Sad Blue Streaks - Fuel Leaks

[Seth]

After my LOVELY flight to College Park, Maryland a week and a half ago, I topped off with fuel at their good rate.

 

My Missile has the extended tanks, so I took off with the full 98 gallons on board.  It was a short flght back to GAI where I touched down very softly, as I usually don't land with 90+ gallons on board. 

 

When I opened the hanger this past Sunday, to my disgust, I had blue stains on the underside of the wing running from about where the connection between the tanks run on both sides.

 

So, it has been FREEZING in DC/MD/VA the week between the flights, and thus, the "leaking" fuel may have not been evaporating as quickly.  OR, with the cold temps, the connections/seals between the extended tank and the main tank may have expanded/contracted, etc, and some fuel leaked.

 

It could also be that I filled the tanks completely, and the tops of the extended tanks may be leaking a bit. 

 

I've flown 250+ hours on this plane and have never had a fuel leak that I noticed (at annual last year, a small amount of residue and very tiny leak was noted in the connection between one of the extended tanks and the main tank - it was a very easy fix. 

 

The plan goes in for annual in about a week and half, so I'll have that issue looked at then.  I do not think it is a leak in the mains, as the streaks are coming from more outboard than where the mains are located.   If the Monroy tanks are leaking completely, I may have to patch or reseal them.  Not what I wanted, but I know Mooney's and know it's something I'll have to do for the entire aircraft and some point.

 

-Seth

[rbridges]

that's too bad.  I hope it turns out to be something simple.  As you already know, leaks can be expensive problems.

[Shadrach]

How old is the reseal?  One of the problems with "extended" tanks is that if you don't use the added capacity often, the sealant can dry out.  Did you happen to take a pic?

[John Pleisse]

Both sides Seth?

[KSMooniac]

I know my seeps turned into pretty noticeable leaks after a really cold stretch ~ 1 year into ownership... Good luck.  Weep No More was my solution, but they're only 3 hours away from here so YMMV.

[aviatoreb]

Sorry to hear Seth - good luck and let us know.

[Dave Marten]

Seth, take/post some pics. Will help determine point of origin.

[Seth]

I'll get some pics if the leaks continued after Sundays flight - I cleaned them off before the flight. Both wings were leaking midway down the wing, right between the inboard and outboard tanks. Yes John - both sides.

It's about a foot outboard of the Landon gear - all of it came from the same inspection panel on both sides.

I'll post some pics after I get back to the airplane on Sunday (or tomorrow after work).

Thanks for the good wishes, I'm already in touch with Paul at weep no more for quotes in case it's a reseal.

-Seth

[Hank]

Best wishes, Seth. I resealed my little tanks two years ago. Don has a good reputation as a leak finder. Typically old sealant opens up during cold weather, and expands to reduce the leak during warm weather.

[OR75]

Seth, take/post some pics. Will help determine point of origin.

very unlikely pictures would allow to determine point of origin.

Article on fuel tank repairs on Don Maxwell website is very good.

[N33GG]

Your Mooney is not really a Mooney, until it has earned it's stripes!

Own one long enough, and you will get your turn. Good luck.

[DC_Mooniac]

Your Mooney is not really a Mooney, until it has earned it's stripes!

Own one long enough, and you will get your turn. Good luck.

 

Unless you have bladders. 

 

Sorry to hear, Seth.  Hope you are able to find a quick fix.

[Seth]

Funny - My first Mooney, my former F model, did have bladders.  This one I knew at some point would need a reseal as it does not have bladders - however the long range Monroy tanks can't have bladders (unless there's an STC I don't know about).

 

Regardless, update:

 

I checked the streaks when i was at the airpark a few minutes ago after last Sunday's flight and as it tunrs out, NO NEW STREAKS.  So - fuel is not leaking anymore, yet there is still fuel in the outboard tanks:

 

Fact:

1.  Only had streaks when below freezing

2.  Only had streaks when nearly completly topped off with 98 gallsons (full one side, 3 gallons missing on the other - from the short flight).

3.  No streaks when 75+ gallons are in tanks

4.  No streaks when above freezing (though, some of the nights since have dipped below freezing)

 

Possibilities

1.  Sealant had issues but expanded back when it wasn't quite as cold

2.  Sealant is not working or has leaks on the top of the outboard/extended tanks on both wings

3.  Pressure of 95+ gallons of gas caused the seal around the transfer tubes from extended/outboard tank to main tank ot leak during cold weather.

 

My gut is it's number 2 - that the top of the outboards need to be patched/resealed.

I admit, in the past, I often to not leave the full 98 gallons full in the hanger, as that cuts too much into the useful load  (588 lbs full fuel, 1067 useful load = 479 full fuel useful load).  However, I have often filled it all the way prior to flying home or flying somwhere, and if there was a leak I was unaware of, I burned the fuel off fast enough to notice.

 

So, we'll see what they say when they take a look at the annual, but right now, with 75 gallons in the wings, she's not leaking.

 

I did reach out to Paul at Weep No More and should I need a reseal, that is indeed where I'll take it.  He knows the airplane from the broker who was invovled in the sale to me and sent a great email.  I will be in touch with him soon as he is familiar with N1165N.

 

I have no pictures of streaks as there are not any at this time - but I cna always top her off, let her sit, and see what happnes again . . . but I'm not going to right now.

 

-Seth

[N33GG]

I have similar leaking rivet on top of wing that only leaks when topped. I just don't fill it very far ahead of time, unless I have an early departure, and then I see blue. Burn about five gallons off, and no more stain. I don't worry about it, not that big of problem for me. I just fill up before departure. Very managable.

I know there are reasons to keep tanks full. I just keep tanks mostly full when the aircraft is going to sit for a while.

FWIW YMMV and etc.