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