Fuel leaks

[Dono]

I recently purchased a RV9A. I have a slow leak at the forward wing root where the fuel lines enter the fuel tank on both wings. I replaced the fuel lines believing that was the issue. But that didn’t work. After about two weeks I still have seepage. I inspected the wings. No indication of fuel anywhere on the aft wing root nor the entire wing. I assume this is just a slow seep but I’m having a hard time finding it. Is there an easy way to easily handle this issue?

[gfb]

post some pics for us to see? try cleaning off all the blue staining to see where the seep is.

[KRviator]

My right tank just about bankrupted me last month after it sprang a leak and piddled all that liquid gold over the hangar floor while I was away overseas. 50-odd litres at $3.01AUD a litre ($7.80USD/USG for those non-metric folk! :P )

It was traced to the rubber seal between the fuel quantity sender and the end rib. Vans no longer supplies this rubber seal, rather, they say to install the sender with tank sealant now. If you still have the rubber ones, that might be the issue - although I'd have expected the dye stain to be visible but your post suggests there's no visible evidence of such a leak?

[Kyle Boatright]

Sounds like a perfect opportunity to drain the tank and check it using soap bubbles to show the leak.

The procedure on an installed tank would be to use blue painters tape or something like that over the fuel cap to prevent major leaks there, cap off the fuel line at the tank, and pressurize the system by placing an inflated balloon over the fitting on the tank where the fuel vent exits. Then spray the area in question with soapy water and look for bubbles.

Do not attempt to pressurize the tank using a compressor or something like that. Anything more than a miniscule amount of pressure can damage the tank.

[Auburntsts]

I just went through this on my my RV-10 right tank. Not sure if the 10 and the 9's fuel plumbing is the same, but for me it turned out to the the fuel pickup-finger strainer fitting. The sealant was at least 10 years old so it developed a seep. The worse part is draining the tank. After that simply unscrewed the fitting, cleaned up all the threads, reapplied new sealant, then reinstalled. I gave it a good 4 days to cure before putting fuel back into the tank.

[Dono]

Someone asked for pics. Here they are last wing first then right. I thought it might be the service hole that the fuel line goes through. But maybe not. I may have to remove the tanks?

[Auburntsts]

Originally Posted by Dono

Someone asked for pics. Here they are last wing first then right. I thought it might be the service hole that the fuel line goes through. But maybe not. I may have to remove the tanks?

Based on the pics, I'm willing to bet it's the same issue that I had. I'd clean everything, reseal, reinstall and then put some fuel back in and see if leaks again.

[sahrens]

If you brought the airplane to me and asked me to attempt to fix the leaks I’d:

1. Pull both tanks for a detailed inspection. Is it leaking from the corner of the tank or somewhere on the back flange. My guess is the corner of the tank near the sump drain.

2. I’d pull the access panel (after draining the tank) and inspect that corner for sealant. I believe BruceH on the forum has a detailed write up about how he removed the existing proseal and resealed a tank.

3. If it’s the corner you might get by with resealing that area with Proseal.

4. Reseal the access cover, pressurize and test for leaks.

5. Hope you don’t need to create access panels in the aft bulkhead.

[Dono]

I guess the pics didn’t go

[Dono]

Thanks all. I think I have a plan. And hopefully I won’t have to cut an access. I think I’ll remove the tanks check for leaks with the soap bubble method and go from there.