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