Anyone have any issues with welds on their metal fuel tank

Aeronca Sedan Airplanes
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joea
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Anyone have any issues with welds on their metal fuel tank

Post by joea » Tue Nov 19, 2013 08:35

Its just been brought to my attention that at least one Sedan owner had a very dangerous situation with their metal fuel tank in the airplane.

Not going to name the person right now but they bought the tanks brand new from the TC holder during a complete restoration of the Sedan. About 200 hours later fuel started dripping from the LH main tank... They pulled the wing, removed the tank and found that a large section of the welds on the tank had started leaking. Also found several "spot welds" that were on the tank that were also leaking.

Due to the location of the airplane getting new ones from the TC holder was going to be difficult (and expensive to ship) so they had them welded up locally and so far seem to be holding. Problem is that the tank in the other wing was built by the same people and the owner is now very concerned about its safety.

The TC holder has been contacted about this other than providing testing info after the first email, from what I understand, three weeks later has not replied to emails that also contained extensive photos of the issues. I have seen a photo of the fuel leaking from the wing and its a massive leak.

This could easily turn into a safety of flight issue, so please be careful and if you have the metal tanks on your Sedan and see ANY leaks, first off would not fly the plane and second please post here on this forum so that we know the extent of the issue. This is not a good situation....

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Re: Anyone have any issues with the welds on their metal fue

Post by hangerash » Tue Nov 19, 2013 12:24

I had to do some research to learn the TC holder is in AK and not WI. Glad to host the space to see some pictures of leaks posted. PM me for an address. Surprised the TC holder is not aggressive about learning all the details.
Richard

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Re: Anyone have any issues with the welds on their metal fue

Post by joea » Tue Nov 19, 2013 12:49

Richard,

Not trying to start a "food fight" with this information, so not naming any names at this time. You are correct with the location of the TC holder, but I am not sure if they produced the fuel tanks "in house" or farmed them out, so somewhat holding off on posting much more.

That said I know of one other Sedan who had leaky fuel tanks but no idea if they were metal or rubber. Either way its not a good situation...

Will keep everyone up on the situation as I receive more info...

Thx, Joe A

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Re: Anyone have any issues with the welds on their metal fue

Post by hangerash » Tue Nov 19, 2013 16:01

Joe,

Understand and agree that it should all be about the safety issue. Pictures or some direction at what area to start looking for leaks would prove beneficial in my opinion.


Richard
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Re: Anyone have any issues with the welds on their metal fue

Post by joea » Tue Nov 19, 2013 16:06

Rich,

Only info I can pass out at this time is that it was the welded seams that were leaking as well as some "spot welds" that were on the tank.

Thats where they found the leaks and where I would start looking, especially if you either have the tanks out for maintenance or are experiencing leaks.

Joe A

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Re: Anyone have any issues with the welds on their metal fue

Post by esandberg » Tue Nov 19, 2013 18:44

Joe,

I realize you're kind of the messenger + middleman in this. Notwithstanding, is it possible to obtain photos or more specific info of the subject tanks, and of the subject wings? It'd be helpful to everybody to know specifics of how these tanks were installed into these wings.

I bought my tanks in 2007 and they're still new-in-box (embarrassingly). If good close-up pictures of specific areas of mine will help somehow, let me know.

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Re: Anyone have any issues with the welds on their metal fue

Post by joea » Tue Nov 19, 2013 20:59

Eric,

Will email the owner and see what I can do and we can all go from there.

Joe

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Re: Anyone have any issues with the welds on their metal fue

Post by Paul Agaliotis » Tue Nov 19, 2013 21:44

Presure check the tanks before you put them in. Even when I send a tank out for weld repair, the welder checks them and I check them before I install them.
I like the bladders better than the welded tanks. They hold more fuel and can be repaired pretty easy. One of the manufacturers has the AD and one does not. The last quote I got was pretty reasonable from F&FC's. You have to keep them full of fuel. If you're going to store it with no or low fuel you need to oil the bladder.
Paul
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Re: Anyone have any issues with the welds on their metal fue

Post by Matt » Tue Nov 19, 2013 23:08

Hello folks,

Let me try to tame this tornado by giving you some background information:
My wife and I just started out on a vacation road trip in the USA. We met with Joe and other Sedan owners and friends, yesterday. Had a great time and, naturally, talked a lot about Sedans. I mentioned that one of our Sedan's aluminum tanks had recently suffered multiple fuel leaks, after three trouble-free years and 180 hours since new. Explaining in detail what had happened and how we identified and repaired the tank, I also mentioned that I had informed the manufacturer and emailed him pictures of the problematic areas, but that I had not received his reply, yet.

My intention was and still is to first clarify things with him, before going public. At the same time, I agree with Joe that other owners of the same type of fuel tank should be cautioned and informed about a latent, possibly dangerous situation, as soon as possible.

So, how to proceed? I will be back home and have access to the pictures, in about three weeks only. So, am sorry to say, no pictures of the defective tank till then. But in the meantime, I will email the manufacturer a link of this thread. And I sincerely hope that he will chime in, so that this issue can be discussed/addressed in a constructive way, as soon as possible.

Matt
Aeronca 15AC Sedan – Restoring and flying the classic 4-seater: http://www.n1331h.com

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Re: Anyone have any issues with the welds on their metal fue

Post by joea » Wed Nov 20, 2013 07:07

Matt,

Thanks for chiming in on the thread. I was not going to name who it was until they were ready to comment.

Since posting this thread I have since received private emails from TWO others who have had leaks in their metal fuel tanks... so this is not a single occurance.

Would love to see some photos and have had several others ask for these so that they know how/where to inspect their tanks.

Thx,

Joe

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Re: Anyone have any issues with the welds on their metal fue

Post by Matt » Wed Nov 20, 2013 20:24

Joe

I will post the pictures, once I get back home. In the meantime, here is a description of what we found, after we had pulled the faulty tank from the wing. There were a total of 4 leaking spots:

#1) Located on the outboard side of the tank in the welded bottom edge, about half-distance between the tank's nose and rear wall. This was the major leak, caused by contact and chafing between the tank and the wing rib just outboard of the tank (visible mark on the wing rib). The thick, black foam tape on the side of the tank obviously was compressed too much, when the tank was slid into the wing. In my opinion, a thicker foam tape or an entirely different spacer should be applied to the tank's sidewalls to ascertain that the tank and the rib cannot make direct contact. During our testing to find the leaks, this one wetted an area of about half a square inch on the tank's bottom, within 30 seconds and a square foot within an hour (lunch break).
This leak was the reason for the tank repairs. (I might never have noticed the other three, except for the faint avgas odor.) Over one night in the hangar (tanks topped off to about 1/2" below filler necks, after an evening flight and before a planned early-morning take-off), this one had let enough fuel seep out into the cavity between the tank and the wing skin and out along the wing skin overlap that the entire lower, outer wing surface behind the wing spar and to the trailing edge, the entire width of the tank's rib bay was blue with streaks of avgas.

#2) Located at the rear, upper, outboard corner of the tank in the welded edge. No visible chafing marks anywhere. Neither on the tank itself nor inside the wing.

## 3+4) These leaks were hidden underneath the rearmost cork strip on the tank's top. After removal of the cork, we could clearly identify two leaking spots in the line of spot welds that runs the entire width of the tank. No visible chafing marks (spot welds protected under the cork).

Identification of leaks: First, we drained the fuel, then only pulled the wing, removed the root rib and used a borescope between the tank, the wing skin and the spar to look for traces of a leak. Without success. Only after pulling the tank out of the wing, entirely emptying it, cleaning its outside and refilling it with gas, did the leaks become qickly apparent.

Hope, this helps for now.

Matt
Aeronca 15AC Sedan – Restoring and flying the classic 4-seater: http://www.n1331h.com

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Re: Anyone have any issues with the welds on their metal fue

Post by AV8R2 » Thu Nov 21, 2013 13:28

I don't know why the welds started to leak after all this time. (200+ hrs?) I have no answers for you on that one; especially since I could not look at the welds directly.

The tanks are manufactured here in our facility, 100%. There is no outside "farming out" of work. The PMA would be no good if we did.

I personally manufactured the forming dies over a 6-week period to do the tank body forming. This allows faster fabrication and consistency in the product. The parts always fit and the assembly process can be streamlined to take less time to manufacture. It still takes 7-8 hours time to complete each tank.

We pressure test every tank @ .75 psi with a compound called Snoop; it is designed just for detecting leaks in pressure tests. It will emit about 10 times the amount of bubbles that ordinary dish soap would if a leak is detected.

This is the first problem of this type (welds) in 66+ tanks that we have built. With the exception of one tank that just plain got missed during pressure testing because the tanks were moved/switched around to sweep the floor by unknowing shop help.

There have been others that had problems but were directly related to improper or rough installation, i.e., tapping the tank into the wing on the end plate welds with a block of wood too hard and cracking the welds, etc.

The tanks are welded twice during fabrication. Once the end plates are tacked into place on the top portion of the tank, the body is then "rolled" around the end plate and clamped to hold its shape. The seam along the back is then aligned and the lap seam is drilled every 2 inches and a draw cleco is installed to pull the 2 edges together tightly to weld the seam. After the seam is welded, every other cleco is removed and the hole is welded shut.

The tank end plates, once the tank is in full configuration, are then fusion welded to the bodies. This is to ensure the seams are sealed ; with no welding filler rod it is easier to see if a seam is not sealed. After all the tank end plates and bodies are fusion welded then each tank is then re-welded with filler rod. After all tanks are re-welded in this manner the outlet fitting doubler pads, sump drain pad and outboard end vent pads are located with positioning fixtures, tacked and welded around. The data plate is installed as the last step.

As for the chafing at the end of the tank against the outboard butt rib; this problem is also a first. That can be easily addressed by adding more insulation/foam strip to the tank end to double its thickness.

If anyone has any constructive suggestions call me. (907)688-3715.

Burl
When all else fails, go to the source. Factory Approved parts and data will get you back in the air.

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Re: Anyone have any issues with the welds on their metal fue

Post by dikholder » Thu Nov 21, 2013 16:08

Let me apologize to Burl for assuming that he imported the major components to make his tank kits. I saw another company name in my box and that led me to an erroneous assumption. On my recently installed tanks I did notice some movement in the diagonal between the tank and the wing skins. It was more noticeable on one side than the other. On the left side, my tank would not clear the button head that held the former bladders top in place. I removed that button head and will put a grommet type cover in that hole.

After removal that tank fit in with only minor tapping the last few inches with a soft wood block. On the other side I found that I could get clearance below the button head by using a small wedge to lift the wing skin up. I covered that button with tape and left it in the tank bay. That tank seemed to fit tighter than the Left one did. Now I have to wonder if there will be any chaffing problem from the button that I left installed. I dont think there will be because the tank skin is actually quite thick. I noticed that when fly-cutting the filler neck holes.

If chaffing on the ends is a problem, would it be possible to use an expanding foam to basically lock the corners in place so it cant move at all? I am directing that question at Burl, I really dont know if it would be needed.

Dik Holder, N1441H
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Re: Anyone have any issues with welds on their metal fuel ta

Post by joea » Thu Nov 21, 2013 17:59

Burl,

Thanks for the info. Sure seems like they are welded up nicely.

I know that its a bit late but sure wish that Matt could have been sent a new tank and then have the old one returned to Burl so that he could investigate and find out what happened to this tank. Now that its been fixed "in the field" by re-welding in Switzerland that chance has now gone and we may never know.

Hope that we do not have any more leaking like this but if they do really hope that they can be checked out to find out the reason behind the leaking and not just re-welded...

Joe A

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Re: Anyone have any issues with welds on their metal fuel ta

Post by Matt » Sat Nov 23, 2013 06:50

Joe

Yes, I agree, it would have been very valuable to analyze and find the reason for the leaks. Of course, we did try that, but with no certain conclusion.

I admit, though, that in my case it was never an option to return/ship the tank from Switzerland to Alaska for analysis or for a replacement. The reason is that the problem required immediate attention and that in most hangars in Switzerland maintenance is not permitted. Since my maintenance shop is located on another airfield, the Sedan, once the wing was off, would have been grounded for quite a while, waiting for the repaired or replaced tank.

You must understand that the space situation in Switzerland is entirely different from the USA and that a maintenance shop cannot afford to have a project sitting for weeks. They need the space for the next scheduled plane. So, after some time, they will usually have to charge you for the "hangar spot" in their shop. At approx. $110 a day, this can get real expensive very quickly. And since 99% of the hangars in Switzerland are cramped full with no space to spare (we have community hangars, no T-hangars), you cannot move your plane into a hangar on the same airfield. So, you would have to move it out into the elements. Just to give you an idea: I have been on a hangar waiting list for 16 years! And this is not unusual in our country. Not seldom, wooden ramps are used under one main wheel to lift a wing above the neighbor's wing in order to eventually make space for one more plane!

Sorry for writing so much. But I wanted to explain and thought, this could also be interesting and an eye-opener for some of you lucky T-hangar owners in the US! :-)

Let's hope that the other two owners of leaking metal fuel tanks can contribute more to the solution.

Matt
Aeronca 15AC Sedan – Restoring and flying the classic 4-seater: http://www.n1331h.com

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