Grinded spar input please

http://i1101.photobucket.com/albums/g427/epsound/Spar.jpg

Hello engineers,

I am a new builder. I do however have what I consider good 'gut' instincts. My gut however still doesn't make me an engineer/builder with appropriate experience and knowledge. So I place this dilemma upon the great VansAirForce alter for comments and input.

Situation---This section of my 9A spar was grinded down prior to my purchase (preowned kit). I am half way towards removing this for total replacement. The picture shows the grinded area. This is the upper section of the left wing spar. This is the only part that has be grinded to fit into the fuse [which was 1:50,000 of an inch too narrow at the top. Subsequently the depth of the grinding measures 1:50,000 of an inch.

Reason for question/dilemma---during the time I have been methodically removing it, I have had three sets of eyes-on from an engineer, and amateur builder, and one professional RV builder. Below are their comments.

1. Engineer--this is minimal and doesn't affect its integrity

2. Pro builder--this doesn't give me 'heartburn.' The amount of area grinded is insignificant and I would fly it with this spar. It's not an aerobatic.

3. Amateur builder---This should be replaced because is might be open to hairline fractures from hormonic frequencies and/or operating vibrations.


I have no issues with just replacing the spar. However I must consider the cost ($2000). In other words, if this really isn't necessary then the time and money could be exhausted in other aspects of this build.

I don't want to appear haphazardly or like I'm trying to cut corners. But then, who am I to argue with serious experience and knowledge. So far, the 'Leave it alone' are winning 2 to 1.

Question---if you have specific expertise that speaks to this, I humbly ask for your input and thoughts.


Respectfully,


E.

Spar Grinding

I'm no expert on spars, but I do have specific expertise on ugly. Thats pretty ugly

At a minimum I would think those grinding marks are unacceptable.

My thoughts are:

Who in their right mind would do that to a spar?

What went wrong in the build of a pre-punched fuse that would have required such a thing to be done to a spar?

Call Vans for an official opinion but I would replace the ground down section! It can be removed from the rest of the spar. I am sure Van's can put you in touch with the people that build the spars and get you some new bars.

Isn't this the same RV-9A spar that appeared in the fifth issue of the 2010 RVator? I seem to recall that Van's advised that the spar was a total loss?

EdH said:

Isn't this the same RV-9A spar that appeared in the fifth issue of the 2010 RVator? I seem to recall that Van's advised that the spar was a total loss?

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Nice catch Ed. Page 13. "The spar was ruined"

http://www.vansaircraft.com/RVator/2010/5-2010-RVator.pdf

Phil

I'll second the ugly comment and note that ugly doesn't mean unsafe. There's more to safety here than a 1/20" (looks like more) of spar thickness.

Van's can give you the best answer but I know that I could not fly knowing this butchered spar was supporting my butt. I doubt that it would fail immediately - or perhaps not even in a few years, but they don't anodize this part just for looks, nor do they make it with such precision, just for looks. The anodizing provides corrosion resistance and that's seriously compromised now. The second thing is the spar transfers loads and I think to do this well there needs to be a close fit between the spar and the center section. I have not seen the part inserted but ugly factor suggests to me the fit is going to be loose and spotty. I don't think that's what Van had in mind for this part. The spar may have 99% of it's strength but if it can't transfer loads efficiently, it isn't doing all of it's job. Think about why we're using close tolerance bolts here. Read the section in the plans on building this part. I'm wondering if those bolts are going to fit after the spar mods. In my experience things need to line up precisely to get those bolts in.

Personally, I wouldn't have any peace of mind flying with that under my behind. Would you? The fact that you posted the question and photo makes me doubt it.

But like a previous commenter said, what could go this wrong in a prepunched kit that would necessitate this kind of a fix? I remember sweating the part of the build where you riveted the fore and aft center sections to the bottom skin. The directions had you bolting the sections together with a wooden or metal spacer that you made, as I recall (at work now). The plans spec'd that spacer to the thousandth of an inch and it took me over a week to make two spacers I was happy with. I remember it well because I missed going to Airventure to complete this task. I fretted another year over whether the wings would fit when it came time to insert them. They fit perfectly. It took 55 minutes to get both wings on and the temporary bolts in. It was a non-event.

My educated guess is the builder skipped the step where you make the spacer blocks and that bit him (or you, now). I'd further opine that if you simply replace the spars (or just the bars, if that's possible), you're not going to be out of the woods. If the old wing spar didn't fit, the new one almost certainly won't either. I'd be wondering exactly what the previous builder did wrong that prevented the wing from fitting as designed. As I recall there are spacers that we make for the bolts that tie the gear supports to the spar. Those spacers keep the space between the fore and aft sections of the spars. If that's the only problem, it should be a easy fix. If he somehow riveted the sections to the skin so they're too close together, that seems like a major problem.

Have you measured (with calipers or a micrometer, using an inside gauge) to see how far off your gap is? I see where the spar section is marked in 32's of an inch. That is seriously disconcerting. It suggests the previous builder didn't even own a caliper that could measure to a thousandth. If he didn't, he couldn't build spacers called for in the plans.

Take lots of photos, call Van's and expect it is going to be a lengthy call...or a short and expensive call.

Having said all of this, part of my building a plane is for my education and I've learned a lot about the structure of a plane. There are two parts I would never monkey with - the main spar is one and the longeron is the other. These two parts seem to carry and distribute all of the loads in one way or another. You're building for your education, too. I suggest you take your time, use think about it carefully and after collecting all the information you can, including from Van's, follow your gut instinct.

By Gollie... Get a Rope! Someone actually sold you that Spar?

Brantel said:

...What went wrong in the build of a pre-punched fuse that would have required such a thing to be done to a spar?...

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I am not an engineer, but that's where I'd start approaching this from. If the former builder encountered interference and responded with this kind of atrocity, what other surprises might be lurking in hidden corners? If this was my airplane, this bit would be something that would always haunt me. I'd always know it was there, and I'd always be a bit worried about it. I'd hesitate to sell it to someone else without telling them, and I were in the market and I was told about it, I'd no way buy it as anything more than parts.

My advice is to stop where you are and go over the rest of the airplane with a fine tooth comb. If there are any more surprises to this airplane, you might as well learn about them all right now. To have them slowly come to light as you proceed would be a death of a thousand cuts. Use mirrors and maybe cameras to get into what nooks and crannies you can. Look for anything that is less than workmanlike, and make a list of anything out of the ordinary. Things like gaps or interferences, rivets where there shouldn't be, bolts or screws where there should be rivets.

As for replacing just the ground-down spar cap, it is certainly possible, but it is not for the faint of heart. The effort required to remove a rivet seems to scale with the volume (area times length) of its hole, so taking out a long line of the 3/16" MS20470AD6 rivets that the spar is assembled with is a real job of work, as is putting it all back together again. If you go that way, look into how the RV-4 guys used to drive their spar rivets using cheap 10-ton presses back in the bad old days.

Edited to add: Just read the RVator article, and I can't have much to add to that, except:

Epsound said:

...So far, the 'Leave it alone' are winning 2 to 1. ...

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Well, it looks like Van's crew has already weighed in, and I'd go with them on it. Design and engineering have not shown themselves to be very conducive to the application of democratic principles.

Thanks, Bob K.

which was 1:50,000 of an inch too narrow at the top. Subsequently the depth of the grinding measures 1:50,000 of an inch.

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Just the scratches alone are way more than 1/50000 of an inch! Note that 1/50000 of an inch is .00002 inches. Are you sure you don't mean 50/1000 or .050 ?

That thing says a lot about the guy who did it. Number one I would get Van's opinion. Number 2 I would look SUPER close at everything else.

Edit: I just saw that it had already been covered in the RV-ator. Also, it says there that it's a full .125 inches taken off. I'd say the engineer you talked to was the wrong kind. Also, the opinion that it's ok since it's a non-acro bird is bass-ackwards. The 9 is stressed to less G, meaning your margin of strength is less than the other models. Weakening it even further with a grinder is a huge mistake. Finally, if you ever want to sell the finished plane you'd have to reveal all this to the prospective buyer. REPLACE IT.

Something else to consider too, if you do indeed decide to install it "as is", is how is the grinding down of the spar going to affect the rigging of the wing, in relation to things like angle of incidence, and possibly the diehedrel.

If you remove material from the forward face of the spar cap, its' likely to pull the top forward, depending of couse, on how the fuselage carry-through structure is built. This in turn may cause the rear attach fittings to be mis-aligned and if you try to force them into position and bolt them together, there's likely to be a significant pre-load on those fittings.

I certainly fall into the "amateur builder" category above, but I couldn't see that making it into my aircraft.

Phil said:

Nice catch Ed. Page 13. "The spar was ruined"

http://www.vansaircraft.com/RVator/2010/5-2010-RVator.pdf

Phil

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I'll be dammed. That's it! That's my kit. Is there on my face?

I hadn't realized this thing was so famous, rather 'INfamous.' Funny thing, I still don't have buyer's remorse. To his credit, the previous owner did make me aware of the spar and the tanks. I was not blind to this.

I am going with the good ole guts on this (with the assistance and guidance of experience here and at VansAirforce). I have spoken to Gus at Vans as well. Their opinion remains the same as in the aforementioned RVator publication.

Thank you all.

That said, I am happy to say that I will replace this spar with a complete new one and also new tanks (which I had already planned on doing). Call me a gluten but, I just don't think this kit is a total loss as of yet. I am excited exited about this potential learning situation to say the least. I know this will take 'lots' of time (time, I have plenty of...knock on wood). For starters, I am going to look especially hard at the bulkhead area where the gap is narrowed. I will get back to you about what I find.

I wonder if it would be noteworthy to publish a followup story about this kit after it has finally been brought back to life and completed....properly.

If any of you are interested I'll keep you posted and, I'm forever open, grateful, and humbled for feedback and suggestions.


Best,


E.

Epsound, I just went back through your posting history, and I have an idea you might look into:

Consider buying a salvage RV-9, and then combining parts from your kit with the broken airplane to come up with something whole.

Something like this might be a good place to start:

http://www.aigaviation.com/aviationsalvage/salvagedetail.aspx?SalvageId=1126

(no comment on the engine)

Think it through beforehand, though. Fixing something that is broken is a very different experience than building something new from a kit. However, you might find that repairing damage is more motivating than repairing mistakes.

If you do decide to go that way, seek expert advice on how much to bid. There's an art and a science to it, and for some airplane types the competition is pretty stiff.

Thanks, Bob K.

Reality check

Epsound,

Your optimism is compelling, but consider a reality check.

Replacing the spars means pretty much a complete disassembly and reconstruction of the wings. Trying to salvage the ribs and skins is a false economy. Doing so will involve far more time and effort than just building new wings, it wouldn't cost much less, and the results will still be of lesser quality and questionable structural integrity.

Replacing the spars, or even the wings entirely, will still leave you with the malformed fuselage center section as described in the article. You'd have to correct that as well, and that's also no small feat.

In general, seeing the incredibly poor judgement exercised by the original builder of that kit, anything and everything else on it is also suspect. It is very unlikely that the spars and tanks are the only major problems on it (although I agree with Van's assessment that even the spars alone are enough to call it a write off).

My advice, as an RV builder and an engineer: scrap it. If you never intend to fly it, then sure, working with it could be a great educational experience. But if you do want an airworthy airframe, then start with a new kit or at least a well-constructed partially built kit. Sorry for your financial loss, but you really should take this kit to the nearest recycling center where it can be shredded and melted down to be safely made into beer cans.

And again sorry for your financial loss, but please also don't pass this kit on to yet another unsuspecting builder. This kit should be destroyed and removed from circulation.

Sorry if that sounds harsh, but this is serious stuff. Yikes!

-Roee

When I was building my -7, a wing kit came up on barnstormers for about 1/2 price. I got my trailer and a buddy and off we went. Long story short- the builder had only just begun one panel, I mean barely started. I bought it. I ended up disassembling what he had done ( a few ribs to one spar). All the parts were there, but the plans were old and missing a rev which cost me a couple bucks for new aileron pushrods. Also becuase the skins had been sitting for a few years, the plastic was heck to remove If I had it to do over I would buy new all the way. For the few thou I saved it was NOT worth it.

That is nothing

compared to injury or death. Sorry for your loss, but rejoice that you took the big leap to verify your plan before going further. You and this forum have made big steps to save lives. Heavy, but true.
Dale

I'm going to second and expand on roee's advice. I still have not heard why the original builder butchered a spar this way. If there's a problem with the fit to the fuselage, you have the potential of redoing a major and critical portion of the fuselage, too. I can't speak directly to the RV-9/9A, but the spars I received with my -6A were very precise and the ones I got for my -10 mic'ed just a couple thou under the gap between the carry-through sections. I can think of no reason why 1/8" would need to be removed unless there was a serious mis-match somewhere.

Also, you would be doing the two people you consulted who said they would pass this spar a favor by bringing this thread to their attention. If they are building or maintaining, their judgment is seriously in question.

Lets suppose...

....I did scrap this kit for the sake of getting it out of circulation. Isn't there a way of recouping some of the cost? For example, aren't any of the parts usable for other kits, etc.? At least then, what is usable wouldn't go to waste.

Just wondering and trying to make this pill a little smaller before swallowing.


E.

Spar caps destroyed

Looks to me that the spar caps had their attach section thickness reduced by about 1/8", as reported in the RVator article:

Somebody had obviously tried to fit the wings before, and when the spar wouldn?t fit between the mis-aligned fuselage bulkheads, they grabbed a belt sander and sanded away 1/8? of the main spar bars!

Click to expand...

That's a gross amount of material to remove in a highly stress critical area. The attach section of the spar cannot be compromised at all and considered safe, IMHO.

I question the validity of an engineer's qualifications who looked at that and said to build on. And after reading the RV-Ator article, I agree with the others who say that you'd spend more time checking out the rest of the kit very carefully than you would just by starting over.

There are probably a lot of untouched parts that could be re-sold though... Wingtips, for example? Things that can be fully inspected, basically. Unfortunately that is probably a small percentage of the money you've got invested in it.

My suggestion

I understand a decision has been made so this is a little late for this situation, but the advise holds for any damage that I can't either justify out of the manual or just don't like.
As an A&P, I would not consider the manufacture as the only source for determining serviceability. As someone who does just this kind of work (repairing wrecks) I how found the only way to proceed is to first remove the damaged section, then draw it up and send it to an engineer for analyses.The manufacture has interests that go beyond what may actually be acceptable that can drive a decision to be more restrictive. Listen to them, but get a qualified and quantified second opinion.

In my experience, every aerospace company gives reliable advice when they say to scrap a part. Don't worry about them having a conflict of interest. Their interest is the same as yours: keeping you alive. They know that they might lose a possible long-term customer if they say to scrap a part. It's not something they do on a whim.

In this particularly egregious case, it's not worth paying someone to do some analysis and give an engineering opinion.

Dave

David Paule said:

In this particularly egregious case, it's not worth paying someone to do some analysis and give an engineering opinion.
Dave

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No kidding... Just have to look at the photo.

What I see in the photo

The material remaining is still more than the first step down in spar cap thickness. Remove the first two rivets, machine the inboard section flat and smooth, install the rivets removed. This appears to be the top cap. Compression loads make the material amount that the attach holes go through less critical than the lowers because the bolts help transmit those loads across those holes. As a mechanic it's a toss up of whether it will fail at the bolt holes or the first step down. Measure and draw it up. Have it evaluated by someone who can't be held liable for the entire aircraft. I believe the manufacturer will avoid setting a precedent on this critical of a component that will increase their liability for the fleet, regardless of how sound the blend repair may be.
The advice extends only to the question asked, and is based on an engineer already looking at it. It does not extend to fit, or of workmanship elsewhere.
But once again, a decision has already been made. This is an example of how to proceed if he wants to exhaust all hope of putting that part into service.

Andrew M said:

The material remaining is still more than the first step down in spar cap thickness. Remove the first two rivets, machine the inboard section flat and smooth, install the rivets removed. This appears to be the top cap. Compression loads make the material amount that the attach holes go through less critical than the lowers because the bolts help transmit those loads across those holes. As a mechanic it's a toss up of whether it will fail at the bolt holes or the first step down. Measure and draw it up. Have it evaluated by someone who can't be held liable for the entire aircraft. I believe the manufacturer will avoid setting a precedent on this critical of a component that will increase their liability for the fleet, regardless of how sound the blend repair may be.
The advice extends only to the question asked, and is based on an engineer already looking at it. It does not extend to fit, or of workmanship elsewhere.
But once again, a decision has already been made. This is an example of how to proceed if he wants to exhaust all hope of putting that part into service.

Click to expand...

It was probable that a machining defect caused the prototype RV-8 to crash using the first example of this spar construction.

Do you really want to experiment with surface finishes and changing stress concentrations in the most highly loaded end of this spar?

Hi Gil

Your experience as an engineer trumps my experience as a mechanic. I'm not seeing where I am experimenting. Preparing a part for proper evaluation is sound advice and I stand by it based on his original engineers statement. The -8 spar failure would be something a manufacture would likely provide, nor did I advocate not listening to the manufacture. Parts, and labor are expensive. My job is to save lives AND save money. Sometime the time and money has to be spent. Sometimes it doesn't. My experience doing just that is what I hope to bring to these forums. My comments are in the spirit of being helpful as I am sure yours are as well.

az_gila said:

It was probable that a machining defect caused the prototype RV-8 to crash using the first example of this spar construction.

Click to expand...

Gil

Where did you learn that from, I would like to read it? The only report I have seen is Van's report that the spar failure was due to excessive G-load from both rolling and pulling out of a loop.

RV8RIVETER said:

Gil

Where did you learn that from, I would like to read it? The only report I have seen is Van's report that the spar failure was due to excessive G-load from both rolling and pulling out of a loop.

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And as I remember, it was from an excessive pull up........from straight and level flight.

L.Adamson

I'm always amazed at some of the feedback you get in the court of public opinion. I'm even more amazed at those who offer opinions to ignore Vans on something that's life critical.

There have been a number of threads where a builder has asked a question on a gray area, and everyone says "call Vans and see what they suggest." And those are for areas of the airplane that are more benign than a wing spar.

There is no way I'd trust my life or my family to someone's opinion on the internet. Especially someone that I have no idea about regardless of what A&P or IA titles they might have. As an opinion giver, I'd be cautious about the liability of sharing a publicly documented opinion of "clean it up and go fly."

This is a clear case where Vans has already offered their ruling and they thought it was serious enough to say "the spar was ruined", and they even thought it was bad enough to point it out publicly. That should be the end of the conversation. The last thing I'd want is to see is this airplane balled up in a field with my documented recommendation to ignore Vans.

Equally worse is the behavior of new builders that are being shaped by members on the message board. Ignoring Vans is not a habit we want to start as an RV community who is already under a safety microscope. Teaching new builders that sloppy is acceptable isn't something we want to foster either.

The behavioral impact of what we do and say goes far beyond the two occupants riding on top of this wing spar.

Phil

az_gila said:

It was probable that a machining defect caused the prototype RV-8 to crash using the first example of this spar construction.

Click to expand...

Tangent alert!

I am with these guys, never heard anything about it being nothing more than excessive G load that caused this wing to fail. There was much testing and evaluation data published on this accident and it all pointed to overstressing the wing.

RV8RIVETER said:

Gil

Where did you learn that from, I would like to read it? The only report I have seen is Van's report that the spar failure was due to excessive G-load from both rolling and pulling out of a loop.

Click to expand...

L.Adamson said:

And as I remember, it was from an excessive pull up........from straight and level flight.

L.Adamson

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Ditto

Phil,

Very well put.

+1 Phil.

And the manufacturer's advice starts with the plans. Plus, you have to look at this assembly as part of the whole. This is more than taking it down a bit to remove scratches so, as a mechanic (I'm only an engineer where computers are concerned), I begin to wonder why. Aside from the strength lost, which is the issue Andrew seems to be focusing on, there is also the issue of fit where the spar joins the fuselage. Either this was done to serve a misfit at the fuselage or there will be a 1/8" gap at the joint. If there's such a large discrepancy at the fuselage, what caused it and what affect will it have on the rig of the aircraft? If there's a gap, it will have to be shimmed or there will be excessive load in compression as the bolts are tightened (assuming you could tighten them enough to close such a large gap). And what will that do with the rig of the aircraft? This alteration to the spar has 'can of worms' written all over it at the best.

I'm not sure I like the sense of complacency and 'salvage the part at all costs' attitude the OP has been exposed to. I feel they have no place in aviation, let alone home-built aviation. Major structural discrepancies should be approached with extreme caution and conservatism.

If you build that spar into an aircraft, do you think it will be worth anything? A spar that has been condemned both in a magazine, and here?

Yes - an engineer might give a report with new structural calculations that says it is "safe", and I am sure it would be. But I would never buy it

Andy

Gil Alexander wrote:

It was probable that a machining defect caused the prototype RV-8 to crash using the first example of this spar construction.

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NTSB Report

The main spar of the left wing was fractured at a point inboard of the aileron and outboard of the flap. The main spar of the right wing was also fractured about the same location,...

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TESTS AND RESEARCH

The fractured wing spars from both wings were submitted to Seal Laboratories in El Segundo, California, for examination. The fracture surfaces were inspected visually and with an optical stereomicroscope. Some fracture surfaces were examined with a scanning electron microscope (SEM). Rockwell hardness was measured on the flat side of spar. Electrical conductivity was measured using an eddy current. A cross section of the spar was mounted in epoxy, mechanically polished, and etched to reveal cladding. A sample from the spar was analyzed for elemental chemical composition by emission spectroscopy. The spar surfaces were analyzed for elemental chemical composition in a scanning electron microscope with an energy dispersive X-ray microprobe attachment containing a "thin window" detector. The EDX microprobe spectra were obtained at 20 kV and 5 kV electron beam voltages, for detection of all elements above the atomic number 5 (boron).

The metallurgist reported that the left wing spar had evidence of a ductile fracture due to a positive overload. The right wing spar had evidence of a ductile fracture due to a transverse (fore to aft) overload. The spar material met design specifications for metal composition and hardness. There was no evidence of fatigue or corrosion found in either spar fracture. The outboard section of the left wing did not exhibit any lateral rippling that could be associated with pre-failure aeroelastic divergence.

.....

Aeroelastic divergence (flutter) analysis for the main wings was performed by Latoni, Inc., in Vero Beach, Florida. In preparation for the analysis, ground vibration test (GVT) was conducted in North Plains, Oregon. The test subjects included a wing with an empty fuel cell and repeated data collection with a full fuel cell. The data obtained from the GVT formed the basis of the flutter analysis.

Wing flutter analysis found no flutter within the aircraft's flight envelope. The analysis included a simulated failure of the aileron control rod.

.....

The report concluded that: "The RV-8 aircraft was shown to be free from flutter to speeds above its design envelope with the amount of balance weights provided by the manufacturer on all control surfaces."

Wing load testing was conducted by an FAA designated engineering representative (DER) at North Plains. The limit load conditions were based on maneuvers and dives in which test the wing is near the maximum or minimum angle of attack at +6 g's. The wing supported limit load conditions up to +6 g's under both symmetrical and unsymmetrical loads. After completion of the limit load testing, the wing was inspected. There was no structural degradation found at loads up to +6 g's. The wing was then tested up to 150 percent of its design limit, +9 g's, ultimate load. The wing supported the application for 3 seconds without failure. At the conclusion of the ultimate load test, the wing exhibited minimal evidence of plastic deformation.

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The National Transportation Safety Board determines the probable cause(s) of this accident as follows. the intentional or unintentional sudden application of aft elevator control by an undetermined aircraft occupant that exceeded the design stress limits of the aircraft. The aircraft gross weight, which exceeded the maximum allowable for aerobatics, and airspeed, which exceeded the maximum maneuvering speed for the weight, were factors in this accident

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I'm having trouble finding any reference to this "probable cause... machining defect" Or you suggesting that there was, and it was somehow covered up? Quite an allegation to make here against Vans

Andy
RV-8 G-HILZ
RV8tors

Update.....

This discussion has branched out somewhat. This is all good information. And I want to sincerely thank all of you for your input. I have learned a great deal.

So here's is an update.

I spent some time on the phone with Guss at Vans this morning. They remember this kit very well. And for the record, they have not stated that the entire kit is a loss i.e. fuse, finish, and emp. They are steadfast in saying that particular wing is a loss. So, when I asked the question "before I take this down to the recycle yard, can you tell me if this thing is a complete loss?" Guss said they don't know anything about what has gone wrong with the applicable area of the fuse but support investigation because this could possibly be a fixable issue that may not affect the integrity. They agreed to look over any pictures I can send of the area for their evaluation. That said, the existing fuse is not complete and is totally accessible for inspection from front to rear. So, there are possibilities here. The emp is a non-issue as I have already evaluated it and it is within the required specs per the plans.

In summary, Vans does not say to 'scrap it.' They do however agree that it should not be passed on anymore. They are beginning to think it's haunted because it keeps popping up or, resurrecting itself through naive newbees like me. Here is what the conclusion of the conversation was this morning.

1. Replace the entire wing...period. No to drilling out and reapplying skins and so forth. Salvage any savable parts such as rods, hardware, etc but build a new one correctly. This would be half the cost of a new wing kit; or less.

2. Inspect the rest of the kit meticulously for variations from the plans.

3. Take plenty of pictures of the fuse area that is suspect and forward them to Guss. It is likely that this can be fixed by replacing specific parts or adjustments.

The optimism is (per this phone conversation) these are worth looking into prior to sending it to the bone yard as a complete loss. Further, if practical and fixable, and done correctly it would result in a structurally safe airworthy frame.


In other words, this thing is still at a very inspect-able stage of construction. Second, completely replacing the wing will eliminate the structural concern of a tear down and rebuild. And third, AND IF, the fuse issues is determined fixable per VANS, I see no reason to shove this whole kit into the fire pit.

At the least...I will be able to report back to all of you and answer the most haunting question of this particular thread--WHAT THE **** DID THIS GUY DO TO OFFSET A PREPUNCHED KIT SO BADLY. FORGET ABOUT THE WING SPAR. THAT WAS JUST INSANE.

I told Gus that no matter what, this kit is going to be either fixed and resurrected properly or headed to the crusher. Yep the buck is going to stop here for this old girl. I agree with all of you in that respect. Gus was pleased with this and we ended the call both looking forward to evaluating the photos soon to come.


I hope this falls within acceptable standards for all of you. I value your input very much. I myself will remain SAFELY optimistic. Later however, I'm not sure if I should just update this thread or start a new one but, I will return with data on how this fuse became so screwed up.


Respectfully,


Epsound.

Excellent. good luck moving forward.

I say start a new thread later after you have found or corrected any discrepancies.

Sounds good to me. If it only had 1 previous builder / owner, one would wonder "how" he built all of it acceptably except for this area and the "grinding". However, hopefully that is the only area the offending person did any work on, and others with good skills did the rest.

Good luck!

Andy

As a first-time builder, I recall being VERY concerned that the plywood spacers that I'd had a friend plane for me to exact specifications would somehow leave me with wings that wouldn't fit into the fuselage section when the time came, especially as the builder groups grew and people started posting about making precision-ground steel spacers, etc.

Common sense told me that, if this were a prevalent problem, others would have written about it, right? Well, when the time came, the wings slid solidly into the fuse section with just some slight persuasion, thankfully.

I hope this works out for you to salvage your project. If not, instead of hauling it to the scrap yard, you might consider donating it to a high school or technical college for practice. It might be a welcome non-flyable project for budding A&Ps.

Good luck, E.

Andy Hill said:

I'm having trouble finding any reference to this "probable cause... machining defect" Or you suggesting that there was, and it was somehow covered up? Quite an allegation to make here against Vans

Andy

Click to expand...

No allegations suggested or implied against anyone.

IIRC the exact physical cause of the spar failure was not determined, and the RV-8 was the prototype with the new design machined spar. It was not a later production spar.

Enough RV-8s have been built - and I bet over-stressed at times - and no other have broken spars. Again, IIRC Vans said the spar machining techniques were improved after the loss.

The NTSB just says the crash spar was over-stressed and all spar testing on other spars showed 9 G capability with no deformation of the spar caps. Isn't 9 G well into the pilot black-out region?

NOTE

I retract all comments on the spar maching - it was speculation at the time - and I am certainly glad that no other RV-8s have exceeded structural limits since.

I apologise for the speculation based on my memory.

Please use the Vans official statement -

http://web.archive.org/web/20030605150233/http://vansaircraft.com/public/58rvconc.htm

Sounds like you're on the right track now

Epsound,

Thanks for posting the update.

I think working closely with Van's and following their guidance on this is a good approach. I commend you for going that route, and for your determination to act responsibly whatever the final outcome will be. I wish you the best of luck, and I'll be eager to hear more as the inspection process progresses.

I have just one other comment / suggestion though. With respect to inspecting the rest of the kit, I think it would be a good idea to could get some more experienced eyes on it, not just inspect it yourself. No disrespect intended. It's just that you're a relatively new builder (I assume), so naturally your knowledge and experience is somewhat limited at this point. If you could get someone like a tech counselor familiar with RV's to conduct a thorough inspection of the other completed structures, that would be due diligence in my opinion.

Good luck!

-Roee

Epsound, Good decision. I'll be interested in hearing what the issue was that caused someone to grind the spar down...if you figure it out.

My only other comment is before you start closing things up, have several experienced builders look the project over. I'm always amazed at what people find. My guess is there will be other stuff but I can't think of anything quite as major that you'll have to deal with.

This thread reminds me of the poorly built RV that flew into a fly-in about a year ago but left quickly without being identified. My first thought was how robust the RV design is that it didn't fall out of the sky. I hope we don't have others out there that are doing the same to their spar but I've got to believe that some are less than ideal after seeing this example yet we're not seeing failures. Makes me feel a little better about fretting over the thickness of paper shims on my spar spacers last week. Have to keep reminding myself that I'm not building a watch.

Aren't the carry through spars and the wings match reamed/drilled at the factory? How can you mix and match wings then?

Also, I never understood the point of the blocks of wood between the carry through spars. They are pre punched and there are bolts and spacers in there that maintain the gap as well. Is this a carry over from the non prepunched kits? Just curious.

ArVeeNiner said:

...Also, I never understood the point of the blocks of wood between the carry through spars. They are pre punched and there are bolts and spacers in there that maintain the gap as well. Is this a carry over from the non prepunched kits? Just curious.

Click to expand...

For me, it was a simple decision on whether to use spacer blocks. Van's instructions say, "make spacer blocks from dense wood...to hold the halves the correct distance apart...these spacers must be 1.438".

I measured the gap without the spacers with everything clecoed together and it was off by .008. Is that too much? Van doesn't often say "must", so I thought it was important. The underline is Van's.

I contracted out 2 things on my RV. The paint and the spacer blocks. Money well spent ($20 for the blocks)

I recently cleaned out the hangar of old junk metal parts, loaded it into the Honda Pilot and took it to a local salvage yard and came away with a check for $85.18.

Aluminum brings .40/lb.
Steel .105/lb.
and copper $3.00-3.15/lb.

Sure is better than nothing and explains why crooks are stealing copper where every then can get it.

N8RV said:

...instead of hauling it to the scrap yard, you might consider donating it to a high school or technical college for practice. It might be a welcome non-flyable project for budding A&Ps.

Click to expand...

Now that sounds like an excellent suggestion.

I'm glad to hear the results of your talk with Gus, and look forward to future updates!

Gil...

Thanks fo the clarification, and that archive article from Vans you provided has some interesting background. From that, it seems to me, that although a "prototype" RV-8, it had some hours on it, and the accident was post sales / production starting i.e. there are plenty of RV-8(A)s out there with that wing design - unmodified.

They did later change the design to the -1 wing. This gave a 50lb increase to the aerobatic weight, and altered where / how various structures joined (?) The latter, IIRC "seemed sensible" although the previous design had no engineering faults.

Andy
RV-8 G-HILZ
RV8tors

roee said:

If you could get someone like a tech counselor familiar with RV's to conduct a thorough inspection of the other completed structures, that would be due diligence in my opinion.

Good luck!

-Roee

Click to expand...

Thank you Roee.

I like this idea. I have recieved an offer resulting from this thread from an stress engineer to come an give an opinion. That said, I have already contacted (left a phone message) with an AI in the Denver area (I am in the Springs). This is a long way to travel just for a look-see but I am hoping this will, at least, lead to other relative points of contact.

Pics will be taken and sent to Vans by the end of this coming weekend.

NOTICE: If there are any experienced in the Springs area that would like to put their eyes on this kit please pm me and we can make arrangements. I welcome you.

And again, thanks for all your input. These next few weeks should be very interesting and infromative.


Best,

E.

N8RV said:

you might consider donating it to a high school or technical college for practice. It might be a welcome non-flyable project for budding A&Ps.

Good luck, E.

Click to expand...

I like this even more. I think there's a A&P school in Denver about 80 miles from here.

If you donate to an A&P or other type of school, be sure to get a signed statement that the parts will NEVER end up in a flyable aircraft.