Leaking fuel tank. How much is too much?

[Niko182]

1 hour ago, Bill_Pyles said:

I am pleased to report that, with the assistance and final approval of Rich, AKA N201MKTurbo, who is an A&P, I was able to detect and repair the leak in my left tank using the Mooney maintenance manual procedure.  The basic steps were:

1)  Drain the fuel from the tank

2)  Remove the three fuel tank access panels.

3)  Fabricate clear Lexan windows, for the access holes and one for the filler hole.

4) Position flashlights and mirrors inside the tank to enable a view of every nook and cranny and seam.

5) Squirt soap bubble solution along the seams inside the tank near the suspected leak location.

6) Install the Lexan windows with blue painters' masking tape.

7) Insert vacuum hose into a cutout in one of the Lexan panels and look for bubbles where outside air is being sucked through the leak.  (I found one significant leak where the stringer passes through the outer tank wall)

8)  Make note of the leak location and check the rest of the tank for leaks.  (There was just the one leak).

9)  Remove Lexan windows and completely remove old sealant from the leak area using MEK and plastic scrapers---no metal scrapers.  This took a while.  

10)  Remove old sealant from the access panels and area inside the wing tank where the panels are mounted.

11) Thoroughly clean the tank with water and cloth that does not shed lint.

11) Using the Mooney Maintenance manual-prescribed sealants, I filled the leak area with filet sealant, brushable sealant and top coat.

12)  Reinstall the access panels with panel sealant and new aircraft grade screws.

13)  Fill both tanks with fuel and fly!

14)  No leaking observed and depleted fuel is consistent with expected fuel burn rate.

Thanks to EricJ for an early discussion and examination of the plane right after I noticed a leak, and thanks to Rich for guidance and encouragement throughout the repair project as well as assistance re-installing the access panels, which is easier with three hands.  I had a great time working on the plane and it was one of those projects that I almost didn't want to end.   "Almost" being the operative ;-)    I am glad to be flying the plane again!

 

 

How long did it take?

[Bill_Pyles]

Eric:  Expert might be a stretch, (Rich is the expert) but I learned a few things and wouldn't mind sharing what I learned.

Niko:  As far as how long the repair took, I didn't keep an exact record, but I estimate the actual work on the plane was around 10-12 hrs although I spent a number of hours corresponding with folks, researching and ordering (or borrowing) the scrapers and sealants (and special tools like the skin wedge and sealant applicator) and watching Youtube videos that related to the repair (there weren't many videos), so the actual work was less than half the total time I spent researching and agonizing over the possibility of flying the plane somewhere to have a professional do the job.

  

 

Edited November 3, 2022 by Bill_Pyles

[LANCECASPER]

9 hours ago, Bill_Pyles said:

Eric:  Expert might be a stretch, (Rich is the expert) but I learned a few things and wouldn't mind sharing what I learned.

Niko:  As far as how long the repair took, I didn't keep an exact record, but I estimate the actual work on the plane was around 10-12 hrs although I spent a number of hours corresponding with folks, researching and ordering (or borrowing) the scrapers and sealants (and special tools like the skin wedge and sealant applicator) and watching Youtube videos that related to the repair (there weren't many videos), so the actual work was less than half the total time I spent researching and agonizing over the possibility of flying the plane somewhere to have a professional do the job.

  

 

Good job!!

[carusoam]

Nice work Bill!

Great pirep for Rich! 

Thanks for sharing all of the details with pics!

1) I really like your writing style!

MSer of the day award for all of the extra effort… shared!

Go MS!

Best regards,

-a-

[tmo]

Congratulations. And a hearty "thank you" for writing up the procedure in a concise post.

[carusoam]

Seeing if @Rrodriguez is cruising by… he is working on a fuel tank project…

Best regards,

-a-

[Denis Mexted]

Thanks for the Pirep Bill. 
 

The vacuum you used was a normal shop vacuum cleaner or household vacuum? (Any photos) 

I guess the vacuum is pulling the LEXAN inspection covers in so the blue tape is just a seal. 

There are a number of old stains, brown in colour on mine. Any idea of the best cleaning product to remove stains? 

Thanks for the write up.

Edited February 10, 2023 by Denis Mexted

[RoundTwo]

4 minutes ago, Denis Mexted said:

Thanks for the Pirep Bill. 
 

The vacuum you used was a normal shop vacuum cleaner or household vacuum? (Any photos) 

I guess the vacuum is pulling the LEXAN inspection covers in so the blue tape is just a seal. 

There are a number of old stains, brown in colour on mine. Any idea of the best cleaning product to remove stains? 

Thanks for the write up.

No magic eraser available. Google “remove 100ll stain” and start reading. Lots of posts here too.

[carusoam]

5 minutes ago, Denis Mexted said:

Thanks for the Pirep Bill. 
 

The vacuum you used was a normal shop vacuum cleaner or household vacuum? (Any photos) 

I guess the vacuum is pulling the LEXAN inspection covers in so the blue tape is just a seal. 

There are a number of old stains, brown in colour on mine. Any idea of the best cleaning product to remove stains? 

Thanks for the write up.

Denis,

its been a while….

Let’s invite @Bill_Pyles to stop by…

Best regards,

-a-