Fuel leak after annual.

[Blueyonder]

Hi everyone.

Happy Holidays to all.

Some more things are showing up after the last annual. If some wants to have a perfectly good plane made somewhat useless, let me know I will tell you where Not to go?

 

This looks like some is not properly tightened? The fuel Level tube on the left side? As you can see one of the screws / nuts, the top one, is further out, not as tight as the other, assuming the same size tubing...? See pics this stain is about 12 in.

 

 

[Madhatter]

If you have any mechanical ability go to a course in LSA maintenance,  Bill can tell you where. You will then always know what should be done even you don't do it. There are a lot of so called mechanics out there that don't know crap. When I knew I was to be in aviation for life I learned everything I could about everything required on aircraft. I need no one for anything, avionics,  maintenance, repairs, etc. But I am still learning and consult with experts in the subject I am working on. You will not regret it.

[Bulldog]

I agree with @Madhatter.

Some of the more veteran guys may chime in, but I'd say this could be a combination of issues. Was a new seal used, was the Hylomar applied properly to both sides of a new seal (or even used at all), were the flange and end cap cleaned thoroughly with acetone prior to assembly, were new nuts used, what torque value was used, were the nuts tightened down in a crisscross pattern?

Nick V

[Tom Baker]

There are a handful things that can cause the fuel staining you have, but the clap on the fuel sight tube is likely not the problem. I have had a couple airplanes that I have chased a similar fuel leak. The wings will likely need to be pulled to find the issue.

[Mike Koerner]

If you don't see or feel wetness around the left-side sight tube or the access plate around it, these items are probably not leaking. But check the right side, too. If the sight tube or access panel on the right side is leaking, and your plane is setting with the left wing even slightly low, leakage on the right side will cross through the wing spar tunnel and leak out under the wing on the left side, just like in your photo.

[Tom Baker]

7 hours ago, Mike Koerner said:

If you don't see or feel wetness around the left-side sight tube or the access plate around it, these items are probably not leaking. But check the right side, too. If the sight tube or access panel on the right side is leaking, and your plane is setting with the left wing even slightly low, leakage on the right side will cross through the wing spar tunnel and leak out under the wing on the left side, just like in your photo.

In my opinion, that would be highly unlikely.

[Blueyonder]

Hi everyone.

I will keep you updated on the fix, it may take a while.

I think that a wing removal / reassembly will be required, there are no stains on the side of the sight tube, in the tube close proximity, which is likely and indicator that the problem is beyond that location, on the outside of it, likely the seal, improper torque, it doe look like the nuts were not replaced, they don't seem to be new...

Thanks everyone.

[FlyingMonkey]

On 12/26/2024 at 11:19 PM, Tom Baker said:

There are a handful things that can cause the fuel staining you have, but the clap on the fuel sight tube is likely not the problem. I have had a couple airplanes that I have chased a similar fuel leak. The wings will likely need to be pulled to find the issue.

Yeah, the tubes are usually on there very tightly and I've never had one leak after several changes over the years.  I see a little fuel residue at the *top* of the bulkhead, which is counter to gravity for a sight tube leak.  I'd suspect a bulkhead seal.

[FlyingMonkey]

On 12/27/2024 at 12:55 PM, Blueyonder said:

Hi everyone.

I will keep you updated on the fix, it may take a while.

I think that a wing removal / reassembly will be required, there are no stains on the side of the sight tube, in the tube close proximity, which is likely and indicator that the problem is beyond that location, on the outside of it, likely the seal, improper torque, it doe look like the nuts were not replaced, they don't seem to be new...

Thanks everyone.

I didn't see in your posts that the bulkhead seals were replaced...is that the case?  If so, why...were they leaking before?

[EricB]

My condolences.  Seems that preventive maintenance thinking needs a revisit.  After my 5 year rubber replacement, I've had several issues keeping the plane grounded for 2 extensive and one short period.  Still have a very slight coolant leak.  I'm considering going with the old "if it ain't broke.." approach within legal limits of course.  As you said, "takiing a perfectly good airplane...."    Good help is truly hard to find.

 

 

[FlyingMonkey]

41 minutes ago, EricB said:

My condolences.  Seems that preventive maintenance thinking needs a revisit.  After my 5 year rubber replacement, I've had several issues keeping the plane grounded for 2 extensive and one short period.  Still have a very slight coolant leak.  I'm considering going with the old "if it ain't broke.." approach within legal limits of course.  As you said, "takiing a perfectly good airplane...."    Good help is truly hard to find.

 

 

For those so inclined, I recommend getting with a mechanic who will let you do most of the work, supervise you, and sign off on it.  I was lucky to be able to do that early on in my CT ownership, and it has been an invaluable education.  Also unless your mechanic is highly CT experienced, I'd ask how to perform any CT-specific maintenance items on this forum, and then present that to the mechanic.  Most A&Ps don't really know all the ins-and-outs of CTs, and it's easy to get it wrong.  Also going E-LSA will make this much easier and save you a lot of money as you can do anything on the airplane you're comfortable with doing without an A&P sign off --  and take the LSRM-I weekend course and you can do your conditional inspections too.

I started with just basic mechanical aptitude and at this point a decade into my CT ownership I'd feel comfortable doing anything on the airplane except heavy engine work (inside the case) or airframe composite repairs.