Answers to questions about formed aluminum parts

[Van's Aircraft]

Van’s Aircraft has recently received questions from several builders about variances in the depth of stiffening rings and beads in formed aluminum ribs. Variances in the depth of stiffening rings and beads for these parts have existed for years. We understand why people have questions about these variations, especially in light of last year's laser-cut parts issue. The primary cause is that, several years ago, Van’s transitioned parts from T0 to T3 temper. Van’s also acquired and began forming parts a using very large hydraulic press, which permitted us to manufacture wing ribs and similar parts in-house. This greatly increased our production volume and reduced manufacturing time. From time to time, the pressure applied by our press while forming parts has varied, resulting in differing depths of the stiffening rings and beads. Although a mix of ring/bead depths may be observed when looking at the parts in your kit, this variance does not a represent a safety or quality issue. However, in light of the concerns expressed by customers on this issue, moving forward Van’s will tighten our specifications related to the depth and appearance of the stiffening beads, to reduce the visual differences observed over the past few years.

For those interested in more background on this topic, here is a brief history of formed RV parts and testing:

• In the earlier days of aluminum homebuilt airplanes, builders fabricated their own wing ribs and other parts, which were generally hand-formed over hardwood form blocks using a soft hammer-bending processes to form the flanges. There were often no stiffening ribs or beads in these ribs.
• Most ribs at that time were made from tempered aluminum, usually 2024-T3. This was true for most early aluminum homebuilts, including the Thorp T-18, Bushby Mustang, Davis DA-2A, etc. These planes flew safely, and many are still flying today. The RV-1 wing ribs were also formed in this manner.
• As Van’s started kit production in volume in the 1970s, ribs and parts were made of formed soft aluminum (T0), to enable the fabrication of more compound curved parts. The use of T0 aluminum required heat treating of the formed aluminum parts to achieve the stiffness and strength needed.
• When we developed the tooling for the RV-3, we decided to add stiffener rings and beads to the webs to produce ribs that emulated those used on major production light aircraft. Although testing never indicated that these features were necessary, since that time, all of our rib tooling includes cutouts for stiffener rings and beads.
• As Van's grew over time, we realized that with proper tooling design we could produce most of our formed aluminum parts from T3 alclad aluminum, eliminating the need for the costly and time-consuming heat-treat process manufacturing and reducing the amount of work for the aircraft builder.
• As we transitioned from T0 to T3 ribs we analyzed and tested T3 ribs with minimum depth stiffening beads in the most critical aircraft structure. Further tests conducted during research on laser cut parts showed that ribs maintained sufficient strength when cuts were introduced across the rib. In this test all ribs in the wing were cut in multiple locations. In many cases these cuts passed through the stiffening bead negating the beads strength. The results of this testing and analysis showed the stiffening rings and beads were not required. However, because these features are already built into all of our manufacturing tooling, we have decided not to create new tooling to remove these features.

Thank you,

Rian Johnson – Chief Engineer
Richard VanGrunsven - Founder

Link to original document: https://www.vansaircraft.com/wp-content/uploads/2024/09/FormedWingRibs.pdf

 

[Freemasm]

Can Vans tell us some more about the forming process? I'd always assumed matched die sets would control the product geometry; thus, applied pressure not having too tight of a tolerance. Let us know if you would.

 

[Brantel]

Can Vans tell us some more about the forming process? I'd always assumed matched die sets would control the product geometry; thus, applied pressure not having too tight of a tolerance. Let us know if you would.

They use a type of hydro forming press. Essentially the press pushes down on a huge chunk of rubber which forces the metal to form around a die.

Look up some Youtube videos of Van's factory tours, the pressing operation is included in most of those videos that I have watched.

This technique has been used for a very long time......
WW2 Video

 

[Brantel]

Van’s Aircraft has recently received questions from several builders about variances in the depth of stiffening rings and beads in formed aluminum ribs. Variances in the depth of stiffening rings and beads for these parts have existed for years.

After building a 7, big chunk of a 10, and finished the airframe of a 12 along with helping many others build various RV's, I have never noticed any significant visual variations in the depth of the stiffening rings or beads on these parts. Never measured any of them because I never felt there was a reason to. In my opinion, visual variations that we are seeing posted here and elsewhere are a recent development. My opinion is worth what I was paid for it. LOL

I have been in manufacturing for over 30 years. Anytime that Engineering starts relaxing tolerances to improve first pass quality, the long term outcome has not been favorable. This is a short sighted way to manage quality and improve OEE. In this case, controlling the minimum peak pressure of this pressing operation is trivial. This should not be the root cause of such a visible quality defect. This is very low hanging fruit.

I am not qualified to agree or disagree on whether or not these beads and stiffening rings are a safety issue or not. They obviously increase strength in various ways otherwise they would have never existed across the industry. However, I do disagree that having multiple similar or same parts with obvious visible differences in how these are formed is somehow not a quality issue.

 

[aeroaddict]

Thank you Van's.

 

[Freemasm]

They use a type of hydro forming press. Essentially the press pushes down on a huge chunk of rubber which forces the metal to form around a die.

Look up some Youtube videos of Van's factory tours, the pressing operation is included in most of those videos that I have watched.

This technique has been used for a very long time......
WW2 Video

Much thanks. Different technique than I would have imagined but saves a lot of tooling/die costs. Clever.

Still surprised by the stated variation in parts. The variation in pressure should not be a hard production parameter to control

 

[bobrv7taildragger]

Sorry vans if you are now going to “control your processes” to limit the visible variations then it’s a quality control issue and I want 10 new ribs. I’ll happily send back the underformed ones which you can re press for someone else or reform them for me. I’ll have weak ribs and strong ribs throughout my structure. Guess you want me to pay for them ……again…..3rd time over. Whether or not the beads are needed or not you are now going to make sure future parts are pressed properly and I want those parts.

 

[PhatRV]

Thanks for the clarification on your rib forming process and the test to prove the strength of the structure with the cut up rib. I realize it is hard to communicate this engineering information to the layman but as an engineer I appreciate the write up. I am definitely happy to fly my new RV8 in its second year.

 

[dgustafson]

I looked at some of the wing ribs that were recently sent to another builder. The stiffening beads were barely visible in some cases, and a single rib had beads of varying depths, presumably because the forming machine did not maintain consistent pressure across the part.

I got all the parts for my RV-14 before Covid, and the rib beads were all consistently formed. Vans is no longer maintaining the consistent manufacturing processes that they used to have. If the beads are not needed, eliminate them. If the beads improve the product, make them consistently. An inconsistent product is not a quality product.

 

[rrfsgh2]

Thanks for the detailed info on the history and process, Vans. I look forward to flying.

 

[stigaro]

I realize this doesn't change anything, but do we know if it was Van's Aircraft that produced all said parts? Is there a chance that they outsourced some of this manufacturing like they did with the LCP's? I wouldn't be surprised if this was the case as they were under a lot of pressure to get LCP's replaced.

 

[Bastien]

I realize this doesn't change anything, but do we know if it was Van's Aircraft that produced all said parts? Is there a chance that they outsourced some of this manufacturing like they did with the LCP's? I wouldn't be surprised if this was the case as they were under a lot of pressure to get LCP's replaced.

"From time to time, the pressure applied by our press while forming parts has varied, resulting in differing depths of the stiffening rings and beads."

 

[Wes H]

I looked at some of the wing ribs that were recently sent to another builder. The stiffening beads were barely visible in some cases, and a single rib had beads of varying depths, presumably because the forming machine did not maintain consistent pressure across the part.

I got all the parts for my RV-14 before Covid, and the rib beads were all consistently formed. Vans is no longer maintaining the consistent manufacturing processes that they used to have. If the beads are not needed, eliminate them. If the beads improve the product, make them consistently. An inconsistent product is not a quality product.

Totally incorrect in stating an inconsistent product is not a quality product. This is why every part print in the manufacturing world has a +/- tolerance, gd&t, datums, etc.. Also the reason all products go through capability studies and validations.

 

[Pdp7427]

Totally incorrect in stating an inconsistent product is not a quality product. This is why every part print in the manufacturing world has a +/- tolerance, gd&t, datums, etc.. Also the reason all products go through capability studies and validations.

Sounds like the bead could be eliminated as testing has proved that it’s not required to meet strength requirements and design goals. Revising the tooling doesn’t make any sense of course, given costs involved.

So to my untrained ear, a fully formed part has an excess of strength required and one without a fully formed bead, though weaker, is still way over-designed and exceeds requirements.

I haven’t seen any significant variation in any of my kit parts either way. Thanks the update.

 

[Brantel]

Totally incorrect in stating an inconsistent product is not a quality product. This is why every part print in the manufacturing world has a +/- tolerance, gd&t, datums, etc.. Also the reason all products go through capability studies and validations.

In a perfect world this would be true. We all know the world is not perfect. I would also question how the tolerances were derived in this case. Highly doubt that the parts in question would fall inside the original tolerance limits unless the limits are so wide that they are meaningless.

Set the bar low enough and anyone can be successful at anything.

 

[Brantel]

Sounds like the bead could be eliminated as testing has proved that it’s not required to meet strength requirements and design goals. Revising the tooling doesn’t make any sense of course, given costs involved.

So to my untrained ear, a fully formed part has an excess of strength required and one without a fully formed bead, though weaker, is still way over-designed and exceeds requirements.

I haven’t seen any significant variation in any of my kit parts either way. Thanks the update.

Why would Vans go thru the extra time and expense of machining these features into the dies if they serve no practical purpose? Those features likely double the cost of the die.

Can we expect the RV-15 to be absent of these unnecessary features?

 

[AeroEngineer]

If the beads are not needed, eliminate them.

Are you kidding? To me, one thing became clear from the complaints about laser-cut parts and from the complaints about these beads: When Van's says "Our new way of making these parts might look worse than the old way, but it does not compromise safety, we have test data", this does not prevent an angry mob from shouting "I insist on sending back these new parts, and on Van's sending me parts made the old way... and paying for the shipping!".

 

[Wes H]

In a perfect world this would be true. We all know the world is not perfect. I would also question how the tolerances were derived in this case. Highly doubt that the parts in question would fall inside the original tolerance limits unless the limits are so wide that they are meaningless.

Set the bar low enough and anyone can be successful at anything.

In no way did I imply the parts in question fall within a specific tolerance. I do not have access to the drawings and to say one way or the other would be pure speculation.

 

[bkc3921]

After the LCP issue, I'm beginning to believe that some folks (mostly "engineer" types) will never be satisfied with Van's products. It's pretty simple. Either you trust Van's to provide a reasonable product at a reasonable cost...or you don't. I've always found Van's to be upfront, and I do believe they are very concerned about safety and customer satisfaction. If I were Van's, I would do this: Sell only a complete kit. If you don't have the dollars, see your banker. Van's would then "pick" the kit, and inform you it was ready. Then you physically go to Aurora and spend as much time as you want "inspecting" your kit. Not happy? Trade it out there. Once content, arrange your own shipping and be on your merry way...forever. I know I'm sounding grumpy, but it just feels like some are trying to pick Van's to death. They received a few complaints about an issue and decided to address it up front. I'm happy they do business that way. Most companies do not.

 

[bertschb]

...Further tests conducted during research on laser cut parts showed that ribs maintained sufficient strength when cuts were introduced across the rib. In this test all ribs in the wing were cut in multiple locations. In many cases these cuts passed through the stiffening bead negating the beads strength. The results of this testing and analysis showed the stiffening rings and beads were not required.

This is why I'm not worried about inconsistencies in the depth of the rings/beads (and I have some ribs that are not fully formed).

 

[Pdp7427]

Why would Vans go thru the extra time and expense of machining these features into the dies if they serve no practical purpose? Those features likely double the cost of the die.

Can we expect the RV-15 to be absent of these unnecessary features?

Sounds like those features are beneficial, though not required. As to “why” include them in the first place, ask the engineers. Maybe because of convention, or because it represents the strongest way of doing it? I don’t know.

 

[MIKE JG]

Although a mix of ring/bead depths may be observed when looking at the parts in your kit, this variance does not a represent a safety or quality issue. However, in light of the concerns expressed by customers on this issue, moving forward Van’s will tighten our specifications related to the depth and appearance of the stiffening beads, to reduce the visual differences observed over the past few years.

So what I'm reading is that the depth of the ring/beads is not critical based on their extensive testing of the wing ribs during the LCP issue. However Van's admits that this isn't a great look to have parts that should look alike, not actually look alike and they will tighten up on the process so that visually, the parts look alike as much as possible. I'm fine with that. Build on.

People are just a bit gun shy after the whole laser cut parts issue, can you blame them?

 

[rdt7]

Whew! I expected much worse. I am satisfied with their answer.

 

[Ben Ellis]

Thank you for following up on this and recognizing the importance of this issue for our safety and peace of mind. I was hoping you could clarify a few things.

• In the earlier days of aluminum homebuilt airplanes, builders fabricated their own wing ribs and other parts, which were generally hand-formed over hardwood form blocks using a soft hammer-bending processes to form the flanges. There were often no stiffening ribs or beads in these ribs.
• Most ribs at that time were made from tempered aluminum, usually 2024-T3. This was true for most early aluminum homebuilts, including the Thorp T-18, Bushby Mustang, Davis DA-2A, etc. These planes flew safely, and many are still flying today. The RV-1 wing ribs were also formed in this manner.

I think what you are saying is that airplanes built long ago that are still safely flying had wings built with wing ribs that did not have stiffening ribs or beads and, therefore, the stiffening ribs and beads in the wing ribs in question, if ineffectual due to their under pressing, would have no affect on the safety and suitability of the ribs. If that is the case, can you please confirm that the ribs on the earlier planes were made from the same thickness of 2024-T3, had the same spacing along the spar, whether they had lightening holes and notches like the modern ribs, and whether there are any other material differences in the ribs, and if so, have those differences been accounted for in drawing this conclusion?

• As we transitioned from T0 to T3 ribs we analyzed and tested T3 ribs with minimum depth stiffening beads in the most critical aircraft structure.

Just to clarify, are you saying you test wing ribs in the wing, or was it different types of ribs in a different aircraft structure?

 

[JonJay]

Ribs used to be made by an outside vendor out of “O”, pressed and then heat treated. I saw it happening at that vendor, but that was years ago.
So, I assume, Vans owned the dies, bought a press, took the dies back, and started experimenting with forming from T3 so they didn’t have to invest in the heat treating equipment or another outside vendor. This is just a guess but there is more to the story if they care to share.
The inconsistencies would not be present when forming “O” and were not when the outside vendor was doing the ribs. This is a relatively new thing.

 

[bobrv7taildragger]

they are inconsistent...just make them look the same....why wouldn't you?....why have inconsistencies? now they will tighten up processes to make them look the same...Ill take some new ones thanks...10 of them...so they can look like my other..."ok" ones. will help my OCD.

 

[Jjackh10]

I think what you are saying is that airplanes built long ago that are still safely flying had wings built with wing ribs that did not have stiffening ribs or beads and, therefore, the stiffening ribs and beads in the wing ribs in question, if ineffectual due to their under pressing, would have no affect on the safety and suitability of the ribs.


Just to clarify, are you saying you test wing ribs in the wing, or was it different types of ribs in a different aircraft structure?

Well stated questions. The Thorp and Mustang wings are very different structures. I'm not familiar with the DA-2 construction. But the design speeds are considerably lower, lower wing loading, and not aerobatic. I didn't think the referenced LCP testing included building a wing and load testing.

 

[Jonnyb]

Well stated questions. The Thorp and Mustang wings are very different structures. I'm not familiar with the DA-2 construction. But the design speeds are considerably lower, lower wing loading, and not aerobatic. I didn't think the referenced LCP testing included building a wing and load testing.

They took an RV10 wing and progressively cut all the ribs up inside while load testing the wing it.
The conclusion was that you could completely destroy all the ribs, including the tank baffle and ribs, and there’s enough strength in the wing to get you home.
It was in the long video they produced for the LCP issue.

 

[Jonnyb]

Residual strength testing starts at 1:31:30

 

[Walt]

Ribs used to be made by an outside vendor out of “O”, pressed and then heat treated. I saw it happening at that vendor, but that was years ago.
So, I assume, Vans owned the dies, bought a press, took the dies back, and started experimenting with forming from T3 so they didn’t have to invest in the heat treating equipment or another outside vendor. This is just a guess but there is more to the story if they care to share.
The inconsistencies would not be present when forming “O” and were not when the outside vendor was doing the ribs. This is a relatively new thing.

That's the difference between aircraft parts and lawn chairs.

 

[Jjackh10]

They took an RV10 wing and progressively cut all the ribs up inside while load testing the wing it.
The conclusion was that you could completely destroy all the ribs, including the tank baffle and ribs, and there’s enough strength in the wing to get you home.
It was in the long video they produced for the LCP issue.

Cool, I didn't see that.

 

[Walt]

They took an RV10 wing and progressively cut all the ribs up inside while load testing the wing it.
The conclusion was that you could completely destroy all the ribs, including the tank baffle and ribs, and there’s enough strength in the wing to get you home.
It was in the long video they produced for the LCP issue.

So, we've come from Van's building what many considered overbuilt strong capable aerobatic aircraft, to "it should be strong enough to get you home"?
Just ask Boeing how cutting corners in manufacturing and QA is working out for them. I don't think Van's will survive long term if they don't change their ways.

 

[rph142]

My rv-3 plans had different dimensions listed on different pages for the same part that was to be fabricated. I considered it a challenge to figure it out.

It sounds like vans will need a QA department 100 people deep to satisfy these requests. Imagine the kit prices to support that overhead.

 

[mstrauss]

People are just a bit gun shy after the whole laser cut parts issue, can you blame them?

And that about sums it up... Only time will tell if the engineering analysis for this, and the LCP holds up. I am not saying it won't. However, it is a factor however small it may or may not be, and that factor is being placed on the builder.

If you think about it, some people wanting the "norm", is no different to the decisions will all make on a regular bases with our builds. Should I replace that not to spec rivet? Some will say always, some depends, some it's just one bad, and I'll make it worse trying to replace, build on. Each builder must make the decision as to what they want in their build.

 

[Jjackh10]

My rv-3 plans had different dimensions listed on different pages for the same part that was to be fabricated. I considered it a challenge to figure it out.

It sounds like vans will need a QA department 100 people deep to satisfy the new crop of builders. Imagine the kit prices to support that overhead.

Making sure a press pushes with the same force every time should be accomplished by the operator. A cursory visual inspection should have noticed this. A QA dept of one should have noticed this. Maybe they did, and the deviations were deemed acceptable to them.

The current kit prices justify a consistency expectation vs the RV-3's sheets of paper and aluminum kit and it's cost.

 

[Jonnyb]

So, we've come from Van's building what many considered overbuilt strong capable aerobatic aircraft, to "it should be strong enough to get you home"?
Just ask Boeing how cutting corners in manufacturing is working out for them. I don't think Van's will survive long term if they don't change their ways.

I think that video shows exactly that doesn’t it? An over built strong capable aircraft.

That RV-10 wing with all the internal ribs completely destroyed was still capable of 4.4G and holding together.

I certainly consider that to be overbuilt.

 

[Mark Curley]

I feel I have something to add to this discussion based on my 40 years experience in the metal stamping industry.

Flat profiles with flanges are often difficult to produce with acceptable flatness due to tension build up in the material (the part ends up with a crown). Stiffening rings and beads are added as a mechanism to achieve flatness, thus increasing the strength of the parts. The quality check is to check the flatness of the part, not the height of the bead. In my experience (I have seen literally millions of parts) the bead is not measured, only the resulting flatness. The strength comes from flatness. This is what we should be looking for.

It also pays to be aware that a bead (or any form) cannot be produced without stretching the material. This results in the bead area having a reduced material thickness. So less bead height results in greater material thickness in that feature which may be good for stiffness. It's a balancing act - too much bead height reduces material thickness too far, too little does not provide a flat part. We desire flat parts with minimum material thickness reduction.

 

[MIKE JG]

I feel I have something to add to this discussion based on my 40 years experience in the metal stamping industry.

Flat profiles with flanges are often difficult to produce with acceptable flatness due to tension build up in the material (the part ends up with a crown). Stiffening rings and beads are added as a mechanism to achieve flatness, thus increasing the strength of the parts. The quality check is to check the flatness of the part, not the height of the bead. In my experience (I have seen literally millions of parts) the bead is not measured, only the resulting flatness. The strength comes from flatness. This is what we should be looking for.

It also pays to be aware that a bead (or any form) cannot be produced without stretching the material. This results in the bead area having a reduced material thickness. So less bead height results in greater material thickness in that feature which may be good for stiffness. It's a balancing act - too much bead height reduces material thickness too far, too little does not provide a flat part. We desire flat parts with minimum material thickness reduction.

That's some good tribal knowledge Mark, thanks for sharing!

 

[mstrauss]

I feel I have something to add to this discussion based on my 40 years experience in the metal stamping industry.

Flat profiles with flanges are often difficult to produce with acceptable flatness due to tension build up in the material (the part ends up with a crown). Stiffening rings and beads are added as a mechanism to achieve flatness, thus increasing the strength of the parts. The quality check is to check the flatness of the part, not the height of the bead. In my experience (I have seen literally millions of parts) the bead is not measured, only the resulting flatness. The strength comes from flatness. This is what we should be looking for.

It also pays to be aware that a bead (or any form) cannot be produced without stretching the material. This results in the bead area having a reduced material thickness. So less bead height results in greater material thickness in that feature which may be good for stiffness. It's a balancing act - too much bead height reduces material thickness too far, too little does not provide a flat part. We desire flat parts with minimum material thickness reduction.

Mark, this is very helpful information. Van's Engineering, please try to share this king of background in the future. I think it would go a long way in helping alleviate the concerns. I assumed the the beads and stiffening rings around the lightening holes were to add needed strength. If what Mark states is true, and they are added to produce a flat part, then I can't see why anyone would have an issue with what was produced. That is assuming the parts are flat (within tolerance).

 

[BrianP]

How much additional flattening should be done while building? I got a fluting tool with my Cleveland kit but the parts seem to be pretty flat to begin with. What is the tolerance allowed for parts being slightly curved? They all seem to come together perfectly when clecoed. How important is it for all flanges to be at 90 degrees? Is 85 degrees close enough? I’m assuming this pruning process is similar to what these beads are trying to accomplish.

 

[PhatRV]

How much additional flattening should be done while building? I got a fluting tool with my Cleveland kit but the parts seem to be pretty flat to begin with. What is the tolerance allowed for parts being slightly curved? They all seem to come together perfectly when clecoed. How important is it for all flanges to be at 90 degrees? Is 85 degrees close enough? I’m assuming this pruning process is similar to what these beads are trying to accomplish.

This is the result of the flutting of the rib to make sure they are flat. I stack them up in the picture in my build log and all are flat. This is good enough for me. The key is to take your time and flute a small amount at the time until the rib is flat against your work table.

 

[JonJay]

To me, the issue isn’t airworthiness, strength, or design, it’s the inconsistency in fabrication of the parts.
Even though you can’t see these parts, it would bug the hell out of me. However, I would get over it and build on…..
The more bothersome issue to me is the lack of any “humility” when it comes to obvious quality control issues. They state “this isn’t a quality issues”. Yes it is.
Evidently, it’s ok to produce inconsistent parts as long as they are deemed to not affect the airworthiness.
This may backfire some day as factory personal develop a casual attitude towards consistemcy and quality. ISO 9000 came into being a certification not because parts were made great, but they had to be consistently produced.

I view Vans as a producer of a premium product. Don’t fall short on simple things and then justify them away….. Own it, take responsibility, and get better. That’s what I want to hear and see. Be humble, recognize and accept your issues, and fix them.

 

[anon2024]

To answer Brians question, how flat is flat enough...? These ribs are pretty easy to get flat within .030" without more than an evenings effort. beyond that, there's not much need, as the flexibility that remains is more than adequate to install them and make sure they are plumb, square and straight.

the question as to over bend angle...just get them to 90. Small square, a little patience...it's not hard, but will make everything else to come later easier.

I am not a fan of fluting pliers, as they don't really offer much benefit, just another lump to deal with, in making a nice flush joint.


I strongly agree with Jonjay above!!!

 

[PhatRV]

Also I want to add that as you flute the ribs, if you press on one corner and the ribs wiggle, then you need to work it some more until they are flat against the work table. It's more like art than science. Slow and is the way to go. This is how ribs had been fluted since ever. I've seen they did it on certificated aircraft too. The only airplanes that don't do this are the heavy iron birds where the ribs are machined from 3" thick forgings.

 

[bobrv7taildragger]

So that’s it? Is everyone just pressing on with these parts even though production processes are going to be “tightened”?

 

[rocketman1988]

So that’s it? Is everyone just pressing on with these parts even though production processes are going to be “tightened”?

Here's the thing, everyone here is building their own aircraft. Everyone here has their own level of risk aversion. Just because you aren't happy with something doesn't mean everyone else is going to agree with you.

You are entitled to your own opinion, as is everyone else...and your opinion is no more or less valid than everyone else's.

 

[Walt]

I get the feeling that some folks are just tired of dealing with all the problems and are willing to overlook almost anything at this point because they know it's futile to complain, and ordering new parts takes so long.
I also think many posters don't have any skin in the game so easy for them to say, 'build on'.
When I was building, I replaced many parts because I knew I could do better and strived for perfection (not always attaining it but strived nonetheless).
Think about how you are going to feel a few years from now when you're practicing aerobatics, are you always going to feel comfortable with the decisions you made?
I know what I would do.
A sad state of affairs for sure.

 

[bobrv7taildragger]

Here's the thing, everyone here is building their own aircraft. Everyone here has their own level of risk aversion. Just because you aren't happy with something doesn't mean everyone else is going to agree with you.

You are entitled to your own opinion, as is everyone else...and your opinion is no more or less valid than everyone else's.

Ring vans and find out what the bead spec is. you might be enlightened to find out there isn't one. so how will that be tightened?
I am the same as Walt. I strive for perfection but rarely attain it but strive nonetheless. I am uncomfortable with vans assessment of the rigidity and strength of these ribs.

I do not expect everyone will agree with me Bob and appreciate everyone has their own risk aversion. But that does not mean I close my mouth and do not ask questions. Vans have responded and I am saying I do not agree with their assessment. The mere fact the parts are not consistent should raise eyebrows. The mere fact they are saying they will tighten their tolerances (which appear to be unquantifiable) admits an issue and should raise eyebrows.

 

[Jonnyb]

Ring vans and find out what the bead spec is. you might be enlightened to find out there isn't one. so how will that be tightened?
I am the same as Walt. I strive for perfection but rarely attain it but strive nonetheless. I am uncomfortable with vans assessment of the rigidity and strength of these ribs.

I do not expect everyone will agree with me Bob and appreciate everyone has their own risk aversion. But that does not mean I close my mouth and do not ask questions. Vans have responded and I am saying I do not agree with their assessment. The mere fact the parts are not consistent should raise eyebrows. The mere fact they are saying they will tighten their tolerances (which appear to be unquantifiable) admits an issue and should raise eyebrows.

Ok, so what are you planning to do about it?

 

[rocketman1988]

Ring vans and find out what the bead spec is. you might be enlightened to find out there isn't one. so how will that be tightened?
I am the same as Walt. I strive for perfection but rarely attain it but strive nonetheless. I am uncomfortable with vans assessment of the rigidity and strength of these ribs.

I do not expect everyone will agree with me Bob and appreciate everyone has their own risk aversion. But that does not mean I close my mouth and do not ask questions. Vans have responded and I am saying I do not agree with their assessment. The mere fact the parts are not consistent should raise eyebrows. The mere fact they are saying they will tighten their tolerances (which appear to be unquantifiable) admits an issue and should raise eyebrows.

There is never harm in asking questions; the issue is when you do not like the answer.

You are uncomfortable. So what will you do about it?

Implying that everyone else should also be uncomfortable changes nothing.

At the end of the day, you can either trust the designers or not.

If it still bothers you, you could always get a bead roller and modify the ribs to your specifications. You could also model the structure in readily available software to verify those specifications and compare that to a flat rib. That would tell you what you want to know…