't permit non-members to read messages. I don't think I want to 

create such an account right now but it appears from your description that 

they have a few members who can't admit they might be wrong. That's too bad, 

they started out with good intentions and if they can accept the results 

they will have been successful. The idea as I understand it was to test the 

airframe, job done I think.



The questions in your "third" paragraph are good ones, I think there are 

some who would rather we don't ask those questions. I come up with the same 

maybe in relation to the first,  but as much as I regard the sensitive pitch 

as unusual, I really don't think it's a big issue. I'm very hopeful that the 

number of flying hours for the XL will increase without incident and it will 

outrun any bad reputation.

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d.goddard(at)ns.sympatico
Guest

Posted: Wed Jun 03, 2009 12:01 pm Post subject: Putting Flutter Issue to Bed

Nothing to forgive, different people have different views on what is 

important or even proper, I stand by my position. Remember that these issues 

were originally brought on by crashes, then exacerbated by silence. I am 

doubtful that the NTSB demanded that Zenith exhibit absolute silence in the 

face of what appeared at the time to be a serious issue, but I don't know. I 

doubt that I said specifically that Zenith did nothing, I'm generally not 

keen on making definitive statements about such things, but I might have.  I 

think I recall saying that Zenith did not wish to do the testing that ZBAG 

wanted. I still understand that to be the case.



Yes, the requirement to check the cable tensions, the elevator stops, and 

the flap stops are all good news. These little things may be the smoking gun 

everyone is still looking for.



---

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