[bertschb]

I made a stupid mistake today while countersinking the W-00002 wing inboard top skin that sits on top of the wing walk doublers on page 16-02. There are three rows of holes that I countersunk rather than dimpled as shown below. The top or forward row attaches to the main wing spar. The holes in the wing spar where the top skin attaches are countersunk. The middle row of holes attaches to the W-00009B J-Stiffener underneath which are supposed to get dimpled in a later step. The bottom (aft) row of holes attaches to the rear spar which is also dimpled.

This mistake stings even though I'm way overdue for a mistake. I'm guessing I could forgo the dimpling on the J-Stiffener and all would be good for the middle row of countersunk holes that I screwed up. I could then "un-dimple" the rear spar holes and that would be OK as well. But, the main spar under the top row of holes is countersunk. No way to "fix" that.

So, do I need to replace this top skin? And yes, I plan to ask Vans but it will be hard to sleep on this one until I can get in touch with them next week. Just curious what you folks think.

 

[mc607]

So, do I need to replace this top skin?

I can’t think of any way to fix, or work around, a countersink over a countersink. I would replace it. For what’s it worth, I dimpled the skin, doubler and ribs in that area and it worked out fine. Also dimpled the baffles in the fuel tanks, worked great there too.

 

[blaplante]

If those are #3 diameter rivets... Go up to a #4, and dimple for those? If possible? It will show, but wing walk material will cover up some of it.

 

[bertschb]

Well, I've decided to just replace the W-00002 top skin.

This is such a frustrating mistake. When I removed the top skin and looked at just the doublers sitting on the wing ribs it's SOOOO obvious what needs to be countersunk. But, I was blindly following the plans and had the top skin cleco'd on top of the doublers when I got to step 4 for countersinking. I remember several times while I was countersinking having some doubts about what exactly needed to be countersunk. I looked at the RV-14 wiki, watched a couple YT videos, etc and still wasn't 100% sure. Rather than proceeding, I should have just disassembled the top skin and doublers and LOOKED at the underlying structure. You don't need plans to figure it out!

As much as it sucks to make mistakes, I really shouldn't beat myself up too bad because this is only the second part I've had to replace since I started my build last fall and I've completed the empennage and fuselage. Being a new builder with no assistance can be challenging at times...

 

[mc607]

You know who never makes mistakes...people that don’t do anything
When you go back at it, mark right on the skin, which ones get countersunk and which don’t. I like to use dry erase markers and or masking tape. In this particular case a strip of tape over the 3 rows and all the other holes that don’t get c/s would probably work.
The biggest problem, as you probably already know, is your mind will wander when doing this repetitive work. And the wings Are repetitive! Hyper concentrated at the beginning….then…wonder what we’re having for dinner…ahhh crap!
Tape it up so you're not able to c/s, dimple the wrong hole. This will be a good habit, especially on the wings, which are repetitive…

 

[bertschb]

Tape it up so you're not able to c/s, dimple the wrong hole. This will be a good habit, especially on the wings, which are repetitive…

Yep! That's what I do! I use 1/4" blue masking tape for covering holes and I do it even when it's obvious that the holes should be avoided. I've gone through several rolls of that tape.

I think the thing that bothers me the most is I KNEW something wasn't quite right. I thought I knew better than to continue when I wasn't 100% sure what I was doing was correct - but I guess not. Sheesh

 

[blaplante]

Not a 14 builder... I'm a little puzzled. Generally you don't countersink anything that isn't at least 0.032 thick (for a 3/32 rivet). But then I don't know how thick this skin is... Why is any of this skin countersunk?

 

[bertschb]

...Generally you don't countersink anything that isn't at least 0.032 thick (for a 3/32 rivet). But then I don't know how thick this skin is... Why is any of this skin countersunk?

The top skin is .032. I'm countersinking it because that's what the plans call for I think the reason Vans call for countersinking here is because we're riveting three pieces of material together and they may be concerned about the accuracy/consistency of three levels of dimpling and making sure they all nest together properly. Having said that, there are a number of people that just dimple everything in the wing walk doublers area as Todd mentioned above.

 

[Ralph Inkster]

The deal breaker for me would be the main spar rivet line, no graceful way around that countersinking error. Order a new part, or if anybody has a big enough spare sheet handy, trace & cut a replacement skin for the job.

 

[bertschb]

The deal breaker for me would be the main spar rivet line, no graceful way around that countersinking error. Order a new part, ...

Yep, I felt the same way. I ordered a replacement top skin earlier this morning. I'm working on the right wing top skin now. Quintuple checking everything before countersinking Kinda paranoid now.

 

[docjjrmd]

Well, I've decided to just replace the W-00002 top skin.

As much as it sucks to make mistakes, I really shouldn't beat myself up too bad because this is only the second part I've had to replace since I started my build last fall and I've completed the empennage and fuselage. Being a new builder with no assistance can be challenging at times...

Yep, feel your pain but consider this, building is an exercise in self discipline, just as good piloting is. Better to do it right on the ground than trying to figure out a fix in the air! I applaud your choice.

 

[bertschb]

What was really hard for me was when I started suspecting I made the mistake and went back out to the hangar and removed the top skin. As soon as I looked at the wing walk doublers sitting on the wing ribs I knew I screwed up. It took one second to know with certainty I did it wrong and that was after spending 30 minutes wondering if I was countersinking the right holes earlier in the day. It never occurred to me to remove the top skin earlier. Sometimes I wonder...

 

[docjjrmd]

What was really hard for me was when I started suspecting I made the mistake and went back out to the hangar and removed the top skin. As soon as I looked at the wing walk doublers sitting on the wing ribs I knew I screwed up. It took one second to know with certainty I did it wrong and that was after spending 30 minutes wondering if I was countersinking the right holes earlier in the day. It never occurred to me to remove the top skin earlier. Sometimes I wonder...

But how easy it would be to say "no biggie", Its covered up, no one but me will ever know. Part of flying an EAB is the knowledge that I know it was built right because of my own self discipline. I have struggled with rebuilding what looks like a perfectly fine and ok horizontal stabilizer on my -12. Issue, 2 spars on the red LCP list that can't be inspected. No one will know if I do or don't except me. Sorry for your error, if its your last, you are incredibly talented. But how many other builders out there don't have the time, patience, money, and self discipline to make a similar error right? (rhetorical question folks!)

 

[toddzz]

Well, I've decided to just replace the W-00002 top skin.

This is such a frustrating mistake. When I removed the top skin and looked at just the doublers sitting on the wing ribs it's SOOOO obvious what needs to be countersunk. But, I was blindly following the plans and had the top skin cleco'd on top of the doublers when I got to step 4 for countersinking. I remember several times while I was countersinking having some doubts about what exactly needed to be countersunk. I looked at the RV-14 wiki, watched a couple YT videos, etc and still wasn't 100% sure. Rather than proceeding, I should have just disassembled the top skin and doublers and LOOKED at the underlying structure. You don't need plans to figure it out!

As much as it sucks to make mistakes, I really shouldn't beat myself up too bad because this is only the second part I've had to replace since I started my build last fall and I've completed the empennage and fuselage. Being a new builder with no assistance can be challenging at times...

I messed up a wing skin. Replaced it. Built my rudder twice. Have a pile of parts I messed up and replaced. Stuff happens. Without fail

 

[Carl Froehlich]

When you do this over again, consider no countersinking.

My first build (8A) the plans called for dimpling the ribs, the doubler and the top skin. Easy. On the second build (10) Van’s started the countersinking instructions. I decided I rather have dimples as 0.032” aluminum is marginally thick to coiuntersink. I dimpled the parts, and did it again on the third and fourth builds.

While I know about the dimple depths this did not seem to make a difference. On the third and fourth builds I did use tank dimple dies on the ribs and the doubler, the top skin got regularly dimple dies. I used the tank dies mainly because I had them in the tool box.

Carl

 

[BigBadBob]

What was really hard for me was when I started suspecting I made the mistake and went back out to the hangar and removed the top skin. As soon as I looked at the wing walk doublers sitting on the wing ribs I knew I screwed up. It took one second to know with certainty I did it wrong and that was after spending 30 minutes wondering if I was countersinking the right holes earlier in the day. It never occurred to me to remove the top skin earlier. Sometimes I wonder...

There's a saying at work: "If it looks wrong it probably is wrong". Of course, you find yourself doing this internal dialog: "That couldn't be wrong could it? Naw, it's OK. But what about...." and so on. And that's after designing and analyzing the thing you're looking at. When it comes to airplanes a fair amount of skepticism and paranoia is a good thing.

What I've learned (over and over again) is to slow down. I just love it when I efficiently and quickly make an expensive mistake!

Interrogo haud defenso

 

[thehagg501]

You know who never makes mistakes...people that don’t do anything
When you go back at it, mark right on the skin, which ones get countersunk and which don’t. I like to use dry erase markers and or masking tape. In this particular case a strip of tape over the 3 rows and all the other holes that don’t get c/s would probably work.
The biggest problem, as you probably already know, is your mind will wander when doing this repetitive work. And the wings Are repetitive! Hyper concentrated at the beginning….then…wonder what we’re having for dinner…ahhh crap!
Tape it up so you're not able to c/s, dimple the wrong hole. This will be a good habit, especially on the wings, which are repetitive…

Your first sentence is spot on.