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Oblong holes = order new part?

F

fritzg

Member
Hi All,

New builder here. The attached picture is the R-904 bottom rib. It is sandwiched between the rudder horn and rudder spar. I am concerned about 2 things:

1. The large hole for the Rudder rod end is way to close to the edge. I dont know of this is an issue as the rod end is not a fastener.

2. The rivet holes seem to be a bit oblong. Is this a problem?

Any thoughts would be great!

2469ul3.jpg
 
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It's early in the build...might as well start off by doing it right. Replace it.

Next time, mark the centerline on the flange before match-drilling, and make sure the centerline is visible in the hole which is being matched.
 
Welcome

Welcome Fritz
I agree. Replace it. You'll feel better. Shipping will cost so consider future needs.
 
Two other alternatives to replacing are available but probably not the best choices over getting a new part:

1. Cut the end off and replace with new rib flange angle of same material. Similar to the way the horizontal stab aft ribs are done after installation of the new doublers specified by SB 14-01-31.

2. Up-size the holes to the next size rivet. Edge distance may become a factor, though.

Call Vans and see what they would do, in any case.
 
Given that optimal is a perfect set of holes in a perfect world, youre gonna come across alot of these less than perfect choices. if this is an easy part to replace or remake then yeah id probably do that, after hopping up and down and cursing a few times. However if you have to use the part, and even more applicable in a sandwich scenario like this, ive riveted the parts together as is and used T88 structural adhesive as an additional binder. In a shear situation youll never get the parts apart again. The stuff is bullet proof. The other thing you could do if you have the edge space is add more rivets judiciously. A few oblong holes wont make much difference if the majority are good to go. You dont have to have a perfect airplane, just a sound one and there is overbuild in our planes. How much well thats a matter of personal choice. Youre building a truck, not a swiss watch. Just my .02
 
Same here

I did the exact same thing to the exact same part. Your large hole is correct, everybody's part is that way (see my blog). Your oblong holes won't do. It happened to me as I didnt radius the R-405PD were it contacts R-904. So then through my sequence of match drilling holes....bang, oblong holes. My opinion..replace the part, it's an inexpensive part....don't feel bad, chalk it up to a lesson learned.

A nice guy in my EAA group gave me some good advice. He says while you first starting out its a good thing to set a high level of standards. It teaches you so much right from the beginning and makes your workmanship improve so much faster. Otherwise he said, you end up becoming a bit sloppy through your whole build. (Good advice I thought but it results in a few extra orders to vans, just save them up so you don't get killed on shipping)

Again..it's just my opinion.....and according to my wife, it's often wrong anyway.
 
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Aero_Octaveus said:
Otherwise he said, you end up becoming a bit sloppy through your whole build.
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I know you're quoting an old and wise person etc, but this statement is so much BS.

Its like saying, if you take a drink, you're gonna be a fall down stupid drunk all your life because you've "courted the devil" once. Really?

Strive for perfection, yes. Absolutely. In everything you do. But, in this case, understanding the structure you're building and what its stresses are, allows you to decide, if put in an other than perfect situation, what's good enough to get the job done. You don't need to do a numerical stress analysis, just use your head and imagine whats pushing or pulling on it. If it doesn't feel right, then don't do it.

I'm glad the OP asked the question. That's using your head. Good job! Build on MacDuff!
 
fritzg said:
This was being matched drilled through 3 parts. I dont think It walked at all.
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Then the parts probably were not clamped together tightly.

As your drill went through the layers it pushed the bent flange out a bit and caused the oblong hole.

That's why the oblong is at a right angle direction to the bend of the rib flange.
 
Aero_Octaveus said:
Your large hole is correct, everybody's part is that way ...
Click to expand...

I don't recall mine being that way, but couldn't find any pictures of that part to prove it. I just remember that I would have remembered it if it was that far off on mine :)

while you first starting out its a good thing to set a high level of standards. It teaches you so much right from the beginning and makes your workmanship improve so much faster. Otherwise he said, you end up becoming a bit sloppy through your whole build.
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I agree. If you start out being sloppy or accepting less than your best, you'll just keep doing it.

Make it right.
 
Clecos?

Just out of curiosity, did you have clecos in the adjacent hole(s)when you were drilling?
 
Don't be afraid to cut the flange off and rivet a new flange onto the web. Just follow bend radius specifications for 2024T3 (it is not very tolerant of sharp bends) and AC-43 for rivet spacing on the web. It is a ten minute job at worst. You can also make the flange a bit wider.
This was pretty common on the older kits as the tolerance of the rib flanges where not very consistent and at times less than needed.
 
az_gila said:
Then the parts probably were not clamped together tightly.

As your drill went through the layers it pushed the bent flange out a bit and caused the oblong hole.

That's why the oblong is at a right angle direction to the bend of the rib flange.
Click to expand...

You are correct, I had them clecoed but not clamped. There were several layers of parts involved.

Great lesson for me.
 
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