Fuel Tank Sealing

[skippydiesel]

Hi Brains Trust,

 

In the very near future, I may have to make a small penetrant in my aluminium fuel thank. In itself not problem however I am concerned about long term sealing, of the fitting I will be putting in.

 

Your recommendations for a reliable fuel tank sealer, readily available in Australia, will be much appreciated.

 

Thanks in advance .

[facthunter]

Find out what they use on a Mooney. It has a "wet" wing.   Nev

[Thruster88]

At work we use this on certified aircraft. 

 

 

Pro-Seal Fuel Tank Sealant P/S 890 B - 1/2 Hour | Aircraft Spruce

WWW.AIRCRAFTSPRUCE.COM

---

Pro-Seal Fuel Tank Sealant P/S 890 B - 1/2 Hour P/S 890 Class A is an aircraft integral fuel tank sealant. It has a service temperature range from -65°F (-54°C) to 250°F (121°C), with intermittent excursions up...

 

[skippydiesel]

Thanks Thruster

 

This will be a very small job (fitting a new fuel sensor flange), so I was hoping for something  little less costly ($62 US + on costs is pretty scary)

[RFguy]

although your 1 hour flight will chew up $50 of fuel  and $17 of engine time ? maybe you can get a bit from the locals. 

Edited July 6, 2023 by RFguy

[RFguy]

Skip, maybe for your experimental application, just some decent automotive fuel tank/ fuel pump gasket silicone

etc

Repco Australia | Auto Parts Store - Aftermarket Car Parts

WWW.REPCO.COM.AU

 

 

Repco Australia | Auto Parts Store - Aftermarket Car Parts

WWW.REPCO.COM.AU

 

 

[skippydiesel]

1 hour ago, RFguy said:

although your 1 hour flight will chew up $50 of fuel  and $17 of engine time ? maybe you can get a bit from the locals. 

Ha ha! - Yours may gobble $50/hr min is about half😁

[skippydiesel]

18 minutes ago, RFguy said:

Skip, maybe for your experimental application, just some decent automotive fuel tank/ fuel pump gasket silicone

etc

Repco Australia | Auto Parts Store - Aftermarket Car Parts

WWW.REPCO.COM.AU

 

 

Repco Australia | Auto Parts Store - Aftermarket Car Parts

WWW.REPCO.COM.AU

 

 

I have a fair sample of this on my shelf BUT this is an in fuselage tank (don't want fumes let alone spillage)  and I would like to think that I have chosen a product known to do an excellent job over extended period of time (nothing like a respondent with first hand experience /knowledge)

[RFguy]

agreed if its in a fuel tank and you do NOT want blobs coming adrift and blocking inlet. good reason to have finger strainers.

[onetrack]

No silicone product that I know of, will resist petrol attack. You need a urethane-type sealant. POR-15 is well known and respected as a rusty fuel tank sealer, and is impervious to all fuels once it hardens.

 

Edited July 7, 2023 by onetrack

[Thruster88]

7 hours ago, skippydiesel said:

Thanks Thruster

 

This will be a very small job (fitting a new fuel sensor flange), so I was hoping for something  little less costly ($62 US + on costs is pretty scary)

If it leaks with an inferior product and you have to do it again $62us will seem cheap. CJ aerospace in Sydney should have it in stock.  

CJ Aerospace: Aircraft Parts | Superior Service | Technical Experts - HOME

WWW.CJAEROSPACE.COM.AU

 

[skippydiesel]

What does the "Brains Trust" think of:

 

Three Bond 1104 or 1207?

 

Permatex Permashield 85420? Permagasket No 2? Aviation Form a gasket No3? High temperature thread sealer?

 

Locktite 1252795? 577 Pipe sealant? 512 Flange sealent?

 

STAG?

 

Others?

 

 

 

Edited July 7, 2023 by skippydiesel

[skippydiesel]

2 hours ago, Thruster88 said:

If it leaks with an inferior product and you have to do it again $62us will seem cheap. CJ aerospace in Sydney should have it in stock.  

CJ Aerospace: Aircraft Parts | Superior Service | Technical Experts - HOME

WWW.CJAEROSPACE.COM.AU

 

One thing I have learned, in my long armature mechanics life - there is a lot of hype out there, its bad in the automotive world and rampant in the  the aviation world. 

 

Not suggesting your recommended product is at all inferior (its probably the creme de la creme) BUT for a job that will probably use up 1/4  or less of a small tube of  automotive sealant, purchasing a tub (never to be used again) for what will probably work out to be $150 -$200 AU delivered to my home, seems a tad overkill  IF a readily available automotive product will do just as well at  a fraction of the cost.

[facthunter]

Gasket substitutes are not  what you need. You need some long lasting "goop" COATING that sticks  strongly to the surface and stays there unaffected by the fuel for many years that you can trust. Nev

[rgmwa]

FWIW I would just pay the money and use this:

Fuel Tank Sealant, 3.5 ounces, 2 hour work time

STORE.VANSAIRCRAFT.COM

$21US plus postage. Probably the same stuff Thruster recommended from ACS. 

 

[Blueadventures]

27 minutes ago, rgmwa said:

FWIW I would just pay the money and use this:

Fuel Tank Sealant, 3.5 ounces, 2 hour work time

STORE.VANSAIRCRAFT.COM

$21US plus postage. Probably the same stuff Thruster recommended from ACS. 

 

Agree; poor man pays twice.  No3 above will not work.

[facthunter]

I wouldn't use any of them.  Nev

[turboplanner]

21 hours ago, skippydiesel said:

Thanks Thruster

 

This will be a very small job (fitting a new fuel sensor flange), so I was hoping for something  little less costly ($62 US + on costs is pretty scary)

This is for an aircraft rather than a 79 Commodore.

Imagine yourself, having saved $61 US, over endless forest and you can see the gauge dropping rapidly; how much would you pay then?

[skippydiesel]

Just so we are all "on the same page" about what is proposed:

 

The tank has been made to facilitate a fuel level pressure sensor, screwed into a small flange at the bottom of the tank. As you may know from other conversations, the fuel level pressure sensor consent just isn't working. The time has come to consider alternative fuel level sensors. So far all of the alternatives would seem to require fitting to the top of the tank. After taking appropriate precautions against fuel vapour ignition, I envisage cutting a circular hole in the top of the tank and installing something like this:

The sensor would then be attached to this flange. There will be a need to ensure that the flange & studs are well sealed (this is where I am looking for a cost effective product). The sensor will come with its own gaskets.

I would seal a "79 Commodore.) withe the same care and attention as I would bring to my aircraft. What will work for a vehicle will altos work for an aircraft ,given the same fuel type, location of flange and metal fuel tank.

 

If I "cock-up" the modification, the risks are: some fuel spillage (not a massive leak), in cockpit fumes,  which will impact on me, from discomfort to explosion, both of which I seek to avoid.

 

The way I see it . the appropriate product will:

Chemically secure (low strength) the inner flange, to the tank wall

Seal the studs where they penetrate the tank wall.

Seal the outer flange, to the external surface.

 

Various processes, to achieve a successful result, have been carried out in the automotive/aircraft world for the last 100 years - its not the problem some would hint at - it just requires selecting the right sealing materials. 

[facthunter]

A neoprene gasket is  all that's required there.  Low pressure test it for leaks, Use soapy water. Nev

[BrendAn]

18 hours ago, Thruster88 said:

If it leaks with an inferior product and you have to do it again $62us will seem cheap. CJ aerospace in Sydney should have it in stock.  

CJ Aerospace: Aircraft Parts | Superior Service | Technical Experts - HOME

WWW.CJAEROSPACE.COM.AU

 

Well said . Skippy is being a tightarse in the wrong area here.

When I was an apprentice I had the bright idea to add a bit of silicon to the caulk gasket because the xc falcon sender's were hard to seal properly.   After a couple of days the car stalled. The silicon had broken into small strands in the petrol. Ended up removing the tank. And blowing out the fuel lines. Cleaning the fuel pump and carby.

[skippydiesel]

35 minutes ago, BrendAn said:

Well said . Skippy is being a tightarse in the wrong area here.

When I was an apprentice I had the bright idea to add a bit of silicon to the caulk gasket because the xc falcon sender's were hard to seal properly.   After a couple of days the car stalled. The silicon had broken into small strands in the petrol. Ended up removing the tank. And blowing out the fuel lines. Cleaning the fuel pump and carby.

The key to all this is the characteristics of the sealant - not the cost.

 

I have yet to hear a convincing argument against a,  (hopefully) "local" readily available, automotive product (which I assume is out there)

 

Just because a product doesn't come from an aviation supplier/ aviation in its title, does not mean its unsuitable for the task.

 

Just because its associated with aviation does not guarantee suitability/quality eg The Belite fuel level sensor for aircraft , supplied from a well know aviation parts business, is  not fit for purpose.

 

I have found that I can get AN fuel fittings from an automotive supplier - way bigger range and cheaper - does this make the fittings unsuitable for aircraft - no way!!!

 

Assuming you are of a certain age - when you were an apprentice "silicon" was the latest fix all product that hit the market, we now know it does do well when exposed to fuel. We had gasket goo's back then, that were nasty to work with but sure did did the job - they lost market share, became hard to get (some probably disappeared) its probably one of these products that I would like to find.

[BrendAn]

2 minutes ago, skippydiesel said:

The key to all this is the characteristics of the sealant - not the cost.

 

I have yet to hear a convincing argument against a,  (hopefully) "local" readily available, automotive product (which I assume is out there)

 

Just because a product doesn't come from an aviation supplier/ aviation in its title, does not mean its unsuitable for the task.

 

Just because its associated with aviation does not guarantee suitability/quality eg The Belite fuel level sensor for aircraft , supplied from a well know aviation parts business, is  not fit for purpose.

 

I have found that I can get AN fuel fittings from an automotive supplier - way bigger range and cheaper - does this make the fittings unsuitable for aircraft - no way!!!

 

Assuming you are of a certain age - when you were an apprentice "silicon" was the latest fix all product that hit the market, we now know it does do well when exposed to fuel. We had gasket goo's back then, that were nasty to work with but sure did did the job - they lost market share, became hard to get (some probably disappeared) its probably one of these products that I would like to find.

I agree with all that. But if it was me for the sake of $100 I would be using what a lame advised because you know it is the best for the job 

[skippydiesel]

15 hours ago, Blueadventures said:

Agree; poor man pays twice.  No3 above will not work.

Which one is No.3?  Permagasket No.2?

[Blueadventures]

18 minutes ago, skippydiesel said:

Which one is No.3?  Permagasket No.2?

The one you referrence in your comment yesterday.  Also called "Aviation Soft Seal No3".  Meaning non-hardening compared to No 2.