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Aeronca 11AC Chief Project FS



 
 
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  #41  
Old July 28th 08, 07:34 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Victor Bravo
external usenet poster
 
Posts: 89
Default Aeronca 11AC Chief Project FS

On Jul 7, 2:00 am, cavelamb himself wrote:


You are coming off pretty snotty, VB.

Show and tell time.

Let's see the airplanes you have designed and built...


I'm holding up my end of an argument, against three or four people who
are being equally snotty. I would be delighted to raise the level of
this "discussion" up to a more genteel level, but it would require the
same commitment from others... who immediately came after me with both
barrels right out of the gate.

As for show and tell, I did not and do not claim to be an aircraft
designer. I've sketched on paper, and head-scratched, and dreamed just
like everyone else on the homebuilt newsgroup. However if you read the
thread from the start I went out of my way to not masquerade as a
structural engineer, and to compliment Chris Heintz on actually being
one.

I will claim only this:

1. After having built and tested and crashed and succeeded and failed
with hundreds of balsa model airplanes, and after having owned 15 or
16 full size aircraft, and after having gone through A&P mechanic
school, and after having listened and learned from several people with
engineering knowledge far greater than my own, and after having
tinkered good and bad with small sheet metal projects on several
airplanes... I have a little better understanding of what I am talking
about on this thread than (let's say) half of the people here.

2. There are some people who probably have a lot more engineering
knowledge than I, there are some with a lot less, and there are a few
with engineering degrees that I definitely do not have.

3. I looked at a CH-601XL and found a fairly obvious problem. I
pointed it out to an Aerospace engineer / A&P in our EAA chapter and
he said there was too much movement there but there might not be any
assymetrical loads on it.

4. There have been now SEVERAL 601XL in-flight wing failures, one or
two new ones since I made the comment that started this flame-fest. If
my big mouth keeps a couple of people from burying their heads in the
sand on this issue, then perhaps there is some good being done.

5. Although I know damned well there are people on this newsgroup with
engineering degrees and greater sheet metal knowledge than mine by
far, for some reason they have NOT participated and NOT explained if
I'm wrong and NOT explained if anyone else is right.

6. I own a CH-701 mini-project (plans and a few tail parts built), and
I would love to build it and fly it. I am a very strong supporter of
Chris Heintz' designs for the most part. He has done something
brilliant, made the airplanes easy to build, and extremely simple.

7. But if Kelly Johnson can make a mistake, and Ed Heinemann, and Kurt
Tank, and Willy Messerschmitt, and Andrei Tupolev, and Matty Laird,
and Igor Sikorsky, and Bill Stout, and even CG Taylor can make a
mistake, then so the hell can Chris Heintz make a mistake. It is my
GUESS that he took the original 601 Zodiac and tried to make a sexy
low drag wing for it, at the same time as he was fighting like hell to
get it light enough for the new LSA category. He had to push too hard
on some engineering issue (or more likely several small ones), he had
to go to a lighter skin gauge or thinner shear webs or spread a load
across too few bolts or something I do not have the college degree to
understand ... and the strength of the airplane fell between what was
good enough on paper and what the real world of ASSYMETRICAL flight
loads or gusts or sub-par workmanship requires.

8. If I'm being snotty I apologize, but I will return fire when fired
upon. And as you can see I will fully substantiate my arguments,
unlike some others here !

From a highly experienced airport bum and highly NON-engineering-
degreed mechanic, I am telling you all that there is an issue on the
tail mounting of the Zenair design. I don't know if it is a big
problem, a fatal accident waiting to happen, hugely overbuilt, or
something that will wiggle but never break. That is a question for the
engineers to clarify but someone needs to look at it.

I'm saying that there is a tragic problem with the CH601XL airplane
design. There are too many catastrophic structural failures that
cannot be swept under the rug of builder error or amateur aerobatics.
If it is a design flaw by Heintz, then he is still a great designer
and deserves the same respect, but he will have to find the problem
and issue a repair or upgrade.

Bill Berle
Ads
  #42  
Old July 29th 08, 03:16 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Jay Maynard
external usenet poster
 
Posts: 521
Default Aeronca 11AC Chief Project FS

On 2008-07-28, Victor Bravo wrote:
I'm holding up my end of an argument, against three or four people who
are being equally snotty. I would be delighted to raise the level of
this "discussion" up to a more genteel level, but it would require the
same commitment from others... who immediately came after me with both
barrels right out of the gate.


Put yourself in my position.

You make comments about an airplane on which I just spent a large sum of
money and invested a lot of personal emotion into, using your experience
with one part of the aircraft to "explain" that another, completely
unrelated part of the aircraft that's been implicated in accidents is
somehow underdesigned, yet not backing up your comments beyond that - and
especially when my experience with your complaint on my aircraft turns out
to be quite different?

Just what kind of a reaction were you expecting?

4. There have been now SEVERAL 601XL in-flight wing failures, one or
two new ones since I made the comment that started this flame-fest. If
my big mouth keeps a couple of people from burying their heads in the
sand on this issue, then perhaps there is some good being done.


Nobody I know of in the Zodiac community is burying their head in the sand.
With a couple of exceptions, nobody's running around in Chicken Little mode,
either. We're watching the situation and doing what we can to minimize the
risks inherent in flying, just as any prudent pilot would do.

One of the Heintz brothers (I think it was Mathieu, but I could be
misremembering) has said that there is no one common factor among the
accidents that are under investigation. Since he's involved in the
investigation, he can't say any more than that until the NTSB has released
its findings.

6. I own a CH-701 mini-project (plans and a few tail parts built), and
I would love to build it and fly it. I am a very strong supporter of
Chris Heintz' designs for the most part. He has done something
brilliant, made the airplanes easy to build, and extremely simple.


Great! Build it and fly it! Even if your scaremongering about the 601XL were
on target, that would not apply to the 701 - as that's a different aircraft,
with a different flight profile, and a safety record even you shouldn't be
able to find fault with.

8. If I'm being snotty I apologize, but I will return fire when fired
upon. And as you can see I will fully substantiate my arguments,
unlike some others here !


Fine. Let me know when you do substantiate your arguments. So far, you have
utterly failed to explain how the one piece of concrete data you have - that
you were able to flex the horizontal stabilizer mounting by moving the
stabilizer tip - has anything at all to do with inflight structural failure
*of* *the* *wings*. Until you do, you're just blowing smoke.

From a highly experienced airport bum and highly NON-engineering-
degreed mechanic, I am telling you all that there is an issue on the
tail mounting of the Zenair design. I don't know if it is a big
problem, a fatal accident waiting to happen, hugely overbuilt, or
something that will wiggle but never break. That is a question for the
engineers to clarify but someone needs to look at it.


This is not borne out on my aircraft.

Further, it has never once been implicated in any accident, fatal or
otherwise, of the 601XL. Therefore, why, exactly, is it relevant?

I'm saying that there is a tragic problem with the CH601XL airplane
design. There are too many catastrophic structural failures that
cannot be swept under the rug of builder error or amateur aerobatics.


That remains to be seen. I do think there's a problem somewhere. There are
enough possibilities, and enough factors that can interact, that I do not
believe there is an inherent design flaw sufficient to cause structural
failure of an aircraft that is properly built, well maintained, and
conservatively flown. That there has been no common factor found in the
accidents in the type tends to bear out that opinion.

Until the problem is found, I intend to maintain my aircraft to the highest
standards of airworthiness possible, and fly it well within its performance
envelope and my capabilities as a 225-hour, non-instrument-rated private
pilot. That's all I can do.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (got it!)
  #43  
Old July 29th 08, 09:08 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Victor Bravo
external usenet poster
 
Posts: 89
Default Aeronca 11AC Chief Project FS

On Jul 29, 7:16 am, Jay Maynard
wrote:


using your experience
with one part of the aircraft to "explain" that another, completely
unrelated part of the aircraft that's been implicated in accidents is
somehow underdesigned, yet not backing up your comments beyond that - and
especially when my experience with your complaint on my aircraft turns out
to be quite different?


What I brought up is two separate issues with the 601, one of which
also applies to the 701. The tail movement has not caused any
accidents to my knowledge, it was simply something that bothered me
about the design, and something that could eventually cause some
inappropriate wear or cracking. If I left you with the opinion that I
was associating the tail flexing with the wing issues I apologize.
They have nothing to do with each other to my limited knowledge.

Nobody I know of in the Zodiac community is burying their head in the sand.


One guy on this newsgroup thread said the 601XL is the safest airplane
in the sky bar none, and apparently got irritated at my mere mention
of a potential problem. His head is buried in something, although it
may not be sand (sorry couldn't resist... no real insult intended)

With a couple of exceptions, nobody's running around in Chicken Little mode,
either.


There are only three 601XL people I know personally. The 3/4 completed
Quick Build kit project with a Jabiru 3300 has been put up for sale by
the builder because of the wing issues. The factory built fly-away LSA
airplane has been put in the back of the hangar until this same issue
is sorted out to his satisfaction. The XL that was built and flown
crashed on the first flight, due to something that had nothing to do
with the wing or tail.

One of the Heintz brothers ... said that there is no one common factor among the
accidents that are under investigation.


Let me get this straight... you're saying there is no one common
factor in the structural inflight failure crashes of... five 601XL
type aircraft ??? Jay, 601XL IS the common factor !

Even if your scaremongering about the 601XL were
on target,


Scaremongering !?!? Kindly explain where you would draw the line
between intelligently discussing a potential problem (that has
resulted in several tragedies) and "scaremongering". Would you prefer
to just not allow any discussions about a potential problem with a
specific airplane?

that would not apply to the 701 - as that's a different aircraft,
with a different flight profile, and a safety record even you shouldn't be
able to find fault with.


The 701 has an excellent safety record, good design features, and a
very clever balance between engineering for strength and engineering
for simplicity. The unique tradeoff between exceptional STOL ability
and cost to build/fly/own is indeed why I am interested in it.

So far, you have utterly failed to explain how ..... the horizontal stabilizer .....
has anything at all to do with inflight structural failure *of* *the* *wings*.
Until you do, you're just blowing smoke.


Once again, I did not and do not believe there is a direct connection
between moving the tail too much with hand pressure and wing failures.
I hope this is not a big surprise... we may be talking about more
than one issue ! The 601 and 701 have an issue which may be a design
flaw or may be a design compromise. I personally didn't like the fact
that you can move the tail in a manner which you cannot on ANY other
similar airplane. So far this has NOT caused any problems or crashes
but I stand by that it was worth mentioning.

The "concrete evidence" that you forgot to mention is that there have
been several fatalities on only one particular variant (XL) of an
otherwise very robust and safe design (Zodiac). For the third and
final time, I am NOT associating these wing failures with the
horizontal tail rigidity... I am associating these wing failures with
the possibility that there is not enough metal in the XL wing.

You sound like the people who stand out in front of a courthouse
screaming "racism !" because the guy who shot four innocent people and
is on trial for murder happens to be a different skin color than the
people on the jury. That has nothing to do with whether he shot the
people or not. Because I have the nerve to hold up an argument and
make people talk about a possible design issue, does not make me a
scaremonger.

(tail movement) This is not borne out on my aircraft.


Good. At least you looked at it, considered my point, and made your
own decision. That's all I wanted out of the tail argument anyway.

Further, it has never once been implicated in any accident, fatal or
otherwise, of the 601XL. Therefore, why, exactly, is it relevant?


The same reason a warning about Salmonella contamination on some food
product is relevant to an automobile recall for bad brakes. You check
your brakes AND you check where your friggin' tomatoes came from,
because you could have, exactly, two separate unrelated problems that
could cause you to get hurt. If you're not getting this concept (of
more than one thing going on at the same time) you might not be an
ideal candidate for aircraft ownership or operation.

I do think there's a problem somewhere.


Ahhh... the dull yellow light of higher brain function flickers
briefly...

I do not
believe there is an inherent design flaw sufficient to cause structural
failure of an aircraft that is properly built, well maintained, and
conservatively flown.


....and just as quickly is extinguished.

In aviation, particularly experimental aviation, we have to be far
more suspicious than complacent. We have to be utterly suspicious of
everything that can affect safety, and ever vigilant. We have to do a
pre-flight inspection assuming that something on the airplane will try
to kill us this day, and it is our job to find it before it does.
Guilty until proven innocent on all matters concerning mechanical
safety. We have to fly knowing the engine IS about to fail, and be
looking for emergency landing areas at all times. There is a very
large burden we have to carry, which makes every flight equally nerve
wracking as it is enjoyable. It is this burden that makes me willing
to argue with and infuriate a total stranger like you, so that perhaps
your anger at me will force you to take that one extra look at a
problem from a different angle.

You say there are no common factors in the failures... which SHOULD
prove that at least one of them was well built and being flown within
its limits. The most recent one was a formation flight, so it can be
assumed that pilot was flying in level flight and not maneuvering
excessively.

Until the problem is found, I intend to maintain my aircraft to the highest
standards of airworthiness possible, and fly it well within its performance
envelope and my capabilities as a 225-hour, non-instrument-rated private
pilot. That's all I can do.


Sorry Jay, I can't let you off the hook. The "highest standards of
airworthiness possible" means you would load test the wings (sandbag
test) to verify structural integrity... at various torsional moments
(wing twisting due to air loads). "Within its performance envelope"
means that you KNOW what the real performance envelope is. If other
601XL aircraft have failed inflight operating within or even near this
envelope, it means the published envelope is really not fully proven
out.

Changing my personalities for a moment, and assuming the role of
someone less antagonistic who only wants you to be able to fly safely,
I will turn off the smart-ass switch and turn on the "help this guy
live to enjoy his airplane" switch. Until a real engineer has
determined the full problem and figured out a real solution, I
sincerely advise you to implement a temporary set of restrictions in
your flight envelope to increase your structural margins.

Reduce your turbulent air penetration speed and VNE speed by 25%
each.
Reduce the allowable gross weight of your airplane by 10%.
Reduce the maximum G loading by one or two G.
Limit aerobatics to low G barrel rolls.
Reduce or eliminate maneuvers that put rolling (wing twisting) loads
on at the same time as G loads.

Taking these precautions WILL greatly reduce the loads on your
structure, until a qualified engineer figures this all out.

Bill Berle
  #44  
Old July 29th 08, 09:45 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Jim Logajan
external usenet poster
 
Posts: 1,958
Default Aeronca 11AC Chief Project FS

Victor Bravo wrote:
Let me get this straight... you're saying there is no one common
factor in the structural inflight failure crashes of... five 601XL
type aircraft ??? Jay, 601XL IS the common factor !


I can only find 2 such cases in the NTSB database - and one of those
appears to have been due to over-control brought on by flight into IMC:

http://www.ntsb.gov/ntsb/brief.asp?e...09X00539&key=1
http://www.ntsb.gov/ntsb/brief.asp?e...17X00209&key=1

It would be helpful if you could provide information on the other three
alleged incidents.

P.S. For comparison, I had no problem finding several incidents of wing
failures on Van's RV models.
  #45  
Old August 4th 08, 02:34 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Jay Maynard
external usenet poster
 
Posts: 521
Default Aeronca 11AC Chief Project FS

On 2008-07-29, Victor Bravo wrote:
If I left you with the opinion that I was associating the tail flexing
with the wing issues I apologize. They have nothing to do with each other
to my limited knowledge.


Well, then, there's little point in harping on it if the subject under
discussion is the cause of what appears to be in-flight structureal failure.

There are only three 601XL people I know personally. The 3/4 completed
Quick Build kit project with a Jabiru 3300 has been put up for sale by
the builder because of the wing issues. The factory built fly-away LSA
airplane has been put in the back of the hangar until this same issue
is sorted out to his satisfaction. The XL that was built and flown
crashed on the first flight, due to something that had nothing to do
with the wing or tail.


Right. Airplanes crash for lots of reasons.

One of the Heintz brothers ... said that there is no one common factor among the
accidents that are under investigation.

Let me get this straight... you're saying there is no one common
factor in the structural inflight failure crashes of... five 601XL
type aircraft ??? Jay, 601XL IS the common factor !


Just like the RV is the common factor in all of the inflight failures Jim
Logajan mentioned. The point is that, if there's no common factor in the
601XL crashes, then there's likely no design flaw - for if there was one, it
would show up as a common factor in the crashes.

Even if your scaremongering about the 601XL were on target,

Scaremongering !?!? Kindly explain where you would draw the line
between intelligently discussing a potential problem (that has
resulted in several tragedies) and "scaremongering". Would you prefer
to just not allow any discussions about a potential problem with a
specific airplane?


Your line right abouve, about the 601 being the common factor - even though
there's no evidence, at this point, that the various crashes are in fact
related by any particular cause - is scaremongering. Intelligent discussion
would be about trying to figure out what the problem is, not railing that
the design is unsafe without anything concrete to back it up.

You sound like the people who stand out in front of a courthouse
screaming "racism !" because the guy who shot four innocent people and
is on trial for murder happens to be a different skin color than the
people on the jury. That has nothing to do with whether he shot the
people or not. Because I have the nerve to hold up an argument and
make people talk about a possible design issue, does not make me a
scaremonger.


Sorry, but I disagree. You fail to advance any other cause that's backed up
by real-world data. There have been lots of crashes in RVs, but you're not
running around calling it unsafe.

Ahhh... the dull yellow light of higher brain function flickers briefly...


For someone who claims not to stoop to personal insult, this is awfully
insulting.

I do not believe there is an inherent design flaw sufficient to cause
structural failure of an aircraft that is properly built, well
maintained, and conservatively flown.

...and just as quickly is extinguished.


....as is this.

I've looked at the available data, and come to my conclusion based on what's
known and what's been disclosed. Because my conclusion is different from
yours, you claim my brain isn't working.

All you're doing is destroying your credibility. You come across like a
salesman for a competitor, trying to destroy the market for the Zodiac, not
like someone interested in improving air safety.

In aviation, particularly experimental aviation, we have to be far
more suspicious than complacent. We have to be utterly suspicious of
everything that can affect safety, and ever vigilant.


This (as well as the rest of your paragraph) is nothing more than saying
that pilots have to manage risks. That's indeed inherent in aviation.
Aviation is not dangerous, but it's terribly unforgiving. The pilot's
defense is to assess each risk and determine whether that risk is
acceptable.

You say there are no common factors in the failures... which SHOULD
prove that at least one of them was well built and being flown within
its limits. The most recent one was a formation flight, so it can be
assumed that pilot was flying in level flight and not maneuvering
excessively.


If you're referring to the crash on the way to Sun n Fun, that aircraft was
built by the Czech Aircraft Works to European LSA standards - which include
a 450 kg (990 pounds) max gross, not the 600 kg the XL was designed to. CZAW
had to modify the design to make that limit reachable. We don't know just
what modifications they made.

Until the problem is found, I intend to maintain my aircraft to the highest
standards of airworthiness possible, and fly it well within its performance
envelope and my capabilities as a 225-hour, non-instrument-rated private
pilot. That's all I can do.

Sorry Jay, I can't let you off the hook. The "highest standards of
airworthiness possible" means you would load test the wings (sandbag
test) to verify structural integrity... at various torsional moments
(wing twisting due to air loads).


This isn't something that's done for any other production aircraft during
maintenance. (Remember, mine's a factory-built SLSA, not an experimental.)
Zenair has done that test, and that's good enough for me.

"Within its performance envelope" means that you KNOW what the real
performance envelope is.


AMD tested the aircraft through a full Part 23 certification flight test
program. That's defined the envelope as well as any 152.

If other 601XL aircraft have failed inflight operating within or even near
this envelope, it means the published envelope is really not fully proven
out.


....assuming that the primary cause of the crash was a structural failure of
an aircraft that had been flown within the envelope for its entire lifetime.

Jim Logajan said:

I can only find 2 such cases in the NTSB database - and one of those
appears to have been due to over-control brought on by flight into IMC:

http://www.ntsb.gov/ntsb/brief.asp?e...09X00539&key=1
http://www.ntsb.gov/ntsb/brief.asp?e...17X00209&key=1


There are at least two other fatal Zodiac crashes that come to mind and
could be attributed to wing failure, though the NTSB has not yet released
final reports:

http://www.ntsb.gov/ntsb/brief.asp?e...15X01677&key=1
http://www.ntsb.gov/ntsb/brief.asp?e...21X00519&key=1

Changing my personalities for a moment, and assuming the role of
someone less antagonistic who only wants you to be able to fly safely,


About damned time.

I will turn off the smart-ass switch and turn on the "help this guy
live to enjoy his airplane" switch. Until a real engineer has
determined the full problem and figured out a real solution, I
sincerely advise you to implement a temporary set of restrictions in
your flight envelope to increase your structural margins.


As it happens, I already do a good number of these...

Reduce your turbulent air penetration speed and VNE speed by 25%
each.


Va is 90 knots in the Zodiac. 75% of that is 67.5 knots...and I come over
the fence on landing at 65.

Vne is 140. 75% of that is 105 knots - where I normally top out at, anyway.

Reduce the allowable gross weight of your airplane by 10%.


The Zodiac XL's 1320 pounds max gross is a regulatory number to meet the LSA
spec. The airframe was designed for a max gross of 1450 pounds. 90% of that
is 1305 pounds; I meet that anyway.

Reduce the maximum G loading by one or two G.
Limit aerobatics to low G barrel rolls.


I do not fly aerobatics, period. I'm too susceptible to motion sickness.

Reduce or eliminate maneuvers that put rolling (wing twisting) loads
on at the same time as G loads.


Such as?

Taking these precautions WILL greatly reduce the loads on your
structure, until a qualified engineer figures this all out.


I know how my aircraft has been flown throughout its lifetime, because I'm
the only one who's flown it since it passed its flight test.

You're also assuming that the Heintzes aren't qualified engineers...
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (got it!)
  #46  
Old August 4th 08, 10:23 PM posted to rec.aviation.marketplace,rec.aviation.homebuilt
Victor Bravo
external usenet poster
 
Posts: 89
Default Aeronca 11AC Chief Project FS

I'm not a salesman for any of the competition, nor am I "against"
Zenair in any way shape or form, sincerely. I've owned an RV-3, which
is one of the RV's that you mentioned have had wing failures. Van in
one case did find that there was something that was appropriate to
change (rear spar attach fitting hole edge distance problem, becoming
RV-3A), and also found it appropriate to change the design later to
make it more immune to hot-dogging pilots (which arguably was an
operational error rather than a design flaw), becoming the RV-3B.

This discussion has gotten somewhat out of hand for perhaps the wrong
reason. I stand by my statement that there appears to be something in
the 601XL that needs to be addressed.

I have personally spoken to TWO professional crash investigators (one
governmental and one engine-related) who have expressed a strong
personal opinion that the XL is too lightly built. These two
investigators have examined one of the non-fatal 601 crash wrecks, and
both have several years of professional experience looking at why
airplanes crashed.

My comments about moving the tail back and forth were meant to further
illustrate the notion that the CH 601 is very lightly built. I found
one airplane where the amount of movement startled me, and I said
something about it publicly. That should not have made you anywhere
near as upset or offended as you apparently got. My apologies, I was
not intending to upset you when I pointed that out.

(design flaw) or if there was one, it
would show up as a common factor in the crashes.


There have been several inflight wing separations on a common aircraft
design. There has been a letter from the factory somewhat addressing
the situation as well... so Heintz understands that there is some kind
of situation. Common sense AND an engineering textbook should tell you
that this needs to be taken very seriously. Van took it seriously
every time, made changes, and the RV's continue to be well respected
designs. Heintz is a well respected designer and I strongly believe he
will continue to be so.

Your line right abouve, about the 601 being the common factor - (snip) - is scaremongering.


Stating a fact (several inflight wing failures in one particular
design) should not be scaremongering. How would you have addressed
this fact without being guilty of scaremongering? If I had reported
that people are putting their 601's up for sale, even though that is
fact (I was told about a factory-built XL being put up for sale today,
and another friend of mine has put his QB project up), it could be
seen as scaremongering. But all I said was that there have been
several similar inflight failures and people need to get to the bottom
of this issue. I stand by that still.

Intelligent discussion
would be about trying to figure out what the problem is, not railing that
the design is unsafe


I thought I HAD been discussing the idea of figuring it out. It's hard
to be open minded enough to figure it out, when people are just
standing there in denial that there COULD even be a problem.

Sorry, but I disagree. You fail to advance any other cause that's backed up
by real-world data.


The real-world data is that four or five of these airplanes have had
the wings come off in flight to one degree or another. That seems to
be more than enough of a cause to me. Real-world data comes in several
flavors... wind tunnel tests, sandbag tests, metallurgy lab tests, and
on and on. Real-world data ALSO includes field testing by non-
engineers in actual flight conditions. The results from this type of
non-engineer testing, which in this case has involved unfortunate
tragedy, is just as valid as scientists in white lab coats running
computer simulations or sandbag tests.

There have been lots of crashes in RVs, but you're not
running around calling it unsafe.


OK, the original RV-3 design is less safe than later versions, and is
shown to be fundamentally unsafe for certain aerobatic or overspeed
flight conditions which have resulted in tragic crashes. The
unmodified original RV-3 can only be flown safely with speed and G
load restrictions compared to later models... just like I am
suggesting with the 601 UNTIL the root cause of the problem is figured
out. The RV-3A and RV-3B upgrades have greatly extended the safe
flight envelope and provide a far greater margin of structural safety.


Ahhh... the dull yellow light of higher brain function flickers briefly...


For someone who claims not to stoop to personal insult, this is awfully
insulting.


I claim that others stooped to personal insult far earlier than I.
After a few people come at me with guns blazing, I'll blaze right
back. No apologies on that particular issue.

I've looked at the available data, and come to my conclusion based on what's
known and what's been disclosed. Because my conclusion is different from
yours, you claim my brain isn't working.


No, I just think you have a beautiful, fun, and flying airplane, and
because of that fact you don't want to even discuss the possibility it
might need another couple of pounds of metal in the wing somewhere.

All you're doing is destroying your credibility. You come across like a
salesman for a competitor, trying to destroy the market for the Zodiac, not
like someone interested in improving air safety.


I am a salesman for one old, tired, Aeronca Chief project that I want
to find a good home for. That's it. I do have a Zenair project in my
garage, and I do not have an RV, Savannah, Sonex, or Thorp. You are
dead wrong, my only interest in (this extended offshoot of my Aeronca
posting) is indeed for air safety. You see, if a structural problem
with ANY small airplane causes a crash, it could have a devastating
effect on my ability to fly my little antique Taylorcraft around ever
again.

If you're referring to the crash on the way to Sun n Fun, that aircraft was
built by the Czech Aircraft Works to European LSA standards - which include
a 450 kg (990 pounds) max gross, not the 600 kg the XL was designed to.
CZAW had to modify the design to make that limit reachable.



Well, that sure as hell sounds like something that needs to be gotten
to the bottom of, now doesn't it? Some of the QB kits I'm told were
built in the Czech Republic too. Some were built elsewhere. So you're
telling me that SOME of the XL airplanes built for one part of the
world have a lot more metal in the structure, than some OTHERS built
in (or for) some other part of the world? That sure as hell needs to
be part of the investigation too.

We don't know just what modifications they made.


You're making my point 100X better than I ever could have made it !!!

This isn't something that's done for any other production aircraft during
maintenance.


No, they only do it after there have been a few suspicious crashes...

(Remember, mine's a factory-built SLSA, not an experimental.)
Zenair has done that test, and that's good enough for me.


Here's where I got upset and started thinking about people's heads
being in the sand. Zenair "had done that test" probably before any of
the crashes, and so perhaps there is something in the real world that
did not show up on the tests. You are drawing arbitrary lines between
this 601XL and that 601XL, between ones built here and ones built
there, between experimental and S-LSA versions, between ones painted
white and ones painted blue. I believe some of each have crashed. If
that is true (that some SLSA's have crashed, some homebuilts, some
Euro models) then the only "common factor" in the crashes would be the
basic airframe design. If only one of the sub-types were crashing
(ones built in Czechoslovakia on Wednesdays with greater than 50%
relative humidity and using green upholstery) then that information
leads you down a different path to finding out what is going on.

AMD tested the aircraft through a full Part 23 certification flight test
program. That's defined the envelope as well as any 152.


And if five 152's had inflight wing failures within a five year
period, what do you think the NTSB and the concerned owners would
do... argue about who's being polite and whose table manners need
polishing?

...assuming that the primary cause of the crash was a structural failure of
an aircraft that had been flown within the envelope for its entire lifetime.


I don't care whether the airplanes are being flown within any
arbitrary envelope, it doesn't matter at the level I am talking about.
Because I'm NOT attacking Zenair, and I'm NOT suing anyone, and I'm
NOT advocating the grounding of the fleet... the legal issues and
operating limits are not the focus of my thinking. I am thinking that
aircraft are being lost in the real-world operating environment...
whether that is within or not within the airplane's POH. If all these
crashes are happening outside the POH limits, then it needs to be
figured out WHY five different people were flying the airplane outside
these limits, and whether these limits are too easily exceeded in real-
world operating conditions by average pilots.

(changing my personality) About damned time.


You too, if we're being honest.You're looking at me like a vicious
party-pooper instead of someobody who thinks there is an issue which
others are not paying enough attention to. It's not my life at stake
here, Hombre, I have a Taylorcraft with a 67 year history of keeping
the wings on.

Va is 90 knots in the Zodiac. 75% of that is 67.5 knots...and I come over
the fence on landing at 65.


You come over the fence at 65 knots on an airplane with a 40 knot
stall speed? would you please get your flight instructor online in
this conversation? I have a few words for him/her about energy
management and landing distance.

I do not fly aerobatics, period. I'm too susceptible to motion sickness.


OK, then that is not a factor.

Reduce or eliminate maneuvers that put rolling (wing twisting) loads
on at the same time as G loads.


Such as?


Pulling the stick back and sideways at the same time. If you want to
do a tight turn then my suggestion is to roll the airplane into the
turn, then wait until the rolling part is complete, put the stick back
in the center, THEN pull back on the stick rather than all at once.

RUMOR is that on one of the crashes the ailerons were found far away
from the crash site. This brings up the POSSIBLE existence of flutter
(TBD by real engineers). I humbly suggest that you check your ailerons
for excess play, flexibility in the system where it is supposed to be
rigid, aileron mass balance, heavy paint on the ailerons, etc.

You're also assuming that the Heintzes aren't qualified engineers...


Oh no not at all... Chris Heintz is one of the most highly qualified
light aircraft engineers around. I don't know about anyone else in the
family's qualifications one way or another.

Fly extra safe Jay, I'd love to have you around for a while if for no
other reason than to argue with









 




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