Graham wrote:
I am not an engineer, but all (real world, not online) conversations I have had with those who are in relation to this matter have indicated that they consider spars primary structure and ribs secondary structure.
Yup, understood. This is why I said “…consider the vertical stabilizer….” (as in, the whole thing) to be a primary structure. I was referring to the entire structure, not its Principal Structural Elements (PSE) and other constituents. That being said, components such as vertical stabilizer inspar ribs (RV-14 VS-707) are normally considered to be PSEs (primary structure), and, typically, so are vertical stabilizer lower close ribs (RV-14 VS-704 root rib), all rudder ribs, and all elevator ribs. Said differently, some ribs are primary structure, and some are secondary structure.
Graham wrote:
The engineering question and the consumer rights question are separate, albeit related, issues.
I totally agree, and I was trying to keep those things separate. I apologize if I wasn’t as clear as I could have been in maintaining the delineation.
Graham wrote:
Incidentally, Van’s marketing materials for all kits -7 onwards make repeated references to everything being pre-punched, so it is not just the -14 that has this mis-sell issue.
Agreed; I used the RV-14 as an example because it is directly relevant to my situation and is thus the one for which I am most familiar. Additionally, finding the reference to punched parts for the RV-14 does not require one to dig deeper into the product’s brochure (a la the RV-7 thru RV-12) – it is literally on the main web page for the RV-14.
Peter wrote:
Maybe the practical solution will be to monitor the situation annually
This may well be the most desirable option for builders who have made significant progress in their builds and do not wish to disassemble to remove LCP; however, I think the risk for builders and owners (current and subsequent) could be future liability and insurability. Insurer appetites for risk change over time, and I would hate to see the fleet and its owners impacted negatively should there be an insurance industry aversion to LCP-affected aircraft in the future.
LeSving wrote:
AC 23-13A is applicable to certified aircraft (part 23). More specifically this AC provides means to comply with Title 14 of part 23. It provide means, but not the only means.
I am well aware.
LeSving wrote:
Unless anyone has made an agreement with Vans that the aircraft is according to part 23, and you are actually building according to part 23, this is of zero legal interest.
Van’s is a supplier of parts. I did not express, suggest, or convey that they or I were required to conform to part 23.
One could easily argue that all Advisory Circulars are of zero legal interest because they are neither binding nor regulatory; however, that has not and does not prevent them from being widely adopted as defacto standards. The well-known aviation legal resource I consulted with had a substantially different opinion than yours with regard to the value of AC 23-13A on experimental category aircraft construction and operation. It may not be binding or regulatory in nature, but one ignores the value of AC 23-13A at his peril.
LeSving wrote:
I think I have read and heard that Vans use part 23 as some kind of “baseline”. I mean, who wouldn’t, or similar such standards.
I have not heard that, but it would seem like a good and reasonable choice.
LeSving wrote:
Let’s for simplicity say this AC is “valid” in a legal sense. Then the only important thing is that Vans indeed is following it. They have through engineering and testing and inspections found applicable means to comply.
The AC is valid, or at least relevant, in a legal sense. That is not a matter of our opinion.
Van’s is not following it, nor would they be required to. They are not manufacturing the airplane, they are manufacturing parts. If you re-read what I actually said, I was referring to my decision, as an aircraft manufacturer, to follow the guidance of AC 23-13A. I did not suggest, at any time, that Van’s had any obligation to comply with AC 23-13A.
Here’s what I said:
ccarlson wrote:
In my build, laser cut VS-702, 704, VS-705, VS-706, VS-707, and VS-803PP (emp kit delivered 1/11/2023) all cracked when dimpled. Those are all core parts of the vertical stabilizer which happens to support what is arguably the most powerful flight control on an airplane: the rudder. The vertical stabilizer and rudder most certainly do carry flight (aerodynamic) loads, and their failure would indeed significantly reduce the structural integrity of the airplane, especially after their failure results in a high speed CFIT event. Consequently, I am inclined to consider the vertical stabilizer a primary structure.
……
Based on all of the above, it seems to me that the use of parts known to be at substantial risk of developing cracks is a definite no-no.
Notice I said “my build,” “I am inclined to consider…,” and “use of parts” not the “manufacture of parts.” No mention of Van’s.
LeSving wrote:
You should read Section 1 of this AC, not just pick out random parts.
I have read the entire document many times, thanks. I opted to reference specific parts of it in this conversation for the sake of brevity. If others wish to view the entire document, it is available here: https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_23-13A.pdf
LeSving wrote:
But again for the x’th time. Vans is NOT the builder. The builder is the builder.
I did not imply or suggested otherwise.
gallois wrote:
If you were building from plans then that might well be the case. But even then if I bought a bunch of spruce I would expect it to be of the quality I have ordered. Eg if I have ordered and paid for wood which has been weathered for 10 years and with an agreed percentage of knots, that is what I would expect to be supplied.
In this case Vans don’t appear to have done this.
Bingo.
Graham wrote:
It is not an aviation matter and nothing to do with part 23 or any engineering aspect.
Directly, no, it isn’t.
I referenced AC 23-13A (and part 23 by inference) as a means to illustrate and substantiate why I will not use laser cut parts in the construction of my aircraft. The commercial implication is that I want Van’s to send me the punched parts I ordered because I do not want to use the laser cut parts they sent.
RV8Bob wrote:
To imply there is no consensus standard on cracks
I have never implied such a thing. I was was commenting on that yellowed out line in the picture of the page above (21.191 (i) ). There are no general “consensus standards” that I am aware of, except some notes about “designed mostly according to part this or that”. Punched holes up to the right dimensions is equally bad (“consensus vise”) as laser cut holes from a pure engineering point of view. In practice though, punched holes works after all, laser cut holes do not. But, the reason for that is probably due to the way the holes were cut, not according to Vans specs.
Kit manufacturers have done lots and lots of things that are way outside any “consensus”. Most have worked well, and so have indeed become a kind of consensus in later years: Punched holes, use of 6061 alloy throughout, SS rivets, aluminium tube frame structures (instead of welded steel), special covering of those aluminium tube structures, and not to mentioned all the different kind of composite methods that have been used.
RV8Bob wrote:
They stepped outside of that box and now we see the results
As mentioned, punched holes are already way outside the box. If you want inside the box, buy a certified aircraft. That’s pretty much the very definition of these things:
ccarlson wrote:
I did not imply or suggested otherwise.
OK, my bad, read to fast 
Edit: Not certified as in experimental. There are many ULs (also in kit form) and engines that are not certified, but still well “inside the” box engineering vise.
For heavens sake apply common sense and stop digging yourself into that hole,
Cracks are bad. Parts were produced for a long time that did not crack. Then the part manufacturing process changed and they developed cracks.
It is completely obvious that the crack-prone parts are defective and that (a) the builder should not use them and (b) the manufacturer should replace them.
This is the case even if I was building a shed!
Hey, I just bought three sheets of plywood to build a workbench top, one of which has damage to one edge and the supplier is sending a new one.
They did not produce engineering reports to show I could use it. Nor did it need hundreds of posts on the internet to establish some kind of “engineering principle” for workbenches to justify the replacement,
And if anyone argued that I am building an amateur workbench hence should use damaged plywood they would be laughed out of court.
@cobolt wrote:
For heavens sake apply common sense and stop digging yourself into that hole,
Cracks are bad. Parts were produced for a long time that did not crack. Then the part manufacturing process changed and they developed cracks.
It is completely obvious that the crack-prone parts are defective and that (a) the builder should not use them and (b) the manufacturer should replace them.
This is the case even if I was building a shed!
Well said,couldn’t agree more. How did we go from this:
“ At Van’s Aircraft, safety is our primary concern — both in terms of the aircraft we design and the way people build, train and operate the airplanes. Dick VanGrunsven himself has made it a point to actively promote safety in the homebuilt world, and the results – especially in the RV world – have been meaningful. There is nothing we take more seriously. To that end, some of the information on this page may seem a bit blunt or direct. We’re okay with that — the consistent safe operation of the RV fleet is our ultimate goal.”
To completely disregard ALL government safety guidelines on cracks and common sense?
My guess is that Vans did what many less than smart manufacturing companies do. You substitute a component with an “equivalent” one, do some “due diligence” perhaps, and off you go. Sometimes it bites you in the bum… But most “retail product” manufacturers get away with it because they have no contact with the end users (ever tried phoning Ford for example?) so they happily force their way through even major reliability problems.
I have often posted on the topic of why certain problems which turn out to be actually quite big are not reported or are under-reported. Like this. There are many reasons. You can get chucked out of a type specific user group for posting negative stuff (I got that with Socata in 2008 ).
In my business (electronics manufacturing) when I substitute a key component I build a small batch of the product, mark them in the stock, and send them only to customers who buy just 1 unit. They never go to a big customer. That way you identify a problem without it blowing up your business, you fix it fast, and a customer who had a problem fixed fast is more loyal than a customer who never had a problem at all.
Look at what mobile phone makers do with OTA (over the air) updates. You really really do not want to brick a million phones in San Francisco. They limit them initially to the 3rd World countries, where people have little money, little voice, little consumer power, and (for Apple) most people buying $1500 phones are probably drug dealers. Look at where Russia draws soldiers from: the poor parts of Russia (basically all of Russia except the rich parts in the west) because 50% of them “fail”. They come back in bags and this system prevents ~15k bags a month coming back to where people are on the internet (basically Moscow and Leningrad).
Vans obviously didn’t do this. They implemented a major change to a manufacturing process and just pushed the new stock out to everybody. Whoever did that was clueless on structures, clueless on aviation structures, and clueless on business risk management. You would be stupid to have done this in any business… aircraft, shampoo, mobile phones, whatever. Even with shampoo (and particularly with shampoo) you will have batch traceability, at least. In fact with shampoo you will have fantastic traceability on every ingredient.
Ford (etc) is protected by the lack of customer contact. What keeps them in line is getting a million crap reviews on social media, if they have a bad batch of engines. Vans sell mostly direct so had no protection. And most kit builders don’t know much about planes, and structures.
And most kit builders don’t know much about planes, and structures.
Just like most website posters… but a little more once they have actually built something.
I’d guess Vans is correct in their assessment of the structural issue. What I find more interesting is the marketing aspect and the lack of appreciation that their customer is not building an industrial device, they are building something personal and have their self image wrapped up in it. Therefore they want it ‘perfect’ (in their own minds) regardless of the technical facts, and so will the resale buyers.
My conjecture is that most kit owners will resolve this to their own satisfaction somehow, either the old fashioned way (make new parts themselves) or via individual negotiation with Vans to buy new parts. If it isn’t strung out over a long enough period, I could imagine Vans ‘doing a Maule’ and reorganizing under a new company name, leaving the problem behind. But I don’t think it will be necessary, these are kits not a finished product and notwithstanding the internet hype the expectations of the typical EAA guy are lower – they do still have some problem solving builder spirit, even with kits.
The situation makes me start looking at RV resale value to see if any of the negativity might somehow be affecting used plane values. Alas for me as a guy who might buy a bargain priced RV-7 or 9 there is no effect that I can see – the RV designs are too well established for that phenomenon to take hold, Vans would have to go out of business for it to occur. If a disruption on the level were ever to suppress values, I’d be buying quickly before it were resolved.
Cobalt wrote:
Cracks are bad
I have never said cracks aren’t bad. Van’s has never said cracks aren’t bad. No one has ever said crack’s aren’t bad. But, cracks is not a religion for haven’s sake I mean seriously.
Cobalt wrote:
Parts were produced for a long time that did not crack
No. This is 100% wrong. Aluminium will crack sooner or later no matter what. This is what decides the life time of aluminium structures. It’s what this whole thing is all about. Will crack develop and extend within the lifetime of the aircraft? What’s bad for crack development is:
What Van’s have said is that the highest stresses are not found at the edges of the holes, but at the edges of the dimple. Can we believe that? of course we can. The billions of punched holes in existence pretty much proves that point 100%. So, Vans thought, why not laser cut the holes. Why not? It’s not like laser cutting is worse than punching, which works just fine. It turns out it’s not that easy in practice. They look ugly, and when not done according to spec they have a tendency to crack when dimpled or riveted.
Vans assessment, tests and engineering is just fine IMO. I suggest anyone having an objection with their assessment do so on an engineering basis, not on the basis of “common sense” and bits and pieces from the internet.
Cobalt wrote:
It is completely obvious that the crack-prone parts are defective and that (a) the builder should not use them and (b) the manufacturer should replace them.
Why is that obvious? What is a crack-prone part? (every single part is crack prone from the very beginning remember). The only important thing is, will the part last the lifetime of the aircraft. If the answer is yes, then the part is OK. Vans has analyzed all the parts, and has given a list of which parts to replace, including all the crack-prone ones.
The thing is, when buying a kit from Vans, you more or less enter a marriage with them. You simply have to live with all the warts. Vans has said that “anyone” can build an RV. The result is that “anyone” does. Should “anyone” build an RV? Why not, if you ask me. Partly because what you also get is access to the expertise at Vans. Vans do make mistakes however, but if you do what they say, you will have an airworthy aircraft in the end.
The other side of the coin is that Vans is not the builder. That marriage with Vans makes things a bit difficult in that respect. A builder may have other goals than just making an airworthy aircraft. A finished RV will easily represent a value of €100k and up on the market for instance. At the same time I don’t really think the more hard core “serial builders” actually are all that upset with this episode. Perhaps it’s the exact opposite, they get bogged down over this, helping others?
It’s a mess though, and largely unnecessary (in hindsight at least).
LeSving wrote:
Pre-stressed materials (punching holes is seriously bad. It’s amazing how this is not understood at all in this thread)
For my part, I actually do understand this. I am not a metallurgist by any stretch of the imagination, but I have researched this extensively because of this debacle. From a technical perspective, I do not disagree with you on this point.
LeSving wrote:
What is a crack-prone part? (every single part is crack prone from the very beginning remember). The only important thing is, will the part last the lifetime of the aircraft. If the answer is yes, then the part is OK
I don’t know if this answers the question, but…
The RV-14 vertical stabilizer consists of a forward spar (VS-702), an aft spar (VS-803PP), a nose rib (VS-705), a root rib (VS-704), an inspar rib (VS-707), a tip rib (VS-706), and the skin (VS-801PP). In the spars and ribs, there are ~196 3/32" holes that require dimpling.
I started building my vertical stabilizer in late April 2023. When I dimpled the relevant 3/32 holes in the (laser cut) parts that came with my kit (delivered 1/11/2023), better than 90% of them cracked. I thought I had a tooling problem. (I am using a DRDT-2 dimpler and Cleaveland dimple dies.) I checked everything I could think of, discussed with my tech counselor, bought new dies, and tested using scrap aluminum sheet. Tools and technique seemed good, so I ordered new parts from Van’s. The new parts – also all laser cut – fared no better than the originals. Cracked holes galore. Consequently, I consider those parts to be crack-prone.
Maybe all aluminum parts are crack-prone, as you said, but these parts seem to crack…. prematurely? At that point, I stopped building because something seemed very wrong to me, but I did not know what it could be. Shortly thereafter, I became aware of the laser cut parts issue.
Not to put you or anyone else on the spot, but would you install parts with cracked holes in an airplane you were building today?
The following questions (rhetorical, really) give me great pause:
If laser cut parts are truly okay, and the only issue was QC with a specific vendor, why did Van’s stop producing them instead of just addressing the QC issue?
If laser cut parts are okay, then why would Van’s recommend replacement of all spars after their extensive testing? Perhaps the process around producing them wasn’t fully baked? I don’t know and they haven’t said.
Would their testing not have demonstrated laser cut parts have superior life compared to punched parts if that was, in fact, true? Maybe that is what they were aiming for with the blue/green designations, but I have laser cut parts they consider blue/green that cracked immediately when dimpled. Those things seem incompatible.
@LeSving wrote:
What is a crack-prone part? (every single part is crack prone from the very beginning remember).
…
Vans has analyzed all the parts, and has given a list of which parts to replace, including all the crack-prone ones.
It was too easy
