[2theskyy]

Completely valid point.


I'd be willing to wager the end result of this will be that testing will show minimal impact on fatigue life and Van's will offer some support as they have already indicated. So it will be left to the builder to decide whether to accept that coupon testing correlates to full scale components, the DAR's will sign off on planes with LCP and/or that resale value won't be adversely affected.

I’m sure your statement will be correct sir.
What I’ve seen in my parts that crack when I dimpled and if the industry is going to buy off on installing cracked parts. Makes me wonder why I spend so much time deburring holes when I can just match drill, dimple, rivet and go on. I know, I know. The engineers and science will say those specific parts will last just like Boeing engineers say the original 737 has the same type cert as a 737 max10. I digress.
From an A&P perspective, I’ve fixed corrosion, cracks, etc, but I’ve never installed a part with a known defect that an engineer has said it’s ok. I’m sure it’s possible but I or the owner would require the test documents be included with the part and would become permanently part of the logbook. Just as AD’s, SB’s etc that address known or suspected issues remain part of the logs.

 

[Snowflake]

And I agree that Van's needs to own this and suffer monetarily. What I don't want to see is this push them over a cliff.

You realize that Van's is a business, right? Where all costs are paid by the customers? If they have to eat $3-6M to replace parts/assemblies/kits, that revenue will need to be made up by builders over time. Unless we think that Van's is stockpiling $3-6M a year that's just sitting there to be spent.

 

[KatanaPilot]

You realize that Van's is a business, right? Where all costs are paid by the customers? If they have to eat $3-6M to replace parts/assemblies/kits, that revenue will need to be made up by builders over time. Unless we think that Van's is stockpiling $3-6M a year that's just sitting there to be spent.

Of course. However, I'm not sure what point you are trying to convey.

Are you suggesting that only customers directly affected by this issue be the ones to foot the bill? If not them, then who?

 

[TX_Flyer]

Perhaps there would be an option where people with QB kits that are willing to wait for a new delivery could transfer their kits to other builders. These builders could buy replacement parts for the LCP at the “kit price” or some discount and put in the sweat equity of disassembling and rebuilding the kits with good parts. This would at least prevent vans from having to deal with taking returns of QB kits and possibly absorb those shipping costs. Just a thought and something I would certainly consider.

 

[RV-Ogler]

One thing I’ve been wondering is will I still be able to buy insurance for my RV-14 if it has some laser cut parts?

 

[TX_Flyer]

One thing I’ve been wondering is will I still be able to buy insurance for my RV-14 if it has some laser cut parts?

This is probably one of the many reasons Vans is undertaking the engineering and analysis efforts on the LCP.

 

[dmattmul]

Hoping

I know hope is not a plan, but my bet is there are very few LCP's if any in QB's. My thoughts are:
1) Vans started LCP early 2022. Doubtful they started shipping to the Philippines early as they probably wanted to get the parts in builders' hands to get some feedback before shipping to the Philippines. (I would) That would put first LCP in the Philippines mid-year. (Assuming 45 days in transit). The Philippines would have had some inventory of traditional punched parts to work through.
2) Vans was getting reports of issues with LCP's early Sept (If someone has a better date love to hear it) I doubt they would have let the Philippines continue using parts with a potential issue especially knowing like the corrosion issue they are on the hook for the lost labor that would go into QB. (The corrosion disaster would be still fresh in their mind) In mid 2022 they were still in the process of replacing QB's and nobody would want to go through that again.
3) IF the Philippines started using LCP's it seems they would have seen something (They are after all professional experienced builders) and stopped.
4) Those that would have received LCP's in QB's by now even if primed I believe would have seen SOMETHING. Those holes were pretty ugly, and I doubt no amount of primer would have covered it up.

This is course is just one person's theory but not having LCP's in QB's would seriously lessen the financial impact.

 

[rocketman1988]

Lcp

One thing I’ve been wondering is will I still be able to buy insurance for my RV-14 if it has some laser cut parts?

You realize that these kits have other laser cut parts that are fine, right?

 

[Mark33]

Of course. However, I'm not sure what point you are trying to convey.

Are you suggesting that only customers directly affected by this issue be the ones to foot the bill? If not them, then who?

Exactly! It’s really pretty simple; those of us with QB kits aren’t asking for anything extra, but we do expect to get what we’ve paid for. It’s hard to argue that anything less should be acceptable.

Perhaps there would be an option where people with QB kits that are willing to wait for a new delivery could transfer their kits to other builders. These builders could buy replacement parts for the LCP at the “kit price” or some discount and put in the sweat equity of disassembling and rebuilding the kits with good parts. This would at least prevent vans from having to deal with taking returns of QB kits and possibly absorb those shipping costs. Just a thought and something I would certainly consider.

This is a good idea, but I’ll bet that very few people would be willing to do this. No one knows what’s going to happen yet but I know everyone with QB kits are still hoping for the best. If it ends up where there’s only a few easy to access parts that need replacing, than I’m sure I’d be willing to do that, however, I do have my limits.

 

[Brantel]

Unfortunately Greg stated at Osh that they know LCP's were sent to the QB factory. He also stated that they could not determine when the parts were used and in what QB, only that they know when they arrived there.

If Van's was telling non QB customers to build on, odds are they were still using them in QB's IMHO.

I know hope is not a plan, but my bet is there are very few LCP's if any in QB's. My thoughts are:
1) Vans started LCP early 2022. Doubtful they started shipping to the Philippines early as they probably wanted to get the parts in builders' hands to get some feedback before shipping to the Philippines. (I would) That would put first LCP in the Philippines mid-year. (Assuming 45 days in transit). The Philippines would have had some inventory of traditional punched parts to work through.
2) Vans was getting reports of issues with LCP's early Sept (If someone has a better date love to hear it) I doubt they would have let the Philippines continue using parts with a potential issue especially knowing like the corrosion issue they are on the hook for the lost labor that would go into QB. (The corrosion disaster would be still fresh in their mind) In mid 2022 they were still in the process of replacing QB's and nobody would want to go through that again.
3) IF the Philippines started using LCP's it seems they would have seen something (They are after all professional experienced builders) and stopped.
4) Those that would have received LCP's in QB's by now even if primed I believe would have seen SOMETHING. Those holes were pretty ugly, and I doubt no amount of primer would have covered it up.

This is course is just one person's theory but not having LCP's in QB's would seriously lessen the financial impact.

 

[Mark33]

I know hope is not a plan, but my bet is there are very few LCP's if any in QB's. My thoughts are:
1) Vans started LCP early 2022. Doubtful they started shipping to the Philippines early as they probably wanted to get the parts in builders' hands to get some feedback before shipping to the Philippines. (I would) That would put first LCP in the Philippines mid-year. (Assuming 45 days in transit). The Philippines would have had some inventory of traditional punched parts to work through.
2) Vans was getting reports of issues with LCP's early Sept (If someone has a better date love to hear it) I doubt they would have let the Philippines continue using parts with a potential issue especially knowing like the corrosion issue they are on the hook for the lost labor that would go into QB. (The corrosion disaster would be still fresh in their mind) In mid 2022 they were still in the process of replacing QB's and nobody would want to go through that again.
3) IF the Philippines started using LCP's it seems they would have seen something (They are after all professional experienced builders) and stopped.
4) Those that would have received LCP's in QB's by now even if primed I believe would have seen SOMETHING. Those holes were pretty ugly, and I doubt no amount of primer would have covered it up.

This is course is just one person's theory but not having LCP's in QB's would seriously lessen the financial impact.

This is what I’m sure everyone is hoping for.

Unfortunately Greg stated at Osh that they know LCP's were sent to the QB factory. He also stated that they could not determine when the parts were used and in what QB, only that they know when they arrived there.
……(snip)

This is concerning.

 

[gotyoke]

I thought I was lucky and that my slow build wing kit, picked up early April, 2022, was not affected. I'd be able to claim minimal laser-cut holes in my build and move on from this fiasco. Then I happened to be pulling scrap from my bucket of shame and saw a wing walk doubler with some rather misshapen laser cut holes (not notched), which I remember at the time thinking "well that's odd, but they are within spec".

Then I remembered my leading edge and tank ribs were backordered, and when they came in they were laser cut. I recall not having any concern about the hole quality in those at the time. I just now looked through some pictures of my wing kit inventory. ALL my wing main ribs were laser cut. Again, I had no concern about hole quality in those at the time.

I just did a spot inspection of dimpled main wing ribs (bottom skin isn't riveted on yet), and sure enough those holes have tiny "notches", which I now know under significant magnification means those holes have tiny cracks. For the top flanges riveted to the top skin, to the naked eye the cracks are not visible, still covered by the shop head of the rivet, so that's perhaps some ray of hope.

Anyway, now I know my wings are "tainted" with laser cut ribs across the board and have to accept that. Even if Van's safety testing finds these not to be a problem and I accept whatever risk there may be for myself and my passengers, I won't know whether the rest of the aviation world will accept the risk until I try to sell it in 2-3 decades. Or possibly when I go to insure it. Do I want to spend another $150k finishing a possibly unsellable plane? That's equity I'd like to get back some day, less standard depreciation. And if Van's outsourced independent testing says anything other than "the risk of failure in normally prepped laser cut wing, leading edge, and tank ribs over the expected life of the airplane is in line with punched parts", I'm not sure I'll have the heart to continue my build. Life is too short.

The tank has got me baffled (pun). I think my baffles may be laser-cut because they didn't have the blue film in my pictures (again I had no concern of hole quality in those). The baffle is not dimpled. The cracking concern has to be very very low, right? So why is it on the "red" list? I know, fuel leaks. But there is no leak if there is no crack.

 

[greghughespdx]

We have posted an update on the Van's website. Our next update post will be made on or before next Friday.

Short version: Testing is ongoing and consists of extensive evaluation of materials, fasteners, hole types, structures, and computer models for stresses and loads. We have completed the first phase of testing and have moved into the second phase, where we address more complex structures. The tests conducted thus far have shown no meaningful reduction in the life of an airframe, and the process is still underway.

We are currently working on a couple of things specifically for builders: A procedure describing methods that can be used to inspect for and identify laser-cut parts, where possible; and a web-based portal where customers will be able to request replacement parts. It will be a few weeks or so before that portal is ready and the necessary data and information can be loaded for use. Both the inspection documentation and the portal are under development, and we will update regarding progress on those as we go.

My work schedule today requires me to be away from the computer for most of the day, but I will try to block out some time over the weekend to answer a few of the questions that have been posted recently.

greg

 

[admin]

Thank you for the update.

...and thanks also for using part of your Saturday to do it.

v/r,dr

 

[Jonnyb]

...and thanks also for using part of your Saturday to do it.

v/r,dr

Absolutely!

Thanks for the update Greg, much appreciated.

 

[Phil Sprang]

Thank you for the update Greg. It is very much appreciated.

 

[gotyoke]

Greg, I think it would be cool if Van's could share close up quality photos of representative holes used in your testing. a) raw, b) after prep, c) dimpled, d) riveted. And what kind of prep was done (deburring, deburring + notch filing, etc.). This would give us a nice basis for comparison to what we see on our own kits. You probably already have such photos you could share sooner rather than later.

If your holes look worse than ours and still perform well, that would go a long way toward inspiring confidence.

 

[GrahamF]

Thanks for the update. Unfortunately it doesn't give a whole lot of new information, other than the extremely unwelcome news that we'll have to pay (albeit at a discount) for parts damaged in removing laser cut parts.

Here's a question. If the testing generally shows laser cut parts to be fine, then why are various spars already marked as 'replace'?

 

[maxmirot]

Here's a question. If the testing generally shows laser cut parts to be fine, then why are various spars already marked as 'replace'?

That has been one of my questions. If a spar shows the same life then why are they being replaced?

 

[Jack_G_S]

That has been one of my questions. If a spar shows the same life then why are they being replaced?

+1. If spars can’t be trusted using laser cut holes then any aircraft with laser cut parts will have a stigma. We are being asked to fall on the sword here. I didn’t even sign up to be a test pilot for this unproven manufacturing technique.

 

[MIKE JG]

67 pages and counting....

@Doug, can we have a sticky thread with just Greg's replies. Having to wade through all these posts is time consuming.

 

[greghughespdx]

Thanks for the update. Unfortunately it doesn't give a whole lot of new information, other than the extremely unwelcome news that we'll have to pay (albeit at a discount) for parts damaged in removing laser cut parts.

Here's a question. If the testing generally shows laser cut parts to be fine, then why are various spars already marked as 'replace'?

Those parts were currently marked as "replace" immediately, without waiting for test results, out of an abundance of caution based on the loads that can be carried by those parts. As we have described previously, we will complete the testing and adjust the status of any part as the testing indicates appropriate and necessary. For now, people with those spar parts on the bench should be waiting to build their kit assemblies, and we felt it necessary to label those parts the way we have before we started testing specifically because those are the parts among the laser-cut ones that carry higher loads than most of the others. Our testing outcomes will determine the final status and category for each part.

Please understand that our testing processes take a conservative, cautious approach in assessing and categorizing each part and that, as described previously, the statuses are subject to change to reflect the results of our testing.

Thanks.

greg

 

[deMan]

Heat treated parts

Hi Greg,

Could you please elaborate a little on why heat treated parts were put into their own category with low testing priority? What was the thinking behind the low testing priority?

Thank you
Lars

 

[RV7A Flyer]

...this unproven manufacturing technique.

That's the thing...laser cutting is NOT "unproven". It's a perfectly good way to make holes and whatnot in metal parts.

This was a *quality assurance* failure, IMO. Van's should, at some point, be open and honest about the root causes of the problem, not just the workarounds.

As someone earlier noted, this was both a failure of the vendor to properly set up or operate the laser cutting system, AND a failure of both the vendor's QA and Van's QA to identify the problem very early and rectify it at the source.

 

[squeakersc063]

That's the thing...laser cutting is NOT "unproven". It's a perfectly good way to make holes and whatnot in metal parts.

This was a *quality assurance* failure, IMO. Van's should, at some point, be open and honest about the root causes of the problem, not just the workarounds.

As someone earlier noted, this was both a failure of the vendor to properly set up or operate the laser cutting system, AND a failure of both the vendor's QA and Van's QA to identify the problem very early and rectify it at the source.

I don't think it would have been as big a deal on parts where we final sized holes.

 

[Jack_G_S]

That's the thing...laser cutting is NOT "unproven". It's a perfectly good way to make holes and whatnot in metal parts…

What aircraft uses laser cut holes? Especially final sized.

 

[RV7A Flyer]

I don't think it would have been as big a deal on parts where we final sized holes.

Maybe, maybe not. But when you don't use the equipment properly, set up the tool correctly, and/or follow proper procedures, all bets are off.

 

[Tankerpilot75]

Thank goodness my RV was built long before this problem developed.

Today I attended a local EAA Chapter meeting where several current builders got up and discussed this issue, their complete frustration with Vans, and how they’ve handled it. Several of these current builders said they attended the OSH briefing at AirVenture and didn’t like what they heard and/or failed to hear. (Initial denial of the problem - January 2022, failure of internal quality controls to catch the problem, lack of documentation relating to parts manufacture tracking, failure to stop shipping flawed parts until June 2023, and inadequate communication to their customers.)

This is obviously a serious issue with the primary opinion expressed by these builders: “this is not the Vans Aircraft Company it once was.” I was sorry to hear that said because I personally love my RV. However, the long term consequences are going to be significant if Vans fails to appropriately address these current builders concerns and the IMPACT this has had on them. One builder discussed a problem he had with his engine order through Vans and how Lycoming would be starting his warranty clock upon receipt of the engine. He said Vans did somewhat facilitate someone else getting his engine order but that resulted in him being put at the end of the order line which he felt could add additional time to his build - assuming Vans adequately addresses the parts issues..

Again, I don’t have a dog in this but just hearing these disgruntled builders express their frustrations to our group wasn’t inspiring. I truly hope Vans goes above and beyond to assist those affected customers. It’s in everyone’s best interest - not just those builders affected by this issue. No one wants to see another Superior Engine camshaft response.

 

[maxmirot]

Those parts were currently marked as "replace" immediately, without waiting for test results, out of an abundance of caution based on the loads that can be carried by those parts. As we have described previously, we will complete the testing and adjust the status of any part as the testing indicates appropriate and necessary. For now, people with those spar parts on the bench should be waiting to build their kit assemblies, and we felt it necessary to label those parts the way we have before we started testing specifically because those are the parts among the laser-cut ones that carry higher loads than most of the others. Our testing outcomes will determine the final status and category for each part.

Please understand that our testing processes take a conservative, cautious approach in assessing and categorizing each part and that, as described previously, the statuses are subject to change to reflect the results of our testing.

Thanks.

greg

I think may be conservative to replace all LCS high load parts regardless of the testing.

Nevertheless, the current replacement policy puts much of the cost and burden on the builders that have assembled their parts.

The replacement policy and the logic they are based on are sure to be a major source of friction between the company and their customer base.

 

[maxmirot]

Thank goodness my RV was built long before this problem developed.

Today I attended a local EAA Chapter meeting where several current builders got up and discussed this issue, their complete frustration with Vans, and how they’ve handled it. Several of these current builders said they attended the OSH briefing at AirVenture and didn’t like what they heard and/or failed to hear. (Initial denial of the problem - January 2022, failure of internal quality controls to catch the problem, lack of documentation relating to parts manufacture tracking, failure to stop shipping flawed parts until June 2023, and inadequate communication to their customers.)

This is obviously a serious issue with the primary opinion expressed by these builders: “this is not the Vans Aircraft Company it once was.” I was sorry to hear that said because I personally love my RV. However, the long term consequences are going to be significant if Vans fails to appropriately address these current builders concerns and the IMPACT this has had on them. One builder discussed a problem he had with his engine order through Vans and how Lycoming would be starting his warranty clock upon receipt of the engine. He said Vans did somewhat facilitate someone else getting his engine order but that resulted in him being put at the end of the order line which he felt could add additional time to his build - assuming Vans adequately addresses the parts issues..

Again, I don’t have a dog in this but just hearing these disgruntled builders express their frustrations to our group wasn’t inspiring. I truly hope Vans goes above and beyond to assist those affected customers. It’s in everyone’s best interest - not just those builders affected by this issue. No one wants to see another Superior Engine camshaft response.

Well said.

 

[Bullpup]

I don't think it would have been as big a deal on parts where we final sized holes.

I thought this as well, but I (and others here) have:

• Taken "good" LCPs (no extreme notch, etc.)
• Drilled/reamed to final size
• Deburred
• Dimpled

and still found cracks under magnification.

I appreciate the optimism of both Vans and those here who want to wait for the results of the testing. But, and I'm seriously asking, if the testing shows that microcracks in dimpled holes are OK would you advocate for not deburring? We all put a lot of time into removing stress concentrations in holes, I can't imagine accepting known cracks regardless of the test results.

IMO, the likely outcome of the testing will be confirmation that Van's designed a pretty bulletproof airplane. Which is awesome, but tangential to the specific LCP issue.

Everything in section 5, tribal knowledge, and I can only assume the collective opinion of DARs says this is a no-go. Each builder will have a personal decision to make about their level of work invested and their personal risk tolerance, but we can't seriously start believing that cracks are OK, right?

I'm really grateful for the update, and the first official confirmation that some consideration will be given for non-LCP attached to affected parts. Hoping for continued news like this and the opening of the replacement process.

 

[deMan]

I appreciate the optimism of both Vans and those here who want to wait for the results of the testing. But, and I'm seriously asking, if the testing shows that microcracks in dimpled holes are OK would you advocate for not deburring? We all put a lot of time into removing stress concentrations in holes, I can't imagine accepting known cracks regardless of the test results.

I thought deburring wasn’t about removing stress concentrations but rather about preventing a bur from causing a small gap between the parts.
Part of the rivet strength is friction between the two sheets around the rivet, so you need the two sheets to be flush to each other around the hole. That’s where a bur would get into the way.
The bur might also eventually get squash together by vibrations causing a smoking rivet.
That was my understanding of why we debur.

 

[gotyoke]

I thought deburring wasn’t about removing stress concentrations but rather about preventing a bur from causing a small gap between the parts.
Part of the rivet strength is friction between the two sheets around the rivet, so you need the two sheets to be flush to each other around the hole. That’s where a bur would get into the way.
The bur might also eventually get squash together by vibrations causing a smoking rivet.
That was my understanding of why we debur.

Section 5.2 says nothing about gaps, and everything about stress concentrations and cracks. "Because it is a hard material, it is scratch and notch sensitive. This means that sharp or rough edges, corners, and scratches can cause stress concentrations which will greatly increase the possibility of local failure, usually in the form of a small crack. The problem with small cracks is that they soon become large cracks, one piece of aluminum becomes two pieces, etc. Obviously, we do not want this happening in our airframe, particularly when separated from solid earth by a lot of very thin air."

 

[Jack_G_S]

Section 5.2 says nothing about gaps, and everything about stress concentrations and cracks. "Because it is a hard material, it is scratch and notch sensitive. This means that sharp or rough edges, corners, and scratches can cause stress concentrations which will greatly increase the possibility of local failure, usually in the form of a small crack. The problem with small cracks is that they soon become large cracks, one piece of aluminum becomes two pieces, etc. Obviously, we do not want this happening in our airframe, particularly when separated from solid earth by a lot of very thin air."

LOL, I was wondering when someone was going to mention that. I guess the air is not so thin anymore. I was surprised Van’s didn’t edit that out and put their February change to Chapter 5 in that section.

 

[mstrauss]

I went back to some of my email correspondence with Vans about the concerns I had with received LC parts. These are some of the images I took for the E-903 and R-903:

 

[Bullpup]

Section 5.2 says nothing about gaps, and everything about stress concentrations and cracks. "Because it is a hard material, it is scratch and notch sensitive. This means that sharp or rough edges, corners, and scratches can cause stress concentrations which will greatly increase the possibility of local failure, usually in the form of a small crack. The problem with small cracks is that they soon become large cracks, one piece of aluminum becomes two pieces, etc. Obviously, we do not want this happening in our airframe, particularly when separated from solid earth by a lot of very thin air."

Following that, they specifically call out the risk of cracks radiating from dimpled holes:

"Burrs around holes are a
problem mainly in riveting and dimple countersinking. The burr can prevent a rivet head
from seating properly and can make dimple countersunk holes more prone to developing
cracks radiating from the hole."

 

[gotyoke]

Following that, they specifically call out the risk of cracks radiating from dimpled holes:

"Burrs around holes are a
problem mainly in riveting and dimple countersinking. The burr can prevent a rivet head
from seating properly and can make dimple countersunk holes more prone to developing
cracks radiating from the hole."

I stand corrected.

 

[swift12]

clarification.

Greg please clarify this statement on the update.

"The forthcoming web portal will allow a builder to select which laser cut parts are needed for replacement as well as any other associated parts needed due to damage, which will be made available at a significant discount. "

I assume the significant discount is only for the parts damaged when rectification work is carried out? The "not fit for purpose" Laser cut parts requested for replacement regardless of testing will be free of charge. Thank you.

 

[lr172]

and still found cracks under magnification.

I appreciate the optimism of both Vans and those here who want to wait for the results of the testing. But, and I'm seriously asking, if the testing shows that microcracks in dimpled holes are OK would you advocate for not deburring? We all put a lot of time into removing stress concentrations in holes, I can't imagine accepting known cracks regardless of the test results.

Before getting concerned, you really should do some research on the mechanics of a dimpled fastening arrangement and how they typically fail. If you do that, I think you will see that the loads are not concentrated anywhere near the hole and instead near the bend radius. If that area is not stressed, then cracks in that area do not propogate. I am not for a second saying I understand the science here, just that you cannot take logic that says cracks are a problem for regular holes with fasteners and just apply it to dimpled holes, as the fundamentals are totally different. Think about it: We conuntersink skins almost down to a knife edge and don't think twice about the stress creating a crack. It takes almost no force to start a crack in the knife edge, but that doesn't mean the fastening doesn't work, as that crack won't propogate. This is a pretty broad and involved body of Engineering here that is well beyond what most of us understand, myself included. We need to leave that work to the Engineers and Scientists who specialize in it. IMHO, if the Engineers say the small crack around the hole is fine, the only analysis that we as builders need to do is ask: do we trust Vans to do the complete, in depth research and give us an honest and complete answer. We can all sit here and say cracks must be bad and must be addressed, but what do we really know?

I find it very interesting that all of the arm chair quarterbacks jump in and say it is a crack and a crack is bad, therefore the entire airplane is compromised and will fail. How can you accept a complex airplane design with literally thousands of engineering choice, like rivet spacing, rivet size, skin thickness for a panel, which alloy is used, when is it annealed and re-hardened, etc., etc. and yet question them on this design issue about whether or not a crack is a problem in a dimple? There are thousands of these planes flying with a very limited number of failure areas. Sure, there are a handleful of SBs that show they under designed an area or stresses were greater than the Engineer assumed, but on balance, their design and the thousands of Engineering choices they made are good and have stood the test of time. Folks need to do what is comfortable for them, but I fail to understand the logic that says I trust the thousands of engineering choices they made in the design, but when it comes to a small crack in a dimple, I know more than they do.

 

[Jack_G_S]

Before getting concerned, you really should do some research on the mechanics of a dimpled fastening arrangement and how they typically fail. If you do that, I think you will see that the loads are not concentrated anywhere near the hole and instead near the bend radius. If that area is not stressed, then cracks in that area do not propogate. I am not for a second saying I understand the science here, just that you cannot take logic that says cracks are a problem for regular holes with fasteners and just apply it to dimpled holes, as the fundamentals are totally different. Think about it: We conuntersink skins almost down to a knife edge and don't think twice about the stress creating a crack. It takes almost no force to start a crack in the knife edge, but that doesn't mean the fastening doesn't work, as that crack won't propogate. This is a pretty broad and involved body of Engineering here that is well beyond what most of us understand, myself included. We need to leave that work to the Engineers and Scientists who specialize in it. IMHO, if the Engineers say the small crack around the hole is fine, the only analysis that we as builders need to do is ask: do we trust Vans to do the complete, in depth research and give us an honest and complete answer. We can all sit here and say cracks must be bad and must be addressed, but what do we really know?

I find it very interesting that all of the arm chair quarterbacks jump in and say it is a crack and a crack is bad, therefore the entire airplane is compromised and will fail. How can you accept a complex airplane design with literally thousands of engineering choice, like rivet spacing, rivet size, skin thickness for a panel, which alloy is used, when is it annealed and re-hardened, etc., etc. and yet question them on this design issue about whether or not a crack is a problem in a dimple? There are thousands of these planes flying with a very limited number of failure areas. Sure, there are a handleful of SBs that show they under designed an area or stresses were greater than the Engineer assumed, but on balance, their design and the thousands of Engineering choices they made are good and have stood the test of time. Folks need to do what is comfortable for them, but I fail to understand the logic that says I trust the thousands of engineering choices they made in the design, but when it comes to a small crack in a dimple, I know more than they do.

Firstly it isn’t just us that said cracks are bad. Until just last month it was the entire aviation industry, Van’s included.

Van’s said, trust us laser cut parts won’t crack. Now it’s trust us cracks are ok. I think you may be failing to understand in some circumstances there is a correlation between science and money.

Just by seeing the different types of flaws on the parts I have, there would be nearly an infinite number of variables to test. I know they say they are testing the worse case scenarios, but I think I’m with the others who would like to see photos of what those look like. Then add corrosion.

I think it would take a lot for us to trust this. Something in the order of having an FAA testing firm put their stamp of approval on this. Otherwise I’m really concerned the next time we hear about laser cut parts it may be in the form of an AD.

 

[Snowflake]

I can remember a time when all kits had punched holes, and the holes were punched undersized relative to the final hole desired. This was purportedly to allow match drilling to final size, both for accuracy in aligning the two holes in the two sheets and *to remove the marks left by punching*. Punching leaves scratches on the hole edges that are parallel to the axis of the hole, and there was thought that these scratches could become cracks if not removed.

I can remember discussions here on VAF where people said they were able to dimple the undersize holes directly without match drilling, and reporting that the rivets were fitting and setting fine. There was considerable discussion about whether or not the holes would crack doing this. I don't recall whether anyone found any cracks doing this, but I don't know if anyone would have pulled out the electron microscope at the time...

 

[Mark33]

Before getting concerned, you really should do some research on the mechanics of a dimpled fastening arrangement and how they typically fail. If you do that, I think you will see that the loads are not concentrated anywhere near the hole and instead near the bend radius. If that area is not stressed, then cracks in that area do not propogate. I am not for a second saying I understand the science here, just that you cannot take logic that says cracks are a problem for regular holes with fasteners and just apply it to dimpled holes, as the fundamentals are totally different. Think about it: We conuntersink skins almost down to a knife edge and don't think twice about the stress creating a crack. It takes almost no force to start a crack in the knife edge, but that doesn't mean the fastening doesn't work, as that crack won't propogate. This is a pretty broad and involved body of Engineering here that is well beyond what most of us understand, myself included. We need to leave that work to the Engineers and Scientists who specialize in it. IMHO, if the Engineers say the small crack around the hole is fine, the only analysis that we as builders need to do is ask: do we trust Vans to do the complete, in depth research and give us an honest and complete answer. We can all sit here and say cracks must be bad and must be addressed, but what do we really know?

I find it very interesting that all of the arm chair quarterbacks jump in and say it is a crack and a crack is bad, therefore the entire airplane is compromised and will fail. How can you accept a complex airplane design with literally thousands of engineering choice, like rivet spacing, rivet size, skin thickness for a panel, which alloy is used, when is it annealed and re-hardened, etc., etc. and yet question them on this design issue about whether or not a crack is a problem in a dimple? There are thousands of these planes flying with a very limited number of failure areas. Sure, there are a handleful of SBs that show they under designed an area or stresses were greater than the Engineer assumed, but on balance, their design and the thousands of Engineering choices they made are good and have stood the test of time. Folks need to do what is comfortable for them, but I fail to understand the logic that says I trust the thousands of engineering choices they made in the design, but when it comes to a small crack in a dimple, I know more than they do.

How exactly does a rivet work? How exactly does a dimple work? As the famous philosopher Fred Ward once pondered the question….”How exactly does a posi-trac rear-end in a Plymouth work? Nobody knows, it just does”!!

Like Fred, I don’t know exactly how a posi-trac rear-end works but I do know that airplanes aren’t suppose to have cracks in them. Parts were once produced one way, that technique was changed to making those parts another way for a short period of time, now those parts are back being produced the original way. So the question must be asked, if it worked okay by making those parts the new way, why are they now back making those parts the original way? There’s no “in between” in my book. You can’t have your cake and eat it to.

 

[lr172]

Firstly it isn’t just us that said cracks are bad. Until just last month it was the entire aviation industry, Van’s included.

Van’s said, trust us laser cut parts won’t crack. Now it’s trust us cracks are ok. I think you may be failing to understand in some circumstances there is a correlation between science and money.

Just by seeing the different types of flaws on the parts I have, there would be nearly an infinite number of variables to test. I know they say they are testing the worse case scenarios, but I think I’m with the others who would like to see photos of what those look like. Then add corrosion.

I think it would take a lot for us to trust this. Something in the order of having an FAA testing firm put their stamp of approval on this. Otherwise I’m really concerned the next time we hear about laser cut parts it may be in the form of an AD.

I think that I understand completely. It is a great goal to not have cracks, as they are rarely helpfull and it is good advice from them for you to take great care during your build to minimize any chance of problems. However, not all cracks carry the same risk. Some folks here can't even see the crack without magnification. I never examined the 10,000 holes in my planes with magnification. For all I know they are full of cracks that are not visible to the naked eye.

I get the apprehension. Lots of folks said hey, what is with the cracking. Vans blew it off and said don't worry about. Clearly they have recognized their error there and not suggesting we let it pass. It was a major problem and points to some leadership or communications issues inside the company. But now that all are in agreement that something is off, we start from a new place. Some intelligent people need to yank and break a lot of parts with expensive instruments to determine if those cracks will result in problems down the road. If they determine it will, then lots of parts to replace and let the complaints rage on. If they determine it is no issue, then it's up to each builder to trust the analysis or not. My only point was that they have made thousands of design engineering decisions for you already, so why are we getting so hung up on this one. If you do not trust their design engineering decisions, why on earth would you consider building an RV? If I thought this issue was reflective of their approach to designing an airplane, I would burn mine to the ground tomorrow. However, I do not. I see this as an error and not a sign of poor design. However, I respect that each of us needs to form their own conclusion.

 

[lr172]

How exactly does a rivet work? How exactly does a dimple work? As the famous philosopher Fred Ward once pondered the question….”How exactly does a posi-trac rear-end in a Plymouth work? Nobody knows, it just does”!!

Like Fred, I don’t know exactly how a posi-trac rear-end works but I do know that airplanes aren’t suppose to have cracks in them. Parts were once produced one way, that technique was changed to making those parts another way for a short period of time, now those parts are back being produced the original way. So the question must be asked, if it worked okay by making those parts the new way, why are they now back making those parts the original way? There’s no “in between” in my book. You can’t have your cake and eat it to.

Clearly the "new way" was flawed and produced sub-standard parts. No one is questioning that. The question is whether or not the sub-standard parts will work just as effectively in the design as the better ones did.

I think there is an in between. Some guys here ream every hole and others drill them. There is no question that a reamer will leave a MUCH cleaner hole edge than a drill bit. Does that mean the plane built with reamed holes is stronger? Maybe, maybe not; Way above my pay grade. I can say that with 1000's of planes built with drilled holes, we have not seen that lack of strength manifest in problems, likely because the design is tolerant of weakness there. You declaring that all cracks lead to failure is kind of like trump saying that global warming is fake news. Without extensive knowledge and training on stress testing, FEM, metallurgy and fastening engineering, you can't really make conclusions on the effect of cracks on numerous different parts of which you have no load data. You CAN generalize that cracks are not good, but CAN'T say that a crack next to the hole inside a dimple on the fuel tank rib will result in fastening failure. If you happen to be an engineer in the business of stress testing with experience in aluminum, then I apologize and ask that you educate us.

 

[Bullpup]

Before getting concerned, you really should do some research on the mechanics of a dimpled fastening arrangement and how they typically fail. If you do that, I think you will see that the loads are not concentrated anywhere near the hole and instead near the bend radius. If that area is not stressed, then cracks in that area do not propogate. I am not for a second saying I understand the science here, just that you cannot take logic that says cracks are a problem for regular holes with fasteners and just apply it to dimpled holes, as the fundamentals are totally different. Think about it: We conuntersink skins almost down to a knife edge and don't think twice about the stress creating a crack. It takes almost no force to start a crack in the knife edge, but that doesn't mean the fastening doesn't work, as that crack won't propogate. This is a pretty broad and involved body of Engineering here that is well beyond what most of us understand, myself included. We need to leave that work to the Engineers and Scientists who specialize in it. IMHO, if the Engineers say the small crack around the hole is fine, the only analysis that we as builders need to do is ask: do we trust Vans to do the complete, in depth research and give us an honest and complete answer. We can all sit here and say cracks must be bad and must be addressed, but what do we really know?

I find it very interesting that all of the arm chair quarterbacks jump in and say it is a crack and a crack is bad, therefore the entire airplane is compromised and will fail. How can you accept a complex airplane design with literally thousands of engineering choice, like rivet spacing, rivet size, skin thickness for a panel, which alloy is used, when is it annealed and re-hardened, etc., etc. and yet question them on this design issue about whether or not a crack is a problem in a dimple? There are thousands of these planes flying with a very limited number of failure areas. Sure, there are a handleful of SBs that show they under designed an area or stresses were greater than the Engineer assumed, but on balance, their design and the thousands of Engineering choices they made are good and have stood the test of time. Folks need to do what is comfortable for them, but I fail to understand the logic that says I trust the thousands of engineering choices they made in the design, but when it comes to a small crack in a dimple, I know more than they do.

For what it is worth, I generally agree with you - I think the aircraft are very well designed, common guidance on edge preparation, etc. is conservative, and that the testing will show this to be true to an even greater degree than previously known.

That said, it doesn't change the common perception on known cracks! If, a year ago, someone had advocated for a time-saving assembly method which countered Section 5 and MIL-STD because "the radius of the dimple is the critical area", and claimed that minor burrs or cracks outside that area don't matter, I'm pretty sure this forum would have ripped them to shreds. Even if I agree with leaving these parts in, it will be a tough sell to potential resale buyers, the broader community, and even potential DARs.

 

[Jack_G_S]

…. Some folks here can't even see the crack without magnification. I never examined the 10,000 holes in my planes with magnification. For all I know they are full of cracks that are not visible to the naked eye…..

…. If you do not trust their design engineering decisions, why on earth would you consider building an RV?

To the first point. If you drill/ream a hole, properly deburr it, and dimple it, you are highly unlikely to see a crack even with modest magnification. If you don’t believe me then try it.

To the second point I was partial done with this project and had all the remaining kits ordered before there was any talk of LCP.

A responsible way to implement a major manufacturing change, that has had scrutiny in the past, would be to make that change only to new designs so that people would know what they are signing up for. Then they could go back and implement it in older designs once it’s a proven method.

 

[Walt]

Even if I agree with leaving these parts in, it will be a tough sell to potential resale buyers, the broader community, and even potential DARs.

I wish folks would stop referring to DAR’s as some kind of experts, they are not responsible for airworthiness and generally are not aeronautical engineers, they are strictly there/responsible for the FAA paperwork when they give you an AW certificate, no more. I’m sure they could care less about this debate.

 

[Mark33]

Clearly the "new way" was flawed and produced sub-standard parts. No one is questioning that. The question is whether or not the sub-standard parts will work just as effectively in the design as the better ones did.

I think there is an in between. Some guys here ream every hole and others drill them. There is no question that a reamer will leave a MUCH cleaner hole edge than a drill bit. Does that mean the plane built with reamed holes is stronger? Maybe, maybe not; Way above my pay grade. I can say that with 1000's of planes built with drilled holes, we have not seen that lack of strength manifest in problems, likely because the design is tolerant of weakness there. You declaring that all cracks lead to failure is kind of like trump saying that global warming is fake news. Without extensive knowledge and training on stress testing, FEM, metallurgy and fastening engineering, you can't really make conclusions on the effect of cracks on numerous different parts of which you have no load data. You CAN generalize that cracks are not good, but CAN'T say that a crack next to the hole inside a dimple on the fuel tank rib will result in fastening failure. If you happen to be an engineer in the business of stress testing with experience in aluminum, then I apologize and ask that you educate us.

I think we can all agree that zero cracks is the goal, but I think we can all also agree that we don’t live in a perfect world and that’s probably not achievable. Even with cracks present, I don’t think any of these airplanes are going to fall out of the sky. However, that still doesn’t diminish the fact that I don’t want to see any cracks in my “very expensive” airplane.

Here are a few questions I ask myself:

1. How bad are the cracks and will they propagate? If they’re microscopic and not propagating, than I’d imagine everything is good to go.

2. Due to the metallurgy dynamics that’s occurring when a hot laser has been used, if a small crack is observed, even if that small crack isn’t currently propagating, will it ever propagate? If there’s a possibility that it will, how long will it take? If its going to take 30k hours, then I’m probably okay with that….but if it’s 300 or 3k hours, then I’m not okay with that.

3. If it’s okay to suddenly accept a certain level of cracking, why has there been a switch back to the original way of producing the parts?

Like Fred, a lot of us don’t know exactly how all this stuff works,….but just know that it does. At the end of the day, I just want the quality product that Vans is known for and a product that’s going to hold its value for years to come. I hope Vans doesn’t try to BS an old BS’er.

 

[bertschb]

...why has there been a switch back to the original way of producing the parts?

Perception

If Vans were to offer builders who are ordering kits the choice of parts with punched holes or parts with laser cut holes, would anybody who is aware of this issue choose laser cut parts?

IMO, the testing results will only matter to builders who have completed or partially completed assemblies. I have 82 laser cut parts in my wing kit that I will be replacing even if Vans says those parts will last 100,000 flight hours. The perception that laser cut parts are inferior is all that matters to me as a new builder.

Now if I had already completed my wings and empennage and was really happy with the build quality....yeah, testing outcomes would matter a LOT.

 

[Mark33]

Perception

If Vans were to offer builders who are ordering kits the choice of parts with punched holes or parts with laser cut holes, would anybody who is aware of this issue choose laser cut parts?

IMO, the testing results will only matter to builders who have completed or partially completed assemblies. I have 82 laser cut parts in my wing kit that I will be replacing even if Vans says those parts will last 100,000 flight hours. The perception that laser cut parts are inferior is all that matters to me as a new builder.

Now if I had already completed my wings and empennage and was really happy with the build quality....yeah, testing outcomes would matter a LOT.

Yep….I totally agree…..and those of us with QB kits are stuck somewhere in between.