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Fuel Leak right gear fairing

This seems to be most prevalent when tank is full.

I would have a better idea of what is going on if I were the builder.

But I'm not.

Anyone have this happen or have an idea how to figure out of fix?

Hoping I dont have to remove wing.

Thanks

Ed W
 

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I just had to fix a leak at the fuel sender unit, and had similar staining. First step would be to remove the wing root fairing, that wraps around the wing at the fuselage intersection. That would give you access to the fuel tank plumbing between the fuselage and the wing tank. Could be a loose fuel or vent fitting.
 
Looks like the classic sender gasket leak. As said, pull the root fairing and it should be obvious. Not as bad of a repair as it appears.
 
Looks like the classic sender gasket leak. As said, pull the root fairing and it should be obvious. Not as bad of a repair as it appears.

Agree; Mine looked nearly identical. And mine too was mostly only appearing to leak when the tanks were full or nearly so.


Pictures start here.
 
Looks like leaks have been there for a while. What starts as a gasket leak (if that is what it is) can cause degradation of the tank PRC seam joints too, if left too long. Pull the fairings & really check it out. You may have to pull the tanks & check the aft bulkhead seams if you find more blue marking between the tank & spar.
Good Luck
 
I'm betting it's the classic sender cover gasket failure. You'll know as soon as you pull the wing filet covers. They are on the tank end as you look up. The senders are installed in the covers. You do not have to remove the tanks to remove and reseal. It's a little tedious and a little messy but can be done in a day or two.
 
You guys are probably right about the source of the leak, but could it also be a fuel vent if he's got the "Rocket loop" style fuel vents?
 
Might as well confirm (via logbooks) whether or not you have the anti-rotation bracket installed and SB 2006-02-23 previously performed. If you have to go in there and start removing the fuel sender, etc you might think about doing the service bulletin at this time.
 
Looks like mine (but worse)

Yeah, mine leaks there. Not nearly that bad though. Mine's NOT the sender gasket but instead the proseal at the nose and top edge of the tank. On my to do list. No fun, this'll be the 3rd time around in there. Just 1 point that it isn't necessarily the easy fix :-(
 
If its any consolation to you, the fuel tank comes off pretty easily.

I was dreading the remove and reinstall process. But it wasn't bad.

My leak was in the lower seam on the rear bulkhead and not around the inspection/sender gasket.

When you remove the root fairing, you can get a cell phone "bore scope" into the space between the spar and rear tank bulkhead and determine if its there or not.


JMHO

cary
 
Had the same thing on my RV9A. Had filled the tank the day before and filled it to overflow for the first time. I removed the fairing and found the leak at the fitting. I was able to tighten the fitting more and stop the leak. My aeroplane has only 10 hours on it. I guess this is only the first of the squeaks I will find as I put on the 25 hours required for the permanent C of A
Ray
 
I will also concur that the easiest way to fix the leak is to remove the tank. You'd think it will be a PITA but it's not bad as long as you have a stubby ratchet. It also makes the repair much easier and ultimately increases the probability it will be successful.

If its the sender gasket (cork) leaking then it's recommended that it's removed and reassembled with PROSEAL/CHEMSEAL only.

You'll be happy to know, once fixed, the fuel smell in the cabin goes away
 
I will also concur that the easiest way to fix the leak is to remove the tank. You'd think it will be a PITA but it's not bad as long as you have a stubby ratchet.

The only hardware holding the fuel tank to the main spar on an RV-6A is the screws through the skin, so no stubby ratchet required.
 
I’m having the same issue and followed the recommendations on this thread. Come to find out it is not the sending unit, it is leaking somewhere behind the tank but I can’t see it.

I’m not a mechanic nor have I ever removed a fuel tank, but I will give it a try. My question is what do you all recommend sealing it with. Can a Non mechanic fix this problem?

Thank you in advance. Recommendation are welcome.

JM
 
Last year I had to reseal my left tank. The only way to do it right is to remove the tank. Then remove all of the old Proseal and make sure the area is clean and then put new Proseal on. Pressure test the tank(6psi) and if no leaks reinstall the tank. So far the tank has had no further leaks. Took me a good week to remove all of the old Proseal and reseal the tank. Well worth the work. I have also done the tank on the right side as it has a leak at the sending unit.
 
Last year I had to reseal my left tank. The only way to do it right is to remove the tank. Then remove all of the old Proseal and make sure the area is clean and then put new Proseal on. Pressure test the tank(6psi) and if no leaks reinstall the tank. So far the tank has had no further leaks. Took me a good week to remove all of the old Proseal and reseal the tank. Well worth the work. I have also done the tank on the right side as it has a leak at the sending unit.

6 psi sounds like way too high of a test pressure. The recommended pressure is 1 psi (27 inches of water column). Mine started to make scary noises even before it got that far...
 
Posted reply in wrong location.

Pulled fairing and found this. Going to clean it up, fill tank, and see what's up. My mechanic says there is sometimes a cork gasket. But I am not seeing that mentioned anywhere. Are these tanks, covers, and senders all sealed up with pro-seal?

As this bird is 7 years old with only a few hundred hours, I am a little disappointed and would like to avoid playing wackamole.

From what I am reading this is not uncommon. Is this more pronounced in colder climates with more expansion and contractions between seasons? Builder workmanship?

Unless this is obvious and simple, I am guessing best option is to pull it and have it professionally sealed. Sounds like a chore.
 

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Posted reply in wrong location.

Pulled fairing and found this. Going to clean it up, fill tank, and see what's up. My mechanic says there is sometimes a cork gasket. But I am not seeing that mentioned anywhere. Are these tanks, covers, and senders all sealed up with pro-seal?

As this bird is 7 years old with only a few hundred hours, I am a little disappointed and would like to avoid playing wackamole.

From what I am reading this is not uncommon. Is this more pronounced in colder climates with more expansion and contractions between seasons? Builder workmanship?

Unless this is obvious and simple, I am guessing best option is to pull it and have it professionally sealed. Sounds like a chore.

Likely that a rubber or cork seal was used on the sender and/or the plate and this is then expected, regardless of local temps. I would not pull the tank. Just pull off the plate and sender. Clean thoroughly and re-install with just proseal.

Larry
 
Those leaks are pretty old! Looks like the cover plate was installed without gasket, just proseal (nothing wrong with this generally, but something in this particular installation didn’t seal like it should have). As well the fuel sender also mounted with proseal, not the rubber gasket. There are other areas showing leaks, fuel line fitting, the center of the tank sender (will need a new one), and multiple leaks through the cover plate screws.
Areas not shown in the pictures that should also be inspected would be the bottom edge of the tank and back corner, and the area between the tank and spar. A fuel leak this old would leave a puddle of raw fuel along these surfaces that would degrade the proseal over time -from the outside inward!
 
recommendation

I recommend removing the tank, it is not that big a deal. Once removed it will be much easier to work on removal, cleaning and reinstallation of the cover plate and sending unit.
 
A RV6 at our airport just had a similar leak, Turns out it was the bulkhead fitting where the fuel line attaches.

This seems to be a trouble spot; the fitting is sealed on the inside with proseal. If you do not use 2 wrenches when you attach the fuel line (one to hold the fitting still and a second to tighten the B nut on the fuel line) the fitting will twist and break the proseal causing an eventual leak.
 
I had a leak at the fuel sender cover plate and at the air vent fitting. I fixed both without removing the tank.

I did not replace the cork gasket but just used Proseal to seal things up.

You may choose to use a different head on the screws - Torx for example. I used all new parts.
 
Two things are worth repeating.

1. Remove the tank, which is a 30 minute job unless the screws are really painted over. How the fuel line (and vent line) are treated inboard of the fuselage side wall will also matter a lot in this effort. If the fuel line cannot be readily moved inward a half inch once disconnected from the tank, the project gets more difficult.

2. Pro-seal is degraded when exposed to both gas and air, surprisingly enough, hence the recommendations to remove and completely clean off the inspection plate and sender. Any pro-seal that has blue on it might be a problem.

It does appear that there are multiple leaks, one at the very top, perhaps a leaking rivet or seam. Those leaks have been going on for a very long time. I have to wonder if the wing root fairing has ever been off for inspection.

Another observation - how rigid is that sealant used where the fuel line goes into the fuselage? There is relative motion between the tank and the fuselage -- not much, but there is motion. If that sealant is pro-seal, a somewhat rigid material, it might be stressing the tank end of that connection. Silicone rubber would be a better material for that fuselage seal (if it isn't already).
 
>1. Remove the tank, which is a 30 minute job unless the screws are really painted over.

...or unless you've never done it before. I got the impression (possibly wrong) that the OP had not done anything like that on an RV.

If the tank has gas you first have to drain that. Which means arranging a grounding strap. More time.

Do you have gas cans? If not will have to go and buy them.

The tasks can pile up if you are doing this for the first time, and haven't done much airplane work. And anyone doing this for the first time will go slowly. Don't know about this RV but getting the inspection plates off and getting at some of the bracket bolts on the back of an -8 tank takes some doing.

Well at least I can say I would go slowly.

I am NOT arguing against removing the tank. I just know what it's like to not have worked on a plane, and be faced with a task such as this. And I know it takes longer than an experienced builder or maintainer would take.
 
Fuel leak

Probably stating the obvious but if you are a member of the local EAA chapter there may be a builder that can help. You also need to have a set of plans if you plan to work on it. Good luck
 
It does appear that there are multiple leaks, one at the very top, perhaps a leaking rivet or seam. Those leaks have been going on for a very long time.

Ed,

Just an observation ... if the fuel level sender and/or ring it is mounted onto is found to be leaking, it wouldn't surprise me. Judging from your photos, it appears the mounting screws were over tightened and squished out all the Pro-seal from between the parts.

If you or your mechanic reseals those parts, place an even 1/16" slathering of Pro-seal onto the parts after a complete cleaning and scuffing ... then tighten the screws (dipped into Pro-seal) progressively a little at a time until the Pro-seal just begins to bulge out evenly from under the parts. You want to end up with an even gasket of Pro-seal between the parts, as indicated by the Pro-seal slightly bulging out from between the two parts ... not totally squished out as it appears to be in your photos.

With winter coming on, you may need to remove the tank for any Pro-seal work ... unless you have a heated hangar. Pro-seal should cure in warmer temps .... in fact, it can be kept in a freezer for a bunch of days after mixing without curing.
 
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Removing tank

+1 here for removing the tank. I've had mine off a couple times and not too much of an issue. The thing is it will give you unhindered access to that area you're working on. The good thing is because of the big hole, leaks right around that area are the easiest to address. With the tank off the frustration levels go way down.

I ended up sending my right tank to Paul Beck at weep no more. My leaks were in several areas of rivits on the bottom which is a whole nother bag of worms. Paul does excellent work. If I was building today I would build the tanks then send them to him for sealing.... A bit pricy but they should NEVER leak after his work.

One other thing... (which I didn't do but wish I had)!... Since you already have the plate off, go ahead and put a brand new fuel float in.
 
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If this is just leaking gaskets, I have simply used Van’s cork gaskets (rubber in the case of the fuel sender gasket) with Aviation Form a Gasket on my RV-4 and RV-7. Very simple and never a leak.
 
6 psi sounds like way too high of a test pressure. The recommended pressure is 1 psi (27 inches of water column). Mine started to make scary noises even before it got that far...

Yeah it was closer to 1 but my gauge is off. Still no leaks and check at condition inspection this year it is still clean as a whistle. The key was getting all of the old proseal off.
 
How do you remove these fuel stains from the paint?

I had a similar, but much smaller, leak around one the access panel & fuel sender on one of my tanks. Vic resealed them with ProSeal when it was in the shop for its most recent CI. The leak appears to be gone & no more fuel smell in the cabin!

My question is, what's the best way to get the stain off the paint on the bottom of the wing? Some of the staining appears reddish-brown rather than blue.
 
Thanks all for the feedback. I am not opposed to and am capable of removing the tank. I have original drawings. However, the seller spent a bunch on a nice paint job and I'd rather avoid cracking those pretty screws unless I must. Which leads me to the question, does the staining on the back flange definitely indicate a leak in that area or is it possible it was blown there by stray air currents? Logically, Shouldnt the spar be stained all the way down?

Also on the original proseal application, the bead appears to be consistent all the way around so I am not clear how one would conclude the screws were overtorqued... I just want to understand the deficiencies.

Also, has anyone ever used bonded washers with screws to assist in the sealing? That seems to be a trouble spot that could use some help.

I cleaned everything off yesterday and will head back to see what it looks like in a day or two.

Carb cleaner worked great getting off the stains and didnt effect the paint. It did dissolve the proseal.

I plan on replacing lines and fuel selector so will be sure to use a fluid sealer.
 
If you remove the fuel sensor or the whole cover you might consider using Socket head cap screws (Allen) for re-assembly. They are easier to remove in a tight space, if you have the right tool.
 
Ok so plates aside, I have confirmed the rivet circled in red is leaking. Is it unrealistic to think I can service this in place? I believe I can access inside corner.....
 

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Hard to tell but it looks like this rivet is on a flange outside the tank? If so it’s not the rivet that is the problem, I think you’ll need to go into the tank, clean up any gooey sealant and re- seal with a nice fillet along the seam inside the tank. Fuel should never reach the rivet line.

I can see why you don’t want to remove the tank, nice paint! I would certainly try with the tank in place.

Best of luck
 
Hard to tell but it looks like this rivet is on a flange outside the tank? If so it’s not the rivet that is the problem, I think you’ll need to go into the tank, clean up any gooey sealant and re- seal with a nice fillet along the seam inside the tank. Fuel should never reach the rivet line.

I can see why you don’t want to remove the tank, nice paint! I would certainly try with the tank in place.

Best of luck

+1

if it is the fillet in that corner, you should be able to re-do it through the 6" access hole without too much drama with the tank in place. It likely won't be fun, but doable.
 
Thanks Gents,

I've got it all apart. And just doing that alerted me to how much easier it would be with the tank out. For kicks I attempted one of the screws and it is socked in pretty good.

What should I use to clean out that inside corner? I have some carb cleaner that does a great job dissolving the proseal but I dont think I want to use that inside the tank. Any suggestions greatly appreciated!!!
 
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