More information has recently been posted about the recent Zodiac GVT results on the Zenair Europe Website. For more details, visit:

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Comment by Chumphol Sirinavin on June 12, 2009 at 12:15am
Thank You, Nicholas, Juan Vega, and a few others.
I have good faith in Chris Heintz, enough to have two CH 701's, and had been much annoyed with careless hard accuses and negative rumors. Homebuilders need to be educated and positive thinking, or else just build wooden carts or cabinets, and stay firm on the ground for the progress of aviation.
Comment by Doug Dugger on June 5, 2009 at 10:31pm
Well maybe the light at the end of the tunnel isn't a train after all it looks like good old sunshine and a good day to fly our 601s How many of us aviators with 601xls will be at osh this year. planning on taking N111TZ the very first elsa 601 flying. hope to see lots more there.
Comment by Juan Vega on June 1, 2009 at 9:08am
See Below. Lets Quit the BS, as the test result show the Flutter is the wrong tree to bark up. Lets look a the quality of the builds, even the AMD one or the lack Pilot control.
This reprot makes it clear Flutter aint happening!

The recent meetings between Zenair and German authorities (the DAeC and their DAR engineers as well as the BFU) were very productive with key steps taken towards re-establishing the good standing of the CH 601 XL aircraft throughout Europe. A very comprehensive presentation by the head of the GVT program that tested the aircraft made it very clear that the oft suggested flutter is an exceedingly unlikely “smoking gun” to explain past accidents. The engineer in charge instead applauded Chris Heintz for the overall scores obtained by the Zodiac throughout the tests, as they were among the best ever seen in his lab. The results of the very thorough linear flutter analysis left no doubts in anyone’s mind: “No tendency to flutter or divergence was found within the flight envelope of the CH 601 XL”. This included tests from minimum to maximum take-off weight; with fixed as well as free controls; with control cable tensions varying from well below 10 lbs. to over 40 lbs, and with standard as well as overweight control surfaces (i.e. possibly due to excessive paint in the “real world”); all from sea level to over 15,000 feet and to speeds well above 400 km/h.

In order to ensure accurate results, all tests were carried out on two different Zodiac aircraft. The significance of the flap stops called-for as part of the regular design was confirmed. The aircraft which did not at first have these installed showed less satisfactory results than Zenair’s own standard demo plane (with stops) which was one of the tested planes. Zenair will be issuing a Service Letter very shortly calling for owners/pilots to check their flap stops (and to install them prior to further flight operations if these have not been previously fitted). By the end of the tests, both aircraft (a classic CH 601 XL and the newer CH 650 E) presented the same consistent results: No tendency to flutter.
Also during this GVT testing process, it was noticed that the German-registered CH 601 XL on which the tests were conducted did not have part of the aileron-stop structure which was an integral part of the CH 601 XL at the time of German certification. Zenair has been asked by the DAeC to issue a Service Letter addressing this potential discrepancy for German-registered CH 601 XL; the DAeC will be issuing its own AD shortly to ensure the aircraft’s ongoing compliance with LTF-UL certification.

Many questions were answered by the flutter expert after his presentation to German authorities; his answers and ample GVT data successfully satisfied those present that flutter was a non-issue for the Zenair Zodiac design. “The complete ground vibration tests (GVT) just completed were conducted to natural frequencies well over 70 Hz. This clearly demonstrates that the standard Zodiac design is flutter-free within (and well beyond) the entire range of its flight envelope” said Chris Heintz, who also attended the meetings.
Comment by Thomas Richardson on May 30, 2009 at 1:10pm
Ok, I dont have a dog in this hunt, However I feel that I must comment. For any of the principals at Zenith to comment at all until the investigations are complete would be completely irresponsible. Any comments at this point would be purely speculative at best and could do more damage than good. I know for a fact after listening to Mathew and Sebastian in Sebring , that they are very involved in this matter, go to all accident sites and cooperate fully with both authorities. I would much rather have a definitive answer concerning the issue than several possibilities that have people running off in different directions trying to solve an as yet to be determined problem or cause. Why you might ask. Open your phone books and look under attorneys. In my city of Jacksonville, Florida there are over 100 pages front to back of attorneys, most of them being personal injury attorneys just hoping one of these brothers will make an offhand comment that can be tied to culpability. If I had a 601 instead of my 701, I would probably park it for a while and go fishing, until the issue is better understood. Even now no one can say for sure that the plane in Calif. was in straight and level, on final or pulled nose up. I have watched thousands of planes come and go at my airport and for the life of me, I dont think I could see a wing vibrating from the ground as some witnesses have said. Let it settle, let them do their jobs and then we will all know what to do.
Comment by Jake Reyna on May 30, 2009 at 6:45am
What's really alarming is that over 90% of accidents are caused by pilot error!! oh my!! When is Zenith going to address this issue? And while they're at it, how about the 15,000 that are murdered in the US annually. Hurricane season is quickly approaching and many are unprepared, what will Zenith do?

It seems that some didn't read the Conditions of Sales and Warning Notice, Section 10.

"Each aircraft ..... is liable to be unpredictable, hazardous, and even potentially lethal. "

How about taking some responsibility for our actions and stop looking to blame others when life and death get in the way.

Comment by Erik McWethy on May 29, 2009 at 5:13pm
If flutter does not appear to be an issue with the 601XL, then what does Zenith believe was the cause of the recent accidents? 6 in flight breakups in the last 3 years is fairly alarming, and the total population of 601XL's flying is small enough that 6 in flight breakups is a noteable failure rate.

I am in the early stages of test flying my 601XL, and am being very carefull to check my cable tensions, but I would feel much more comfortable if Zenith gave a more definative explanation for the recent problems.
Comment by Doug Sire on May 29, 2009 at 2:56pm
When will you make the data available for independent review?
Comment by John Davis on May 29, 2009 at 1:52pm
Hi Nicholas,

Will the actual reports be available for download ?

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