Trick for fuel tank repair

[flyby201]

My A&P and I stripped and resealed my fuel tanks a while back. Since then, I have had a nagging leak which had resisited our attempts to repair. The leak is at the lap seam of the wing skins between the middle and outboard access panels. Last week, I drained the tanks and apparently fixed the leak using the following (improvised) procedure.

1. Thoroughly cleaned the lap seam area with MEK.

2. I got a small (5 ML) oral syringe from the pharmacy.

3. Filled the syringe with the slosh sealant (CS 3600).

4. Used the syringe as a mini caulking gun and applied it from the exterior all along the lap seam taking care to force the sealant into in the seam.

5. I let the sealant cure.

6. Cleaned up all excess sealant with MEK.

7. Re-fueled the tank, and

8 So far, no leak

I was always told a fuel tank leak could not be repaired from the outside, but apparently this technique has worked (at least for the present). I guess time will tell if this is a successful permanent fix.

Just thought I would share this with everyone in case anyone has a similar problem

[philipneeper]

see how it looks after a few landings. From what i hear thats the meain cause of seal failure. I just got my mooney and i need tank reseals as well.

[gregwatts]

Yea...that is a bandaide. One or two un-pretty landings may challenge your theory.

My opinion only!

[AndyFromCB]

For a while there was a kit available that supposedly worked great, you pump up the tanks, find out where the leaks were with soap. Then you'd reverse it, vacuum the tank down a few inches with a vacuum cleaner and a regulator and basically inject a substance into it from the outside. My understanding was the substance in question was more or less loctite.

[marks]

Remember, if the sealant inside the tanks is deteriorating then you have tiny pieces of sealant floating around in your fuel. If you use Weep No More all the sealant that's falling apart will be removed and chemically improved sealant will be in its place. You really shouldn't have little pieces of failed sealant floating around with the fuel headed for your injectors. Also, when you previously tried to seal the tank, did you make sure that the holes for water transfer remained open so that any water will make it down to the sumps? If you didn't then any moisture that condenses in the tanks will add up right at the rib where your leak is showing and will be trapped under the fuel until in a banking turn, water makes it over the rib headed for to fuel pump. - Do you really think the tank sealing was done in the safest professional way? Fuel and spark run the engine. My advice is to see that both arrive clean.

[Sabremech]

So why do so many people believe that A&P's don't know how to seal or repair a fuel leak in our Mooney's? It's great that there are business's like Weep No More, but are they really the only people competent enough to fix a Mooney? I'm in my 28th year of being an aviation maintenance professional (A&P/IA, pilot) and still find it insulting that we are assumed to be less than able to complete a simple task on a very simple airplane. Yes, the Mooney is a very simple airplane. The vast majority of us take our profession very seriously and would appreciate a little respect for what we do and what we put on the line everyday so you can safely fly your Mooney.

[aerobat95]

So why do so many people believe that A&P's don't know how to seal or repair a fuel leak in our Mooney's? It's great that there are business's like Weep No More, but are they really the only people competent enough to fix a Mooney? I'm in my 28th year of being an aviation maintenance professional (A&P/IA, pilot) and still find it insulting that we are assumed to be less than able to complete a simple task on a very simple airplane. Yes, the Mooney is a very simple airplane. The vast majority of us take our profession very seriously and would appreciate a little respect for what we do and what we put on the line everyday so you can safely fly your Mooney.

Amen to that. My A&P/IA has worked on all sorts of planes from Cessna 414 to Piper Lance & Matrix and from what he says Mooneys are about as simple as they come for being complex. Other that the tight working spaces they are easy. He just finished putting a m20a back together after a gear up. I completely trust his work. I know there are a lot of guys out there that swear on only MSC but his work like other A&P's is second to none.

[bd32322]

So why do so many people believe that A&P's don't know how to seal or repair a fuel leak in our Mooney's? It's great that there are business's like Weep No More, but are they really the only people competent enough to fix a Mooney? I'm in my 28th year of being an aviation maintenance professional (A&P/IA, pilot) and still find it insulting that we are assumed to be less than able to complete a simple task on a very simple airplane. Yes, the Mooney is a very simple airplane. The vast majority of us take our profession very seriously and would appreciate a little respect for what we do and what we put on the line everyday so you can safely fly your Mooney.

I understand the feeling, although my issue is with another industry. Problem is that no one knows what quality of work you do. Maybe we need an online ratings site where people leave ratings for work their A&P did. People can pick and choose the clsest a&p with good ratings at the correct price.

[Sabremech]

The rating system has been talked about ad nauseum. It already exists by the number of posts on this and other forums of the bad experiences with shop X or A&P X without hearing their side of the story. It won't work because people are unable to take emotion out of their experience and give only the facts.

What do you think is the correct price for an A&P's service?

[bd32322]

The rating system has been talked about ad nauseum. It already exists by the number of posts on this and other forums of the bad experiences with shop X or A&P X without hearing their side of the story. It won't work because people are unable to take emotion out of their experience and give only the facts.

What do you think is the correct price for an A&P's service?

Posts on a site hardly work, judging from the number of people who dont search forums i think a review system works perfectly well instead of a numerical rating. People can read the reviews themselves and judge emotional versus factual content. Case in point are restaurant reviews - highly subjective but statistics is on the restaurant's side. If an overwhelming number of people are positive, the business is doing something right. But reading those reviews you will also see a Lot of emotional content that you dont care about also ...

Frankly the only difference between you and the big name tank sealers might just be their web presence? Add a few glowing reviews and details of how carefully the process is done and the business instantly becomes famous

[gregwatts]

So why do so many people believe that A&P's don't know how to seal or repair a fuel leak in our Mooney's? It's great that there are business's like Weep No More, but are they really the only people competent enough to fix a Mooney? I'm in my 28th year of being an aviation maintenance professional (A&P/IA, pilot) and still find it insulting that we are assumed to be less than able to complete a simple task on a very simple airplane. Yes, the Mooney is a very simple airplane. The vast majority of us take our profession very seriously and would appreciate a little respect for what we do and what we put on the line everyday so you can safely fly your Mooney.

The OP stated that he and his A&P attempted to repair a leak and was not successful. I didn't read anywhere, a statement that A&Ps don't know how to seal or repair a fuel leak. Perhaps, rather than getting defensive for no obvious reason, you should offer your insight and services to those that don't know who you are or what your expertise is.

Just sayin'

[Sabremech]

My post wasn't aimed at the original poster, but the posts after his questioning what he and his A&P did to solve a fuel leak issue. I wouldn't have a problem giving his technique a try if it slowed or eliminated my leak until I either was due for my annual or it got me back home.

If you go back and read all the posts, I think you'll find where I get defensive and why. I don't think even a newly licensed A&P would have a problem with following the Mooney maintenance manual and repairing a leak. There's my insight, Mooney's are not a difficult airplane to work on. I'd be happy to share some horror stories of maintaining an A4 Skyhawk in airworthy condition or an F86.

[1964-M20E]

So why do so many people believe that A&P's don't know how to seal or repair a fuel leak in our Mooney's? It's great that there are business's like Weep No More, but are they really the only people competent enough to fix a Mooney? I'm in my 28th year of being an aviation maintenance professional (A&P/IA, pilot) and still find it insulting that we are assumed to be less than able to complete a simple task on a very simple airplane. Yes, the Mooney is a very simple airplane. The vast majority of us take our profession very seriously and would appreciate a little respect for what we do and what we put on the line everyday so you can safely fly your Mooney.

I agree with you a Mooney is a simple plane especially the pre-j models with manual gear and flaps and with the correct tools and the maintenance manuals there is nothing any good A&P cannot fix on a Mooney. Under the supervision of my mechanic/IA I re-rigged the flight controls and landing gear on my former Mooney and it flew great and the gear was correct after we were finished. I’m not sure about before. The only thing an MSC might give you is experience and speed on a repair since they may have done it many times before and a non MSC A&P might have a learning curve. Furthermore, a good mechanic will not charge you all of his time for his education on the plane.

Finally, be involved in the maintenance of your plane read the mantneace manuals youself so you know what is expected to be done. Talk with you mechanic regularly about what is happening with your plane and any mods you want to do. Get out there with the mechanic and help turn the wrenches, open up the inspection panels, remove your interior, clean and lube your own plane for annual.

OH and be good to your mechanic do not whine about his fee especially if he is good and fair with you.

[Piloto]

Flyby201

You have sealed the exit point on the outside but the internal leak is there. It will probably show up at another point as the fuel runs down until it finds another exit point. Wait until winter when leaks no longer evaporate before showing up. But most leaks are not flight critical but an esthetics issue. Like they say is not a genuine Mooney if there are no fuel stains.

José

[flyby201]

Remember, if the sealant inside the tanks is deteriorating then you have tiny pieces of sealant floating around in your fuel. If you use Weep No More all the sealant that's falling apart will be removed and chemically improved sealant will be in its place. You really shouldn't have little pieces of failed sealant floating around with the fuel headed for your injectors. Also, when you previously tried to seal the tank, did you make sure that the holes for water transfer remained open so that any water will make it down to the sumps? If you didn't then any moisture that condenses in the tanks will add up right at the rib where your leak is showing and will be trapped under the fuel until in a banking turn, water makes it over the rib headed for to fuel pump. - Do you really think the tank sealing was done in the safest professional way? Fuel and spark run the engine. My advice is to see that both arrive clean.

Sealant inside tanks is not deteriorating, we removed all old sealant down to bare metal with Poly-Gone (which is what Wilmar and others use), used sealants and application methods per service manual, verified weep holes in ribs were open, etc, etc.

We did use the soap bubble/vacuum method to try and locate the leak with no success.

[bd32322]

I wonder if its possible to pump the tank with hot air from a compressor and then look at the tank with an infra red camera in darkness?

Should show the leaky hot air coming out in a stream.

[Piloto]

I wonder if its possible to pump the tank with hot air from a compressor and then look at the tank with an infra red camera in darkness?

Should show the leaky hot air coming out in a stream.

You should never use a compressor to pressurize a Mooney tank. The skin surfaces are to thin and may stretch causing oil canning. Best safest way to pressurize is by blowing air by mouth. It only takes a couple of blows and insure that your lungs will stretch before the skin. Typical by mouth pressure is less than 1 psi that is more than enough to detect air bubbles on the outside. SD-20 cleaner is very good for checking for bubbles. Unlike fuel stains that may show up far away from the actual leak point, bubbles are much closer to the leak point.

José

José

[N201MKTurbo]

I have used Dom Maxwells method for fixing leaks on two airplanes with perfect sucess. It is documented on his website. it takes about 10 hours per tank in labor and about $150 in supplies.

I am an amateur A&P, I have the license, but never did it for a living.

[N201MKTurbo]

If you have a leak the soap bubble method will work. I had a tremendus leak and the bubbles were very hard to spot, but if you keep looking you will find them. I found that if I applied the liquid hand soap as heavy as I could with a paint brush, making sure you cover everywhere with the soap. Just before you tape the plexiglass panels over the access holes, lightly spray the inside of the tanks with water from a spray bottle to activate the soap. It usually takes me about an hour to paint the soap on the inside of all three cells of a tank and the soap will dry out before you are done. Also use the thickest heaviest hand soap you can find. BTW it will make your tanks smell wonderful.

In both tanks that I've fixed the leaks were quite a ways from where I thought they would be from the stains, so don't make the mistake of only checking near where you think the leak is, check the whole tank. You need to remove all six panels to see every nook and cranny. PITA for sure.

[Sabremech]

For those who asked, my main job is an aircraft technician for a corporate flight dept. maintaining 3 Falcon 2000's. My second job is the Director of Maintenance for the Warbird Heritage Foundation maintaining 10 airworthy warbirds from a Stearman to an A4 Skyhawk. My third job is co owner / founder of GDS Aero which manufactures FAA/PMA parts and specialized tooling for corporate business jets. My fourth job is owner / founder of Vintage Airworks which manufactures parts for aircraft that parts aren't readily available for. I also maintain a Cessna CJ 1 for a private owner. In my spare time, I'm building an experimental airplane and occasionally fly my Mooney. By no means am I any kind of expert, but continue to learn something new everyday. Just like the original poster informed us of how he made a fix for a fuel leak. Nice information to know in case I need a similar repair.

David Staffeldt

[johnggreen]

So why do so many people believe that A&P's don't know how to seal or repair a fuel leak in our Mooney's? It's great that there are business's like Weep No More, but are they really the only people competent enough to fix a Mooney? I'm in my 28th year of being an aviation maintenance professional (A&P/IA, pilot) and still find it insulting that we are assumed to be less than able to complete a simple task on a very simple airplane. Yes, the Mooney is a very simple airplane. The vast majority of us take our profession very seriously and would appreciate a little respect for what we do and what we put on the line everyday so you can safely fly your Mooney.

Sabremech,

Amen a thousand times over. I've listened to this nauseating crap about how special the maintenance is on a Mooney until I'm about to puke. I have used a very competent shop for over ten years that maintains exactly one Mooney, mine. I bought the service manuals and no problem has even been an issue including a leaking tank that was resealed, successfully, for a fraction of what some bozos are spending.

If ignorance is bliss, there must be a lot of happy Mooney owners hauling their airplanes 1000 miles for an over priced annual on a dumb simple airplane.

Jgreen

[marks]

I think Weep No More has equipment that the average A&P does not. I think Paul has more experience at this one task than any A&P I have ever met. Repairing leaks will work until there are more leaks and during the interim sealant deteriorates. Repairing leaks according to the manual works until it doesn't. Sometimes leaks are simple to find and repair, other times where the leak shows up has nothing to do where the leak originates. Like many others, I too had leaks fixed, got sealant crap in a wing drain that didn't clear well, had more leaks develop and got tired of chasing down the problem. I wish I spent the money in the first place at Weep No More. I met two guys at my airport who flew to MN from our airport in Massachusetts and both were glad they did. I say good luck to everyone dealing with this Mooney problem and I'm not trying to offend or insult anyone.

[marks]

If A&P's had no problem sealing fuel tanks on a stupid simple airplane like a Mooney, we wouldn't be having this discussion. Flyby is frustrated because he and his A&P have done everything to fix his tanks and now he's trying to fix the leak from the outside! Of course people use their mechanics and follow the manuals and do what they can to fix leaks, both old and new leaks, and clearly some efforts have success. But sometimes as Flyby has related, the A&P and his best efforts have failed to fix the problem. Others of us would like to rely on the more expensive expert fix. Some people may say "ignorance is bliss" but if I'm ignorant at least my Mooney doesn't leak.

[Sabremech]

Many fuel leaks are successfully repaired by A&P's on Mooneys. Does Weep No More or any of the other experts never have to repair a leak after they've been in the tanks? Is their system exclusive to them that we can't do the same thing in the field? I'll be repairing a leak in my right wing at my annual which is due in the next two weeks. I'll let you know how it goes. I suspect I'll have more money in my pocket to use burning 100 LL than paying the experts. I hope I never achieve the title of expert! That means I know it all!

[mike28w]

If A&P's had no problem sealing fuel tanks on a stupid simple airplane like a Mooney, we wouldn't be having this discussion. Flyby is frustrated because he and his A&P have done everything to fix his tanks and now he's trying to fix the leak from the outside! Of course people use their mechanics and follow the manuals and do what they can to fix leaks, both old and new leaks, and clearly some efforts have success. But sometimes as Flyby has related, the A&P and his best efforts have failed to fix the problem. Others of us would like to rely on the more expensive expert fix. Some people may say "ignorance is bliss" but if I'm ignorant at least my Mooney doesn't leak.

When it came time to fix my leaky tanks, I decided to bite the bullet and do it "right" the first time,,,,,, Took it to a specialist, did the whole strip and reseal...... ~ $9000 , if I remember correctly. I've since had leaks re-repaired ,three different times . Under warranty, but still ( I'm out about another $2000 or so for transport and motel and plane tickets, etc)

Now , I'm not saying that the fellow is incompetent. He most definitely is not ! What I'm saying is that these tanks can be tricky to reseal completely......... In retrospect, I think that I would be comfortable using any qualified person who was properly motivated to do the job.....And then hope for the best !!