Wing falls off the table

It was bound to happen sooner or later, and today it happened. While preparing the left wing for bottom skin riveting session, it slid off the work table and the wing tip leading edge skin and rib took the major, if not all, of the fall. The skins and spars still appear to be in alignment . But I am not sure what the best course of action to be, repair or replace. From the picture / link posted here, I would appreciate some advice, suggestions and possible solutions.

Hope this doesn't happen to other builders out there.

my suggestion would be to trim back as far as needed and cut that entire section from the leading edge, replace the Ribs that need to be replaced and then using a new piece of aluminum for the new skin replace what was removed. Create another lap joint very similar to the one midway down the wing. The only complication I could see is if you use a new piece of aluminum that was not meant for the leading edge, getting the bend perfect so that everything lies flat.

my 2 cents
-david

Sorry to hear about your misfortune. If it were mine, I would drill out the rivets on the leading edge skin as well as the ribs involved and replace them. I think it would be very difficult to make a decent looking repair. I would check for twist in the wing also, if its an older wing you could put it in the jig to aid in checking for this. If it is the newer match drilled and was never in a jig I would stand it leading edge up and lay straight edges along the main spar, parallel to the face of the spar web, perpendicular to the long axis of the web, and sight down the spar from the root to the tip to see if the "sticks" are in the same plane (parallel).
Hope this helps.
Jim

Dan, this thread took me back to one of those days when I thought I had really made a costly mistake.

http://www.vansairforce.com/community/showthread.php?t=11000&page=2

I got lot's of good advice as you can see on that thread. The best was to find a really good sheet metal/auto body person (that had some grey hair) to take a look. My damage was on the tank end of the wing. I ended up replacing the end rib and the sheet metal guy made the skin look good as new. I would not be too quick to start cutting metal.

Good luck.

Dan,
It's difficult to judge the damage from the picture but it looks like more than one rib is affected. I would take my time, carefully drill out all the rivets at leading edge and replace the leading edge skin and rib(s). In big picture of building time it won't take long.

no worries

Easy Fix. I have had success pulling the Rib, straighten the skin, then straighten or replace the Rib and put it back together. Any ripples in the skin can be cleaned up with a little Epoxy filler. Since it is at the tip there should not be a lot of stressing or loading to worry about. Good luck.
Jackson

1 Gallon can of Bondo?

Sorry, I couldn't resist.

I agree

Pull the rib(s) then get a good body shop guy to bang out the leading edge. The wing tip of my Cherokee was clipped on the ramp by another airplane wing. The mechanic and I pulled the wingtip and he banged out the dent using a rubber mallet backed inside with an appropriately shaped (curved to match the radius on the leading edge) block of metal. We did this at my tie down and it took 15 minutes. Except for some cracked and chipped paint, it was good as new.

Tom

May I suggest......

If you still have work to do on the wings, may I recommend using a jig. I modified my wing jig in about 30 minutes to hold the wing for installing the guts and bottom skin. The jig also allowed me to rivet on the bottom skins solo.

Paul
N277PM
LAF
Fuselage

http://www.youtube.com/watch?v=y_JYPrt5GF8

Thanks for the encouragement....

I really appreciate the responses and to know that I haven't been the only one to have this happen to. Lesson learned, when things seem to be going well, be extra careful. Something bad is about to happen. I will be looking at the damage more closely over the next couple of weeks and work at getting the outboard rib out. One of the respondents indicated that as long as the skin wasn't creased you would be ok. What constitutes a crease, a sharp bend or a seam? Also, does anyone know of a body shop person in the Katy, Texas area? I have done some minor sheet metal repair but not on aluminum. May want to enlist the help of experience on this little problem.

Here are a couple more views to help clarify the extent of the damage.





Once again many thanks for the responses and encouraging words. All is not lost.

I would define...

snoopyflys said:

....What constitutes a crease, a sharp bend or a seam? .....

Click to expand...

...a crease as a sharp bend with a zero internal radius.

Your photos do not seem to show a crease, and seem to confine the damage to only one rib bay and one rib.

Remove the outboard rib and find your local aluminum body expert...

az_gila said:

...a crease as a sharp bend with a zero internal radius.

Your photos do not seem to show a crease, and seem to confine the damage to only one rib bay and one rib.

Remove the outboard rib and find your local aluminum body expert...

Click to expand...

Agreed. That last photo shows a lot better the limit of damage. From the first photo it looked like it may have been more severe. Good luck and please post a pic after the repair.

Jim

Just my .02. If it was my wings I would probably re-skin the leading edge. That said, there is a lot of issues that go along with that. Enlarged holes and blind fasteners to name a few. You could also remove the outboard rib and outer 10 or so inches of the skin (depending on how far the damage extends inbd) and splice a new section of skin in. The seams will not be an eye sore if you fill them carefully. If the splice is done right there shouldn't be a compromise in strength. I have never liked the idea of straightening bent aluminum in primary structural components. Either way, it's not as bad as it may seem. Good luck.

I agree...

db9469 said:

...... I have never liked the idea of straightening bent aluminum in primary structural components. Either way, it's not as bad as it may seem. Good luck.

Click to expand...

...but in this case the stresses are a lot lower at the tip.

Heck, the bay just inboard has had a large chunk of the skin removed for a landing light - with essentially no reinforcement of the edge of the hole...

Thanks for the comments. I have given this some thought and I am going to use this as an opportunity to further my education and attempt to straighten out the leading edge skin and replace the rib myself. I figure if that doesn't work to my satisfaction using body mallet/hammer and an assortment of dolly's, I have the other suggestions to fall back on. I have an extra rib to use as a gauge for shaping the leading edge. Working slow and methodically, I believe this should be an easier fix than I originally thought.

I am a little concerned with removing the rib. Drilling out the universal rivets that attach the leading edge rib to the main spar web with the top skin is riveted in place is going to be a challenge for me. My rivet drill-out technique still isn't that great. So, removing these rivets will take longer for me than straightening out the LE skin We'll see.

Another question for the group, do I run the risk of thinning the skin while striking it with the mallet/hammer? I assume the "strikes" being backed up by the dolly are akin to using a rivet gun/bucking bar combination. Just use short/light strikes until I get the desired shape, right? Opinions please.

I hope to get back at first of next week. I'll try to update this thread with my progress.

Thanks again.

dont removue entire rib

I wouldnt remove the entire rib. just drill out the several rivets aft of the damage . trim off the rib at the formed stiffener and rivet in a short peice of rib. id be suprised if this takes more than a hr or two for a repair. I would never consider replacing 6 feet of skin for this! Let us know how it turns out

Careful not to stretch the skin...

Dan,

If you use a body hammer and dolly you will stretch the skin. Hitting the skin between two metal objects will displace material and thin it. Auto body repairmen use a hammer and dolly combination but they also use shrinking techniques to deal with the stretching of the material. Usually involving heating with a oxy-acetylene torch creating a high spot, hammering down and then quenching with a wet rag. Since this is out of the question in this case I would suggest using a soft mallet with a dolly or a body hammer with a piece of shaped wood for the inside oh the leading edge. You just want to push the material not compress it. Light taps will give you the best results.

Good Luck!

Steve

Hammer and shot bag.

Small and light hammer-----plastic face mallet would be good.

Go slow-------maybe even practice on some scrap that you bend up in a manner similar to the damage on your wing.

Good luck, keep us posted as to how it goes.

If you sacrifice the rib...

snoopyflys said:

..... Drilling out the universal rivets that attach the leading edge rib to the main spar web with the top skin is riveted in place is going to be a challenge for me. My rivet drill-out technique still isn't that great. So, removing these rivets will take longer for me than straightening out the LE skin We'll see.
....Thanks again.

Click to expand...

...sometimes a grinding bit on a Dremel can be used to remove most of a rivet from one side.

In this case, I think I would drill out all of the skin rivets, and then cut most of the rib away with a small cutting wheel on a Dremel, just leaving the flange attached to the spar. The rivet can then be ground away, with the remaining flange protecting the spar. CherryMax rivets can be used to attach the replacement rib if access is too difficult for a rivet gun.

Not all rivets need to be drilled out to remove...

snoopyflys said:

I am a little concerned with removing the rib. Drilling out the universal rivets that attach the leading edge rib to the main spar web with the top skin is riveted in place is going to be a challenge for me......
Another question....do I run the risk of thinning the skin while striking it with the mallet/hammer? I assume the "strikes" being backed up by the dolly are akin to using a rivet gun/bucking bar combination. Just use short/light strikes until I get the desired shape, right? Opinions please.

Click to expand...

First let me say how sorry I was to see this. I dropped an aileron in the paint booth last week; only a small dent but it made my stomach flop. You must feel terrible.

FWIW, I'd just splice in a little bitty section at the nose of that rib, from the rear edge of the stiffening bead forward. Use your extra rib for a donor or quickly hammerform what you need. The blank would look like the image on the right. Note the joggled flanges.



Simple hammerform work:

http://www.vansairforce.com/community/showpost.php?p=291273&postcount=6

As for straightening skin, start with a homemade wooden mallet with a smooth dome face roughly matching the desired skin curve. Use many small hits evenly applied; any big hit will stretch a dome. Better yet, push out the majority with short length of large diameter pipe. No shot bags; they're for stretching. For the small stuff, yes, hitting "on dolly" compresses metal between the hammer and dolly faces, thinning it, forcing it sideways, and raising a dome. You want to hit slightly "off dolly" to remove wrinkles and dings. I don't think there will be much shrinking required. Hope not; 2024 T3 or T4 is hard to shrink. Worst case you tap a slight inward dome to get rid of the excess metal and use a little filler.

Have patience and think before you hit. Metalworking is fun.

DanH said:

First let me say how sorry I was to see this. I dropped an aileron in the paint booth last week; only a small dent but it made my stomach flop. You must feel terrible.

FWIW, I'd just splice in a little bitty section at the nose of that rib, from the rear edge of the stiffening bead forward. Use your extra rib for a donor or quickly hammerform what you need. The blank would look like the image on the right. Note the joggled flanges.



Simple hammerform work:

http://www.vansairforce.com/community/showpost.php?p=291273&postcount=6

As for straightening skin, start with a homemade wooden mallet with a smooth dome face roughly matching the desired skin curve. Use many small hits evenly applied; any big hit will stretch a dome. Better yet, push out the majority with short length of large diameter pipe. No shot bags; they're for stretching. For the small stuff, yes, hitting "on dolly" compresses metal between the hammer and dolly faces, thinning it, forcing it sideways, and raising a dome. You want to hit slightly "off dolly" to remove wrinkles and dings. I don't think there will be much shrinking required. Hope not; 2024 T3 or T4 is hard to shrink. Worst case you tap a slight inward dome to get rid of the excess metal and use a little filler.

Have patience and think before you hit. Metalworking is fun.

Click to expand...

Dan,

Let me just say that I said a few choice words, dropped everything and stood in the street for a bit hoping someone would run me over. But VAF is pulling me through this . Thanks alot. I am a little confused, when you say "..splice in a little bitty section at the nose of that rib" are you saying cut out a piece of flat aluminum and rivet it to the face or flange side of the rib? Do I use the damaged rib flanges to re-rivet the skin or fab new ones as part of the splice you mention?

If you're asking how to make a rib from scratch, there's a nice 6 part video on the EAA website under Hints for Homebuilders titled "Sheet metal ribs from scratch". The link below is part 1.

http://link.brightcove.com/services/player/bcpid1431564069?bclid=1432790122&bctid=1772030477

snoopyflys said:

Dan, Let me just say that I said a few choice words, dropped everything and stood in the street for a bit hoping someone would run me over.

Click to expand...

I'll bet. My compliments...a tough break, but you're not whining.

....when you say "..splice in a little bitty section at the nose of that rib" are you saying cut out a piece of flat aluminum and rivet it to the face or flange side of the rib? Do I use the damaged rib flanges to re-rivet the skin or fab new ones as part of the splice you mention?

Click to expand...

You won't re-use any old bent parts. The new nose section would have its own new flanges. And you don't have to do it at all. Try this:

(1) drill out all the skin-to-flange rivets from leading edge to spar, top and bottom. Use the "drill the head and pop it off with a punch" method. Drill a 1/4" hole in the toe of a spare bucking bar. Position the hole over the shop heads of the rivets and use the punch to knock them out from the manufactured side. A helper is good here. A 3/32 punch for your rivet gun is marvelous.

(2) pull the rib out of the skin. Yeah, it's still attached to the spar so you'll bend that flange just a little. You only need to swing the nose end of the rib out far enough to reach inside and work the leading edge skin. However, at this point you have good access to remove the rib-to-spar rivets. You could just buy a new rib instead of forming a new nose for the old one. If you don't have a rivet removal tool for universal rivets, buy one

(3) if you're going with a shop-made rib nose, cut off the damaged section of the old rib. I'd cut right at the aft edge of the stiffening bead.

(4) hammerform a new rib nose. It has its own a new flange and a joggled strip for riveting to the original rib.

If you're asking how to make a rib from scratch, there's a nice 6 part video on the EAA website under Hints for Homebuilders titled "Sheet metal ribs from scratch".

Click to expand...

Way to go Larry! That's the ticket.

I watched an old time metal man who straightened an RV-8 wing out after a bird strike. When he was done you could absolutely not tell whatsoever that a bird hit it. He made a wood block form the shape of the leading edge and along with some wood blocks and a small bottle jack, popped the damage out by using the wing spar as the floor for the jack. After that he used a "spoon" and a leather block to smooth out the creases. Took him about an hour to do. What ever you do, do NOT take a hammer to it as others have suggested. My buddy's RV-8 was damaged much worse than this is, with a crease on an adjoining rib. The damage was just outboard of the right fuel tank.

UPDATE - 99% Good as New

Since I originally posted here about what I believed to be an impossible task, the support received here both public and private has helped me get over this latest of many hurdles. I have successfully restored my bent leading edge to almost like new status (except for riveting). Here are the basic steps I followed;

1. Removed all of the AN426AD3-3.5 rivets from the top and bottom skin to damaged rib using a #40 drill bit mounted in a rechargeable drill. I felt I had better control with this drill as the variable trigger allowed the bit to turn much slower, making it easier to start and maintain center of the rivet being drilled out. The trigger on my air drill is a bit more unforgiving here.

2. Once all of the skin rivets were removed, I carefully pulled the rib outboard to expose the shop heads of the rib to spar web.

3. I used a Dremel tool with a grinding/cutoff wheel to remove the shop heads, using the rib flange as protection for the spar web.





4. After the shop heads were removed, I used a punch to locate the center of each rivet to prepare each rivet for drilling.

5. Using a #40 drill bit to drill out the center of each rivet, I drilled just deep enough to get a #40 punch into the hole. For the top and bottom rivet shop heads, I used a angle drill attachment I borrowed from a fellow builder. This is an amazing tool that I will be adding to my tool box as I am sure I will need one again.

6. Using the punch and a rubber mallet, I tapped the drilled universal rivets out of the rib. I was surprised to see no damage to the hole. I must admit this was my biggest mental block of the effort. FUD (Fear, Uncertainty, Doubt) factor. Big confidence builder see this work out.

7. Turning my attention to the bent leading edge, I managed to hand-massage out about 60% of the bent skin. The creases (not sharp bends) proved to be rather stubborn.



Here is a test fit of the replacement rib.



8. Taking a clue from one of the many suggestions, I fabricated a leading edge form from the scrap MDF left over from building the wing cradle. I sanded it down to match the replacement rib LE shape and shortened it to allow a bottle jack to fit between the form and the wing spar.



9. I placed the bottle jack on the 2x4 block to spread the load on the spar web. But the jack would not move when actuated. So, I resorted to plan b, I used an old scissor jack to force the LE form into the skin leading edge. I found that if you are not aligned with the cord line of the wing, the LE form will cause the skin to oil can. This may have been caused by the fact the landing light cut out reduced the strength of the LE. Not totally sure, maybe one of the engineers or AP guys/gals on the VAF can help shed some light on this.

10. Applied pressure to the LE with the form and scissor jack to the point where I felt the shape was close to matching the form.

11. Using a plastic 1.5lb deadblow hammer, I lightly tapped the skin to get the shape back.

12. Removed the LE form and jack. Worked the skin a little more by hand. I kept this up until the rib fit and the skin to rib holes lined up.





Whew!

After all of this, I still have a slight crease and a ?pimple? on the bottom skin near the LE where the damaged rib dug into the skin. The pimple is about the size of a pencil lead and the crease is about 1/32 high by about 1 to 2 inches long. Not sure how to get these out/repaired or leave them alone.



Any suggestions?

Once again, thanks to all who have replied. This is one of the many reasons why I chose to build an RV. The support group and the collective knowledge/experience is just simply amazing.

Keep sharing, we all benefit from each and every one.

Dan,

I applaud you for making lemonade out of lemons. Most of us might have just given up. Fantastic job you've done fixing the problem!

greg

That's nice work....well done!

The crease and pimple should work easily with a hammer and dolly (or slapper and dolly). Remember, to shrink you hit off-dolly. Off-dolly = dull sound. On-dolly = ringing.

Excellent recovery Dan - I think you are learning the real art of building now - how to fix problems! It's no about building perfect the first time - it is how you can recover from "less than perfect".

Paul

Nice work Dan. That wing will end up being a case where no one will every know unless you point it out to them.
I knew you'd never be able to give up that angle drill once you got your hands on one!

extremely impressed by this recovery, well done!

Nice Job!

Very impressive--you are a true craftsman!

Skyking902001

DanH said:

That's nice work....well done!

The crease and pimple should work easily with a hammer and dolly (or slapper and dolly). Remember, to shrink you hit off-dolly. Off-dolly = dull sound. On-dolly = ringing.

Click to expand...

Thanks Dan. You've done some really nice work yourself and offered some helpful suggestions. Not quite sure I fully understand the on/off-dolly you mention. If I place the dolly on the inside of the leading edge over the crease, and strike the crease with a body hammer, is that considered on-dolly and why doesn't that action shrink the metal? I'm confused and not clear or just plain dense.

Thanks to everyone who replied as well. It really means a lot to hear/read from others that you are building/repairing is ok or doing well. Especially since this is my first rodeo.

snoopyflys said:

Not quite sure I fully understand the on/off-dolly you mention. If I place the dolly on the inside of the leading edge over the crease, and strike the crease with a body hammer, is that considered on-dolly and why doesn't that action shrink the metal?

Click to expand...

Sometimes the names we use can mislead. In this case shrinking and stretching should perhaps be called "thickening" and "thinning".

Let's walk through the basics. Imagine something knocked a small raised dent in your sheetmetal (your pimple is a good example):



The key is to realize the dent is stretched metal....it is now thinner in the area of the dome.

Ok, now place a steel dolly under the dome and hammer from the top:



Notice the arrows. As you drive the dome downward toward the dolly, you are actually forcing metal back into the stretched area. It gets thicker as the dome gets shorter. The sound you hear each time you strike with the hammer is rather dull. That's because the metal immediately under the hammer face is not in contact with the dolly. It is "off-dolly".

OK, so you're tapping and grinning because the ugly 'ole dent is going away. As the metal gets almost flat the sound changes. Now it has more of a ringing tone because the metal under the hammer is coming into contact with the dolly face...it's now "on-dolly". Metal compressed between the hammer face and the dolly flows outward:



Since it is almost flat you keep tapping....but to your horror the small dent is replaced with a gentle raised dome:



Yep, you went too far. On-dolly hammering thins the sheet, so it domes upward.

You can't see both sides of the sheet and hammer with accuracy at the same time, so listen to the dolly. Dull is off-dolly and thickening the sheet. A ringing bell is on-dolly and thinning the sheet.

There are a lot of variations on the above, the details being curved surfaces, curved dollys and rounded hammer faces, and the relative positions of each in relation to the metal feature you're working. However, most of it is common sense if you have the basics in hand, and you seem to have plenty of common sense craftsmanship.

Thanks Dan, that is very helpful.

I remember early on in my project, I dimpled a piece that I didn't want to dimple, and thought I would just be slick and use my flat faced rivet set and 2X gun to flatten it out, against my backriveting plate. Ended up replacing the piece... didn't do that again!

FYI - when you inevitably do what I did, you get better results by using a squeezer to squeeze the dimple (one time!) between the two flat faced dies.

Dan - Many, many thanks. Your explanation of on/off dolly makes perfect sense. I especially appreciate your illustrations as they help me visualize the process and techniques employed.

Greg - I had a similar dimpling issue, right piece dimpled the wrong direction. I found on the VAF and confirmed by VANs that you could reverse the dimple once using the squeezer. Saved me a rib.