Leaking fuel tank. How much is too much?

[Bill_Pyles]

The left tank on my Mooney N239SW has developed leaks around two access panels on the underside of the left wing.  The tanks were re-sealed 11 years ago by Weep No More which everyone says is the gold standard for tank repair but I am in AZ and they are in MN.

 

I flew the plane for two hours using only the right tank and the leakage rate for the left tank is about a gallon per hour while in flight.  However, while the plane is parked in my hangar, the leak rate for the left tank is about 6 gallons per week.

 

How does this leak rate compare with your experience?  Do leaks tend to get worse?

 

Has anyone used Southwest Airframe and Tank Services to fix a leaky fuel tank on a Mooney?  

 

Can anyone recommend a tank repair expert in AZ?

 

Thanks,

 

Bill

KDVT

408-717-2771

 

 

[Bill_Pyles]

I should have attached photos of the leak in N239SW

[Shadrach]

The maintenance manual clearly differentiates between a seep and a leak with regards to airworthiness. I’m not going to render an opinion with regards to airworthiness based on pictures but will say that in my view what is depicted is beyond the “keep an eye on it “stage. The good news is that resealing access panels is relatively quick and easy. The bad news is it looks like some of the leaks/seeps are not related to access panels.  It’s likely that the tanks can be easily (relatively speaking) repaired. Do you have a relationship with a local A&P/IA?

[Yetti]

Hard landing?   You have a couple of leaks.   The access panel Which might just be the screws.   I would take the screws out one by one and put some permetex #3 on them and replace.   a small amount is all you need.   If you gunk it on you risk popping the covers off the screws inside.   If they are really gunked up inside the in the plane threads you want to clean them out.   use a small screw driver in your hand.

 

The weep holes is coming from someplace else.   I found that replacing the fuel sender gaskets from Brown Gasket company fixed those.   You might just need to tighten them up.   Look for the last access panel on the front side of the wing (underneath) to get at the outboard sender.   The other one is in behind the side panel.

[EricJ]

That definitely needs attention.   I wish I knew an experienced available local resource for this (I'm also at DVT), but I don't.   I need to learn how to do it but don't want to experiment on somebody else's airplane.

If you're up for a trip, Maxwells in TX were doing tank patches for flat rate a few years ago and repaired mine.   

[Guest]

The leak in the first picture is coming from the dry bay in front of the forward spar.  The leak in the fourth picture is from the dry bay outside the tip end of the tank.  The panel is not sealed in any way.  Generally,  leak on exterior surfaces are OK, leaks within the wing in sealed areas are not.  Aside from the dollars you're spilling on the ground, you're ruining your paint the longer it goes on.

Clarence

[N201MKTurbo]

That leak could be from the level sensor. I would pull that panel and check that before I did anything else. You might be able to fix it with a $10 gasket.

Actually, leaking that much, the screws may have come loose. you might be able to fix it by just tightening the screws.

[N201MKTurbo]

2 hours ago, Bill_Pyles said:

The left tank on my Mooney N239SW has developed leaks around two access panels on the underside of the left wing.  The tanks were re-sealed 11 years ago by Weep No More which everyone says is the gold standard for tank repair but I am in AZ and they are in MN.

 

I flew the plane for two hours using only the right tank and the leakage rate for the left tank is about a gallon per hour while in flight.  However, while the plane is parked in my hangar, the leak rate for the left tank is about 6 gallons per week.

 

How does this leak rate compare with your experience?  Do leaks tend to get worse?

 

Has anyone used Southwest Airframe and Tank Services to fix a leaky fuel tank on a Mooney?  

 

Can anyone recommend a tank repair expert in AZ?

 

Thanks,

 

Bill

KDVT

408-717-2771

 

 

If you bring it by KCHD this weekend, I'll take a look at it. I'm fixing my right tank right now. You can see what the inside of your tanks look like.

[EricJ]

18 minutes ago, N201MKTurbo said:

If you bring it by KCHD this weekend, I'll take a look at it. I'm fixing my right tank right now. You can see what the inside of your tanks look like.

I didn't want to volunteer you, so good on ya. 

 

[EricJ]

2 hours ago, Bill_Pyles said:

I should have attached photos of the leak in N239SW

If you don't have a chance to take it down to see Rich at CHD, who has done this a lot on his airplane, I could at least look at it and sort out whether it is the sender gasket or not or get a better idea of where the leaks might be coming from.    You may have more than one.

[231LV]

2 hours ago, Bill_Pyles said:

The left tank on my Mooney N239SW has developed leaks around two access panels on the underside of the left wing.  The tanks were re-sealed 11 years ago by Weep No More which everyone says is the gold standard for tank repair but I am in AZ and they are in MN.

 

I flew the plane for two hours using only the right tank and the leakage rate for the left tank is about a gallon per hour while in flight.  However, while the plane is parked in my hangar, the leak rate for the left tank is about 6 gallons per week.

 

How does this leak rate compare with your experience?  Do leaks tend to get worse?

 

Has anyone used Southwest Airframe and Tank Services to fix a leaky fuel tank on a Mooney?  

 

Can anyone recommend a tank repair expert in AZ?

 

Thanks,

 

Bill

KDVT

408-717-2771

 

 

I have an appt with Chandler Aviation in early Sept for a patch. They don't do strip/reseal...only patch and they won't warranty the patch. I found the only two strip/reseals are in MN Weep No More and Wet Wingologists in FL. If someone knows of a reputable  third shop, I would like to hear about it.

[ArtVandelay]

I have an appt with Chandler Aviation in early Sept for a patch. They don't do strip/reseal...only patch and they won't warranty the patch. I found the only two strip/reseals are in MN Weep No More and Wet Wingologists in FL. If someone knows of a reputable  third shop, I would like to hear about it.

Houston Tank Specialists…much closer for the OP.

[Bill_Pyles]

Thanks everyone.  Sounds like the tank is leaking into the dry part of the wing. 

For the past few years I have been going to Falcon Aviation Services at KFFZ and they are currently working with Southwest Airframe and Tank on another Mooney tank leak, and Falcon will speak to Southwest about my plane.  

[cnoe]

In case you don't have it, here's Mooney's guidance on the issue.

I offer no other advice than to use your common sense, and keep a fire extinguisher handy.

CNoe

[1980Mooney]

On 7/29/2022 at 5:57 PM, Bill_Pyles said:

Thanks everyone.  Sounds like the tank is leaking into the dry part of the wing. 

For the past few years I have been going to Falcon Aviation Services at KFFZ and they are currently working with Southwest Airframe and Tank on another Mooney tank leak, and Falcon will speak to Southwest about my plane.  

FWIW - I had a leak similar to yours in my left wing during Annual.  This particular A&P brought in a subcontractor to work on my leaking tank which unfortunately didn't work out.  The A&P declared my plane Unairworthy. They signed off on my Annual With Exceptions.  I had to get a Ferry Permit to go to another A&P at a different field that knew what they were doing and successfully patched my tank. 

[231LV]

On 7/29/2022 at 11:32 AM, ArtVandelay said:

Houston Tank Specialists…much closer for the OP.

Thanks Art...has anyone else used them and if so, what was your experience?

[carusoam]

@HoustonTankSpecialistsLLC has a steady flow of business… and a few pireps around here…

They also have supported MooneySummit in the past…

Call them and ask all the important questions…. It’s a great conversation.  I had lunch with Carl Sharon at Mooney Summit a few years ago…

Best regards,

-a-

[Rjfanjet]

I flew to Houston from SLC last year. No complaints!

[Guest]

10 hours ago, 231LV said:

Thanks Art...has anyone else used them and if so, what was your experience?

A client of mine used them, it was a disaster.  Ended up going to Minnesota to get it redone.

[Fly Boomer]

5 hours ago, M20Doc said:

A client of mine used them, it was a disaster.

Can you elaborate?  Did you see the disaster?  Did the Minnesota company strip them again, or were they able to salvage the Houston Job?

[Guest]

22 minutes ago, Fly Boomer said:

Can you elaborate?  Did you see the disaster?  Did the Minnesota company strip them again, or were they able to salvage the Houston Job?

Leaks from the moment it was picked up,  they ended up draining the Monroe extension tank and capping the lines.  The additional fuel filler caps holes were drilled too large and the new cap flanges weren’t centred in the now oversized holes.  Minnesota ended up doing another strip and reseal to fix it right.

It certainly wasn’t a great job.

[Fly Boomer]

2 minutes ago, M20Doc said:

It certainly wasn’t a great job.

Yikes!  Thanks for the info.

[1980Mooney]

Here are a few threads on MS with PIREPS on Houston Tank Specialties (HTC) - Good and Bad.  Tank resealing is tedious and an art.  You spend the money and roll the dice....

Good

From 2016 and 2021 some good comments.

And not so good or bad...

From 2022 - read down to @louisut  he said "Unfortunately our experience has been somewhat mixed. While I think he's a meticulous A&P who knows Mooneys and does a good job, I think he might be taking in more work than he has capacity for. Our reseal job began mid-July 2021 and the reseal, annual, and replacement of two cylinders took nine months, and that's with frequent nagging towards the end. I'm not sure how long Wet Wingologists and Weep-No-More are taking, but it seems like a long time.

Most recently, a leak developed in one of our tanks and so the plane is going back. While he guarantees his work with a seven year warranty, I'm hesitant to take it back based on how long it took the last time."

From 2018 @M20Doc reported poor workmanship on some Monroy tank work.

 

 

And not so good or bad...

 

 

[Bill_Pyles]

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!

 

 

Edited November 2, 2022 by Bill_Pyles

[EricJ]

59 minutes 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!

Nice!   Glad you got it sorted out and the repair done!    That was a fairly nasty leak because of the fuel amounts that were accumulating in the surrounding spaces.

Now you're the local DVT expert on tank patching.