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Quick Question for Rivet Experts

cderk

cderk

Well Known Member
So I may have inadvertently forgotten to put in a rivet (or 4). Is there a chart or an easy way to cross reference an AN470AD4-5 rivet to something like a CherryMax? In building my VS, for some unknown reason, I left out rivets on the hinge doubler for the rudder. Now the whole thing is closed up and I would hate to have to tear the skin off to get to it.

Looks like there is a spreadsheet online from Cherry Aerospace, but it appears that you need to know what kind of rivet you're replacing - as in Mfg part number.
Thanks
Charlie
 
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Are all 4 rivets next to each other? If not, just use a solid CherryMax 1/8th. If they are next to each other I would call Vans. I would be worried about the integrety.
Just my opinion.
Nordo
 
Yes, they're all next to each other...
I see the 1/8" rivets - but there are a number of them with different "grips" and i'm trying to figure out how to determine which one will work best. Looks like the CR3213-4-3?
I'm trying to determine the thicknesses of everything to figure out the right one. It looks like the Rear Spar is about .04" thick, the Top Rudder Hinge is .06" and then I'm guessing that the Hinge Doubler is about .07 or .08" thick. CR3213-4-3 grip is .126 to .187



Thanks
Charlie
 
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Cherry

Measure the thickness of the parts, add them up and reference the chart.
I agree, ask Vans to be sure.
 
That may be a hard place to get a rivet puller. They are structural rivets, and I believe approved by the FAA as substitutes for AN solid rivets, HOWEVER, you need to be able to visualize the other side of it to ensure that it set properly. Could probably do this with a borescope type camera if needed. Remember that they aren't sized the same as AN rivets so you will need the chart and material thickness. All that said, it's an important area and certainly worth running by Vans.

UPDATE: Per the FAA AC "...they should not be used where the looseness or failure of a few rivets will impair the airworthiness of the aircraft." I would think this situation may qualify for that scenario...

Chris
 
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Spruce has a good chart with the "grip" limits for each cherry max. You need the 3213 for the correct diameter. To find your grip size, simply add the thickness of the parts that are being riveted together. My guess would be the CR3213-4-2, which gives you a grip range of .063 - .125. My assumption is that the two pieces being mated together are .032 (spar) and .075 (bracket). If there is a doubler on the spar, then you'd need to account for that in the grip size and may need to go up to a CR3213-4-3, which has a grip range of .126 - .187.
 
Thanks for the replies - yes, I have a boroscope, so I can certainly inspect the inside.

Keith - thanks... that's what I was thinking, the -3 rivets. I've sent an email into Van's, so hopefully they'll let me know for sure tomorrow when they get in.
 
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To be honest, I wouldn't mess around with this one. I would kick myself, throw some things, then move on and open it up and install the rivets. That part is too important.

My 2 cents...
 
papamike said:
To be honest, I wouldn't mess around with this one. I would kick myself, throw some things, then move on and open it up and install the rivets. That part is too important.

My 2 cents...
Click to expand...

Why? A Cherry Max is a full-strength rivet (unlike some other kinds of "pop" rivets).

I'd use Cherry Max rivets and avoid the risk of messing up other parts drilling out all those rivets on the skin. I'd bet dollars to donuts that Van's says the same thing...
 
Did you already put the ribs on the top/bottom? you can fit your arm in there and buck those rivets if the rib isn't on, it really isn't that hard. Its easier with two people, but you can do it with one.

You dont have to take the skin off, just the rib.
 
Cherry max rivets are stronger in sheer, but weaker in tension. I've read elsewhere that certain manufacturers forbid cherry max rivets in this sort of application, where they are loaded in tension. For what it is worth, I had a couple of rivets with cut heads in this location (my first part), and later went back, removed enough rivets to peel the skin back enough to allow access, and replaced them. An easy and satisfying job.
 
Drill the skin

aturner said:
Cherry max rivets are stronger in sheer, but weaker in tension. I've read elsewhere that certain manufacturers forbid cherry max rivets in this sort of application, where they are loaded in tension. For what it is worth, I had a couple of rivets with cut heads in this location (my first part), and later went back, removed enough rivets to peel the skin back enough to allow access, and replaced them. An easy and satisfying job.
Click to expand...

I agree.
Four maybe. Eight drill the rib or skin.
If you haven't drilled rivets, search for tips and practice first.
 
cderk said:
More screw ups. I thought it was 4 rivets i forgot - its really 8... <sigh>
Click to expand...

So now a somewhat more serious question...how are you missing these steps? This sounds like something of a *process* problem which you may need to address, lest you get further into the build and miss other steps which are harder to correct.

Granted this is a -10, and I built a -7, so I don't know how the instructions are laid out for yours, but just a suggestion to figure out *why* you missed these...
 
RV7A Flyer said:
So now a somewhat more serious question...how are you missing these steps? This sounds like something of a *process* problem which you may need to address, lest you get further into the build and miss other steps which are harder to correct.

Granted this is a -10, and I built a -7, so I don't know how the instructions are laid out for yours, but just a suggestion to figure out *why* you missed these...
Click to expand...

Yep, you are exactly right. It's a problem. It's an interpretation of the instructions problem. I was looking at the illustrations and the illustrations could be interpreted wrong, which I did. I'm not saying it's Vans fault because I didn't fully understand it, but it could be clearer. Moving forward I need to cross reference the text and images.
 
Do overs

We've all made mistakes requiring do overs. Your rivets look good. How's your rivet removing skills? If it were mine, I would start drilling/snapping out the skin to spar rivets, remove spar and put in the missing 470-4-5 rivets. When reinstalling the skin to spar 426 rivets, give them a slight squeeze before putting them in holes to fit oversized holes. It will take less time than you think to fix this and you will learn a new skill in the process. Fixing our mistakes is gratifying in itself knowing you did it right. Bucking bars have been sealed inside stabs! Makes for good builder stories.
 
bobbyhargrave said:
We've all made mistakes requiring do overs. Your rivets look good. How's your rivet removing skills? If it were mine, I would start drilling/snapping out the skin to spar rivets, remove spar and put in the missing 470-4-5 rivets. When reinstalling the skin to spar 426 rivets, give them a slight squeeze before putting them in holes to fit oversized holes. It will take less time than you think to fix this and you will learn a new skill in the process. Fixing our mistakes is gratifying in itself knowing you did it right. Bucking bars have been sealed inside stabs! Makes for good builder stories.
Click to expand...

Thanks Bob... that is probably what I will wind up doing. Its all a learning process and this site is what makes it great - so many folks willing to share their experiences. I can't believe how much I've learned already. This is a new skill for me. I've never built anything like this before.

I'm waiting to hear back from Van's - but I have a feeling that I will do what you're suggesting. I think I can do it by just removing the rivets along the edges, which I squeezed. I'm waiting for a few "rivet removal" tools to arrive, then I will tackle this.

Some of the take-aways from this...
1. Read everything twice, then read it again
2. Make sure that the illustrations and text match - if not, ask
3. Prior to closing parts up, go through all the previous steps again to make sure nothing was forgotten.
4. If there are open holes where it looks like rivets should go, go back through and make sure you didn't miss a step.
 
I hate to say it, and I am sure Vans will agree, with all of those missing, you need to do it all over. Too important of a part to leave that doubler as is.
Better safe than sorry!
Take your time with the rest of the build:)
Nordo
 
cderk said:
Some of the take-aways from this...
1. Read everything twice, then read it again
2. Make sure that the illustrations and text match - if not, ask
3. Prior to closing parts up, go through all the previous steps again to make sure nothing was forgotten.
4. If there are open holes where it looks like rivets should go, go back through and make sure you didn't miss a step.
Click to expand...

I've only been building for about 3 months or so. I used to beat myself up on the mistakes and some of them really made me sick. However it really just comes down to time and money - time to redo the parts and money to buy the new parts or materials. In the end taking the time to correct your mistakes and do it right is the best way because you won't have to worry about it again.

Just really double check the HS Spars and what you're doing. I made about 3 mistakes before I noticed it and had to scrap the part... getting things shipped by freight wasn't the cheapest.
 
Ooops rivets

Also remember oops rivets are your friend when you are concerned you've enlarged the hole after drilling out a rivet. I had to drill out 20 rivets on my elevator when I realized I'd forgotten to dimple the stiffener ribs... Go slow, take your time, you'll be amazed how quickly and easily you can fix this. This is NO BIG DEAL - we all do this stupid stuff.
 
I got a response back from Van's. Those guys are great. The recommendation action was to follow SB-06-2-3 for the Vertical Stabilizer. Back in 2006, they introduced the SB because of cracking in the web of the rear spar. They added a hinge doubler.

The instructions are straight forward and it doesn't look terribly painful - maybe 20 rivets to remove.

Thanks for all the feedback.
Charlie
 
cderk said:
I got a response back from Van's. Those guys are great. The recommendation action was to follow SB-06-2-3 for the Vertical Stabilizer. Back in 2006, they introduced the SB because of cracking in the web of the rear spar. They added a hinge doubler.

The instructions are straight forward and it doesn't look terribly painful - maybe 20 rivets to remove.

Thanks for all the feedback.
Charlie
Click to expand...

Hmmmm...so *that's* what those other 4 open holes were for, eh?

Again, I don't know about the -10, but if you bought the empennage kit after 2006, shouldn't it have included the doubler (and shown it on the instructions/plans)?

And if it didn't...then did you not check the SBs ahead of time? If you had, then you should have seen this SB and the purpose of those "extra" holes would have been clear.

It's early in the game to be missing things like this...
 
They sent me the SB because it provides good illustration on how to disassemble to get to that area, NOT because I need to perform the SB. So, while I appreciate your concern, no, I'm not missing anything else. I already have the hinge doubler installed.
Thanks
 
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cderk said:
They sent me the SB because it provides good illustration on how to disassemble to get to that area, NOT because I need to perform the SB. So, while I appreciate your concern, no, I'm not missing anything else. I already have the hinge doubler installed.
Thanks
Click to expand...

Ah, good. Not trying to be harsh, just trying to "cast a critical eye" and help out.

In any case, looks like an easy fix just by removing that small upper rib.
 
Yep, looks simple enough and seems to be a better solution than putting the CherryMax rivets in there. I'd rather "fix" it the right way.

Now that I learned my lesson, I'll move on...
(kind of like my first wife)
 
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