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Service Bulletin Fix in the works

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PerfTech

PerfTech

Well Known Member
Service Bulletin Alternative Fix in the works!

... We have created a test product to address this new issue with the H/S spar, and are currently performing a few final tests before posting it to the forums etc. It requires a considerably less involved and far less intrusive installation than the current SB. It should accomplish the same end result as to strength, and prevent the cracking from starting or propagating as well. This may not be the answer for everyone, but may save many a tremendous amount of grief with paint damage etc. We hope to post a drawing and video when we let this out for the scrutiny of the forums in a few days. Thanks, Allan ...:)
 
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PerfTech said:
... We have created a test product to address this new issue with the H/S spar, and are currently performing a few final tests before posting it to the forums etc. It requires a considerably less involved and far less intrusive installation than the current SB. It should accomplish the same end result as to strength, and prevent the cracking from starting or propagating as well. This may not be the answer for everyone, but may save many a tremendous amount of grief with paint damage etc. We hope to post a drawing and video when we let this out for the scrutiny of the forums in a few days. Thanks, Allan ...:)
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I had been wondering for an alternative fix, specially for those that they don?t have the crack and mainly want a ?preventive/proactive? type solution.

I will be looking for your innovation on this area.
 
As I understand from what was posted in the SB threads, Van's did an FEA model to determine how to address the issue. Can I presume that your fix is also based on such an analysis?
 
Allan, with all due respect, please consider re-wording the title of your post. There isn't a "service bulleting fix". You either comply with the SB, or you don't.
I am sure there are alternate ways of reinforcing the structure here, but, the SB is what it is....
Some people may be confused by your wording. Not trying to be nit picky, but there is already a lot of confusion about SB's in experimental aircraft.

There is only one way to comply with the SB issued by Van's; do the SB as it is written, that is if you care to comply with it.
 
ChiefPilot said:
Finite Element Analysis. Computer model of a design to determine stresses etc. of a given design or part. Solidworks can do this, as can other packages.
Click to expand...

Would it be a reasonable conclusion that FEA was not performed when the HS originally designed - or perhaps that FEA was not bullet proof then or now?

I am a sceptic of computer generated solutions to complex problems or a conclusion that the human mind is not caple of solving problems without FEA, whatever it is. Computers are wonderful but they do not have a lick of common sense.
 
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David,

You make a good point .... is the RV tail designed SO complex that you really need a FEA model ?

How many FEA models was around when the Spitfire or the P51 was designed ... ;-) ...
 
...please consider re-wording the title of your post. There isn't a "service bulleting fix"... There is only one way to comply with the SB issued by Van's; do the SB as it is written....
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Well, in the certified world, people come up with AMOCs all the time (alternative method of compliance). Maybe he'll have something that Vans will acknowledge as an alternative.

Even if not, I would be very interested in what Allan comes up with - as one without cracks and very much on the fence as to which evil is worse (doing the SB or just building new HS when the revised plans come out) - I'd certainly welcome options. The only downside I can see is that one might conclude that, even with Allan's proposal installed, it would be nevertheless necessary to look at it once a year to make sure there were still no cracks.

Dan
 
FEA is excellent for identifying area where some result is dependent upon local stiffness, which was described earlier as being an issue here. Classical stress analysis, as was probably used originally, is excellent for determining if the basic strength is adequate. And we can see that both give valid results: the structure has proven its strength, and the change in local stiffness is causing local stress increases which is leading to fatigue damage.

Dave
 
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So True

David-aviator said:
Would it be a reasonable conclusion that FEA was not performed when the HS originally designed - or perhaps that FEA was not bullet proof then or now?

I am a sceptic of computer generated solutions to complex problems or a conclusion that the human mind is not caple of solving problems without FEA, whatever it is. Computers are wonderful but they do not have a lick of common sense.
Click to expand...

Exactly David... Exactly. :)
 
FEA is a tool available to an engineer. The fact is it should be 1 of many tools in his toolbox though. 1 of the key tools is experience and common sense.

Some engineers coming out of school believing everything the computer tells them which is very misleading.

I am one of those engineers, and my biggest pet peeves is engineers with no common sense.
 
DanBaier said:
Well, in the certified world, people come up with AMOCs all the time (alternative method of compliance). Maybe he'll have something that Vans will acknowledge as an alternative.

Even if not, I would be very interested in what Allan comes up with - as one without cracks and very much on the fence as to which evil is worse (doing the SB or just building new HS when the revised plans come out) - I'd certainly welcome options. The only downside I can see is that one might conclude that, even with Allan's proposal installed, it would be nevertheless necessary to look at it once a year to make sure there were still no cracks.

Dan
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.
.... The parts that we are making, after installation will allow full view of the area that is subject to cracking. This provision makes it possible to inspect these areas when desired to verify no cracks or that they are not propagating. As I said in the first post on this thread, "This may not be right for everybody". Thanks, Allan...:)
 
Yes, but even if it is for some, like the others have already said, unless Vans accepts, and adopts it, it is not a "Service bulletin fix".
 
DanBaier said:
Well, in the certified world, people come up with AMOCs all the time (alternative method of compliance). Maybe he'll have something that Vans will acknowledge as an alternative.

Even if not, I would be very interested in what Allan comes up with - as one without cracks and very much on the fence as to which evil is worse (doing the SB or just building new HS when the revised plans come out) - I'd certainly welcome options. The only downside I can see is that one might conclude that, even with Allan's proposal installed, it would be nevertheless necessary to look at it once a year to make sure there were still no cracks.

Dan
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I agree. (Extra letters)
 
JonJay said:
Allan, with all due respect, please consider re-wording the title of your post. There isn't a "service bulleting fix". You either comply with the SB, or you don't.
I am sure there are alternate ways of reinforcing the structure here, but, the SB is what it is....
Some people may be confused by your wording. Not trying to be nit picky, but there is already a lot of confusion about SB's in experimental aircraft.

There is only one way to comply with the SB issued by Van's; do the SB as it is written, that is if you care to comply with it.
Click to expand...

My thinking to Jay
 
I have nowhere near the experience of many of you having only built one plane, an RV12. But I study a lot. One thing is clear is that Vans is a master at engineering a fix involving the lowest possible cost and simplicity of the parts involved. Simplicity is key. These are GOOD things. The labor involved is a consideration, but in my opinion it is way down the list. For some (not all) of us, a different balance would be preferable.

If you look at the recent RV12 fuel tank SBs, its all just little pieces of bent aluminum that takes many hours to messily install. Other methods could have accomplished the same end result, but might have been much more expensive to BUY, but involved far less labor. A bunch of us would be interested in such fixes. This HS SB is, I think, another example of this paradigm.

I, for one, am quite open to other approaches than Vans to fix an identified problem. A solution that is great for "during a build" might be quite suboptimal for post-build.

In comparing an RV to other kitplanes, the engineering quality stands far above! Do NOT get me wrong on this. But they are not the only good engineers.
 
When dealing with problems with a SB for a Horizontal stab/elevator on a plane in which im riding in I will trust the manufacturer. but thats just me.
 
You are the manufacturer... I think we should give Allan a chance and see what he comes up with. For me I see the SB as a fix for a spar crack . If someone comes up with a mod to improve the strength of the front spar to prevent a crack from forming in the first place ,I will say fantastic. I know Vans engineers are very good, but out of the thousands of builders out there someone will come up with a stroke of genius. Lets wait and see...
 
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This is well said. As an engineer who designs a fair number of mods and repairs to address fatigue issues, hand calculations can never tell the whole story, and fea can definitely tell you lies (fortunately for the green guys who haven't figured that out yet, fea usually over estimates stresses around fasteners).

P51 designers didn't have a lot of tools we have now, and I'm always hugely impressed with those guys, but if w designed it now it'd be a much better airplane. it'd cost 50 million a copy, but it'd be better :)


David Paule said:
BillL has it exactly right.

FEA is excellent for identifying area where some result is dependent upon local stiffness, which was described earlier as being an issue here. Classical stress analysis, as was probably used originally, is excellent for determining if the basic strength is adequate. And we can see that both give valid results: the structure has proven its strength, and the change in local stiffness is causing local stress increases which is leading to fatigue damage.

Dave
Click to expand...
 
Arie said:
If someone comes up with a mod to improve the strength of the front spar to prevent a crack from forming in the first place ,I will say fantastic.
Click to expand...

The mod. that gets installed for complying with the SB to repair cracks is designed to do just that. It is being incorporated into the emp. kits for installation during a new build.
 
JonJay said:
Allan, with all due respect, please consider re-wording the title of your post. There isn't a "service bulleting fix". You either comply with the SB, or you don't.
I am sure there are alternate ways of reinforcing the structure here, but, the SB is what it is....
Some people may be confused by your wording. Not trying to be nit picky, but there is already a lot of confusion about SB's in experimental aircraft.

There is only one way to comply with the SB issued by Van's; do the SB as it is written, that is if you care to comply with it.
Click to expand...

If you modify the HS structure as a builder, maybe the SB does not apply to you;)

Just my 2 cents
 
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rvbuilder2002 said:
The mod. that gets installed for complying with the SB to repair cracks is designed to do just that.
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Scott,

Maybe I'm not getting this?? How is the SB mod going to "repair cracks"? I think the cracks will still be there, just patched over/around. What in the SB mod design would "repair cracks"?
 
LifeofReiley said:
Scott,

Maybe I'm not getting this?? How is the SB mod going to "repair cracks"? I think the cracks will still be there, just patched over/around. What in the SB mod design would "repair cracks"?
Click to expand...

Sorry, Scott's ability to answer sarcastic questions based on semantics is currently out of service for the above VAF forum member.
Please (don't) try again later.

;)
 
Steps 8 and 9 of the SB address how to "repair" the cracks in a few different ways.
 
I think announcing that "hey, another option is coming, don't do the Van's SB yet" is rather crass. To do so casts doubt that the factory-offered solution is valid.

This isn't the same situation as the nosewheel on the -A models, where no problem or fix has been acknowledged or offered by the factory. There's enough people with -A model aircraft who aren't really happy with their nose-gear-leg, and Alan has come up with a product that alleviates those concerns. Fair enough.

But for the Horizontal Stab, the factory has identified the issue, designed a solution that looks reasonable to implement, and offered it to the market. I would be surprised if an "alternate" solution is any easier to install, and if so, if it's any "better" structurally.
 
It will be interesting to see how Vans addresses any "fix" other than the ones in the SB. Perhaps here are some possibilities:

1) Endorse it. Seems very unlikely for legal and ethical reasons unless they run complete engineering studies similar to those conducted on their repair procedures.

2) Publicly denounce it. Also unlikely because Vans is based on a premise of conducting business in a civil, non-confrontational manner.

3) Officially ignore it while privately gritting their teeth. Seems likely for the above reasons.

However, if a non-Vans endorsed/tested procedure picks up momentum they may be forced to publicly question it if they are convinced the root reasons for the SB are not being addressed. There is also the thorny issue of the SB not being complied with if a procedure other than the one stated in the SB is used.

We are in an intriguing place with this situation. Will be interesting to see how it plays out. It also puts us RVers in a position that we have not previously experienced when making decisions about how to maintain our planes.
 
What about the no crackers ....

So what if you have no cracks :) but now just want a little feel good additional strength without doing the Vans mod. I for one, would like to see a reasonable mod for the no crackers.

Having said that, I'm not sure what it would mean if it obscured your ability to continually check for cracks since it technically would not terminate Vans SB.... but then I remember someone saying that SBs aren't mandatory for experimentals.... it's an odd position and interesting discussion.
 
rvbuilder2002 said:
The mod. that gets installed for complying with the SB to repair cracks is designed to do just that. It is being incorporated into the emp. kits for installation during a new build.
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Scott, you caught me out. Sorry ,what I should have said is that maybe someone comes up with another way to improve the strength of the front spar. Let me add that I have the greatest of respect for you ,and your engineering ability and I would also assume that you are an very open minded person willing to look at someone else's suggestions. The fact that you posted here proves that point and I THANK YOU for doing so.
Regards
Arie
 
BillSchlatterer said:
.... but then I remember someone saying that SBs aren't mandatory for experimentals.... it's an odd position and interesting discussion.
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It's not odd if you think straight and technical about this technical issue. The factory of a kit has found a technical issue that is potentially very dangerous; cracks in the HS main spar. The factory has issued a way to fix it that is both preventive and fixes those that has developed cracks. It's a no brainer if you ask me.

But, this doesn't mean that this "SB fix" necessarily is a poor fix. We don't know what it is yet, but technically, if it only prevents cracks from happening, this is often a much easier thing to do than to fix it once the crack is there. We just have to wait and see.
 
After all the speculation, assumptions, and pure emotional reaction that I have seen on this forum, I will be surprised if anyone from Vans Inc. will ever post here again.

That will be our loss. :(

Can anyone please tell me how Vans could have possibly handled this situation any better??

A couple of problems have been discovered, and a couple of well-thought-out solutions have been announced.

What more would you expect? I SAY AGAIN: For those of you complaining and demeaning: What more would you expect?

Speaking only for myself, I think that Vans Aircraft Inc has done exactly the right thing.

EDIT: After I posted this, I saw the following post, which says it far better than I did:

http://www.vansairforce.com/community/showthread.php?t=109601
 
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Have revised parts made!!!!

... We went back to the drawing board and revised our first parts some to make them even more user friendly and less intrusive as well. This is a very simple fix with our little kit and we feel it will fix the cracking issue. I will attempt to make a small video and get it up for review in a couple of days. I think you guys will like this alternative method. Thanks, Allan....:D
 
The primer wars have evolved into the "Van's doesn't know what they're talking about vs. the "Van's knows what they're doing" crowd.

But they're pretty much just as boorish.
 
LettersFromFlyoverCountry said:
The primer wars have evolved into the "Van's doesn't know what they're talking about vs. the "Van's knows what they're doing" crowd.

But they're pretty much just as boorish.
Click to expand...

I think it is more "Vans is the only one that can issue a SB on their own product" vs "there are other ways to "fix" the "problem"".

There is no argument; the only way to comply with the SB is by doing what Van's laid out to do. However, nobody says anybody has to comply with it.

Pretty simple....
 
PerfTech said:
... We went back to the drawing board and revised our first parts some to make them even more user friendly and less intrusive as well. This is a very simple fix with our little kit and we feel it will fix the cracking issue. I will attempt to make a small video and get it up for review in a couple of days. I think you guys will like this alternative method. Thanks, Allan....:D
Click to expand...

Look forward to the video or even some info on the part. Nothing is showing so far on your web page for this.
 
Allen, inasmuch as Van's put some serious engineering into their SB, it would be interesting to see the engineering behind your new product.

Thanks,
Dave
 
For what it is worth, I see the alternative (Allan's) fix route going like this -

If you install the alternative fix, and no cracks ever develop, then you continue to inspect and can never sign off compliance to Van's SB. - Not a bad option if it is easier to install AND it prevents cracks - forever.

If it does not work, and cracks develop, then the only fix is complying with the Van's SB. (or a new HS). But if cracks happen, I presume that you will now have a HS spar with new holes in it (needed to install Allan's fix) that would be a very compromised (and totally Van "un-approved") structure.

I guess if you go Allan's route you really better hope you never see cracks!!

Is that about it??
 
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Maybe this should not bother me as much as it does, and maybe it is just semantics, but I don't understand why anyone other than Vans could in good conscience advertise a "Service bulletin fix". I shake my head in amazement when I read this. At the very least change the name to "alternative to the service bulletin".

As an aside I would never even consider buying a flying aircraft with something other than the factory fix for something as important as this. I wonder how many others feel the same way. I know most builders don't build to sell, but there are a lot of bought planes out there.

Just some thoughts.
Mark
 
First take on the fix for the fix

My first impression when I read this was the poster was sharing that Van's SB needed fixing based on their observation of the fix which at the time hadn't been fixed yet.

If we were talking about a sub-structure fix I guess it wouldn't have caught my attention but this is a spar area and most folks stay away from those areas except the designer. Who wants the liability?

If Van's gives the fix to the fix their seal of approval, then all is well. If not, then its going to be somebody else's problem down the road. Our planes tend to hang around for several generations and who wants to look at a logbook entry years from now and see an unauthorized (not from designer) fix to a spar?

On the other hand, our planes are experimental and we can do anything we want to. Right? :eek:
 
I am having a little trouble in my mind on this subject. It's about liability and old age. If the lawyers get involved in an interrogation and find that the repair wasn't done according to the manufactures instructions is there a penalty to pay besides the mental anguish you have to live through the rest of your life? If the airplane wasn't built to be sold is it going to be scrapped when you no longer are able to fly?
 
RV Wannabe said:
Maybe this should not bother me as much as it does, and maybe it is just semantics, but I don't understand why anyone other than Vans could in good conscience advertise a "Service bulletin fix". I shake my head in amazement when I read this. At the very least change the name to "alternative to the service bulletin".

As an aside I would never even consider buying a flying aircraft with something other than the factory fix for something as important as this. I wonder how many others feel the same way. I know most builders don't build to sell, but there are a lot of bought planes out there.

Just some thoughts.
Mark
Click to expand...


You are not alone. I've purchased a few things from Alan now and have grown to like him....but I really hope he has a HUGE liability policy. An alternative to a service bulletin on spar cracks? One guy blowing through VNE on the backside of a botched loop and his empennage comes apart with Alan's mod in it....even a bad lawyer would clean him out.
 
SB

Remember guys the SB says to inspect for cracks. If no cracks you have complied with the SB. If you have cracks you NEED to install the Vans fix.

Allan's fix should only work if you have no cracks. It is more of a preventive measure. The way I understand it is it will allow you to still inspect for cracks in the future, again allowing you to comply with the SB.

I do not think his intent is for his fix to replace the Vans SB.

IF I have this wrong by all means flame suit is on.
 
Van's New Tail

My guess is that Van's knows they have a weak spot they will come out with a new spar design. May be thicker stronger. I have no cracks yet but I hope if one ever develops by then Van's will have the new stronger tail to build.
 
DarylT said:
If you have cracks you NEED to install the Vans fix.
IF I have this wrong by all means flame suit is on.
Click to expand...

You don't have to do anything. SB's are not mandatory, cracks or not. Now, what is prudent and responsible might be something different.
 
Considering we don't know yet what Allen's product is, many are jumping to conclusion. Why not wait a bit longer to see it and then offer your criticism or praise. Unless of course you have had a special preview ahead of many of us.
 
This SB is particularly frustrating to me

I was one who found a very small crack in my right elevator spar. We called Van's 3 times to get their advice. We were told to just replace the spar and put it back together the way it was originally designed. We asked about ideas about how to strengthen and they did not think it was necessary.

So we rebuilt and repainted the elevator at a cost of well over $1000 and the plane was down for a month.

Now they come out with an SB for a patch that does not require disassembly that would have been a simple and fast fix for us. Plus it strengthens the attach points in the process.

Don't get me wrong, thrilled that they got around to this. Just wish they would have given us this option when we originally asked.

Done venting, I still love my RV7a and Vans!
 
Bavafa said:
Considering we don't know yet what Allen's product is, many are jumping to conclusion. Why not wait a bit longer to see it and then offer your criticism or praise. Unless of course you have had a special preview ahead of many of us.
Click to expand...

To me just the fact that he is advertising it as a "Service Bulletin Fix" it doesn't matter what it is. The Factory is the only one that can do that. He is just being rude to an organization that is doing the right thing by its customers. And insulting the intelligence of the customers in the process. Hopefully he does not catch someone unaware of his deceiving choice of words. I can just see some poor guy saying "but I bought and installed "the fix", what do you mean it is not the right one?!?" "Potential buyers are walking away from my plane because of it!"

Maybe he does not mean it that way. And maybe I am being too sensitive, but his choice of words really offends my sensibilities. I do notice it has been brought up quite a while ago in this thread (multiple times, by multiple people) and he has not changed it yet. Makes me seriously question the ethics involved.

Mark
 
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