Mooney Fuel Tank Leak

[RonM]

Friends:  I have a 1991 Mooney MSE / 1997 Missile Conversion.  I am the original owner having owned the airplane 30 years, and I am based in Caldwell, N.J.  I have a fuel leak in my left fuel tank.  ( I have inner and outer tanks by the way for total fuel capacity of 93 gallons.)  The leak in the left fuel tank is very bad.  My right tank still holds fuel and appears to be leak free.  Any suggestions for repair appreciated.   Thanks - RonM

[N201MKTurbo]

5 minutes ago, RonM said:

Friends:  I have a 1991 Mooney MSE / 1997 Missile Conversion.  I am the original owner having owned the airplane 30 years, and I am based in Caldwell, N.J.  I have a fuel leak in my left fuel tank.  ( I have inner and outer tanks by the way for total fuel capacity of 93 gallons.)  The leak in the left fuel tank is very bad.  My right tank still holds fuel and appears to be leak free.  Any suggestions for repair appreciated.   Thanks - RonM

Pictures would help.

[RonM]

Wish I could figure out how to attach my video which is on my phone taken yesterday. Being a dummy is such a pain.

[DCarlton]

Your not too far from these guys.  I haven't been but that's where I'm thinking about taking mine.  

https://www.weepnomorellc.com

[LANCECASPER]

1 hour ago, RonM said:

Wish I could figure out how to attach my video which is on my phone taken yesterday. Being a dummy is such a pain.

Easiest way is to upload your video from your phone to YouTube and then just share a link in your post.

[Vance Harral]

2 hours ago, RonM said:

The leak in the left fuel tank is very bad.

The official definition of "bad" is found in the service manual.  To quote from that manual, "Slow-to-heavy seeps occurring in open areas, such as wing surfaces  exposed to the airstream, are leaks which do not constitute a flight hazard and and need not be repaired prior to flight, providing the condition causing the leak cannot result in a leak of greater intensity during flight."

So if your "very bad" leak is on the wing surface or in the gear well, and isn't causing a stain of greater than 4 inches in diameter, you have some time to consider your options while continuing to fly the airplane.  That's the case with most leaks.  If you actually have a running leak as shown below, or fuel is pooling and/or leaking down into the belly of the fuselage, a more urgent repair is necessary.

We've had both conditions on our airplane.  Over the course of 17 years of ownership, we've had the fuel tanks patched three times, at a cost of $1-2K each time.  Only one of those was an urgent situation.  Fortunately in that case, the leak was on the outboard side of the tank.  We were able to drain that tank down below the level of the leak, keep the other tank full, and fly to the nearest MSC for a patch.

 

[RonM]

I was aware of the leak for a while and planned to have the fuel tank resealed - on my schedule. Now the leak has all of a sudden become urgent, dripping a puddle below the wing and also leaking down to the belly forming another puddle. My right tanks are leak free (inner and outer) total 46.5 gallons. I am hoping to fly from Caldwell NJ to Willmar, MN. (Mooney leak shop)  exclusively on the right tank. I plan to fly legs of 2 hr or so to stop and refuel. Will that work?  

Edited November 25, 2021 by RonM

[RonM]

1 hour ago, LANCECASPER said:

Easiest way is to upload your video from your phone to YouTube and then just share a link in your post.

I did upload video to You Tube.  However, I did not see how I could share any link.  Much Thanks - RonM

[LANCECASPER]

18 minutes ago, RonM said:

I did upload video to You Tube.  However, I did not see how I could share any link.  Much Thanks - RonM

Go to the YouTube page where the video is.

 

Then click on Share

Then click on COPY

Then when you come to the Mooneyspace post, Paste it in your post.

 

[JWJR]

I was aware of the leak for a while and planned to have the fuel tank resealed - on my schedule. Now the leak has all of a sudden become urgent, dripping a puddle below the wing and also leaking down to the belly forming another puddle. My right tanks are leak free (inner and outer) total 46.5 gallons. I am hoping to fly from Caldwell NJ to Willmar, MN. (Mooney leak shop)  exclusively on the right tank. I plan to fly legs of 2 hr or so to stop and refuel. Will that work?  

Not sure what you mean by “will that work?”
If the plan is a reseal at Willmar give them a call with your questions. Im sure they deal with Mooneys flying there with leaking tanks to various degrees week in week out and will offer advice.

Another option as Vance mentioned is to have the leak repaired. ( some refer to as patch) Perhaps call around the shops in your area and see if anyone wants to tackle the job,has some experience and will give you a quote. It’s not a complex job/process.
The materials needed are less than a couple hundred and the rest is the labor/time. This may be convenient, considerably less expensive and buy you many years until the full reseal,however no guarantees!

Good luck


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[RonM]

Mooney Friends:  Thank you all for all the helpful commentary on my Fuel Leak situation.  You are all so friendly, knowledgeable, and generous with your time.  I can't thank you enough and it is so great to be able to consult Mooneyspace for advice.  As it turns out, I will be headed down to Wet Wingologist at Fort Lauderdale Executive Airport.  I know the Minnesota place (Weep No More) is superb, and it would have been fun to fly out to Minnesota. However, I consulted with Edison from Wet Wingologist and he answered all my questions.  I now have a plan of action to resolve my leaking fuel tanks once and for all.  I wish everyone happy, fun and safe flying this holiday season.

   Best - RonM

[1980Mooney]

On 11/25/2021 at 12:23 PM, RonM said:

I was aware of the leak for a while and planned to have the fuel tank resealed - on my schedule. Now the leak has all of a sudden become urgent, dripping a puddle below the wing and also leaking down to the belly forming another puddle. My right tanks are leak free (inner and outer) total 46.5 gallons. I am hoping to fly from Caldwell NJ to Willmar, MN. (Mooney leak shop)  exclusively on the right tank. I plan to fly legs of 2 hr or so to stop and refuel. Will that work?  

I also am the longtime owner of a J that I had converted to a "Missile" and equipped with the Monroy Long Range Tanks.  I also have a leak in the left wing tank.  The leak started slow but h has gotten worse.  It is near the main seam just outboard of the left main landing gear.  When we open the inspection panel (red circle) adjacent the left main gear we can see some fuel puddling in the cavity.  I am going to try to have it patched rather then completely reseal the tanks.

I don't understand why you feel that you should only fly on the right tank to get to Willmar.  It is just a slow leak.  It is best to have some fuel in the left tank for balance.  I just flew mine to a shop that will work on it and I had fuel in the left tank.  The shop will pump out the fuel in order to investigate for the leak and then clean the exterior stains after the patch is complete.

In your case do you already have an appointment in Willmar? - I know that the waiting list at Houston Tank Specialists is about 3 months for a complete reseal.  I don't want to bear the cost or the delay so I am going to try the patch with a recommended A&P.

Edit - I posted this just as you posted that you are going to Florida for a reseal. 

Edited November 26, 2021 by 1980Mooney

[RonM]

1980Mooney:  Thanks for your reply!  I have been very happy with my Missile all these years and hope you are too.  My left wing leak is pretty bad.  There was a steady flow of fuel dripping creating a puddle under the wing and also the belly.  I was putting off the repair to when was convenient, but after the puddles occurred it was time for me to do the scrape and re-seal. My mechanic drained my left tanks and put the fuel in the right wing.  Yes, before I go to Florida I will top off all tanks and fly on the leaky tank first and then the good tank.  I was advised that was okay. Until I leave, though - I plan to just fly on the right tanks which total 46.5 gallons.  Just taking local trips and practicing approaches which is what I like to do. I will take 2 to 3 hour legs when I go to Florida, I imagine. Your decision to do a patch repair sounds reasonable to me, and I hope it solves the issue for you.   Regards - RonM

[IFLYIFR]

I took my M20J to WeepNoMore in May 2019 to do both sides (one needed the repairs and the other side would eventually). Paul Beck and Eric Rudningen are excellent. I cannot imagine a better more professional experience. You should take your plane to them. I have no first hand experience with the Florida shop but I heard less than positive feedback about them from the director of maintenance at the shop where I get my annuals. Good luck.


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[RonM]

Thanks all - again for all the commentary on my Mooney Fuel Tank Leak.  I read all comments very carefully.  So much appreciated.   Have a wonderful holiday season all!

   Best - RonM

[Hank]

@RonM, Edison did a great job on my C in 2010, a complete reseal. I expect that you will be similarly pleased. Like Paul, it's his total business, but Edison has been doing it longer, and with much less paint damage.

[mike_elliott]

Weep no More is a founding sponsor of the Mooney Summit, so I am biased. Hank has been to all of the Summits, I believe, so he can attest to Pauls integrity to treat the Mooney Community right. Hundreds of Mooneys have had Paul repair the tanks, many more than Edison.

I am sure Edison is a fine gent, but I personally have never met him nor has he supported the Mooney Community like Paul has. I am sure  Hank would have considered Paul if he knew about him and the benefits of his process back when he had Edison scrap his tanks.

Paul doesnt damage paint, Hank. You must be thinking or inferring someone else. Edison does a mechanical scraping of the sealant vs Paul's chemical stripping process. Personally, I wouldnt want the mechanical stripping done as it poses some potential issues, but this is an owners call and I am sure Edison takes great precautions not to compromise the Alcladding when he scraps.

Houston tank has also supported the Mooney Summit and is another option.

Thanks Paul, Carl, for supporting the Mooney Summit! Edison, if you got your ears on here, reach out to Rick and join the great service companies and suppliers that support the Mooney Community!

 

[Brent]

A guy I work with happened to send the attached article on Mooney wet wing tanks today. That caused me to look to see what's on Mooneyspace regarding "reseal." In addition, my colleague is a long-time export in aircraft sealants, and he offered the following regarding my J Model: "your 1985 plane s/b PR-1422B, over coated w/ PR-1422AW brush coat, then finished with PR-1005L slosh coat. This is the same sealing method that was used on the Lockheed P-3’s." 

To date, my 1985 J-model is on the original tank seal and leak free. I try to keep fuel in the tanks and avoid drying the sealant out, but I have only owned the plane for four of its 36 years. A little luck probably helps, not to mention that belt and suspenders three-step process mentioned above.  

Hope this proves of interest. I appreciate seeing the maintenance manual pages above. 

Mooney IFT Leaks.pdf

[Jim Peace]

I spoke to Edison this week about doing a minor repair on my right wing tank.  On the phone with him I decided to do the entire tank then he informed me he is booked out until March.  So going a different route.

 

 

[Fly Boomer]

9 hours ago, JimK said:

ou should now have a cover that looks almost like the original factory installation (see attached  Before & After photos.  Also please see the thread titled “Mooney Fuel Tank Leak” for my write-up on detecting and repairing the fuel leak while the cover is removed.

Very nice write-up.

[JimK]

Here is how I find and fix fuel tank leaks:

Step 1, Clean up – Completely drain all fuel from the tank by removing the drain valve on the inboard lower surface of the wing.  Once all fuel is drained, leave the fuel cap and drain valve open overnight to evaporate all explosive fuel vapors.  Remove the appropriate access covers and interior panels (Not the fuel tank covers yet) to gain access to the all outside surfaces of the tank.  Note: You can delete interior panel removal if there is no fuel smell inside the cockpit.  Using an effective solvent like MEK, do a really good job of cleaning all blue fuel stains off of the outer surfaces of the tank.

Step 2, Find leaks on the outside – Reinstall drain valve and turn fuel selector valve to OFF.  Connect a very low pressure gage to the fuel vent.   Devise a plug for the fuel filler neck that will connect to the exhaust side of a shop vac or some other very low pressure, accurately controlled supply and pressurize the tank.  WARNING: DO NOT APPLY MORE THAN 1.0 PSI PRESSURE TO THE TANK BECAUSE HIGHER PRESSURE COULD SERIOUSLY DAMAGE THE WING STRUCTURE!  With pressure applied, brush Snoop leak detection fluid over all exterior seams/joints/fasteners and mark everywhere that bubbles form until you have marked all of the leaks coming from the outside of the tank.  Note: This step is only to get a general idea of where the leaks are in order to know which fuel tank access covers need to be removed. 

Step 3, Remove inspection covers – Use directions I have provided in a Mooney Space post to remove the appropriate fuel tank inspection cover(s).

Step 4, Find leaks on the inside – Plug the fuel tank vent and position the fuel selector to off.  Fabricate a clear plastic panel (.060 is sufficient thickness) large enough to cover one inspection cover opening.  Mount a vacuum gage in this cover to indicate the vacuum level in the tank (do not seal this cover to the fuel tank opening because you need to be able to quickly remove it periodically and the vacuum will keep it in place anyway).  Connect a shop vac hose to the fuel filler neck.  Brush Snoop or other leak detection fluid on a small joint/fastener row and quickly place cover over the wing opening and turn on the vacuum source.  DO NOT APPLY MORE THAN 1.0 PSI VACUUM TO THE TANK BECAUSE HIGHER VACUUM COULD SERIOUSLY DAMAGE THE WING STRUCTURE!   Either a bright light inside the tank before placing the plastic panel or a light shined through the plastic panel will allow you to see bubbles at the leak.  Again, mark all the leaks on the inside of the tank.

Step 5, Repair the leaks from the inside – Under the supervision of an A&P mechanic and using the procedure and materials specified in the Maintenance Manual section 28-11 & 28-12, repair the fuel tank leaks.

Step 6, Reinstall inspection covers – Use directions I have provided in a Mooney Space post to reinstall the fuel tank inspection covers.

Please see attached photos of the special tools I made to do this job.

[John Mininger]

I'm getting to the point where I'm going to need schedule a tank reseal. The last reseal was done by Wet Wingologist in 11/1994.

The consensus seems to be Weep No More in Willmar MN. But Wet Wingologist in Fort Lauderdale is much more convenient to the areas that I normally fly. This is a job that I would hope would last another 31 years. So, I really want to go to the best shop. What are the current recommendations?

Thanks

John

[LANCECASPER]

20 minutes ago, John Mininger said:

I'm getting to the point where I'm going to need schedule a tank reseal. The last reseal was done by Wet Wingologist in 11/1994.

The consensus seems to be Weep No More in Willmar MN. But Wet Wingologist in Fort Lauderdale is much more convenient to the areas that I normally fly. This is a job that I would hope would last another 31 years. So, I really want to go to the best shop. What are the current recommendations?

Thanks

John

They're both great.  If the last one (Wet Wingologist) lasted 31 years and it's more convenient for you seems like an easy choice.

[NickG]

Also Don Maxwell and Houston Tax Specialists.