KITPLANES Roundtable on Van's Laser-Cut Parts Tech Briefing

[@kentcolgan6139]

With one caveat, you’ve validated my takeaway from watching the 2 hour presentation. Thanks for taking the time to do this. Van’s attacked the problem with integrity and I’m impressed and comfortable with the results. (I’ve been a mechanical engineer for 40 years in the nuclear power industry. In the process of building an RV9A) CAVEAT: The presentation didn’t address (I may have missed it) un-dimpled joints. In the absence of the compressive hoop stress near the edge of the hole (due to the absence of a dimple), the discontinuities in the LCP holes will not be isolated from the alternating stress of flight (or fatigue testing). Given some of the gross discontinuities that have been seen in delivered LCPs, I’d expect a much shorter fatigue life in LCPs than in punched holes in un-dimpled joints. Would love for Van’s to explain why this is not a problem.

[@SoloRenegade]

Same here, Mechanical and Aerospace engineer, design riveted shtmtl structures, and building a Onex right now (hope to build a Vans next). Their presentation was very interesting and well put together.

[@stevejahr5527]

I had to chuckle at Paul's closing: this is *experimental* aviation and a major purpose of it is for education. I was just telling a Young Eagle that same thing yesterday as we did a fuel flow test and *learned* a bit more about the airplane when the test failed. I am not a builder nor owner of a RV but following this just the same because I learn from it. I am a Kitplanes Magazine fan because I learn cool interesting stuff from them. Part of the Human Condition is we learn more from our failures than our successes. Van's will be even better from this experience because they are taking an open learning approach. Thanks for doing this and continuing the education.

[@Geymanc]

excellent presentation and analysis. The Pilot is by far the largest risk (currency, training, recent BFI teaching, reflexes with current plane, etc.). The airframe, and properly cared for engine, are much lower on the risk equation. I appreciate and trust the panel. They have "skin in the game" flying themselves and family all the time in their RV's. Thanks again.

[@hefeibao]

Am considering buying a (used, pre-built) Van's and this is very timely. Your expertise is remarkable. FWIW regarding your comment at 19:33, I turned wrenches on OH-58 (Bell 206) scout helicopters as a young man, and as you say it can be illuminating how little holds things together.

[@LTVoyager]

As an engineer, I fully appreciate the data that says that these parts are just fine. However, as one who worked in product development towards the end of his career before retiring, I remember that many of the sales and marketing folks often said “perception is reality.” For those not familiar with science and engineering, the data doesn’t matter. If there is a perception of a problem, then there is a problem. And once the perception goes viral, it is often a mistake to double down on engineering and try to use data to change perceptions. I suspect it may well have cost Van’s much less money and much less loss of trust if they had simply recalled the laser drilled parts and replaced them with punched parts.

[@SoloRenegade]

It's a valid point. But some people will never be convinced no matter what you do either. And unfortunately we can't change the past. But definitely should be a learning lesson for any other companies out there, and they should think ahead how they intend to handle such a crisis of their own if it were to happen (and then strive to ensure it never happens).

[@LTVoyager]

@@SoloRenegade As an engineer myself, I am a big fan of having engineers run companies that make products or deliver technology. However, as I learned during my engineering career, most customers operate on emotion, not on logic. And it cases like this, engineers tend to revert to their logical nature and think that if they just provide customers enough data all will be well. Sadly, that is seldom successful unless you have a very technically savvy customer base. Most customers will view that as you being defensive and trying to justify your actions and not listening to them and taking their concerns seriously. This is the one case where I think a company led by engineers will fall on its face every time. Sometimes you just have to accept that it doesn’t matter if the parts really are perfectly fine. What matters is that your customers, whose money sustains your business, think the parts aren’t fine and you really need to respond with that perspective in mind. Often much less expensive in the long run to just give them equivalent parts that they think are fine rather than trying to convince them to change their perception.

[@augustoaguirre2574]

Great presentation. I built my RV6A 1993-1999, (this was before pre-punched parts) still flying after 25 years. I have no concerns regarding LCP parts. I’m now building a RV14A and hopefully will be flying it by 2025. Builders should be more concerned about the attention to detail while building than having LCP parts in our airplanes.

[@deeremeyer1749]

Took you 6 years to build the first and you're going.to knock out the second in a year? ROFLMAO.

[@rickh4310]

Great report guys! I’m not building an RV, but I am building a Panther. Interesting info none the less. And Paul, I’ve referenced your “Metal Magic” series many times during my build process.

[@SoloRenegade]

The Vans 2hr presentation was so good that I'd even recommend engineers in general take a watch, even if they aren't involved in experimental aviation in any way. Many new/young engineers could learn a lot from watching it.

[@MikeDennin-l4j]

Really appreciate the panel’s discussion and outside perspective on the LCP issue. Very refreshing to have experienced and knowledgeable people in a reasoned discussion instead of the social media maelstrom. Thank you for building my confidence in Vans test results and recommendations.

[@stefanballmer7526]

Thank you, all - this video was extremely helpful, and concludes the LCP issue for me. Time to continue building the RV14a.

[@SoloRenegade]

I've noticed people are also misunderstanding the difference between the laser cut holes, and the need for bankruptcy. Bankruptcy isn't about the engineering of the laser parts. it's about making sure they can financially handle the costs of dealing with the replacement of affected parts, namely quick build kits. Filing for bankruptcy does not indicate a lack of confidence by Vans in their laser cut parts, the quality of their designs, etc. It's only about the financial burden/costs they are facing with replacing things like quick build assys and such.

[@daryltolliver7271]

Communications main issue. Go Ugly Early and stay up to date. Great video Paul and team!

[@michaelguy7168]

Great informative presentation. Would love to see this group take on more aviation issues.

[@murryrozansky8753]

Good presentation of the testing at Vans. One interesting take away for me is that aluminum is not quite as notch sensitive as I have been lead to believe. RVs have earned their popularity. Kitplanes too.

[@AlexPetersonRV]

Great job guys, thanks. Afterwatching the 2 hour engr presentation, I too was curious about the lack of data on non-dimpled holes as others have mentioned. It is obviously a very, very different situation from a dimpled joint. And, internal, non-inspectable components typically are not dimpled.

[@dannyadventurer1172]

Great virtual round table discussion. I hope this adds comfort to all those involved with the LCPs building. I've been flying my RV7 since my first flight in 2006. Currently @ 1300hrs

[@willonthewing2860]

Despite the engineering analysis of LCP, the fact is that they have not been validated by years of actual flight experience, as the punched parts have. Many people ordered Van’s kits based on the years of actual real world flight experience.

[@SoloRenegade]

nobody in the early years of Vans built airplanes based upon actual flight data. the engineering fatigue analysis is VALID equivalent to flight test. And Vans was overly conservative multiple times over in their testing. so what they say it can handle, is actually less than it can actually handle. People who don't understand engineering, should trust the engineers who've done valid testing with 3rd party oversight. Vans did testing, got outside feedback, followed decades of established testing, and allowed many expert observers to look over their shoulder at all the work/testing they did. Everyone has backed up Van's testing and conclusions. If you don't like it, then stay away from Experimental Aviation.

[@jameseclark]

As a builder, I know that my (20+ year old RV6) plane has FAR MORE flaws that **I** introduced in my non-perfect construction than ANYTHING that I saw at Van's. This plane has over 2500 hours on it, has done years of airshows, has been "upside down" a few times, and has pulled more "G's" than probably 90+% of kit-built planes. Still going strong. And oh, the earlier kits were not PERFECT either. What I saw and felt at Van's FAR EXCEEDED what I thought I might see. The impression that I get from the presentations/videos that they have presented don't fully capture how much they have done and are doing. They are VERY conservative (in my opinion). They tested many, many samples ("coupons") to failure. The stress crack to failure were NOT from the LCP crack. The highest stress points were shown to be elsewhere in the dimpled area. And THAT stress area is what we have been flying to "+6.0/-3.0 G's" for 30+ years.

[@rbux24]

Good discussion. A couple notes, not an "expert" on fatigue, but I do a lot of fatigue analysis: 1. I generally agree, not likely a fatigue or strength issue, but most of aviation has fatigue issues which is why we do inspections... to watch cracks grow. If RVs are free of that, then they are among the best. 2. If I was in their position, I'd put a strain gauge near the most critical area(s) and get some flight data along with speed sweep to see contribution of engine excitation orders and structure/panel natural modes. Hard to predict but can be significant. Keep your setup dynamically balanced. 3. Effects of corrosion? Use corrosion protection. 4. What are the impacts of a drilled hole (vs laser or stamped)? Personally I like the CNC router solution. 5. I was expecting a bit more variation in fatigue data, but I normally work with welded structures fatigue.

[@damongulick4306]

Thanks so much for the thoughtful and comprehensive discussion!!!

[@Sideways71]

Summary: Worry more about getting on a 737 than cracks in Vans LCP.

[@stephenphoenix2919]

Laser cut parts have two problems: 1. Rough edges which are stress risers. 2. Heat affected zone loss of heat treat properties. The stress risers will be the origin of cracks if the stresses are high enough. The rivets will bear out and loosen (fret) in the heat affected zones in a high frequency load environment; if the load is high enough. My suspicion is that the loads are very low on the wing skins and will not show problems. If they do show up, it will be small cracks or rivet fretting at the inboard ends of the wings. Might note that Boeing does prohibit Laser cutting of metallic parts on their drawings.

[@n539rv]

Great discussion and not surprised. My big question is was the laser “punching” process originally started at the hole edge or was this something that got changed later by the 3rd party? If it always started at the hole edge, why wasn’t this edge defect noted, questioned and analyzed? If it was changed later by the 3rd party, how did Van’s not know about it or catch it during inspections when they received the parts in-house. Bottom line is this was a QC program failure.

[@billhollifield9086]

Van's specified cutting paths that started and returned to the middle, as part of subcontracting these parts. Somewhere along the line, subcontractors started using other paths. Yes, Van's should have caught that in the QC. But your direct question is something that Van's as not addressed publicly. Likely there are legal reasons for that. Potential lawsuits about unauthorized cutting path changes, perhaps... (that is speculative.)

[@jvtaylor3]

The issue isn't as clearly defined to just laser cut part safety. Van's didn't test the defective 3rd party laser cut parts, they also didn't provide sourcing data behind those parts. I have no idea if the parts I have were cut by Vans or cut by one of the 3rd parties.

[@KitplanesMagazine]

As far as we know, the laser-cut parts in question were done by an outside contractor.

[@jvtaylor3]

@@KitplanesMagazine cut with incorrect toolpaths to mimic the defects?

[@KitplanesMagazine]

@@jvtaylor3 Sorry, misunderstood the question. They did use the third-party parts in their testing.

[@brianlhickman1]

Yes. This is touched on a number of times in the long presentation. @@jvtaylor3

[@Susieandchris]

Thankyou so much excellent information and will help a lot of people. A lot of worried builders here in Perth Australia and beyond that will be more happy now

[@thomasmurray1807]

Lets dump this down to the average builder. If you went to buy a mirror with a crack accross the face you would not buy it. The mirror would still work and last for 50 years but you would always see the crack. If Vans and make new parts without cracks they should do it right. I have built 3 planes one of which is a RV 14A and I love it. Best aircraft I have ever flown.

[@LTVoyager]

I know most of the Van’s airframe is flush riveted, but do you know if they did any tests on standard rivets in holes no dimpled? I am a retired engineer (electrical and structural), but am not an expert in rivets and their behavior. However, it seems to me that the load path through a dimpled rivet connection is likely quite different than through two flat sheets riveted together. I wonder if the crack initiation would be different between these two cases.

[@LTVoyager]

Paul may want to wear a hat if he is going to use a virtual background. 😁

[@deeremeyer1749]

So who is doing the "dimpling" on CUSTOMER PARTS VS. "ENGINEERING ANALYSIS" PARTS AND WHAT TOOLS ARE USED?

[@chadpm11]

What's up, James Clark, i remember watching you build your RV at Columbia Owen's Downtown when i used to work out there. This was before Jim Hamilton let me go for telling a person that was getting ready to buy a plane jim had for sale to get a mechanic from another shop to do a prebuy due to visible corrosion on a wing spar that was overlooked by his. The plane didn't sell to that guy. 😂

[@SoloRenegade]

Builder Guidance: deburr every hole, clean up all scratches, etc. Why? Because by cleaning up everything, you're ensuring a higher overall margin of safety. If you don't clean things up well, you're missing out on safety margin in the design. If you clean things up properly, you're reducing the chances of something going wrong later on due to fatigue. If we start getting lax in our efforts, eventually you start missing more critical errors due to corner cutting.

[@saranaccamper547]

Fail Safe fatigue testing of cracked components should be left to the megabuck commercial and military aerospace industry with carefully regulated and documented inspection procedures. The average experimental/homebuilt owner/builder is not going to know which cracks are acceptable and in which locations. This push by Vans to "allow" cracks bucks the long history of normal workmanship standards, which is that cracks are not right and inherently bad and cause for concern and contemplation. The typical kit builder who is unable to complete a scratch built project because there are no detailed instruction manuals available does not have the ability to determine whether an existing crack is critical or not. This "good news" that testing has shown that not all cracks are created equal is not a suitable conclusion for use by the general population. Much confusion is going to occur if this is the path that is encouraged to accept. This is not a dig at Joe Builder, it is a dig at pushing complex acceptance criteria for cracks onto an untrained community at large. This is not following the KISS principle.

[@doncatchpole]

Great program. Proves that aluminum is a safe forgiving metal to use in aircraft construction.

[@davefoord1259]

A lot of feel good statements but answer me 2 questions. Will vans publish an acceptable crack length per location document so that when you find a crack on an RV , you can say that crack is okay vs that needs to be rectified? Will vans indemnify each aircraft and all future owners of that aircraft against future cracking in LCPs?

[@kylegoldston]

I would add that the b-17's and other war birds flying are often many thousands of lbs under gross and don't have a hundred or more bullet holes in random bits of structure. I wouldn't ride in one with 8,000lbs of live ordinance and full fuel today though.

[@jimbo7445]

There's a culture issue at Vans - kinda hard to buy into folks that have skin in the game cheering Vans on. Hindsight is 20-20... if engineering has proven that the cracks are safe one would think they would have stopped production, done the engineering and not went through trying to replace these parts. Kinda hard to believe where they're at given the last 6 months.

[@deeremeyer1749]

Functionally equivalent. NO SHIT!

[@damongulick4306]

Why have adhesive not been considered as a way to reduce the focused stress on the rivets? This would seem to be an inexpensive, light weight of the shelf solution that would increase strength without any major negative effects. Or at least to a relatively uninformed person.

[@KitplanesMagazine]

Except for the time to apply the adhesive and the difficulty of replacing parts (for any reason) with a bonded joint.

[@djquick]

Vans: laser cut parts are perfectly safe. Also Vans: we’re no longer laser cutting parts! Actions speak louder than words and the actions show laser cut parts are inferior.

[@KitplanesMagazine]

Two good reasons for stopping the use of LCP. First, while all this was going on, Van's added another punch press, which gave them needed capacity. Two, with that in mind, the outsourced LCPs were actually more expensive than punched parts.

[@djquick]

@@KitplanesMagazine then why LCP in the first place if all they had to do was source a press? It wasn’t a short period of time that LCP was used and now they magically source a press. Nahh… there’s more here and this is all just CYA and you’re complicit.

[@SoloRenegade]

@@djquick Short term you can use Laser Cut outsourcing to meet demands while you get more tooling. You're reading far too much into this, seeing conspiracies where there are none. You're letting your emotions, fear, and ignorance guide you, rather than listing to the experts and the scientific facts. Vans went above and beyond in their analysis of the laser cut parts.

[@djquick]

@@SoloRenegade short term?1 😀1800 kits were laser cut! 😂

[@SoloRenegade]

@@djquick you clearly have no understanding what "short term" means. 1800 parts is nothing. that is a very small order for any company. It can take months to buy new machines, grow shop space and hire people. In the meantime a laser cutter can crank out a lot of parts until the new tools, space, and employes are ready to take over again. Have you ever seen a commercial sheet metal fabrication facility? They crank out a lot of parts very quickly. I'm a Mechanical and Aersopace engineer and design shtmtl riveted structures for a living. My preferred sheet metal vendor can crank out 1800 parts in mere days.

[@deeremeyer1749]

Shills.