Fuel Tank Poll

[AH-1 Cobra Pilot]

My 1978 J tanks were resealed before I bought it.  They just went out of warranty; no leaks.

[Fritz Kaiser]

My '95 O is right now for resealing in Netherland. The maintenance shop is the european depandance from Paul Becks " weep-no-more"

i'm hope they will do a good job!!

Fritz 

[mike_elliott]

After 35 years, I had my F model stripped and resealed by Weep no more in 2005 because of small staining beginning to develop on the co pilot wing and I was going to have it painted. 12 years later, no problems per the current owner.

35 years on the original 70's sealant....Dang wish they put in those "guaranteed until the rapture" bladders when it was new. :)

(I didn't select bladders because 1 there was no guarantee they would last more than the 35 years I got out of a "shoddy" factory seal job using old technology sealant and 2) they didn't make a 64 gal kit at the time, only a 52 which is debatable if you get 52 I hear)

 

 

[cnoe]

At this point we have 74 responses to the poll. While the poll is not a "scientific poll" there is still some good information we can gather from it IMO.

As it stands now the indications are:

1. 80% of respondents have had fuel tank leaks in the past or in the present.

2. 24% of respondents currently have a fuel leakage issue.

3. 54% of respondents who've patched/repaired their tanks continue to have fuel leakage issues.

4. 21% of respondents who've stripped/resealed their tanks continue to have fuel leakage issues.

5. Though the question was not listed in the poll one instance of bladder leakage was reported but my assumption is that bladder leakage is a rare event when properly installed.

Note: No valid information could be derived regarding the age of those aircraft whose tanks are original and are still leak-free. Due to my poorly-worded question 10 individuals posted the age of their aircraft even though they had repairs and/or leakage. My assumption is that older planes are more likely to leak than newer ones but this cannot be supported by the data as collected.

Anybody else have any thoughts or comments?

[mike_elliott]

Of the 21% who have had a strip/reseal, and continue to have leaks,how many of those were done by a "pro" shop vs. the local "can do" A$P or DYI?

[gsxrpilot]

My K is in the shop right now getting the Right tank stripped and resealed. 1987 model. This is the first work done on the tanks.

[Marauder]

  On 2/1/2017 at 4:24 PM, Hyett6420 said:

Talking of bladders, the fuel line I assume then becomes a urethra, Do Mooneys have Prostates?  

Never stuck my hand far enough up the exhaust pipe to figure that out.


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[RobertGary1]

  On 2/1/2017 at 5:11 PM, gsxrpilot said:

My K is in the shop right now getting the Right tank stripped and resealed. 1987 model. This is the first work done on the tanks.

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Curious what motived this vs a simple inexpensive patch.

 

-Robert

[gsxrpilot]

  On 2/1/2017 at 6:30 PM, RobertGary1 said:

Curious what motived this vs a simple inexpensive patch.

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I wasn't convinced that the patch would be any more than a short term solution.  But now that the tank has been opened and stripped, we've discovered some pretty serious spar corrosion. That is likely worthy of it's own thread.

[cnoe]

  On 2/1/2017 at 5:05 PM, mike_elliott said:

Of the 21% who have had a strip/reseal, and continue to have leaks,how many of those were done by a "pro" shop vs. the local "can do" A$P or DYI?

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I am one of the 21%. Both my tanks were stripped and resealed by Weep-No-More 5 years ago. I noticed a leaking rivet in the top of the right wing 2 years ago and called Paul about it. He offered to provide the necessary instructions to have an A&P repair it locally or said he'd repair it in-house if I brought it to Wilmar. Since it's only one rivet, is on top of the wing, and only leaks when the tanks are full I've chosen to defer the repair for now.

I'm generally satisfied with the work that WNM did but would suggest that nobody is perfect, even the best shops. I'd be thrilled if they offered to pay a local shop to make the necessary repair for me, but I don't expect it. If it was leaking along a seam I'd probably fly it back to Wilmar.

[mooniac15u]

  On 2/1/2017 at 10:56 PM, gsxrpilot said:

I wasn't convinced that the patch would be any more than a short term solution.  But now that the tank has been opened and stripped, we've discovered some pretty serious spar corrosion. That is likely worthy of it's own thread.

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That doesn't sound good. Can you share some details?

[gsxrpilot]

  On 2/2/2017 at 1:15 AM, mooniac15u said:

That doesn't sound good. Can you share some details?

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Let me wait to hear back from Mooney and Don Maxwell before I post too many details here.  As soon as I know what we're dealing with, I'll start a thread and give all the details I can.

[Mooney_Allegro]

  On 2/2/2017 at 12:46 AM, cnoe said:

  On 2/2/2017 at 12:46 AM, cnoe said:

Of the 21% who have had a strip/reseal, and continue to have leaks,how many of those were done by a "pro" shop vs. the local "can do" A$P or DYI?

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I had a complete strip/reseal done at Weep No More in summer 2015.  During the summer of 2016 my cabin started smelling like a refinery again.  I lost 2 gallons of fuel/week in the left tank.  I couldn't find the leak.  After calling WNM, I was advised the leak was from the fuel sending unit area behind the interior.  I could have flown the plane back up to MN for the repair, but for one it would have cost lots of money in fuel to fly it there and two, the leak was so bad I didn't want to fly it.  I ended up having to remove the seats, and the left side interior and fixed it myself.  All of the screws for the pickup were not tight, and it was leaking a drop of fuel every second into the cabin.  About 3 months later, another leak developed on the wing-walk.  Again, it would have cost too much to fly to MN for the warranty work, so I ended up paying a few hundred dollars out of pocket, and had it fixed by a MSC in Georgia.  If I lived closer, I would have taken advantage of the warranty, but paying out of pocket was cheaper.  Paul is super great with communications, and he helped me diagnose the issues.  I expected not to have any problems for years though after spending so much money, so I was a bit disappointed.  Things happen though in aviation. 

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[mooniac15u]

  On 2/2/2017 at 1:24 AM, gsxrpilot said:

Let me wait to hear back from Mooney and Don Maxwell before I post too many details here.  As soon as I know what we're dealing with, I'll start a thread and give all the details I can.

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That's fair. I hope it isn't too bad. It seems like @Hyett6420 might have come across some corrosion during a reseal recently too. I wonder if it's in a similar location. 

[LANCECASPER]

  On 2/1/2017 at 1:12 PM, teejayevans said:

With 1 exception, I believe they started to apply sealant during the assembly process and got it between the seems, not just applied over them, don't remember where I read that.

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This began around 2006.

[cnoe]

  On 2/2/2017 at 1:19 AM, bluehighwayflyer said:

Interesting data collection, cnoe.
Jim

'Twas Teejayvan's idea; he gets credit.


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[ArtVandelay]

Andrew, I wonder if your corrosion was a result of water getting into the tanks?

[mooniac15u]

  On 2/2/2017 at 12:42 PM, Hyett6420 said:

I think almost certainly.  She was parked outside in our lovely climate, for a few years and I don't think this helped her at all.  Interestingly though when you Pre flight drained her she never had any water in the tanks.  So that goes against that theory, I am minded to think of that as a red herring however.  

It would be interesting to see what the chemical reaction over time is with avgas and aluminium, when temperatures vary to create evaporation. Etc.  Any chemists out there.  I only did chemistry till I was 15 and my teacher was more interested in eyeing us up I think than chemistry. 

Andrew

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Avgas should not react with aluminum.  It is mostly hydrocarbons like the oils we use to protect metals.

[Guitarmaster]

  On 2/1/2017 at 5:35 PM, Hyett6420 said:

Then we can do a poll on LOP v ROP. . 
Andrew

Let's add no-flap takeoffs to the poll!!

[mooniac15u]

  On 2/2/2017 at 1:59 PM, Hyett6420 said:

Agreed so what causes the corrosion then.  It can't just be water unless the skin joints are loose.  

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I don't know what metals are used inside the fuel tank.  Is there a combination of aluminum and steel?  That would make galvanic corrosion a possibility.

Was the corrosion in your tanks in a low area where you would expect water to accumulate?

[kris_adams]

  On 2/2/2017 at 1:41 PM, Guitarmaster said:

Let's add no-flap takeoffs to the poll!!

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when flying a no-flap LOP departure I still can't get the ROP-LOP debate out of my head...

[wrench]

1978 M20J ~5500TT. Right side stripped and resealed 2011, doesn't leak. Left side never touched per logs, doesn't leak.

 

[jetdriven]

  On 2/2/2017 at 2:19 PM, mooniac15u said:

I don't know what metals are used inside the fuel tank.  Is there a combination of aluminum and steel?  That would make galvanic corrosion a possibility.

Was the corrosion in your tanks in a low area where you would expect water to accumulate?

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Perhaps the corrosion is from the humidity in the air when the tanks sit partially full

[ArtVandelay]

  On 2/2/2017 at 2:55 PM, jetdriven said:

Perhaps the corrosion is from the humidity in the air when the tanks sit partially full

The pictures in his other thread about the refit shows the corrosion on the bottom, which makes me think it was water resting on the bottom.

[ArtVandelay]

  On 2/2/2017 at 1:59 PM, Hyett6420 said:

Agreed so what causes the corrosion then.  It can't just be water unless the skin joints are loose.  

Lets see, we have water, avgas AND whatever additives they use these days, don't know if EU fuel has different additives than USA.