Reparing Crumpled Aluminum

[BertP]

Hi All,

I recently purchased a damaged home built (Cessna 182 copy) and I am looking for some advice on what to do with it. Specifically, I am trying to answer the following questions:



How does one determine if a sheet of aluminum on an aircraft is fixable or not? I have been told that aluminum doesn't tolerate having dents, etc bashed out of it the way you might fix the fender of a car. Is this true?
Assuming that the aluminum can be straightened, what tool(s) would a person use to bash the dents out? I was thinking of something like an air hammer (on gentle) with a soft head might do the trick but I can't seem to find such an animal.
I haven't taken the wing apart yet (it is one of the damaged parts) so I don't know if anything inside is damaged or if this is strictly a surface issue. How can a person tell if the damage is more extensive (spar, ribs, etc)? Yes, I do intend to get help from my local EAA chapter but I would like to figure out as much as possible before I invite anyone over to do an inspection. I don't want to waste anyone's time.


Thanks in advance for any suggestions.

Bert

[martymayes]

Hey Bert - one typically determines damage by visual inspection. Some aluminum can be straightened but it might be easier to replace, especially flat panels. Since it's a 182 clone, I'd recommend a Cessna 182 repair manual for guidance.

[BertP]

Thanks, Marty. I'll check around to see what I can find for a maintenance manual.

Bert

[Mike Switzer]

There were a couple places online that had them in pdf format for download.

[cub builder]

Hi All,

I recently purchased a damaged home built (Cessna 182 copy) and I am looking for some advice on what to do with it. Specifically, I am trying to answer the following questions:



How does one determine if a sheet of aluminum on an aircraft is fixable or not? I have been told that aluminum doesn't tolerate having dents, etc bashed out of it the way you might fix the fender of a car. Is this true?
Assuming that the aluminum can be straightened, what tool(s) would a person use to bash the dents out? I was thinking of something like an air hammer (on gentle) with a soft head might do the trick but I can't seem to find such an animal.
I haven't taken the wing apart yet (it is one of the damaged parts) so I don't know if anything inside is damaged or if this is strictly a surface issue. How can a person tell if the damage is more extensive (spar, ribs, etc)? Yes, I do intend to get help from my local EAA chapter but I would like to figure out as much as possible before I invite anyone over to do an inspection. I don't want to waste anyone's time.


Thanks in advance for any suggestions.

Bert

Bert,

You really need to spend some quality time with AC 43.13-1B (especially Chapter 4) and perhaps some time with an A&P mechanic that specializes in sheet metal. Some aluminum can be gently worked with a shot bag and small plenishing hammers. Working aluminum is typically performed as an incremental process. It also depends a great deal on the alloy and temper of the aluminum as well as the type of damage as to whether you need to add doublers or splices, gently hammer it back to shape, or replace it. All of AC 41.13 is available for free on line in .pdf format, or can be purchased in book form. As an aircraft repairman, this is your bible for acceptable practices.

-Cub Builder

[BertP]

Bert,

You really need to spend some quality time with AC 43.13-1B (especially Chapter 4) and perhaps some time with an A&P mechanic that specializes in sheet metal. Some aluminum can be gently worked with a shot bag and small plenishing hammers. Working aluminum is typically performed as an incremental process. It also depends a great deal on the alloy and temper of the aluminum as well as the type of damage as to whether you need to add doublers or splices, gently hammer it back to shape, or replace it. All of AC 41.13 is available for free on line in .pdf format, or can be purchased in book form. As an aircraft repairman, this is your bible for acceptable practices.

-Cub Builder

Thanks for the suggestion.

I downloaded a copy of the manual and decided, at first glance, that this is beyond my expertise. I think I will have to hire someone to teach me how do do this. I simply don't have enough experience to decide what is right and what is wrong.

Bert

[cub builder]

Thanks for the suggestion.

I downloaded a copy of the manual and decided, at first glance, that this is beyond my expertise. I think I will have to hire someone to teach me how do do this. I simply don't have enough experience to decide what is right and what is wrong.

Bert

Bert, this is what Experimental aircraft are all about; an opportunity to learn. Get with your chapter tech counselor and walk down your issues with him. Depending on his level of knowledge, he may be able to get you started down the right path. If not, get with an A&P that does sheet metal work and talk to him about working with you doing supervised/assisted repairs. Remember, you are in this to learn!

-Cub Builder

[Bob H]

Without actually seeing damage and not knowing where on the structure the problem occurred, it's impossible to give good advice, except that getting a knowledgeable technical person to look at it is smart.
Aluminum is more sensitive to local yielding than steel and more prone to initiation of fatigue cracks. If the damage is just cosmetic and in a low stress area, you might get away with minor check and straightening. But if it's in a wing spar that's more highly stressed, you don't want to pull a spar cap or web into place and inadvertently strain harden or preload the member to where it may crack sooner than later. You can learn much from a short time with a good metals guy.

[BertP]

Bert, this is what Experimental aircraft are all about; an opportunity to learn. Get with your chapter tech counselor and walk down your issues with him. Depending on his level of knowledge, he may be able to get you started down the right path. If not, get with an A&P that does sheet metal work and talk to him about working with you doing supervised/assisted repairs. Remember, you are in this to learn!

-Cub Builder

Very true. But, we are dealing with a damaged wing here so I am a bit hesitant to experiment very much with it. The consequences of a failed wing can be quite exciting, to say the least.


Without actually seeing damage and not knowing where on the structure the problem occurred, it's impossible to give good advice, except that getting a knowledgeable technical person to look at it is smart.
Aluminum is more sensitive to local yielding than steel and more prone to initiation of fatigue cracks. If the damage is just cosmetic and in a low stress area, you might get away with minor check and straightening. But if it's in a wing spar that's more highly stressed, you don't want to pull a spar cap or web into place and inadvertently strain harden or preload the member to where it may crack sooner than later. You can learn much from a short time with a good metals guy.

Those are some of the things I was concerned about. I understand that fixing crumpled aluminum isn't quite the same as bashing out the fender of a 50's Buick.

If it will help, I have added a couple if pictures. The damage is on the leading edge close to the wingtip. I have already removed the slightly damaged wingtip itself so it doesn't appear in the pictures.

5401540254035404

[cub builder]

If it will help, I have added a couple if pictures. The damage is on the leading edge close to the wingtip. I have already removed the slightly damaged wingtip itself so it doesn't appear in the pictures.


Yes, it's pretty well buggered. No doubt a couple of ribs and some skin material. I can't tell for sure from the pictures whether the spar is involved or not, or if so, how badly it's damaged. But this really is just the typical sheet metal repair done by A&Ps in shops all over the country every day.

You drill out the damaged panels until you run out of damaged panels to remove. Gently hammer them out flat to use as a template for the new panels. Order new aluminum of the same thickness, grade, and temper as what is being replaced. Depending on the hardness condition of the ribs, you either bump them back out, use doublers to splice/repair them, or fabricate new and replace. The spar will also need to be evaluated once it's properly exposed. Get with a good sheet metal guy. He can point to what all you need to drill out. Any RV builder knows how to drill rivets and can teach you how to do so properly. Then it's just a matter of deciding what to repair, and what to replace, then drilling and riveting.

Of course you can always hire someone to do it for you, but didn't you buy an Experimental so you can learn how to do this stuff?

-Cub Builder

[BertP]

Yes, it's pretty well buggered. No doubt a couple of ribs and some skin material. I can't tell for sure from the pictures whether the spar is involved or not, or if so, how badly it's damaged. But this really is just the typical sheet metal repair done by A&Ps in shops all over the country every day.

You drill out the damaged panels until you run out of damaged panels to remove. Gently hammer them out flat to use as a template for the new panels. Order new aluminum of the same thickness, grade, and temper as what is being replaced. Depending on the hardness condition of the ribs, you either bump them back out, use doublers to splice/repair them, or fabricate new and replace. The spar will also need to be evaluated once it's properly exposed. Get with a good sheet metal guy. He can point to what all you need to drill out. Any RV builder knows how to drill rivets and can teach you how to do so properly. Then it's just a matter of deciding what to repair, and what to replace, then drilling and riveting.

Of course you can always hire someone to do it for you, but didn't you buy an Experimental so you can learn how to do this stuff?

-Cub Builder

Most of that sounds like what I thought it might be. I wasn't sure about templates and if I could use the existing parts to create new parts from since some of them are so badly deformed.

The hiring I was referring to wasn't so much to hire someone to do the work but to hold my hand while I did it myself. I have no problem with getting my hands dirty, I just want to make sure that whatever I do, I do it correctly.

BTW I noticed that some of the tool suppliers have rivet removal tools. Are they of any value or is a person better off just drilling the rivets out by hand? The tools I have seen are basically a drill bit enclosed in a guide to control the angle and location of the drilling.

Bert

[Frank Giger]

I'd remove those rivets by hand.

From the looks of it that skin is nice scrap (don't throw it out!) and the ribs are going to need to be replaced. Elongating a hole in scrap isn't a problem.

The thing is that aluminum isn't prohibitively expensive and widely available in the grades required for replacement.

It looks really dire, but as we know it's really all about the spar.

[edit]

And yes, I'd replace it as a patch, putting a seam along the first undamaged rib rather than re-skin the whole thing.

[martymayes]

Most of that sounds like what I thought it might be. I wasn't sure about templates and if I could use the existing parts to create new parts from since some of them are so badly deformed.

The hiring I was referring to wasn't so much to hire someone to do the work but to hold my hand while I did it myself. I have no problem with getting my hands dirty, I just want to make sure that whatever I do, I do it correctly.

BTW I noticed that some of the tool suppliers have rivet removal tools. Are they of any value or is a person better off just drilling the rivets out by hand? The tools I have seen are basically a drill bit enclosed in a guide to control the angle and location of the drilling.

That's a BIG project Bert. Likely require jigs to put it back together. By all means, utilize the tools and aids for removing rivets. It's very easy to cause a lot of damage during disassembly by oversizing or elongating holes in the structure.

[cub builder]

Most of that sounds like what I thought it might be. I wasn't sure about templates and if I could use the existing parts to create new parts from since some of them are so badly deformed.

That's the nice thing about aluminum. you can bump out some pretty wadded up stuff well enough to use as a template.


The hiring I was referring to wasn't so much to hire someone to do the work but to hold my hand while I did it myself. I have no problem with getting my hands dirty, I just want to make sure that whatever I do, I do it correctly.

BTW I noticed that some of the tool suppliers have rivet removal tools. Are they of any value or is a person better off just drilling the rivets out by hand? The tools I have seen are basically a drill bit enclosed in a guide to control the angle and location of the drilling.


I view projects as a good excuse to buy tools. ;) So here's your first educational opportunity. Try drilling some rivets out by hand, then try some with a rivet drill guide. You can probably borrow a rivet drill guide (rivet removal tool) from an RV builder to give it a try, or ask your Tech Counselor or A&P that's going to oversee to bring along a drill guide so you can try it and ask for some instruction. I would use the guide for the rivets where they are riveted to something you think you might be able to re-use.

I really prefer using an air drill with a feathering throttle. It's just easier than using my heavy DeWalt cordless. All that weight turns into inertia as soon as the bit pops through. But either will work.

-Cub Builder

[Bob H]

I'd call that damage severe and as others indicated, all effected skin panels need to be replaced and the damaged ribs addressed also. But the real concern is with the spar in the impacted area. After opening the skin, you should be able to access spar and determine damage to web or caps and straightness. I would get a knowledgable repairman to look at it with you and itemize what needs to be done and sequence of repairs. When visually inspecting damage, you want to use a 10X manifying glass in questionable areas to look for cracks or dye pen with developer. I'd also check replacement price for wing half should the damage be more extensive than anticipated.

[martymayes]

I'd also check replacement price for wing half should the damage be more extensive than anticipated.

being a homebuilt, not sure that is an option. For sure, repairs could be as labor intensive as building a new wing.

[BertP]

Thanks for all of your replies. I hope to have our local Tech rep come out to my place for a visit soon so I can get some pointers on what I should and shouldn't do.

I have already bought a bunch of shop tools and a used Sioux drill so I am slowly adding to my collection. I know I will need a riveter, some bucking bars and a bunch of rivets but that's a ways off.

I guess I'll start pulling pieces off and see what I find. It'll take me a bit to get my garage ready but I hope to start the serious dismantling soon.

I don't think I could buy a new wing even if it was allowed. While this aircraft is a Cessna 182 look alike - and it really does look like one - it was hand built from scratch so I don't think a 182's wing would work. Nice thought, though :-)

Bert

[cliffo]

I would check out the measurements for a Cessna wing , the builders had to get their specs from somewhere to make a clone so you might be surprised. I like the challenge of repairing it and it's such a skills building activity, but if you have a tweaked spar you're looking at a lot of work. I'm a pretty good scrounger and check out any surplus stores, I found MIL-SPEC rivets at one along with other tools at like 20% of regular retail. Do definitely seek out the pros for advice, I had the pleasure of watching a couple guys in Edmonton Alberta who rebuild Beavers, Otters and the like,they had the throttled air drills and they wasted no time. Like the guys are saying any device or gadget that makes your work easier or more accurate, like the drill guides is money well spent , I'm sure some journeyman will steer you right. Good luck with your endeavor and I hope you find the pleasure and satisfaction of repairing it yourself.