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Oversized hole question

F

FlyingHippo

I'm New Here
Hi,

I have just started assembling the front spar of my RV9 horizontal stabilizer and have immediately found myself with problem of over sized holes.

Not too sure how this actually happened however I believe all 9 holes attaching the bracket to the spar are way too big. As I have tried to set the rivets I have been unable to make suitable shop heads with the head diameter being too small and height too small.

Below is an image to show the scale of the issue.
open


Any help or guidance would be gratefully received.
 
Get the Mil specs off of Vans site or the specs in AC-43-1b. They will have maximum allowable hole size for a given rivet diameter. If they meet spec, drive them. You can squeeze them slightly before insertion or squeeze them in the hole a bit then buck them.
If the hole doesn't meet spec, call Vans. It is likely they will approve a rivet the next size up if the edge distance and rise are within spec, also shown in the AC and Mil spec on Vans site.
 
Different part (elevator spar), but just did this myself .. like an hour ago .. $46 worth of replacement parts from Vans .. parts are cheap .. don't waste too much time trying to fix it, depending on where you are in the assembly sometimes it's easier just to scrap and rebuild.
 
erich weaver said:
Upsizing your rivets should solve the problem

erich
Click to expand...

While you are probably correct, it is a Spar, a very important one in a very critical area. Call the aircraft designer, Vans, on any spar deviations from plans or for repairs to Spars.
There are minimum distances for "rise" and spacing for a given rivet size. Bigger isn't always better even if edge distances are not an issue.
 
I would make sure your drill bits are the correct size you think they are. Get some calipers and see what the diameters are for your #40 and #30 drill bits. A 3/32 rivet doesn't get a 3/32" hole!
 
Order new parts and find out EXACTLY how this happened. Look at everything. Section 5, rivets, drill bits, until you can get to the root cause.

Then - don't do it again. It is more than a drill bit, before that there was an assumption, or guessing. Be sure you include your thinking and training in the evaluation.

It is part of the learning experience.
 
Thanks everyone for your help and advice.
I was able to use the specs as suggested to definitively conclude the holes were outwith the required dimensions.
I will be ordering the required new parts.
There is still the outstanding question about how this has happened which I am struggling to get to the bottom of.
 
FlyingHippo said:
Thanks everyone for your help and advice.
I was able to use the specs as suggested to definitively conclude the holes were outwith the required dimensions.
I will be ordering the required new parts.
There is still the outstanding question about how this has happened which I am struggling to get to the bottom of.
Click to expand...

I have to agree with Bill L, as usual, and you. Your path with new parts is best. Even if Vans approved the upsized rivet solution, that isn't what was originally designed and proven in service for tens of thousands of hours across hundreds if not thousands of machines.
You will get to the bottom of how it happened.
Good catch. It shows you are paying attention and not just moving on. That is good discipline and I have no doubt you will produce a safe machine. This forum is full of examples of those that didn't.
 
FlyingHippo said:
Thanks everyone for your help and advice.
I was able to use the specs as suggested to definitively conclude the holes were outwith the required dimensions.
I will be ordering the required new parts.
There is still the outstanding question about how this has happened which I am struggling to get to the bottom of.
Click to expand...
Have you taken a build class? The one weekend and couple hundred bucks it will cost are well worth it on a $60K plus project. You'll be less stressed, enjoy your build more, and be much more confident in your ability to know when you need to question things and when you can build on. Good luck.
 
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