What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Dimple without a hole...

spacedoc

Member
Hi, all.

I'm a couple of months into my RV-14A empennage build and am working on the rudder. I was dimpling one of the skins today with my DRDT-2 and while I was moving between holes in the trailing edge the handle came down on it's own and made an indentation on the skin. I didn't touch the handle or put any pressure on it, so the dent was just from the handle closing on it's own.

Pics attached. Again, this is in the trailing edge. I've sent pics to Van's builder support but figured I'd also ask the hive mind (and share Van's answer when I get it). Build on? The dimple is smooth and even and there was no skin penetration. It doesn't look like there are any hard creases in the dimple. Since this is in the trailing edge and will be backed by the extrusion and I don't think this part of the skin is going to see significant stresses, I figure I'm OK to continue.

I was considering trying to flatten the skin back out- gently. Either by very gently applying the dimple dies partially in the opposite direction, or by using a flat set of padded duckbill pliers as a sort of seamer to flatten it. Or both...

Thoughts?
 

Attachments

  • IMG_7279.jpg
    IMG_7279.jpg
    207.2 KB · Views: 255
  • IMG_7280.jpg
    IMG_7280.jpg
    178.8 KB · Views: 229
  • IMG_7281.jpg
    IMG_7281.jpg
    356.8 KB · Views: 207
  • IMG_7282.jpg
    IMG_7282.jpg
    241.7 KB · Views: 206
Is there a hole? One of the pics looks like there might be but the others don’t.

Two options

1. Use a flat squeezer to flatten it out and move on.

2. Drill it to a 40, make it a real dimple, and fill it with a flush rivet, though this might not work on the trailing edge since the shop head may interfere with the other skin.

I’d go with option 1 personally.
 
I would do a test first by replicating the problem on a piece of scrap and see what effect there is on the trailing edge from flattening the dint. I suspect that it may cause a rippled edge, because the metal has been stretched and it will need to go somewhere if it is forced flat.

Another option is to leave the little dent and just fill it in with filler at the time of painting. This would require a small depression in the wedge to accommodate the false dimple.
 
Last edited:
This is where your wedge goes, I would do my best to flatten it well so it does not cause any distortion when you install the wedge and build on.
 
I would NOT try to flatten it. You are likely to get wavyness around the area next to it and this is not something you want on a trailing edge. There is a real art to shrinking and stretching metal. I personally would drill it out or grind it out, leaving a hole. Then just use some type of filler to cosmetically deal with the hole. As long as you meet edge distance specs, the hole in that area should have no negatives.

The idea above to grind out a depression in the wedge would also work, but I think removing the dimple creates a stronger TE.

Larry
 
Last edited:
Can you countersink or drill the wedge to fit the dimple? If so, then don't try to flatten it, just build on and you can simply fill the depression later.

I agree that flattening it will warp it.

Dave
 
Last edited:
Squeeze it flat. Won't look perfect, but after paint only you will know it's there.
Do Not hammer it flat as there is potential of stretching the metal.
 
Cold work the dent flat, take care not to damage the adjacent hole. Inspect for cracks at the rework.
 
Last edited:
Cold work the dent flat, take care not to damage the adjacent hole. Inspect for cracks at the rework. Conductivity test to ensure no change in material properties.

Apologies for the thread drift. I worked for a Canadian manufacturer of business aircraft and regional airliners. When there were construction "nonconformities", an engineering disposition was required to make things right. Having read his post, I'd be willing to bet that echostar7 is familiar with engineering dispositions.
 
Apologies for the thread drift. I worked for a Canadian manufacturer of business aircraft and regional airliners. When there were construction "nonconformities", an engineering disposition was required to make things right. Having read his post, I'd be willing to bet that echostar7 is familiar with engineering dispositions.
I have worked engineering dispositions, good catch.
Do you have any other suggestions for what he might do, aside from calling vans for support which is what I would have done first.:cool:
 
Last edited:
Echostar, I did send an email with pics to Van's but it was after business hours on Friday! I'll share their response with the group- I assume I'll hear from them tomorrow.
 
I would drill the errant dimple with a #40 bit (or slightly smaller) and then use a flat squeezer set to flatten any remaining dimple. The relief of the hole should allow the stretched metal to flow more towards the hole and minimize any stress on the edge. Then prior to finishing you can use a bit of micro or other material to fill the small hole. If you're still worried about the edge being wavy, you could test this on a piece of scrap and see what the results are.
 
I would drill the errant dimple with a #40 bit (or slightly smaller) and then use a flat squeezer set to flatten any remaining dimple. The relief of the hole should allow the stretched metal to flow more towards the hole and minimize any stress on the edge. Then prior to finishing you can use a bit of micro or other material to fill the small hole. If you're still worried about the edge being wavy, you could test this on a piece of scrap and see what the results are.

Best answer I’ve read.

Use some scrap and try several ways. Remember that perfect is the enemy of excellence. If you are painting and not polishing, a good fix will disappear with paint.
 
Nothing bad that isn’t good for something. You are at the start of the build so this is the time to establish a process for dealing with these situations moving forward.
#1 Figure out what caused the damage and put safeguards in place to prevent it from happening again. Nothing worse than making the same mistakes.
#2 Establish a process for how to deal with these decisions moving forward. Personally, I use a mathematical scoring process of 1 to 5 for each of the following
How much to replace the part…48.00 plus s&h say 20.00. $68.00 score 2 out 5
How much time to get back to square one. Edge prep 1/2 hr, dimple 1 hour, prep and prime 1 hour. 2 1/2 hours. Score 2 out of 5
Is it structural score 1 out of 5
Will it bother me score 1 out of 5 (this one is very subjective)
Total 6 out of 20. Relatively low. So even though looking at the size of the damage it sounds ridiculous to replace it, when you look at the numbers, think of 68.00 dollars and 2 1/2 hours your back to square one, is it that crazy? Keep in mind you likely already spent an hour or so on this issue just determining what to do.
Now compare this process to fixing, repairing.
How much time to repair, likely 1 hour if you add in the micro, sanding etc. 1 out of 5
Cost to repair 1 out of 5
Will it bother me 1 out of 5
Is repair approved by Van’s 1 out of 5 (assumed)
4 out of 20.
Repair is the better choice based on the numbers. Unfortunately, you will cross this bridge again so having some sort of process in place to deal with it makes it easier and less likely to get stuck in the weeds. If repairing, I personally would go with drilling and flattening as has been mentioned. Hopefully this helps you going forward with making these decisions.
Regards,
Todd
 
Heard back from Van's. Recommendation is to squeeze it out with a flat set and then build on. I went ahead and squeezed it and it looked fine afterwards. A very small dent remained where the tip of the male die locator pin imprinted the metal. Nothing that couldn't be filled. Of course I ignored the maxim that "perfect is the enemy of good enough" and tried to squeeze a second time, and that put a bit of waviness in the edge. I stretched the metal too much when I did the 2nd squeeze...

Lesson learned- don't muck with it too much! I will continue assembly and expect a bit of a gap there in the trailing edge. Luckily I'm not OCD so I'll likely never think of it again once I'm flying!

Thanks for all the suggestions.
 
There is a metal shrinker from ATS for around $235. Will take wave out. Buy, use, and sell. You might find one you can borrow. Good luck.
 
Back
Top