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Fun comes to a halt–Fuel Tank Leak

Michael Burbidge

Michael Burbidge

Well Known Member
I'm so bummed out.

I discovered this evening that fuel has been leaking from the cover on the fuselage end of the tank. I guess that's what I get for deviating from the plans. I used tank sealer instead of the supplied gasket. I had read that people had problems with the gasket.

It appears that the tank sealant is just lifting away from the aluminum on the tank. I checked the other side and no leaks there.

Here's a couple of pictures.

9muY3pP.jpg


lFfmFdQ.jpg


I have a few questions.

? Is there a chance I can remove the cover, and fuel sender without removing the tank?

? What tricks are there to removing the bolts from the z-brackets? Special tools that help, etc.?

? The tank is full. What precautions need I take to empty the tank? I plan on draining the fuel into 5 gallons fuels containers from the fuel drain.

? I assume it is best to remove the bolts from the z-bracket first, followed by the screws into the spar. Is that correct?

Any other suggestions you have would be greatly appreciated!

Thanks,
Michael-
 
Bummer

I had similar issue, found it during tank calibration. I'd get it off the plane and onto a work bench. Removing the tanks is tedious but in reality can be done in only about a half hour. I used a pneumatic ratchet on the tank bolts, it's a pain working thought access panels but better than the one click shuffle you'll have to do with a manual ratchet.

Drain the tank into cans like you suggested. Make sure you find the leak before taking that access plate off. It might be the end rib or something and draining across the plate. Fuel leaks easier than water. I put a couple gallons of fuel back in the tank and pressurized it (slightly) to find my leak that was not detectable with air or water.

Polygone gel from Vans cleans that proseal off like nothing. Get everything cleaned up, re scuffed, acetoned and seal it back up. I didn't use the gaskets either time.

Cheer up! This is only a morning job... Few hours tops. Your forearms will be beat up though!
 
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Draining the fuel tanks

For about $15 I went to the hardware store and bought a brass nipple (NPT) to screw into the fuel quick drain hole, a couple feet of fuel hose and a brass valve to make fuel draining controllable. I was surprised at how little fuel is spilled when I remove the quick drain and screw in my drain valve (I've already used it 3 times And working on a 4th), the valve makes it easy to swap gas cans etc.
 
no need to remove the tank

Although it is not too tough to do, as others have pointed out, you do NOT need to remove the tank.
On my RV-8 I have removed the cover and removed and replaced the fuel sender on the plane.

To get the phillips head screws out, use a short phillips insert like what you would put in a drill or electric screw driver. To turn it, get a 1/4" ratcheting box wrench, which will fit on the hex side of the insert, and then you can ratchet out the screws. You might need to make a block of wood the right width to wedge against the back side of the insert to keep the phillips from coming out of the screw when you turn it. It also helps to use some tape to wrap around the insert and the ratchet to try to keep the insert from falling out of the ratchet.

When I re-assembled, I used socket-head cap screws so "next time" I can use an Allen wrench to get them out.

Also, many folks have recommended using Proseal instead of the cork gasket.

*** BUT, THERE IS A BETTER WAY ***

Use the cork gasket, and use a gasket sealant called Permatex High-Tack. Or a very similar product, Permatex Aviation Form-a-Gasket.
Either of these products is a thick brown syrup that you brush onto the gasket (both sides). I have used this for years on cars and airplanes and anything else where fuel or oil needs to be sealed with a gasket. I have NEVER had it let me down, EVER. And the best part, if you ever need to take it apart, it is pretty easy. Unlike using pro-seal, which will be very difficult to ever disassemble.
 
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A de-fueling operation should include grounding, as fuel can build a static charge as it falls from the drain to a container. It's easy to be safe; all you need is two lengths of wire and two alligator clips. One alligator attaches to the airframe. From it run a short wire to the fuel container; simply strip the end and submerge it in the fuel. A longer wire runs from the same alligator to an earth ground; a hanger door track is good. Everything remains at the same potential.
The fitting, valve, and hose Andy described is fine idea. Use the same two wires, or a graphite-lined fuel hose and make sure the end is down in the fuel.
 
Tanks

Remove the tank, it's not hard to do. I don't think you will ever get the cover free of the Proseal working with it in place. You will need heat from a hair dryer or heat gun and some plastic scrapers and wood wedges to work it free. I didn't try it but the stuff that dissolves Proseal might help if you use it around the edges of the cover. My cover had been sealed about 15 yrs ago and the Proseal was a bear to get lose. Mine was not leaking but had slosh that needed to be removed.
 
I had the same problem last month with my -4. I had drained a tank to calibrate a new fuel gage during annual. During the week the tank was empty, the cork gasket dried out and it leaked horribly when I refilled the tank.

Originally, the I built the tank using cork gaskets and Permatex gasket material. I believe that was a mistake. I pulled the tank, cleaned it up and replaced the access panel with polysulfide access door sealant. It is the same stuff used for building tanks, but it has less adhesion, so you can more easily remove it if necessary. The stuff I used came from here:

http://www.skygeek.com/flamemaster-cs-3330b1-2-sealant-pint.html

Good luck,
 
Michael keep the fun going while removing the tank it's an easy fix. Exercise the privilege of your wet FAA repairman certificate. All above advice is great make sure you unscrew ALL bolts from z brackets. Report back here :)
 
Easy enough to do without removing the tank. This Craftman screwdriver ( http://c.shld.net/rpx/i/s/i/spin/image/spin_prod_1059295312?hei=185&wid=185&op_sharpen=1&qlt=85 ) will make it SOOOOO much easier: It accepts a 1/8" socket for leverage and has great grip. - Replace the screws with socket head cap screws so that you can put a socket on them in the future.
You want to be very careful not to bend the cover plate or the tank wall by prying off the old lid/sealant. I used a thin piece of sheet metal to make a 2" wide X 9" long scraper with rounded edges that you can work between the two to cut the sealant. If you keep it well lubricated with (Cant remember if I used MEK or Acetone ) It will very slowly slice through the sealant like butter.
Once the cover is off you can use scotch bright soaked with the same solvent to clean up the surface.

I think it took me about 1.5 hrs to get the old one off, 1 hr to clean up all of the parts for re-assembly, and 1 hr to put it all back together. I think removing the tank would have taken longer, and risked scratching the paint.

Be careful not to get the new sealant on your float when you go back in, and if you have not already done the SB on the fitting, this is a good time to do it.
 
I have a bad fuel sender in the RV6. I was told the tank has to come out to replace the senior. Can the sendor be removed and replaced on a six without pulling the tank?

George
 
Yes. Same steps as above and replace the sender when you get the plate off. It will not ad any time to the job.
Are you sure it is the sender, and not the wiring?
 
sailvi767 said:
I have a bad fuel sender in the RV6. I was told the tank has to come out to replace the senior. Can the sendor be removed and replaced on a six without pulling the tank?

George
Click to expand...

Yes, I have done it numerous times.
As already mentioned, use a offset ratchet screw driver or a 1/4" drive ratchet with a 1/4" socket with a screw bit inserted into it to remove the screws.
 
Vlad said:
Exercise the privilege of your wet FAA repairman certificate.
Click to expand...

In the interest of clarity and keeping everyone properly informed...

A repairmans certificate is not required to do this (or any) repair work on a E-AB aircraft. Anyone can do it, and sign off on the work.
The repairmans certificate only authorizes a person to do and sign off an annual condition inspection.
 
pa38112 said:
Yes. Same steps as above and replace the sender when you get the plate off. It will not ad any time to the job.
Are you sure it is the sender, and not the wiring?
Click to expand...

We have checked the wiring and the symptoms match other reports where the contact pad for the wiper has come loose.

George
 
Consider this first...

Why remove the plate? If it were me, I'd thoroughly clean the top 1/3 of the perimeter of the plate and end of the tank. That means using acetone or similar. Rough up the exposed metal a little with Scotchbrite. Remove loose sealant. Reclean thoroughly. Overlay a layer of Proseal *carefully*. Don't go crazy and get it all over the place. Just cover the exposed sealant and extend back onto the exposed aluminum 1/4-1/2 inch. If it works, you might make it another few years, or forever. If it doesn't then explore removing the cover.

BTW, I've never used cork gaskets on my plates in 15 years. One seeping leak that is evident with full tanks. (And I plan to do the above procedure over the next couple of days.)
 
Why did this leak?

Looking at the picture, there is nice squeeze-out of proseal all the way around.

It looks like something interfered with the adhesion of the proseal to the aluminum cover plate. Maybe not clean? maybe they left the vinyl film on the plate? I wonder what could make the proseal not wet onto the aluminum plate?

Also for clarity, the Permatex products I recommend are NOT "gasket material". Most of the Permatex gasket products are various silicone or other material made to create a gasket - and I have never had success with those.

But Permatex High Tack is a sealant, not gasket material.
 
Why leak?

Looking at all the other items sealed & the cover is the only place leaking, I'd guess possibility out of date PRC, bad batch mix, or dirty flange.

I repaired one tank a while back with perfectly cured PRC most of the way around the tank except for 1/2 of the rear baffle. The builder must have ran out half way thru gooping for the baffle & quickly mixed up another portion of sealant... 10 years later that section was still the consistancy of peanut butter.
 
Sealant not out of date...

When I did my tanks I had fresh sealant. I'm wondering if I tightened the screw too tight and squeezed out all but a paper thin layer of sealant. That might cause a problem.

The sealant is firm, but it does appear to have pulled away from the tank.

Michael-
 
Michael Burbidge said:
I'm wondering if I tightened the screw too tight and squeezed out all but a paper thin layer of sealant. That might cause a problem.
Click to expand...

That wouldn't have any impact on whether it would seal well, but it will make it a bit more difficult to remove the cover (no space to tap a putty knife in between the cover and rib).
 
I used the same product Dean in his earlier post did to seal up the access covers, Flamemaster CS3330B1/2 Access door sealant. Very easy to work with. Be sure and read all the product info sheet though. It is not resistant to ethanol if you run Mogas in your plane!
 
rvbuilder2002 said:
That wouldn't have any impact on whether it would seal well, but it will make it a bit more difficult to remove the cover (no space to tap a putty knife in between the cover and rib).
Click to expand...

It's not too difficult to squeeze ALL of the proseal out and lose the seal. Lightly tighten the screws, just enough to get a uniform bead of proseal to squeeze out. Let it cure for a day then put another quarter turn on each screw.
 
ronschreck said:
It's not too difficult to squeeze ALL of the proseal out and lose the seal. Lightly tighten the screws, just enough to get a uniform bead of proseal to squeeze out. Let it cure for a day then put another quarter turn on each screw.
Click to expand...

I disagree, and would bet that the majority of people that used tank sealant instead of the cork gasket, fully tightened the screws... there is not very many leaks when tank sealant is used.
It does make the cover or sender much harder to remove which is probably why a lot of people complain when they have to remove it after having used sealant.
 
Step one complete

A local A&P that works on RVs a lot helped me remove the tank today. I did all the prep work and he removed the 21 bolts in about 45 minutes.

gyuwoH7.jpg


A small 1/4 inch drive air rachet made most of the bolts easy to remove. We didn't even remove the aileron push tube. We simply disconnected it at the outboard end.

When I removed the bottom skin screws last night, several of them had blue fuel die on them. So I was fully expecting that there were places on the back baffle that were leaking also. But after removing the tank it looks like the leaking fuel from the cover plate was wicking most of the way up the bottom aft edge of the tank. Weird.

Michael-
 
ProSeal on Fuel Drain threads

I need to drain the fuel on a friends RV. I was planning on pulling the drain plugs and screw in a fitting with a hose. The owner advised me he put some ProSeal on the threads to ensure they wouldn't leak. Knowing how tough ProSeal is, do you think I'll have any problem removing the drains? Any one come across something similar?
I plan to re-install the drains with FuelLube.
 
Nope

C. Brenden said:
I need to drain the fuel on a friends RV. I was planning on pulling the drain plugs and screw in a fitting with a hose. The owner advised me he put some ProSeal on the threads to ensure they wouldn't leak. Knowing how tough ProSeal is, do you think I'll have any problem removing the drains? Any one come across something similar?
I plan to re-install the drains with FuelLube.
Click to expand...

Easy to get a socket on those. Should come off easy, proseal is non skinning, sort of like caulking, not hard like epoxy.
 
C. Brenden said:
I need to drain the fuel on a friends RV. I was planning on pulling the drain plugs and screw in a fitting with a hose. The owner advised me he put some ProSeal on the threads to ensure they wouldn't leak. Knowing how tough ProSeal is, do you think I'll have any problem removing the drains? Any one come across something similar?
I plan to re-install the drains with FuelLube.
Click to expand...

Proseal and Fuel Lube (EZ Turn) are not for pipe thread sealing.

There are a number of different pipe thread sealants that work well, my preference is Titeseal.
 
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C. Brenden said:
I need to drain the fuel on a friends RV. I was planning on pulling the drain plugs and screw in a fitting with a hose. The owner advised me he put some ProSeal on the threads to ensure they wouldn't leak. Knowing how tough ProSeal is, do you think I'll have any problem removing the drains? Any one come across something similar?
I plan to re-install the drains with FuelLube.
Click to expand...

Using ProSeal sounds strange. Since the fuel drains have a rubber seal, you need a way to easily replace the seal. In fact, I always carry extra seals - and a new drain ready to go - in my tool kit.

John
 
Best sealant on drains? Titeseal, EZ Turn ??

When I re install the drains is Titeseal the best product? Or have you used EZ Turn Lubricant? Here is what the description says of EZ Turn: EZ Turn is a specialty lubricant/sealant used for fuel and oil line valves & is resistant to high temps. Especially effective where high octane fuels and aromatics are present. EZ Turn is also extremely efficient as a gasket paste & anti- seize agent. EZ Turn will not gum, crack or dry out. Each shipment is independently tested. Excellent for tapered plug valves, aircraft engine manufacturing, and marine applications. EZ Turn is the functional equivalent of fuel lube.
Here is a description of TiteSeal:Prevents corrosion and seizing of metal parts. Assures leakproof, pressure tight connections. Unaffected by water, oil, gasoline.

It does seem that Titeseal may be the best choice but have never used it.
 
C. Brenden said:
I need to drain the fuel on a friends RV. I was planning on pulling the drain plugs and screw in a fitting with a hose. The owner advised me he put some ProSeal on the threads to ensure they wouldn't leak. Knowing how tough ProSeal is, do you think I'll have any problem removing the drains? Any one come across something similar?
I plan to re-install the drains with FuelLube.
Click to expand...

If all you're doing is draining the tanks, I don't see any reason to use sealant on the temporary fitting. There will be far more fuel vapor from your storage container than from any slight seeping at the fitting. FWIW...
 
Sealant on drains ?

The sealant will be used for re installing the drains after the fuel is removed. I won't use any while defueling. . .
 
To Michael Burbidge: Just a question about the tank sealant you used, was this the Flame Master sold by Vans? The only stuff I've seen was the dark gray colored sealant, have they changed it?
 
Whole again...

Fuel tank leak repaired. It was just the cover plate, so it was a fairly easy repair. I Can't wait to fly again.

i9A4UJH.jpg


Michael-
 
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