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: 2461

Replies are closed for this discussion.

Replies to This Discussion

Hi Mathieu,

The way I read the current letter, the FAA is asking that the analysis be done now rather than accepting the previous analysis you seem to think solves the problem.

The letter clearly states flight testing is sufficient for meeting the FAA requirement for flutter analysis, but I think you need to think about this a little. If you can find a "Noted Expert" on flutter who will perform the flight test without any ground testing then that might be a good choice. However, I doubt any such expert would be willing to do that. Also, you might expect there is at least a small possibility of loss of the aircraft when high speed flutter flight testing is performed. This is one of the expected outcomes of such a test on any airframe. I guess you need to compare the cost of the ground testing against the possible loss of the aircraft before making a final decision on this point.

As others have said, I suggest you get an engineer to discuss the requirements with the FAA. You are just not qualified to make engineering decisions. You have said many times you are not an engineer, but you are in a position to hire one. Indeed, I thought you already have several engineers working for you. I think we all would gain if you got someone who speaks "Engineer" to discuss this with the FAA folks.

I really don't understand why you continue to pretend to be an engineer. These issues need to be resolved with the FAA and your saying you think their requirements are already met does nothing to actually make them go away.

I know you feel you are in charge of this whole mess, and indeed you are. I fear if you don't meet the FAA's stated requirements they will, once again, ground all the Zodiacs.

Currently installing upgrade.
Hi Doug,

Perhaps I am all wet here. However, it seems to me Mathieu is trying to compare numbers like "missed total load by 5%" and "Improved by 15%" as being proper to directly compare. He tried to make the same argument weeks ago before getting the latest letter from the FAA guys and it didn't satisfy them then. I don't see how it will satisfy them now.

It seems to me like comparing apples and oranges. Of course, I am not a qualified aeronautical engineer. That means I am not qualified to make such comparisons. My point is that Mathieu isn't either.

This whole process could fall apart if communications with the FAA are not handled properly.

I just don't understand why Zenith/Zenair/Amd engineers are not involved in this whole communication process. Are there any engineers left at these companies?

Best regards,

Paul, I understand you concerns and desire to put all this behind us once and for all. But dude, give it a rest. Your condescending beratement of Mathieu is getting tiresome. Mathieu never insinuated that he makes engineering decisions nor does he pretend to be an engineer.

The FAA in essence agrees that the structural modifications address the issues surrounding thr 601. It is now a matter of CYA. I don't believe the FAA, NTSB, or any government agency is going to proclaim the that the 601 is 100% safe and structually sound no matter what Zenith does or how many tests and engineering reviews are performed. The most we can expect from the FAA is a statement to the effect that the 601 meets ASTM standards. Standards which they themselves feel are inadequate in certain respects to begin with.

Ultimately it boils down to personal decision and comfort level. We review the available information and make an educated decision to build, buy or fly a 601.
Sorry, I must be slow this morning. Can someone give a direct link to the FAA Special Report? It does not seem to be in the EAA page. Thanks.
Here they are.
If the FAA and all the other authorities around the world had any doubts that the aircraft when upgraded was not strong enough, they would continue to ground them. All the different CAA's around the world that had grounded the aircraft are allowing the aircraft to fly again, including the FAA.
You are right. Way stronger is a strange term. So exceeding the FAA's conservative analysis is better wording. I will see if Chris can come up with a percentage on this, but this will take time.
I do not remember ever seen any bolts that have been sheared at the spar root area.
The bolts that we are supplying in the upgrade kit are NAS and similar to yours.
Please note that the FAA did their calculations with the AN bolts and had no issues with them, even though they bent in the test.
So by changing the AN to NAS bolts and by adding a 1.125" plate at the root, we are stronger.
Mathieu, when will AMD and ZAC begin offering the upgraded 650?
I will see with Zenith on this but there is no reason why Zenith or AMD cannot offer the 650 at this time. Zenair in Canada will be shipping about 10 650 upgraded spars to Zenith next week. We are also finalizing the 650 drawings to include the upgrade.

First let me say I appreciate the openness of this whole discussion. I am hopeful we will eventually reach a level of comfort with the Zodiac design that has been sorely lacking for years.

After reading the FAA report (at least the parts I could understand) and reading the comments on this Q&A I'm afraid we are almost back where we started last year when the NTSB letter came out. It seems you are saying all is well and the government is saying there is need for major further effort and potential changes. The FAA report calls for many additional tests and you are saying the stuff submitted months before the report was written takes care of all the needs.

I realize there are a lot of expensive things under discussion. These are not only expensive for Zenair/Zenith/AMD they are also expensive for every builder/owner of this design. The government has a significant interest in seeing this question reach a happy conclusion. I suspect there are many owners who feel like I do that the costs involved in further testing and analysis should not prevent having them take place. We are all in this together.

As an owner, I stand to lose the investment I have already made in this plane. However, I would rather scrap it than take undue risk flying it when it needs further evaluation and possible improvement. Unfortunately, I don't have the knowledge or resources to take the further steps by myself. I would certainly consider contributing a share of the funds needed to get this design to the level needed for all of us to sleep well at night

I think the next step should be an open discussion with all the parties to this fiasco present. This should include representatives from the NTSB, FAA, Zenith/Zenair/AMD (particularly Mathieu and Sebastian Heintz) and builders and owners of these planes. Perhaps Sun n Fun could provide a suitable venue for this big meeting. I would expect the meeting to take at least several hours and possibly several days.

My goals for such a meeting are:
1. A clear understanding by all major parties that answers the question: Is the current set of changes sufficient to be comfortable with this design or is further testing and possible design change needed?
2. A plan for conducting any further tests that are needed including who will conduct the tests and where the funding will come from. This requires several phases- first define the needs, then estimate the costs, finally come up with a funding plan. Furthermore, we should examine the availability of government engineers to aid in the design and evaluation of any further testing that is required. Clearly, the FAA and NTSB have more engineering manpower than either the builders or Zenair/Zenith/AMD.
3. Since the NTSB letter really started this public discussion of the Zodiac problems, I suggest the NTSB provide a chairman to lead this discussion. If that choice doesn't work, then I suggest the FAA provide a chairman.
4. I hope any further engineering analysis can be done as an open and public event rather than the secretive style used so far in this situation. That way we should all be able to reach the same general conclusions about the engineering judgments that are currently under significant dispute.

If such a meeting is scheduled, I will personally attend it (after traveling 3,000 miles) and I will also consider contributing funds toward the costs of further testing.

I hope we can eventually reach a point where we all can sleep well while flying and selling our Zodiacs.

Paul Mulwitz
Camas, WA


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