August 22, 2017, 03:40:20 PM

Author Topic: N7 fuel tank grommet seal  (Read 231 times)

Offline G.ford

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N7 fuel tank grommet seal
« on: June 19, 2017, 07:32:13 AM »
Hi guys,

I looked at my work bench this morning to find my N7 sitting in a large pool of fuel that had leaked from the fuel tank.

I did a pressure test in some water and saw air bubbling out of the side of the grommet. Has anyone else had this issue?

I've pulled everything apart and the grommet seems to be intact still. I've sanded the edges and front of the tank itself. Was a little disappointed the tank had sharp, jaggered edges from the factory. I thought I sanded it enough, but maybe not?

Has anyone sealed the grommet in place? If so, using what?

Thanks in advance

Greg

Offline Danny Dugger

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Re: N7 fuel tank grommet seal
« Reply #1 on: June 19, 2017, 09:05:20 PM »
How old is the grommet and has it ever been pulled out of the tank and then put back? I always keep spares on hand and use a new grommet after removal. It should seal very tightly with no leaks at all, I've never used any sealant on mine.
  Regarding sanding - did you perhaps use sand paper on the ID surface of the hole in the tank? If that surface got roughed up too much or the ID was opened up it may not seal to the grommet properly.

Offline G.ford

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Re: N7 fuel tank grommet seal
« Reply #2 on: June 19, 2017, 10:12:46 PM »
G'day Danny, thanks for the reply.
The grommet hasn't been pulled out before. I'll replace it with a new one.

The sand paper I used was extremely fine and only made the surface smooth. I've also had 50 odd flight with no issues until now.

I'll replace the grommet and am going to try the new SAB fuel magnet and see how we go. Failing that it will be a new tank.

Offline cml001

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Re: N7 fuel tank grommet seal
« Reply #3 on: June 20, 2017, 05:19:46 AM »
What Danny said.. I've yet to have one leak myself.
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Offline Gabriel Sandoval

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Re: N7 fuel tank grommet seal
« Reply #4 on: June 20, 2017, 10:20:08 AM »
I had to replace my tank recently at my Fun Fly after a full tank went in 3 minutes and she flamed out. Whole heli was soaked in Byron's perfume so out came the tank. Installed a new grommet and fired it up...same thing...went home grabbed new tank off shelf and compared hole sizes. Apparently after many changes of clunk line and new Lynx filters I have somehow made the hole larger and no more perfect seal. New tank sealed perfectly the 1st time and all is well again.
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Offline G.ford

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Re: N7 fuel tank grommet seal
« Reply #5 on: June 20, 2017, 03:39:40 PM »
Damn, that would be frustrating!