Fuel tank leak

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Fuel tank leak

Unread post by TerryE » Sun Jun 24, 2012 8:47 am

They say that if you own a Mooney, you will have to deal with a fuel tank leak at some point, and my time seems to have come.

Looks like the left wing is leaking when filled to 20 gal, so I suspect it is on the outboard end.

My usual AMO is quoting R2 k in materials and approx 25 hours labour per side, So I have a few questions

1. Does this quote sound reasonable ?
2. Any recommendations, success stories on tank reseals / AMO's to use ?
3. Are bladders a viable option ?

I have also now heard that leaks can be caused by leaving the tanks low, as the sealant can dry out. We always refuel before flight, so that you can choose your fuel load, should we change to leaving her full ?
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Re: Fuel tank leak

Unread post by Lood » Sun Jul 01, 2012 7:13 pm

Hi Terry, been there and had one tank completely stripped and resealed at the end of last year. So, I know exactly what you're going through. :(
Firstly, if your tank has never been repaired, or patched in the past, you might get away for a short while by having it patched. This will not cost an arm and a leg, but also, it will not last, unfortunately.
The only way is to have it done properly by doing a complete strip and reseal. It is very important to have this job done by somebody with experience - not only on sealing fuel tanks in general, but on Mooney tanks in particular. There are quite a few horror stories around about complete strip and reseal exercises that have gone bad due to inexperience and simple mistakes.
The quote sounds about right. Mine was done last year at SA Mooney for R20k, IIRC and I supplied the sealant. It is a huge, huge task and over in the US, the cost is around $8k.
Many US Mooney pilot are happy with their bladders. The downside is that you'll loose quite a few very valuable pounds in useful load and the bladders also cost around $8k when I last checked. I'm not sure whether they are available locally and if not, they're going to set you back in the region of R80k just to get them here. IIRC, installation is about 50hrs :!: :shock: :shock:
WRT the sealant going bad as a result of tanks not being kept full, this is only applicable if your Mooney is kept outside in direct sun. The sealant doesn't go hard or dry out because of not being submerged in Avgas, but as a result of heat buildup inside the fuel tank.

My newly sealed tank is 100% leak free and as soon as I have funds available, I'm getting the other side done as well. I can definitely recommend SA Mooney. They know their way around Mooney's and they have successfully done this exercise a number of times. Good luck.
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Re: Fuel tank leak

Unread post by pieter001 » Tue Jul 03, 2012 8:20 pm

I hope my time is far off still...

Good luck, I'm keen to hear the outcome. Seems the stripping is a serious amount of work!
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Re: Fuel tank leak

Unread post by TerryE » Wed Jul 04, 2012 8:10 pm

She is in at the moment, looks like at some point in the past the tank was patched, as there are 2 types on sealant in the tank, and some idiot at some point, has epoxied over the inspection hatches. So the stripping is a bitch :roll: :roll:

The other side is also leaking, and that one is leaking into the cabin (check the carpets in the back right corner, nice wet patch with a blue stain). So that one is now also being stripped.

I'm doing a full strip down and reseal, much moola :cry:
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Re: Fuel tank leak

Unread post by TerryE » Thu Jul 05, 2012 8:01 am

Some Pics

Left wing stripping
IMG-20120704-00492.jpg
All masked up
Randburg-20120704-00493.jpg
Randburg-20120704-00495.jpg
Randburg-20120704-00497.jpg
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Re: Fuel tank leak

Unread post by Lood » Thu Jul 05, 2012 9:28 pm

Hi Terry, I feel your pain, but when all is done, you'll be happy that you went all the way. If you don't mind, what stripper are you using :?: I went through an extremely time consuming exercise to try and find a chemical that actually works without success. In the end, my tank was stripped manually. This takes about 3 weeks and makes for the ;largest part of the total cost.
My right tank also leaked into the cockpit. There wasn't much evidence on the wing itself, but when filled to the top, the fuel would actually drip slowly from beneath the center of the cockpit floor. #-o
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Re: Fuel tank leak

Unread post by TerryE » Fri Jul 06, 2012 7:21 am

I will ask what stripper they are using. My understanding is that at some point the tank was sealed over an existing seal. The chemical stripper seems to work on the top layer, but only softens the bottom layer and they are having to scrape this second layer.

She originally went in to have only the left wing tank done, but we filled the right tank as a double check -
Randburg-20120705-00509.jpg
This is what happened about 24 hours into the process - and when you think about the ignition sources under there - Strobe power unit, UC motor, UC floor repeater light, Aux fuel pump (which burned out in December :shock: )

:shock: :shock: :shock: Scared the Cr@p out of me :shock: :shock: :shock: took about 2 seconds to make the decision to do the right tank.
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Last edited by TerryE on Mon Mar 23, 2015 4:40 pm, edited 1 time in total.
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Re: Fuel tank leak

Unread post by pieter001 » Fri Jul 06, 2012 7:54 am

I need to check my right tank too, fuel just dissapears from it. The fuel strainer valve is certainly suspect, but I think the may be more than meets the eye...
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Re: Fuel tank leak

Unread post by TerryE » Fri Jul 06, 2012 11:21 am

Randburg-20120705-00510.jpg
Check inside the cabin against the back seat on the right side wall - We found a blue stain next to the seat rail, and this hidden behind the carpet. what is interesting is that I didn't smell fumes in the cabin - it looks like it drains under the floor, and that the floor and carpets seem to isolate the fuel smell from the cabin.

We never refill before parking - so that before the next flight you can decide on the fuel upload vs cabin load - and this leak seems to only happen when the tank is full, so it does not show up on the preflight. I'm very glad we decided to check the other tank ...
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Re: Fuel tank leak

Unread post by TerryE » Fri Jul 06, 2012 5:44 pm

what stripper are you using
They are using "Turco 5351" for removal of polyurethane and epoxy surface coatings.
Last edited by TerryE on Mon Mar 23, 2015 4:42 pm, edited 1 time in total.
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Re: Fuel tank leak

Unread post by Lood » Sun Jul 15, 2012 5:31 pm

Thanks Terry.
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Re: Fuel tank leak

Unread post by flashfly » Wed May 20, 2015 5:36 pm

Eish. Left wing is leaking. Maybe I need to take your advise and take it to SA Mooney Lood.
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Re: Fuel tank leak

Unread post by Lood » Wed May 20, 2015 6:34 pm

Sorry to hear that FF. Unfortunately, there are no shortcuts once a tank starts leaking. All quick solutions are only temporary.
A complete strip and reseal is the only way. I can fill both my tanks until they're about to overflow and they will keep that level indefinitely. If you do the major stripping yourself, it will save you you at least R15k.
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Re: Fuel tank leak

Unread post by andrem » Wed May 20, 2015 6:57 pm

Hi Nick,

Sorry to hear about that! Mine was completely stripped and sealed last year too - both tanks. I witnessed some of the work being done and can tell you that shortcuts should be avoided - having fuel leaking where exhaust gasses are blowing is no joke.

You can also try Eric Cook down towards Cape Town and make a holiday of it ;-). Although I suppose can be said of SA Mooney in East London.
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Re: Fuel tank leak

Unread post by Chimsoro » Thu May 21, 2015 9:09 pm

SA Mooney,,,for a good job..the best

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