Fuel dye

My plane was down for painting for quite a while. When I picked it up the painter asked if I knew about the fuel leak. "Fuel leak" I said? I wasn't aware of one. Anyway, it turns out that I've been using (clear) auto fuel for all my flying. I refilled with 100LL before taking it to the painter because it would tolerate the down time better than the ethanol auto fuel I'd been using. During that long down time, the fuel seeped out of a very small leak around a screw head and left a stain. I would have eventually discovered it by the smell but I would have had a heck of a time finding it without the dye.

So, the question: is there any sort of dye we can put in auto fuel to help detect the presence and location of small leaks? I could have just used 100LL once I realized there was a leak but, in this case, that would have meant a lot of the 100LL - the leak turned out to be around a screw near the top of the tank. It would only appear if the tank were 3/4 full. If I'd been using auto fuel with a dye it would have eventually been evident.

Hi Tom,

This might not apply to auto fuel in your area, but here in MS, I've been running E-free mogas (premium) in my -4 for almost two decades. I've had several leaks in my -4; tanks were built sometime before its 1992 registration date (I suspect that the sealant available back then wasn't mogas proof). Whenever I've had a leak, there have been very obvious brown stains on the skin trailing from the leak point. For me, it's been just as, or more, obvious than a leak with avgas.

Any chance you just had the bad luck to spring a leak just when it's headed for paint?

Charlie

rv7charlie said:

Hi Tom,

This might not apply to auto fuel in your area, but here in MS, I've been running E-free mogas (premium) in my -4 for almost two decades. I've had several leaks in my -4; tanks were built sometime before its 1992 registration date (I suspect that the sealant available back then wasn't mogas proof). Whenever I've had a leak, there have been very obvious brown stains on the skin trailing from the leak point. For me, it's been just as, or more, obvious than a leak with avgas.

Any chance you just had the bad luck to spring a leak just when it's headed for paint?

Charlie

Click to expand...

Interesting. I'm surprised it left a brown stain but good to know it did. Don't know, to tell the honest truth. It's possible it's a new leak, I didn't notice a fuel smell before I left it there and it seems like I would have.

Oh well, at least it's an easy fix this time ...

rv7charlie said:

Hi Tom,

This might not apply to auto fuel in your area, but here in MS, I've been running E-free mogas (premium) in my -4 for almost two decades. I've had several leaks in my -4; tanks were built sometime before its 1992 registration date (I suspect that the sealant available back then wasn't mogas proof). Whenever I've had a leak, there have been very obvious brown stains on the skin trailing from the leak point. For me, it's been just as, or more, obvious than a leak with avgas.

Any chance you just had the bad luck to spring a leak just when it's headed for paint?

Charlie

Click to expand...

Aren't you worried about that sealant clogging a pickup tube or something further upstream?

I assume you mean downstream. But I'm not talking about chunks of sealant rolling around in the tank; I'm talking about fuel leaks.

I suppose that it could be dissolved sealant that was showing on the outside of the tanks, but it seems unlikely since the old sealant isn't brown.

Could just be dust attaching to the only wet spot around...

Re-Visiting Fuel Dye

I've got a small fuel leak and want to pin it down. There are many fuel dye products on the market. D\Has anyone used one, or know FOR SURE it's safety in aviation-use mogas?

Brown stain

Tom,
Mogas will definitely leave a brown stain you can see. As they say, don't ask me how I know.

fuel dye

I have a slight smell of fuel in the cockpit under some circumstances - trying to nail it down. I added some ebay fuel dye to the left tank to try to track it down. What I found out surprised me. Both the "torque seal" I use and the pipe thread sealant is fluorescent. So is the plastic on some locknuts.



No sign of a real leak (yet) but still looking. Going to run 100LL in the right tank in case I can find some blue dye somewhere.