Fuel leak

[Doug G]

I’m sure there is a post in history but I sure can’t find one. I’m dealing with a second fuel leak in 3 months, since it’s a 1977 J I’m sure there will be more. So, facing a full repair or replacement. Bladder will add 55 pounds but should last many years. A full reseal will be 7 years and reasonably priced repairs after that. So what has been the experience of this group? The price difference isn’t enough to worry me, I do wonder if the bladder will still yield 64 gallons usable and if the reseal will give me at least 10 years.

 

 

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[Fly Boomer]

34 minutes ago, Doug G said:

I do wonder if the bladder will still yield 64 gallons usable and if the reseal will give me at least 10 years.

Some shorter; some longer.  Longer if done by one of the professionals.

[Paul Thomas]

I bought my airplane this year. It's an 84 on original tanks. I didn't look at bladder airplanes. Bladders add weight and require a modification that is very expensive to undo if you ever want to go back to a wet tank. Bladders also mean a weight penalty.

Both will eventually leak but I don't want to be in a situation where I can't get a replacement bladder. I've built 4 tanks for RV airplanes. While I wouldn't want to get in my tanks, I'm comfortable doing a reseal if I ever have to (I hope I won't). I'm honestly much more worried about cleaning and prepping the tanks than applying the sealant.

[jetdriven]

Bladders add 37-40 pounds,  but they effectively end the risk of future fuel leaks. Plenty of airplanes on here lamenting fuel leaks, but none lamenting bladders leaking.  Theyre made of really thick rubber, about 3/16". and theyre durable.  We just did a set of fuel bladders for a PA30 Twin Comanche.  The bladders in these are very thin and flexible. About 1/32" thick.  But guess what, 3 of the 4 were original 1969.  One was leaking a little, so we did the whole set.

I had the 10 gallon add on kit added to my plane a couple years ago. This requires removing the outboard bladder and gluing a nipple onto it to connect to the new bladder.  Still supple, still great condition.  It was installed in 1992.  So I guess were good for a while.

We do patch wing tank fuel leaks occasionally. You'd be surprised the crap we see. People use non-approved sealants, or they dont mix the approved sealant properly.  They dont prep the work, they dont find the leak, they smear it with their gloved fingers. We recently fixed a wing tank that the client paid amost 3K to a well known east coast MSC.  The sealant was light gray and it was gooey like putty, it was the wrong stuff, not mixed right, or both. The tank was leaking again after half a year.  We've got a 177 Cardinal in our shop right now actually, it was leaking from the outboard corner of the wing tank, the owner is working with us on this, he pulled the top cover off, was sealed with orange RTV and it was gooey and smearing off because it's not supposed to be there, the end board corner of the tank had at least two different kinds of crap smeared all over it, and it was leaking underneath that. After spending the better part of two days, stripping and scraping and stripping and scraping, it's cleaned up enough where we can probably put sealant on it now.  Point being, sometimes properly and accurately fixing a wet tank Mooney leak can get very expensive. One client just paid nearly 30 grand to get his 100 gallon tanks stripped and resealed.   Prayer is not a strategy. I'm not saying take your plane to O&N and have bladders put in it, but I would say that if the plane has bladders and they're not leaking, that is one $20-$30,000 repair job you're probably not gonna have to ever worry about. 

[Pinecone]

Knock on wood, the tanks in my plane were resealed in 2009 by Wet Wingologist East and are fine.

Monroy tanks were in stalled in 1998.

[Marc_B]

I think it all depends on the age of the original sealant.  Problem with patching is trying to find the leak, remove bad material and prep, and then patch.  If more sealant is placed over old sealant then when that material contracts sometimes it puts more tension on the bad sealant and makes a leak worse.

But you can't beat the efficiency of a wet wing...with a bladder you give up fuel capacity and give up useful load.  And bladder material also has a finite lifespan as well.  Most estimates I've seen say a bladder should last 20+ years...which is similar to well applied sealant that is care for by hangar/leaving fuel in the tank.

So the big question is the overall condition and age of your sealant.  By the time you hit 25-30 years, it's probably a good time to start thinking of a reseal if you develop significant leaks.  There are a few shops who take the time to locate leaks, and prep/patch correctly.  But in the hands of someone not experienced, you may kick the can down the road to more issues in the future and given it's more labor than product you typically spend at least an AMU or so for patch work.

[Marc_B]

@Doug G If your aircraft has original sealant, you're overdue for a reseal.  But if you do get it resealed, most on Mooneyspace recommend specialty shops such as WeepNoMore in MN, or WetWingologists in FL.  Those shops have refined their technique to a science and an art and stand behind their work with a warranty.  Worth the cost and wait.

You might as well replace the fuel sumps at the same time as a reseal (I'm not sure if the o-rings in these are field serviceable).

For me, I'd rather have 55# fuel rather than 55# of rubber.  If you hangar and keep fuel in the tank your tank sealant can last 20 years+.  If you're tied down and you have heating and cooling regularly, it's rough on tanks and bladders alike.

 

[A64Pilot]

I manufactured aircraft for years with wet wings, 114 gl per side, I’m very familiar with wet wings.

One of the reasons I bought my airplane was it has bladders, bladders last decades longer than sealant. Don’t worry about whether they will be available, there are several companies that rebuild bladders.

Here is a good one https://www.eaglefuelcells.com

My airplane’s bladders only hold roughly 55 gls, I could add the extra ones to increase capacity but I don’t have the need.

[DCarlton]

I opted for bladders due to the cost and logistics of getting from SOCAL to MN after missing my first reseal appointment due to an aircraft issue.  The next available appointment was in the triple digit heat of summer so I aborted.  Didn’t want any risk of a rework.  So… my bladder installation starts next week.  I could care less about the extra 32 lbs; I’ll be carrying 10 gal less fuel and I’ll be able to keep my tanks full with only 55 gallons (more than enough).  I’ve convinced myself it’s a win win win.  I’m planning to post a few pictures during installation.  

[jetdriven]

May want to  reconsider the extra 10 gallons, it also allows you to tanker fuel to someplace that has eight dollar a gallon gas that you can avoid buying it.

[Paul Thomas]

2 hours ago, jetdriven said:

May want to  reconsider the extra 10 gallons, it also allows you to tanker fuel to someplace that has eight dollar a gallon gas that you can avoid buying it.

It also impacts the future marketability of the aircraft. I almost broke my no bladder rule for an aircraft but it had 50 gallon bladders.

I don't need 64 gallons mission most days, but it's great to have when you have a big headwind your destination is IFR.

It's also great when you land someplace and the fuel pump breaks. I'd rather fly with extra fuel for all kind of reasons.

Edited January 2 by Paul Thomas

[Doug G]

Pulling off the inspection panels I saw no previous patches, surprising considering the age. Will try to patch it but will stick with the wet tank and get on the schedule at Ft. Lauderdale for a strip and reseal. It just looks too good as it is. Thanks for everyone’s input!

[Marc_B]

4 minutes ago, Doug G said:

Pulling off the inspection panels I saw no previous patches, surprising considering the age.

I think these wet tanks are WAY more robust when properly applied than we give them credit for!  48 years in a solvent and still kickin.  Outstanding!

(but certainly sounds like time for reseal!)

[dzeleski]

On 12/30/2024 at 9:43 PM, jetdriven said:

We do patch wing tank fuel leaks occasionally. You'd be surprised the crap we see. People use non-approved sealants, or they dont mix the approved sealant properly.  They dont prep the work, they dont find the leak, they smear it with their gloved fingers. We recently fixed a wing tank that the client paid amost 3K to a well known east coast MSC.

You could've tagged me That photo is of my airplane unfortunately and the leak it caused actually caused me to declare an emergency over the North Shore of Long Island headed to CT, the fuel leak puddled in the belly pan and caused a fuel smell that was quite alarming. I got the fire truck parade and a date with the FAA. Going through my logs there have been at least 5 or 6 different shops that have "fixed" leaks. Its clearly quite critical that you have someone that knows how to do this properly. Byron did a great job fixing the mess that was there. I am impatiently waiting for my reseal appointment.