Minor crack in aluminum- best way to fix it? Photos attached!

[StreamingB]

Hi guys,

We did a thorough look at the airstream we just purchased and it looks like there is a minor crack in the aluminum, where the rock guard attaches. Is there a more cost effective easy way to fix this (without replacing the panel)? We were thinking maybe silicon?

Please let me know your thoughts! Advice is welcomed and much appreciated.

[A W Warn]

Don't use silicone caulk anywhere on your trailer. If you do it will make future repairs more difficult (nothing adheres to silicone)

A photo would help

[StreamingB]

Hi there,

I thought I did post a photo- weird. Still adjusting to the forum. My apologies.

[AlinCal]

Well thats pretty minor but still of concern, lets see if any metal gurus show up here but if it is indeed a crack then drilling a very small hole in the end of it to stop the progression and then using some sikaflex or vulkem to seal it may be in order.

[A W Warn]

I'm definitely not a metal guru.

My opinion:
I think that crack was caused by something hitting hard, not a stress crack.
I would drill a very small hole at each end of the crack and caulk it then keep an eye on it. Silver Parrbond or gray urethane caulk will would be my choice.

If the crack starts to extend, my choice would be to add a patch over it.
Use the search function for decorative patch if that might work for you.

[jdalrymple]

I would remove the bracket and plate,or patch, over the cracked area with new material. Sealing between the new plate and skin with Vulkem. Re-install the bracket on the plate.

Regards,

JD

[uncle_bob]

Hi

The first question is why did it crack? The bracket should be riveted into something more sturdy than the skin. If it's simply (miss)mounted to the skin, further flexing will occur and the skin will degrade further.

Patching with an aluminum compatible epoxy is probably the most easy approach. It may not be the best looking ....

Bob

[Kevin245]

That appears to be a tear rather than a crack. I would remove the bracket, drill the crack ends, and apply an oversized patch. Then reinstall the bracket.

[Coopdejour]

Back in the day, going through airframe repair school in the Air Force, I think, as previously mentioned, it was called stop drilling. Drilling a tiny hole on each end to stem any further progression of the crack, hopefully. And then proceed to seal it with a sealant that works well on an Airstream, which I am not familiar with, but learning from some of replies to your dilemma.
Any visible damage to the rock guard in that area that could have caused the crack? I know that this was also previously mentioned, but at least it may provide the why.
My concern would be doing more than what may be needed to address the problem. And monitor the site as suggested.
Just the beginning of the bumps to come, but we enjoy our unit.

[AtomicNo13]

I have an identical tear curbside.
I'm using a clear non sliicone gutter sealant.
It's forever flexible, and the stickiest caulk I have used..

[steverino]

Stop drill it. It removes the stress at the end of the crack that would otherwise cause the crack to grow.

[Silvr_Bullet]

Originally Posted by StreamingB

Hi there,

I thought I did post a photo- weird. Still adjusting to the forum. My apologies.Attachment 315868

Hard to tell from photo but is the bracket cracked also?

[lyleapgmc]

Originally Posted by steverino

Stop drill it. It removes the stress at the end of the crack that would otherwise cause the crack to grow.

Stop drilling is standard practice for cracks and tears that may continue to grow. It isn't at all difficult. A small drill bit is all that is needed, like 1/8" or even smaller. After drilling use a slightly larger drill bit held in your hand to deburr the newly drilled hole. It would be ideal to deburr both sides of the hole but in most cases this is not possible.

[Travel Pro]

Originally Posted by lyleapgmc

Stop drilling is standard practice for cracks and tears that may continue to grow. It isn't at all difficult. A small drill bit is all that is needed, like 1/8" or even smaller. After drilling use a slightly larger drill bit held in your hand to deburr the newly drilled hole. It would be ideal to deburr both sides of the hole but in most cases this is not possible.

Other people here will have better answers than me on the best sealant.

On the other hand, stopping a crack properly requires stop drilling. Look at the width of the crack and then select a drill bit that is SLIGHTLY bigger in diameter than the width of the crack (it does look like a 1/8" or close would work for that crack). Drill in at both ends and be sure to control depth so that you don't push through the thickness of the skin more than one diameter of the drill bit (the point is that you want to get a true diameter round hole but not drill through to and damage what is behind the skin you are repairing). Deburr the outside of the holes you drill at each end of the crack using the next largest size drill bit twisted with finger pressure only, not a drill). The drilling needs to be done so that the closest edge of the drilled hole to the crack actually cuts into the end of the crack and the center of the hole is beyond the end of where the crack ended. To see what I mean, draw a line on a piece of paper, then draw a circle where the tip of the line just barely penetrates the edge of the circle on the line side of it (kind of looks like a lollipop on it's side).

I agree with one of the other responders that you need to figure out what caused the crack. More support like removing the bracket and adding a support plate behind it sealed/bonded to the damaged skin sounds like it might be a good idea (only after you do the stop drilling to the existing crack). You will need to make it larger than the base of the bracket or it will not add support (actually adds stress to the area in my opinion if not sized properly. Good luck.

[steverino]

I have seen cracks like this formed on the front of other units. It’s possible this resulted from frame stresses caused by driving over a severe grade transition such as a steep driveway with the WD bars attached. But hard to know for sure.

[BDowse]

This is what I used after drilling out old rivets and installed new rivets. Also drilled a larger hole in the aluminum rock shield to relieve stress. Don’t Over tighten the cap nut to give the shield room to flex.

[BDowse]

J-B Weld available at any hardware store

[BoMan]

My wife and I purchased a 27' 2014 International Sterling which we love! I don't want this to freak you out, but I wanted to add my 2 cents because cracks and stress dents in the outer shell can be a precursor of another underlying issue. Our AS goes to Jackson Center every spring for a full check up. (that is just the way we roll). Before our last visit this spring, I was waxing and I opened the rock shields to clean and wax behind. Lo and behold, the outer shell had a dent in it! No damage whatsoever to the rock shield. Well, while at Jackson Center, I had the techs look at it and the conclusion was the front struts holding the shell to the frame had sheared off! What! We ended up having the guys open up the inside front skin to reveal that, yes indeed, the tiny rivets holding the tiny "L" bracket that holds the support struts for the outer shell had sheared off. What happens next is as the frame flexes while driving over bumps and pot holes, it causes the outer skin to flex, thus the "dent". The repair was a substantial "L" bracket with substantial bolts to hold it firmly in place. If left un-repaired, the situation gets worse and the aluminum can tear and then water can infiltrate and... well, you can guess the rest. If you look at the threads on "shell separation from frame", you will see this is a common problem especially with the longer units. Now I am not saying this is what is going on with your unit, but fore knowledge is good as you inspect your trailer in the future and keep an eye out for stress dents and tears in the outer shell, especially in the front and rear.
BoMan

[GM Airstream]

Originally Posted by StreamingB

Hi there,

I thought I did post a photo- weird. Still adjusting to the forum. My apologies.Attachment 315868

Well... you have a problem...

The metal bracket is called a hat section so that the bolt can be spaced away from the sheet metal.

If you notice the crack is right along the same line as the bolt center... thus something is flexing the sheet metal as the bolted section puts stress on it.

You can try to stop drill it.. but its not going too... as what we see...

It appear that they used some oversized pop rivets to hold the hat section to the body metal. The crack appears to be along the bottom side of the hat section... which is causing the body metal to flex... it will contenue... what a lousy design.

To keep the crack from getting larger you need to give the body metal and the bracket some more support other than just the body alu.

Thus if you want to do it right... you should drill out the pop rivets... and remove the hat section... clean the metal under it.. check for small hair line cracks using the dye penatrant spot check... if found.. stop drill at the end of the crack.

You then need to make a doubbler plate to go over the crack section and existing pop rivets holes... here you would want to go with at least a piece of 2024 , 6061, etc... aircraft grade alclad... 0.032-0.050 thick... that you might get for free at the local airport FBO shop scrap cutoff pieces... and if you talk nice to them they might even sheer (cut) the scrap pieces to size for you...

The plate should extend at least 3/4 - 1 inch outside ...past the crack.. drill stopped area... making it rectangular... and giving the body metal some back up support... by taking the stress outside the existing teared area...

Do not use silicone.. it contains urea.. and will cause the alu to corrode etc... (best way to kill alu is to use silicone that is not designed for aircraft) Use the recommended sheet sealant that will not attack the sheet metal...

You only need to put it in /along the crack area... at least covering about 1/2 inch wide over the crack line... it will act as a seal...then...

Now you need to use some 1/8 in olympic cherry max rivets coated with sealant.... spaced about 1 inch apart (starting at the corner ) and at least 2-1/2 dia from the edge. (if you use 1/8 inch rivets.. it about 1/4 in...) Thus you may want to do the math and layout the plate so you get even spacing... Try to keep 'em in a streight line.. by pre drilling the plate and then attaching by drilling through the holes etc... Then use the rivet shaver to make it look factory

When done it will be noticed... as a second piece of metal attached... but it will transfer the stress to a larger area.. that shouldn't flex and crack.

Then finally re-locate the Hat section on top of the doubble plate... and again use the cherry max rivets... (don't use the same holes... hat section alu can be had at aircraft metal supply store... if you want to make new... shave when finished... and it will look professional...

You can do the same size doubbler plate to the other areas that airstream put the hat sections on to hold the rockshelds... to make it look like it was factory done...

good to go... and shouldn't have any more problems with the flexing of the body sheet metal...

hope this helps... to do it right.

[Ldytraveller]

Has exactly the same problem on my 1998 29 ft Excella. Removed the mounting bkt. Bought a piece of aluminium from Jackson Centre 6" x 6". Rounded the corners about a 1/4 " radius and siliconed and pop riveted it over the crack. Start the pop rivets on one vertical edge and work it around the corner. Then remount the bracket for the stone guard. hardly noticable when finished.
Ross