Dan wrote:
the intergranular structure of the aluminum must be affected by the heat of the laser cutting process, and lead to embrittlement.
I’m following the subject carefully and my understanding is that laser cut parts might be more prone to crack when dimpling than punched parts. Those laser cut parts were in circulation for how long? two years? Did you hear people complaining in the meantime? Yes, of courses, single cases. Vans ships several kits every day, that’s thousands of parts. Every day. Now everybody who got a laser cut part cries a foul.
Graham wrote:
There appears to be no real parts traceability, all we’re hearing is “you may have received”
Graham, are you sure a homebuilt is the right choice for you? Really, you could get a C172 for a fraction of the price and peace of mind. Complete traceability 
BTW, the above statement AFAIK is wrong
Graham wrote:
Any quickbuild kit between the relevant dates is liable to be affected
Affected by what exactly? I mean it’s easy to throw such statements over the internet, but would you care to explain what’s exactly wrong about those quick build kits?
Graham wrote:
shoddy parts problem
Again, with all due respect, what’s wrong with your parts? I did have a look at the photos you published and didn’t notice anything seriously wrong. I’m not an expert in riveting dimpled laser cut parts… Who is? I do understand it must be a difficult time for anybody building with those parts. I’m sure Vans will solve the problem.
Reading @Peter post above could go a long way in explaining the problems plaguing GA in Europe, pity really.
Nevertheless a sentence I can agree with:
Peter wrote:
Some serial RV builder, or really any mechanical engineer, would have spotted holes like that right away.
I could add that any aircraft engineer, serious builder, building advisor would also have spotted that right away. And that leaves one hell of a question mark, why did the problem take so long to surface?
@Peter we did spot the holes – large numbers of builders spotted the holes and complained to Van’s requesting replacement with punched parts. Van’s consistently refused to replace them, told us to clean up the holes as best we could and build on. Many could not be cleaned up within any sort of sensible diameter and many cracked under dimpling and riveting.
A further complication is that not all laser cut parts had this problem, only a particular subset from a particular contractor during a particular time period. They used incorrect programming which started the cut at the perimeter of the hole and made a mess of it.
I had numerous laser cut parts in my empennage kit but none had this problem. I would have noticed those holes. My wing kit, which is all still on the shelf awaiting preparation (well, replacement really) has many parts with bad holes.
Thus the issue has only come to my attention relatively recently because I only got bad parts recently, but it turns out builders have been complaining since day 1 of laser cut parts.
Graham wrote:
Here my perspective is one of a customer. The part is not of appropriate quality, therefore I reject it. It is not my role to find workarounds for their manufacturing mistakes.
The idea of rework is to turn it into an a finished product (assembly) which does have appropriate quality, and with parts already on hand you may be put in that position. Factory production aircraft often have quality deviations that require the same basic engineering resolution process with subcontractor supplied parts. A difference is that the eventual owner/pilot usually doesn’t ever know, unless their organization has embedded engineering staff and/or mandatory quality deviation reporting under contract. Vans has customers who look at each part and incessantly talk to each other, so is otherwise under more end-user scrutiny.
Dan wrote:
The cost will be directly for Vans for now, but rest assured that it will be fully reflected in the next price increase for present and future customers
For sure much of the cost of whatever is done will in the end be reflected in Vans price and revenue increases, nobody goes to work to lose money. I think in this situation the cost will be high, too high and the customer will be dealing with no one and Vans employees will be working elsewhere. Better that they come up with a fix that has appropriate quality at manageable cost, as I’d expect they will.
Peter wrote:
You can’t rivet parts like that (regardless of any undesired “heat treatment”) because a rivet relies partly on being a good fit
The beauty of riveted joints is that they don’t rely on good fit, unlike bolted joints, but there is a tolerance limit to their ability to create their own perfect fit as they normally do. The primary issue described here is regardless different, the skins are cracking when plastically deformed in tension around the hole for dimpling, before they are riveted. This is presumably caused by rough holes creating stress risers and/or hardening of the material around the hole due to laser cutting. As per my comments above I would guess that drilling the holes 1/64 in oversize would resolve the issue unless the material is work hardened before the operation. The latter is therefore an important issue and could be checked by a lab test on a number of holes and skins.
eurogaguest1980 wrote:
Having worked with some very small “mom and pop” shops many years ago. I’m guessing that the owner made all the early parts, and they were good, and passed Van’s QA checks. Van’s assumed that they would continue with this same level of quality and didn’t do enough QA on subsequent parts.
Sound right to me, although the volume of parts Vans is producing is somewhat above the "mom and pop’ level. I wonder if the supplier of the skins is in e.g the Philippines or somewhere else geographically distant like the previous Vans QB supplier.
There is obviously no need for parts traceability for certification reasons here, but if I was making RV kits I would still put a batch code or some such on parts, otherwise I have no hope whatever of detecting supplier-specific QA issues.
Otherwise, the only way is segregation in the storeroom, which is a total hostage to fortune 
The obvious way is, wait for it, laser marking
why did the problem take so long to surface?
Good question… I’ve been in manufacturing since 1978 and there are interesting reasons for why one can ship a dodgy product and it doesn’t get discovered e.g.
Given that most users will be in the USA, some of the above obviously does not apply.
VAF contributor Will posted following:
It’s educational to review the Jan 15, 2022 business update video from Vans where they discuss introducing the laser cutting process, starting at about the 11 min mark.
Graham wrote:
Sure, that is naturally an engineer’s approach to it. I’ve been in similar positions trying to find pragmatic solutions to avoid total re-work, although not in an engineering capacity.Here my perspective is one of a customer. The part is not of appropriate quality, therefore I reject it. It is not my role to find workarounds for their manufacturing mistakes.
Just remember that Van’s is an engineering capacity, the internet is not Problems tends to be exaggerated on the internet, and greatly so. Solutions on the other hand…
Viewing that video, it’s clear they have done fatigue tests, and they turned out OK. What I would do is to have them send over a report of those tests and call the case closed. I mean, what else is there to do? The only other option here, from an engineering point of view (and yes, I have a PhD to prove it ), is to scrap all the laser cut parts. As I understand, this will in many cases put you back at point zero. There is also another clue in that video. Most of the internal parts are T0 (or 0), not T4. They are not heat treated, and as such have no heat treating to lose/mess up. T0 has only 1/3 of the tensile strength compared with T4 by the way. Skins are done inhouse using their Trump 200 (what a name )
Clearly there is an internet over reaction phenomenon taking place here. The problem has been blown out of proportion. If Van’s, for some reason, refuses to hand you a report of those fatigue tests, then there is a problem.
But then if you are a customer you might have to send a copy of those fatigue tests to someone else to have them “translated” so to speak.
I can see @Graham’s point. When you buy something you expect it to be “fit for purpose”.
Are these parts “fit for purpose?” It would seem not. No amount of engineers wriggling and flashing their PhDs will cure that.
If you buy something and you have paid for all the holes to be pre drilled which is what Van’s is making its business model as opposed to other kit suppliers who just sell the parts and you ate expected to drill them yourself, then surely if the holes are wrong, too big, too small, need redrilling or whatever the customer can rightly say these parts are not " fit for purpose".
IIRC that is UK and EU consumer law.
LeSving wrote:
Just remember that Van’s is an engineering capacity, the internet is not Problems tends to be exaggerated on the internet, and greatly so. Solutions on the other hand…Viewing that video, it’s clear they have done fatigue tests, and they turned out OK. What I would do is to have them send over a report of those tests and call the case closed. I mean, what else is there to do? The only other option here, from an engineering point of view (and yes, I have a PhD to prove it ), is to scrap all the laser cut parts. As I understand, this will in many cases put you back at point zero. There is also another clue in that video. Most of the internal parts are T0 (or 0), not T4. They are not heat treated, and as such have no heat treating to lose/mess up. T0 has only 1/3 of the tensile strength compared with T4 by the way. Skins are done inhouse using their Trump 200 (what a name )
Clearly there is an internet over reaction phenomenon taking place here. The problem has been blown out of proportion. If Van’s, for some reason, refuses to hand you a report of those fatigue tests, then there is a problem.
I suggest you read about it more widely and attempt to understand the problem fully, because your conclusions above make it clear that you do not.
Yes they did extensive testing before introducing laser cutting. Yes the parts they tested were fine, although to my knowledge no testing data or reports have been shared. In any case those tests were performed on ‘good’ parts without irregular, oversized and cracked holes. They are now performing testing on ‘bad’ parts and seeing how these hold up. These tests are ongoing, working down a list ordered by part criticality, but have already produced a recommendation to replace any laser-cut spars.
The reason we have ‘good’ laser-cut parts and ‘bad’ laser-cut parts is that one particular contractor during one particular time window started delivering defective parts that were nothing like the ones Van’s tested. Instead of programming the laser cutter to start well within the boundary of the intended hole and work out to the edge before proceeding round the perimeter, someone programmed it to start on the perimeter itself and proceed round – presumably to save a fraction of a second on the process time. The kerf created by the initial piercing is greater than that of the subsequent cut. The perimeter location is programmed to produce an edge according to the standard cutting kerf, not the wider initial piercing kerf – thus when you start right on the perimeter the hole ends up with a notch in it that extends beyond the intended boundary. Additionally the holes aren’t even close to round, and the reasons for this are beyond my competence but my guess would be that (again to save process time) the track the laser was asked to follow around the perimeter did not contain enough individual locations – i.e. it was an approximation of a circle rather than a circle.
No QC at the contractor or at Van’s picked up these bad batches.
Builders complained about these parts on receipt but were rebuffed. They attempted to clean up these holes in the normal drilling/reaming and de-burring process, but generally found they were unable to remove the notch without reaming beyond the maximum allowable hole diameter. They complained en masse about this to Van’s, who repeatedly denied that any issue existed and told builders to find the best compromise they could between a clean hole and the maximum diameter, even if neither could be satisfied. Many builders attempted to reject parts and were refused, with Van’s repeatedly doubling-down on their position that there was no problem with them. Builders were left with a choice between proceeding per Van’s instructions and abandoning their build and sunk costs entirely, so obviously most proceeded. They soon found that the affected holes cracked either when dimpled or when riveted.
Eventually enough pictures of holes that cracked after dimpling or riveting reached Van’s and got pushed far enough up the chain that someone decided they couldn’t double-down on their position any more. So here we are – Van’s have stopped all laser cutting and reverted everything to punching, and are no longer shipping the laser-cut parts they have in stock. They’ve issued this warning to all customers who had kits shipped in the relevant date windows and have said they will replace all laser-cut parts on request, but have not commented on solutions for customers who may have laser-cut parts entombed in completed assemblies (whether quick or slow build). The quickbuilders have a simpler situation because they can just reject the entire assembly and ask for another one. Slowbuilders like myself are potentially faced with being expected to drill out every single rivet in an assembly to replace a spar and/or ribs, and the chances of doing this without destroying other parts in the process are close to nil.
And there is zero parts traceability. So many laser-cut parts which will have to be replaced are in fact fine, because it’s only a subset of the laser-cut parts that aren’t but no-one knows who got what. Especially in the quickbuild kits, where QC is known to be iffy and they could well be full of cracks that no-one paid any attention to.
