Some are having an issue going past page 9 of this Q&A so I am starting a new discussion.

Please note that the upgrade package kit goes well beyond just meeting the FAA’s conservative
methods and no changes are being considered.

Like previous Q&A's, post all your questions / concerns at the bottom of the last page of this Q&A.  If I do not have the answer, I will consult with Chris Heintz and or other engineers.
If you have a very technical question or just want to vent, call me at 705-526-2871.
Thank you for your continued support.
Mathieu Heintz
Zenair Ltd

Views: 2179

Replies are closed for this discussion.

Replies to This Discussion

Having an open discussion with all parties is a good idea and will invite the FAA and NTSB to attend our Zodiac forum at Sun-n-Fun.
Yes, it is frustrating that the FAA did not reevaluate their calculations based on the last upgrade.

I cannot speak on behalf of the the FAA but a good question would be "why is the FAA not concerned about the present design with the upgrade?"

1, Static load tests were done within 5% of the FAA's very conservative load analysis, which is more than what is required in FAR23.
2, Upgrade kit further increases the margines
3, German flutter report was very clear from the start that if the aircraft is built to the drawings, there is no flutter. We have not seen a report from the FAA or NTSB finding a fault with our flutter report.
4, Upgrade addresses potential flutter for aircraft not built as per drawings by adding aileron counter balance weights.

For Experimental aircraft owners, since the FAA has confirmed that the LSA rule exceeds FAR23, there should be even less concern about all this. Experimental aircraft are not expected to exceed the LSA rule.
Paul, you have done nothing to help the process except whine about everything. The only problem with your XL is you.

You said it best, "Sadly, I feel you are (once again) the real problem here rather than the solution." It is not possible for you to be a helpful contributor. We're not all in this together, you're out there all by yourself.

What Planet are you from? You built an experimental aircraft, you are the manufacturer. Quit making excuses that you are scared of flying your plane. Sell it. The aircraft has been modified, everyone is doing the mods, quit wining. Now go a do yhour mods or sell it.

Uh, guys, calm down and think how this discussion came about.

In a Zenith-List post dated 2/23/10, 03:09 p.m., Mat invited Paul to "post your question at"

Paul did so. The discussion evolved from there. Paul has concerns about his airplane and would like to see an open discussion at, e.g., Sun n Fun.

You can agree or disagree, but don't shoot Paul for following Mat's suggestion and moving the discussion to this forum.

Just my 2 penny's worth.

And speaking money, I'm sending a $100 personal check today to Zenith Aircraft to help with the cost of flutter and/or load tests for the upgraded 601XL/650. I support the upgrade, I believe in the upgrade, and I'm willing to put my money where my mouth is.

Thanks for the offer but your offer will cost us more as we would have to spend even more money supplying you with another product.

Again, for experimental aircraft owners, the present Zodiac design well exceeds FAR23 requirements. The static load test proves this.
Thankyou for doing this Q&A as well as the others. I think this shows a great deal of effort,openness and communication on the Zenith side. you guys have done a great job on this.
Your answers to this and other posts have helped a lot of us understand what has been going on behind the scenes.
I am well into the upgrade, and appreciate howluch strength this kit adds to a fine airplane.
Thanks for the support.
I agree with the last part of your post completely. I would also like to the tail section included also. I'm guessing the same non conservative caculations were used there also.

I would prefer that the meeting I want be led by someone other than you. I feel you are not unbiased in this matter and I would prefer a truly open discussion. Also, I don't think the one hour time slot you probably have for a Zenith update is sufficient to completely discuss this matter.

Good idea. I am sure that by Sun-n-Fun things will be resolved. What Chris Heintz needs now is a letter from the FAA requesting exactly what is required if any, and based only on the existing LSA rule and nothing else. Chris is not interested in proving that the design meets "estimates" and does not want to be in the middle of a political mess between the FAA and other government agencies.
I think that we all need to very carefully read the first and second "summary of recommendations". I will have more on this shortly.
I like the idea of a builders meeting and I would hope it would go for more than an hour as Paul said. We could also have a secondary meeting with the builders some evening in Florida where we can take our time and discuss things at length. It would be interesting to find out how many builders will be at the Florida airshow this year. As far as having someone else lead the meeting, I would like to have Mathieu, Sebastian, and Chris there in the front taking questions from the builders. And I like Doug's idea about flight testing the prototype with a video camera. I don't need the destruction of another plane on the ground to prove to me it's strong enough to fly. Put a test pilot in the prototype at full gross with a few video cameras’ rolling and pull 6 or more G's a few times. That would send a strong message to the building community that you trust your design.

As a sideline, I put the project away for almost 2 years while things were being sorted out. After seeing the improvements made to the kit with the upgrade, I'm back working every day on my plane with new enthusiasm. This will pass, and when it does, we will all have much better airplanes and the manufacturer will once again have a dominant reputation in aviation. To Mathiew and the family, thanks for communicating so well with the builders.
I hope that all this will be cleared up soon and before SNF.

The question I have for everyone is this. If in fact the FAA does confirm that it is up to the LSA manufacturer to do more testing (that the FAA is not demanding that more tests must be done), are you ready to accept that no more testing is required?

Are you ready to accept the FAA's statement in the Summary of Recommendations #1 which states that:

"According to 14 CFR Part 21 § 21.190(c)(5), owners and operators of S-LSA CH
601 XL and CH 650 must adhere to the requirements of the AMD safety
directive, dated November 7, 2009 to address the potential safety issues listed in
this report. In a related FAA SAIB CE-10-08, the FAA also recommended that
owners and operators of the kit built versions of these aircraft review the SAIB
and follow the AMD safety directive. The FAA will continue to monitor the
situation to verify the SAIB, Airworthiness Memo, and Safety Directive are
having the desired impact on the CH 601 XL and CH 650 fleet".

If the above FAA statement was the only statement issued by the FAA, would you be thrilled that your aircraft is now safe (after the upgrade)?

I am not trying to be sarcastic here. I want to know if you are ready to accept what the FAA may be politically trying to say.


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