z601c(at)anemicaardvark.c
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 Posted: Thu Jan 28, 2010 8:18 am Post subject: Recommended Letter-writing campaign, follow-up |
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Here is the email I sent AOPA. I encourage everyone to express their concerns
to them, whether they specifically agree with me or not.
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I was both surprised and disappointed when I read the article on the Zenith
601XL. Filled with misinformation, the story makes a bad situation worse.
First, Zenith does not offer an E-LSA version of the 601XL. It offers a factory-
built LSA version, or a kit for an experimental, amateur-built version (EAB).
An EAB is not an E-LSA; there are significant differences.
Second, although the 601XL has had more than its share of accidents, I am not
aware of any knowledgeable witnesses to any of them. The witnesses have been
well-meaning people of the same caliber that think an engine stall and a wing
stall are the same thing. That has been one of the problems: aircraft which
fail in flight, yet without a single common thread that defines the exact
problem, and no reliable witnesses.
Your article implies that flutter is at fault. That should be discernible with
ground vibration testing (GVT). Yet when Zenith had GVT done by an independent
authority, a properly rigged aircraft showed no resonance. Flutter seems
pretty unlikely.
A second GVT was conducted by the LAA in England. Examination of the
methodology of that test raises significant questions about the validity of the
test. However, the only resonance it indicated was the aircraft swaying from
side to side on its gear. Despite the fact that it did not indicate flutter as
the problem, it was used as the justification to require UK 601XLs to install
aileron balances.
Zenith's demonstrator aircraft has well over 1,000 hours on it, but has shown
no problems. Numerous privately built aircraft have also amassed significant
hours without difficulty. The individual in the hangar next to me, who has a
Czech factory built version, put over 300 hours on the aircraft last year
without problems.
Since aircraft built by individuals, Zenith's facility in Georgia, and one
aircraft built under license in eastern Europe have all experienced breakups,
it may be the problem is how the aircraft is flown. A search on YouTube has
shown 601XLs performing acrobatic maneuvers, suggesting some may have
overstressed their aircraft.
Despite the lack of a definite cause, Zenith has, in good faith, released a
modification kit that essentially fixes everything that might be wrong. Whether
or not this targets whatever the actual problem may be is open to question,
because that remains unknown.
I normally depend on AOPA to at least get the facts straight. Please, do a
better investigation, get the facts, and THEN publish a revision to the
article. AOPA is supposed to be promoting general aviation, not publishing
negative articles that are short on facts.
--
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Jim B. Belcher
BS,MS Physics
A&P/IA
General Radio Telephone Certificate
Instrument Rated Pilot
Retired Aerospace Technical Manager
601XL Builder
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