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psm(at)att.net
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 Posted: Wed Apr 22, 2009 4:24 pm Post subject: Report no. 2 from Sun n Fun - The Heintz clan reactions t |
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Hi Jay,
I believe your comments are quite valid and interesting so I will try
to continue the discussion down your path. I have decided the
flaming is just irritating and not worth reply.
I will try again to deal with the engineering vs. political issue here.
There are definite engineering questions about the quality of the
Zodiac XL design. So far as I know there have been exactly zero
reasonable answers to most or all of them. The exception to this in
my mind is the new issue raised by the NTSB report about the stick
gradient. That one seems to be a very simple engineering flaw in the
design. I personally don't know that it is true or false, but it
should be nearly child's play to confirm it and design a fix -
compared to the other issues at hand. I believe Matthew would agree
that there is no real engineering confirmation of most of the issues
(the stick one is brand new, while the accidents have been going on
over years). He has said many times in my presence that the
engineering report he expects soon is needed for him to believe there
is a problem in the design.
This is an entirely different question than the NTSB "Authority" in
this matter. My understanding (subject to more correction if needed)
is that their role is in accident analysis which is not even close to
engineering design analysis. The two are completely different
efforts done with different data and different thinking. Their
conclusion which seems completely clear to me is that the XL needs
aileron balancing. I merely accept their conclusion because they
made it. I don't know if it is right or not from an engineering
analysis point of view, but I don't think they or the FAA or I care
one iota if the engineering analysis agrees with the NTSB ruling or
not. They are just different issues.
If everyone could just agree that these are separate issues, then the
whole mess could be cleaned up very quickly.
I see the design process as disconnected from the accident analysis
process. If it is needed to implement a design change, then it
doesn't really matter why the change is needed to do a professional
job of designing the change. I know this sounds crazy, but please
give me a little respect here. I spent a career doing just this sort
of thing in the electronics and communication industry. I really do
know what I am saying here is rational even if the whole group of
non-engineers in the group doesn't get it or disagrees.
I am out of time for now, so please forgive me if I missed an
important point or two. The restaurants here in Florida are getting
close to closing time and I want my dinner.
Paul
XL grounded
do not archive
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rsteele(at)rjsit.com
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| Posted: Wed Apr 22, 2009 5:04 pm Post subject: Report no. 2 from Sun n Fun - The Heintz clan reactions t |
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Paul,
I think one of the issues here is that the NTSB report appears to be
internally inconsistent. Regardless of their political or other
authority, this undermines their credibility, at least in regards to
this specific issue. In particular, any engineer examining the issue
is going to pick up on this immediately and discount such flawed
logic. Regardless of the correctness of their conclusions (and I make
no effort to support or dispute them) they just plain blew this report.
Now, you may respect the organization enough to accept their
conclusions regardless of the logic. Personally, I was very
disappointed in the sloppiness of this work and I'm very glad other
organizations/people are looking at this problem and are not relaying
on such a flawed report to make life and death engineering changes.
I'm sure Zen* could design a perfectly adequate mass balancer in a
matter of days. It's not so clear that it would actually solve
anything other quieting some critics.
Ron
XL wings
do not archive
On Apr 22, 2009, at 8:23 PM, Paul Mulwitz wrote:
| Quote: |
Hi Jay,
I believe your comments are quite valid and interesting so I will
try to continue the discussion down your path. I have decided the
flaming is just irritating and not worth reply.
I will try again to deal with the engineering vs. political issue
here.
There are definite engineering questions about the quality of the
Zodiac XL design. So far as I know there have been exactly zero
reasonable answers to most or all of them. The exception to this in
my mind is the new issue raised by the NTSB report about the stick
gradient. That one seems to be a very simple engineering flaw in
the design. I personally don't know that it is true or false, but
it should be nearly child's play to confirm it and design a fix -
compared to the other issues at hand. I believe Matthew would agree
that there is no real engineering confirmation of most of the issues
(the stick one is brand new, while the accidents have been going on
over years). He has said many times in my presence that the
engineering report he expects soon is needed for him to believe
there is a problem in the design.
This is an entirely different question than the NTSB "Authority" in
this matter. My understanding (subject to more correction if
needed) is that their role is in accident analysis which is not even
close to engineering design analysis. The two are completely
different efforts done with different data and different thinking.
Their conclusion which seems completely clear to me is that the XL
needs aileron balancing. I merely accept their conclusion because
they made it. I don't know if it is right or not from an
engineering analysis point of view, but I don't think they or the
FAA or I care one iota if the engineering analysis agrees with the
NTSB ruling or not. They are just different issues.
If everyone could just agree that these are separate issues, then
the whole mess could be cleaned up very quickly.
I see the design process as disconnected from the accident analysis
process. If it is needed to implement a design change, then it
doesn't really matter why the change is needed to do a professional
job of designing the change. I know this sounds crazy, but please
give me a little respect here. I spent a career doing just this
sort of thing in the electronics and communication industry. I
really do know what I am saying here is rational even if the whole
group of non-engineers in the group doesn't get it or disagrees.
I am out of time for now, so please forgive me if I missed an
important point or two. The restaurants here in Florida are getting
close to closing time and I want my dinner.
Paul
XL grounded
do not archive
> ==============================================
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tigerrick(at)mindspring.c
Guest
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| Posted: Thu Apr 23, 2009 5:14 am Post subject: Report no. 2 from Sun n Fun - The Heintz clan reactions t |
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Hi, Ron.
Your $0.02 is worth so much more than that, you've just stated a very well-reasoned and clear assessment of the 601 issue. And I'm using the word "issue" because it is exactly that, we seem to have elements of a lynch-mob mentality at play here that appears to feed on itself instead of hard facts.
Throw around words like "problem" and "flutter" in cyberspace enough times, and it becomes accepted as fact. As far as I know, there still have been no concrete findings from any reliable source about a single source of the 601 crashes. We tend to lose sight of the big picture sometimes here, which is that everybody involved; builder, pilot, manufacturer, insurer, or passenger; ALL would like to put this matter to rest and get back to building and flying.
Personally, I'm appalled that so many here, people I've considered good cyber-friends in the past, have indulged in name calling, character assassination, outright threats, and other forms of rudeness over this matter. There's been no shortage of chest-thumping and posturing either, and although it might feel good at the moment, it can be very damaging long term. Words are powerful, and they do have meaning. And these messages stay with us long after the "send" button is pressed.
Do we really want to impugn the integrity of a fine light aircraft manufacturer that is working hard on this, and alienate them? If so, what will we do for factory support? True, it's frustrating not to hear anything from them while the chatter reaches a fever pitch on the list, but I think they're wise in only releasing information that's solidly researched and confirmed. In my opinion, there are a few folks here who owe the Heintz family a large apology. We all trusted them enough to buy their airplane kit, and trust our lives to it. Let's trust them a bit more to address this issue in their usual conservative, scientific manner.
Those who think the risk of flying their 601s is currently too great have voluntarily grounded them, which is wise in my opinion. Those who don't, haven't. This is OK, too. Every time we strap on an airplane, we go through a new risk analysis session, and make decisions accordingly. My own 601XL lost its hangar space last fall, so I moved it to my shop for some upgrades in the meantime. Until I can find another hangar for it, it will remain AOG. But I was flying it regularily even while this debate was already hot and heavy, as it's proven its airworthiness time and time again, and still shows zero signs of any sort of incipent design flaw after encountering all sorts of weather and turbulence.
Let's not forget that builder care, pilot technique, and accumulated airframe stresses might also play some huge parts here. Loose or oversized spar bolts, rough handling of the stick at high airspeeds, unauthorized aerobatics, or improper airframe materials all seem to go unnoticed here while the emphasis centers on aileron flutter (which although likely, has still not been proven to the point of requiring mods beyond keeping proper cable tension).
I certainly don't want any more crashes and fatalities. No one does. Everyone who has a 601, or loves someone who flies one, has a dog in this fight. But, please, let's not let our fear and uncertainty result in biting the hands that feed us while we await the hard data. Let's not demonize those who should be our staunchest allies, because only through working as a team will we resolve this in the shortest order. To do otherwise only drags things out, and stifles the free exchange of crucial information.
Sorry this was so long, gang.
Rick Lindstrom
Zenvair N42KP
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