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Thread: Reparing Crumpled Aluminum

  1. #1

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    Reparing Crumpled Aluminum

    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:


    1. 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?
    2. 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.
    3. 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

  2. #2

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    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.

  3. #3

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

    Bert

  4. #4
    Mike Switzer's Avatar
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    There were a couple places online that had them in pdf format for download.

  5. #5
    cub builder's Avatar
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    Quote Originally Posted by BertP View Post
    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:


    1. 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?
    2. 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.
    3. 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
    Last edited by cub builder; 03-14-2016 at 01:18 PM.

  6. #6

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    Quote Originally Posted by cub builder View Post
    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

  7. #7
    cub builder's Avatar
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    Quote Originally Posted by BertP View Post
    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

  8. #8

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    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.

  9. #9

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    Quote Originally Posted by cub builder View Post
    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.

    Quote Originally Posted by Bob H View Post
    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.

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  10. #10
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    Quote Originally Posted by BertP View Post

    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

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