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-   -   Aluminum skin crack (https://www.airforums.com/forums/f381/aluminum-skin-crack-201170.html)

dvgofaz 09-23-2019 03:28 PM

Aluminum skin crack
 
2 Attachment(s)
I know the aluminum split over the door is not a new thing, but, I'm wondering what creative ideas 'the village' may have for making a not too unsightly repair of this one.
I'll drill the 1/8 stop holes at each end of the crack, apply some jb weld or alumi-weld to the split, but does anyone have an idea for an attractive(?) patch I can apply??
My wife suggested an arch shaped patch that traveled around the corner, and another on the left side to match so they look like a set.

PeterH-Airstreamer 09-23-2019 04:12 PM

Quote:

Originally Posted by dvgofaz (Post 2291820)
I know the aluminum split over the door is not a new thing, but, I'm wondering what creative ideas 'the village' may have for making a not too unsightly repair of this one.
I'll drill the 1/8 stop holes at each end of the crack, apply some jb weld or alumi-weld to the split, but does anyone have an idea for an attractive(?) patch I can apply??
My wife suggested an arch shaped patch that traveled around the corner, and another on the left side to match so they look like a set.


Before looking for a repair solution, I would investigate the cause first. Take a good look above the lower belt line behind the propane tanks to check for ripples, dents or movement of the skin. You may have a front skin/body separation often caused by excessive weight distribution bars (1200 pounds and up) in conjunction with heavy duty (1 ton) tow trucks.

Lumatic 09-23-2019 06:55 PM

i agree with the above post.

Consider the if you can't beat them join them approach you could cover the crack with a decal or an aluminum patch. If you search "Show us your patches you will find a bunch of ideas.

You could also bondo the crack and finish with a good aerosol aluminum spray and a clear coat such as Nylac.

dvgofaz 09-24-2019 12:06 PM

No signs of anything misshapen in the skin anywhere else. I did a methodical hand wash a month ago after we did 10,000 miles from AZ to Maine and back and saw nothing out of the ordinary.
The wind grabbed the door a few days ago and gave it the hardest slam imaginable and that's when the crack appeared. I thought the frame would be way too solid for the stress to spread to the skin but maybe not. Given that all else looks ok I'm thinking that may have been the cause.
Will a 'bondo' type fix with alumiweld be sufficient or will it need a scab over aluminum band-aid to keep the filler from coming out?

rmkrum 09-24-2019 02:00 PM

Aluminum skin crack
 
Bondo won’t stay over a crack, period. Nor will it hold a crack together and prevent spread. Paint matching to bare aluminum is a total pain as well.

“Stop drill” a small hole at the ends of the crack, and cut a custom patch to suit. Use a paper pattern to determine how you like the look and to allow ‘flipping’ it to make a symmetrical patch for the other side if need be.


Put sealant under it as well. Drill holes and use Cleco clamps to keep it aligned. Put on with Olympic rivets dipped in sealant. Discard the O-rings under the heads of the rivets if any. They fail and leak.

For symmetry, I’d do both corners as suggested previously.

Airstream skin repairs at just like aircraft or boat aluminum skin repairs, BTW.

Bigdaddy_2 09-24-2019 05:23 PM

I had the same crack and once I removed the gutter above the door I discovered several broken rivets. They allow to much twist in the door frame with the resulting cracked. Used olympic rivets to repair broken as well as putting a patch over crack. Used silkaflex 221 under patch so no chance for leak. Trick is to get a small piece of aluminum skin for repair. I used a 12 × 12 piece that wraps around the frame curve

cwf 09-26-2019 10:02 PM

Busted rivets. Check squareness of door in frame.

These long trailers can take a beating.. for a while.

Was door slammed open or closed?

Looking at picture At the rivets looks like whole right side of frame was moved because there is a lot of pressure on the other rivets

perryg114 09-27-2019 08:07 AM

The cause is the sharper corners around the door on the new trailers and the constant opening and closing of the door. I would make a bow shaped arch that goes over the entire door and rivet it to the top. A better repair would be to remove the door frame and do this. The bow could even be on the inside at that point. If you don't add some structure it will get bigger and bigger. That corner and the door opening in general is what is called a stress concentration. The door frame should help replace that lost structure but it looks like it is not getting it done. Adding more rivets around the frame can help as well. AS using fewer rivets on the newer trails just compounds the problems. I don't think they will last as long as the older trailers. You will also find loose rivets to the upper right of the door. This is coming from an aerospace engineer and yes I have studied aircraft structures. An Airstream would not fly for long if it had wings.



Aerowood on here is another good resource.




Perry

dvgofaz 09-28-2019 09:58 AM

Thanks for the suggestions, yes the door slammed shut really hard. Had it gone the other way I would have expected to see a hole in the skin beneath the latch that holds the door open.
Today is the day as the rains have stopped and I can pull the gutter and see whats going on. Im thinking I'll end up with a pair of riveted 'eyebrows' over the corners of the door. I have a 15x15 piece of skin that was left over from a body repair(not mine) at my local AS shop.

PeterH-Airstreamer 09-29-2019 08:25 AM

Quote:

Originally Posted by perryg114 (Post 2293108)
.... That corner and the door opening in general is what is called a stress concentration. The door frame should help replace that lost structure but it looks like it is not getting it done. ....

Perry


Like you said, it looks like is is not getting it done. The frame rivets may not be hitting the skin and are partly just for decoration, due to a poorly executed cut out. If this would be my trailer, I would pull the door and investigate further, reinforce if needed AND continue to keep a close eye on the front belt line.
IMHO the door slam did not cause the crack, it just was the last straw to release the existing stress on the skin.

dvgofaz 09-30-2019 11:35 AM

Thanks for this, as you thought I would, I found a half dozen holes where I should have seen rivet heads when I pulled the rain gutter. There is definitely stress there as a couple of the rivet studs don't want to be tapped through with my punch. I haven't 'forced' the issue.

Pull the door frame huh? Drilling out all those rivets seems do-able....but do I need to cut holes on the interior wall to release the mounting bolts?

Bigdaddy_2 09-30-2019 05:08 PM

Stick with replacing the broken rivets and patching the crack. Drill out any rivet "stem" that will not punch out. No need to remove door frame.

dvgofaz 09-30-2019 06:12 PM

Thanks BigDaddy, just finished doing that very thing.
Next I'll get underneath and do a more thorough check of the frame/skin. I don't have crawl room right now but whether something is amiss there or not, the repair needed to be taken care of.

J. Morgan 09-30-2019 09:42 PM

Quote:

Originally Posted by dvgofaz (Post 2292108)
No signs of anything misshapen in the skin anywhere else. I did a methodical hand wash a month ago after we did 10,000 miles from AZ to Maine and back and saw nothing out of the ordinary.
The wind grabbed the door a few days ago and gave it the hardest slam imaginable and that's when the crack appeared. I thought the frame would be way too solid for the stress to spread to the skin but maybe not. Given that all else looks ok I'm thinking that may have been the cause.
Will a 'bondo' type fix with alumiweld be sufficient or will it need a scab over aluminum band-aid to keep the filler from coming out?



Bondo won't fix that, Put an "eyebrow" patch over the crack like your wife recommended, it'll look like an airliner window.

Vey few people will know you've done anything apart from stock if you do a nice clean job.

J. Morgan 10-01-2019 11:19 AM

As to what caused that, it could have just been a burr or a divot left from when the radius was cut leaving a stress riser. I wouldn't take my trailer apart chasing gremlins when the eyebrow will fix the issue at hand either way.

perryg114 10-02-2019 07:19 AM

Whatever you put in there as an eyebrow it should be riveted or bolted to the door frame. Also smooth all corners and edges on the old and new sheet metal. Ragged edges which are common in RV's won't fly if it was a plane. Drill a hole at the end of the crack before you put it back together. You will probably find that crack started where the metal was jagged. It also won't hurt to put some epoxy like JB weld between the new eyebrows and the skin. This acts like a continuous rivet.


All the loads that were carried by the skin before the door was cutout should be handled by the door frame but the frame needs to be well attached to the skin with no missing rivets.



Here is some stuff on aircraft repair. Remember if it was built like and aircraft, it would not be failing.



https://www.aircraftsystemstech.com/...structure.html



Perry

J. Morgan 10-02-2019 12:31 PM

If it was built like an aircraft it would cost a million bucks......

Bigdaddy_2 10-03-2019 03:50 PM

JB Weld won't flex like Silkaflex caulk. Use generous amount under the patch and rivets every 2-3 inches around patch. Dip rivet in caulk when installing to insure a good seal.
Eyebrow attached to skin works fine.

Bigdaddy_2 10-03-2019 03:58 PM

1 Attachment(s)
My patchAttachment 353488

cwf 10-03-2019 10:15 PM

I did not have to cut the wall out behind the frame hinge mount on our 1999. I slowly removed the top screws and it continued to back out.. I slowly turned the screw until I could grab with pliers or hand and push the screw in. I then tightened the screw again... and it did tighten.

If it moves, then you will probably have to cut the wall.. so, this is a key step.

I then backed out the lower screw, repeating the above steps... once loosened, I was able to remove the top screw and install a longer 4" bolt (1/4" coarse thread on ours) to capture the nut in the wall.

The door is HEAVY. Don't remove by yourself.

Repeat on the lower screw.. install another bolt as above... Once you verify the nuts are captured, perform same on lower hinge.

Once you have the bolts in place, you can slide the hinge and door away from the frame. Now remove one bolt at a time when you have the door 2 inches or so..Now you can remove one bolt at a time and reach behind the hinge to replace the original screws into the door frame. When the bolts are removed and screws have been replaced to hold the nuts in place, you can clear the door away and continue with your work. Reverse the process to reinstall.


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