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Andre

Fuel Tank Leak - What to do?

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I had the worse surprise today when I got to the hangar and did my preflight.  My right fuel tank is leaking at the bottom of the wing about 2 feet inboard of the fuel cap.  This is not a self-repair job and I have no clue who can do the work and how long it will take.

Attached is the picture of the leak with the paint starting to peel offFuel_Leak2.thumb.jpg.dff196ea7b0644d9228e109796685ad4.jpg.  I could not take a picture of the inside of the tank where the leak is because my borescope is too short.  

After discovering the leak, I emptied my fuel tanks through the gascolator and then isolated the right fuel tank from the rest of the fuel system by disconnecting it just in front of the right top firewall.  My plan was to keep flying the aircraft using only the left fuel tank for the time being.  After disconnecting (and plugging) the right fuel line line, I put some fuel in the left tank but it is not feeding the engine as far as I can tell - at least nothing comes out of the drain valve at the bottom of the gascolator.  That makes no sense to me but I decided to call it quit as I was not in the best frame of mind by that point.

I would appreciate any advice from people who have had this problem and any recommendations about how to handle the repair.   

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I would check with Flight Design USA, Airtime Aviation, or maybe Lockwood for help on the repair.

It is not unusual for the fuel not to flow on its own after the tanks have been drained. You can probably get the fuel flowing by blowing in the vent with your mouth. DO NOT USE COMPRESSED AIR!

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I have a friend/acquaintance who had that happen and he had a mechanic remove his wings (both were leaking) and he transported them to Airtime (Riverside Airport on the south edge of Tulsa) for repair. The repair is via a slosh sealant technique. Such a scary situation for all we CT owners. Not sure if it is just certain years that are susceptible. I never heard how my friend did, I think it was a financial disaster for him and that he sold the airplane (since he quit communicating with me about it). I'll send an email to him and see if he will let me know what happened and see if Airtime was a good choice. 

ET 

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Yes, I am worried about the "financial disaster" aspect of this.  My airplane is in Florida so Tulsa is a long-way away.  Thank you for asking your friend.

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Oh, yes, for Florida there must be other shops back East that have been certified. I haven't heard back from Ron Hansen yet, I'll let you know any insight he provides. 

ET

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Andre,

I hate to add to your problems, but I don't think flying a CT with fuel in only one wing is a good idea. There is not enough dihedral in the wing to feed reliably. You may experience premature fuel starvation if though it seems like you are flying coordinated.

Mike Koerner

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Thanks guys,

I have been sick since the day I discovered the fuel leak so I have not been at the hangar since then.  There is no correlation between the fuel leak and my flu/cold or whatever it is so it is only a coincidence.  The Young Eagles the day before probably had more to do with it.

I am not worried about getting the fuel flowing.  There was obviously lots of air in the line when I left it and it may have worked its way out by now.  Worse case. I will just unplug the right fuel line temporarily so the air can escaped through it and re-plug it when I see fuel coming out.  I'll drag myself to the hangar today to take care of that.

If I fly, then I will make sure that the left tank is always full and fly from the right seat.  And I will be very careful and aware.   If the repair can happen soon, that is one thing.  If I have to wait two months, that's another thing.  

Not a lot of progress on the repair so far but that has lots to do with me losing my voice and being unable to have a useful conversation over the phone.  I do now know that this is a common problem with CTs though, something I was not aware of before.  I bought my CTSW used and I would probably have passed if I had known because one important criteria for me in buying the aircraft was reliability.   C'est la vie.

 

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I have been working on CT's since 2007, and have yet to personally see the problem. Since I have worked on quite a few and have never seen the problem, I wouldn't consider it common. I'm not saying that it doesn't happen, just that it is not common. I know that doesn't help you at all.

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I had a fuel tank leak and had it repaired.   There have been other CT's with this.  There is an access port about 10" x 8"  that is out about 2' from the fuselage that can be cut out on the bottom of the wing to gain access to the fuel tank.  If you happen to look at the wings on a warm humid morning after a cold nite has cooled the fuel in the tank, this port will have condensation on it and is visable.  Since this is a "Wet Wing" the skin of the wing is also the fuel tank.  The leaking area will probably be cut out and new skin will be patched in.  Then, the tank is sloshed with sealant.  If you are near Tad, I would recommend following Bill's advice and would call Tad to get his advice.  He knows our CT's inside/out.  This will not be a cheap fix.

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On 12/29/2019 at 8:58 AM, Runtoeat said:

Since this is a "Wet Wing" the skin of the wing is also the fuel tank.

I was under the impression the tanks had their own lower bulkheads separate from the bottom wing skin.  Is that incorrect?

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From what I have gathered so far, (dealing with the leak as well) there are 3 layers, the composite on the tank side, the middle foam layer and the composite on the outside of the structure. The inside of the tank is sealed between the fuel and composite except for the area the patch is located. My patch, not sure if all are the same, was bonded in place and does not have any sealant over it. So if you send a scope into the tank you will actually see the patch in all it’s glory (not so much). It looks like a messy patch job but according to FDUSA it’s as expected. 
 

Plane is in for annual and some upgrades. I’ll will be working through this fix once my mechanic returns from the holiday. I’ll post more once we have all the information and the suggested fix from FD. 

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3 hours ago, FlyingMonkey said:

I was under the impression the tanks had their own lower bulkheads separate from the bottom wing skin.  Is that incorrect?

The wing skins form the top and bottom of the tank. The rear spar and ribs form the rest of the tank. 

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I got in touch with John Hurst.  He has a composite expert from Germany come to the US to do tank fuel leak repairs in addition to other composite work.   That person has done many in the past and is very efficient at it so probably will be cheaper than somebody who has not done any before.  When a backlog of work is large enough, he will bring the expert from Germany and do my tank.  I will fly with one tank until then.

John confirmed that fuel leaks in CTs are not rare.  Arian also confirmed that as well. 

 

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All CT models ? All years ?  You are Saying Andre that this fuel tank leak is an issue that has not been addressed ? Please clarify thx 

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The foam in the wing skin is porous. While you would think the layers of carbon fiber and resin are not porous there a little holes throughout. The inside of the tank is coated to seal the porosity, but if something happens to this coating the tank can leak. This is not an issue with Flight Design in general, but rather a fuel tank issue. It happens to other aircraft with fuel tanks of all kinds. Personally I have dealt with fuel tanks leaking on several different aircraft, but as of yet not a Flight Design.

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Agreed Tom... thank you.  

My question for Andre is what exactly did John and Arian say regarding this issue.  I read about fuel tank leaks all the time on the old metal GA planes we know, love and learned on... but I would like to figure out if FD addressed the "leak issue" at some time in the past based on experience.  I am seeing Arian soon, I will follow up with him.  Thanks again, Andrew

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I cannot quantify anything or tie it up to any model although I have only heard of CTSWs with the problem but I am more ignorant than knowledgeable about this so I would not draw any conclusions.  All I can say is that this is a problem that all four CT maintainers (that includes Arian and John and two more) that I have communicated directly with have seen before.   From what I understand, the leak is usually (always?) around the patch at the bottom of the wing (where it is on mine).  The solution is to remove (i.e. destroy on removal) the old patch, fabricate a new one, bond it in place and slosh the tank with a sealant.   And repaint the wing if you do not want an ugly-looking patch.

If you look at my picture, the fuel leak starts along the edge of the patch at the top of the picture, follows the patch along its periphery, and comes through the paint at the bottom of the picture (which is likely the low point).

You now know about as much as I do on the topic.  I expect to learn a lot more in the next couple of weeks now that the holidays are over.   

 

  

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Andre, where are you located?  Is Ottawa in Canada or where?

I do have personal positive feedback about Airtime in Tulsa but I thought you were a long way away from them>>

Larry

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I spend the winter in Leesburg, FL.  This is where the plane is at the moment.  Ottawa in Canada is where I spend the summer.

    

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