Wing Root Fuel Vent hardware after 200 Hrs Pilot Side

[Jesse23]

Originally Posted by fixnflyguy

Over the last couple years, I have been "talked into" repairing about a dozen leaky RV tanks.. I don't do it for a living or for fun, but I spend a lot of time around Proseal and leaking KC-10 tanks. Finding the actual leak can be undaunting, and wide area resealing is often the only answer. Most recently, I di an RV-10 tank which had constant drip from the vent line. As mentioned ,access through the sender hole with tank installed is a PITA. The owner removed the tank and brought it o me (he was still paintless and in phase 1). He tried the re-torque of the B nut with a funky tool through sender hole and no success. I made an access hole on the I/B bay and disconnected the line, finding a kindergarten level flare that wasn't sealing. The bulkhead fitting was sealed very well and wasn't leaking as in your case, however, I am an advocate of topcoat sealing any fitting inside the tank, and outside the tank. After I installed the line with a flareseal, the fitting received full topcoating of PR1422A1/2 , which is a thinner brushable high flow Proseal. Even when I do 1422"B" sealant, I topcoat with "A". In your case, you may get a successful exterior fix by thorough cleaning, SS wire brush abrading and topcoating of the entire area including the B-nut and furrel .Remove as much old sealant as possible first. While its not optimum (going inside is), it may seal forever. I use Coleman camp fuel as final wipe for all my sealant work (except on KC-10's as the manual requires MEK or Acetone.

Thanks Bill - taking a hard look this morning with the builder on possibly installing 2 CherryMax PBR rivets along with a thorough cleaning as much as possible. Thanks for both responses on the better flowing A ProSeal.

[kearney]

Bill

Your work is way neater than mine - your experience shows.

[rongawer]

In case you decide to go inside, Van's does sell a Fuel Tank Repair Kit, which is a plate cut to patch an opening with instructions and a bunch of AD-42H rivets.

I've stocked up on these over the years...

[Ralph Inkster]

Problem with leaving that leak, eventually the seeping fuel will contaminate the sealant it contacts around it. What starts as a small leak problem expands into a big one.

[D-Dubya]

Bill, that is the best ProSeal work I have ever seen. Uncle Sam must be proud of you!

[Jesse23]

Originally Posted by fixnflyguy

Over the last couple years, I have been "talked into" repairing about a dozen leaky RV tanks.. I don't do it for a living or for fun, but I spend a lot of time around Proseal and leaking KC-10 tanks. Finding the actual leak can be undaunting, and wide area resealing is often the only answer. Most recently, I di an RV-10 tank which had constant drip from the vent line. As mentioned ,access through the sender hole with tank installed is a PITA. The owner removed the tank and brought it o me (he was still paintless and in phase 1). He tried the re-torque of the B nut with a funky tool through sender hole and no success. I made an access hole on the I/B bay and disconnected the line, finding a kindergarten level flare that wasn't sealing. The bulkhead fitting was sealed very well and wasn't leaking as in your case, however, I am an advocate of topcoat sealing any fitting inside the tank, and outside the tank. After I installed the line with a flareseal, the fitting received full topcoating of PR1422A1/2 , which is a thinner brushable high flow Proseal. Even when I do 1422"B" sealant, I topcoat with "A". In your case, you may get a successful exterior fix by thorough cleaning, SS wire brush abrading and topcoating of the entire area including the B-nut and furrel .Remove as much old sealant as possible first. While its not optimum (going inside is), it may seal forever. I use Coleman camp fuel as final wipe for all my sealant work (except on KC-10's as the manual requires MEK or Acetone.

Bill E, you are an artist.

[Bill Boyd]

Okay, I've got the dreaded vent leak going on in one (slow-build by another builder) tank when it's over half full. Looked inside the tank with a boroscope to check out the possibilities with the bespoke wacky-wrench through the fuel sender hole, and to my surprise and disappointment, found the flare nut on the vent bulkhead fitting is slathered in a thick coat of ProSeal already. This tells me I'll never get a wrench on those flats without cleaning the sealant off first, and especially trying to do laparoscopic surgery through the sender hole with tank attached to wing. Also suggests that sealant application over the nut either wasn't done properly or won't help even if it is.

I've been dealing with this up till now by anticipatory fuel load management, never parking the plane for more than a few hours with the offending tank over half-full. It's worked fine until a recent scrubbed X/C before which I topped off both sides to the brim. The leak rate is about a quart a day - significant.

I know the proper, permanent way to address this is to pull the tank and go in through the rear baffle and do what needs to be done. I'm looking for a temporary kludge to stop the leak until I'm sufficiently psyched to undertake the correct fix. The leak as far as I can determine is inside the vent tube, not wicking down the outside. It looks easy enough to re-route the vent line into the slipstream through the top of the wing root instead of the bottom, and bend/orient the open end forward into the slipstream. Other that creating a possible trip hazard for boarding passengers and a bit of an unsightly appearance, the "Cessna approach" seems to have merit, even if out of place on a low-wing aircraft. I could carry this out by drilling one new hole in the wing root closure skin and bending and re-clockcking the existing drain line 180 degrees. 20 minutes of work v. 20 hours.

Anyone see a safety or bad physics issue with this approach?

[Jesse23]

Originally Posted by kearney

Bill.

Get some pro seal type A. It flows quite easily where as b sealant will not. Get a syringe and graft a piece of -4 versa tube to the end. You can bend the tube into a hook and then go in through the fuel sender hole.

If the tank is out you can stand it in the end till it sets.

I did this to seal the seam below sender hole. Worked like a charm.

No tank removal. Drilled out top rivet and used a sealed rivet in the top offending hole. Looks to be resolved and not leaking. It is not pretty.

[lr172]

Originally Posted by Bill Boyd

Okay, I've got the dreaded vent leak going on in one (slow-build by another builder) tank when it's over half full. Looked inside the tank with a boroscope to check out the possibilities with the bespoke wacky-wrench through the fuel sender hole, and to my surprise and disappointment, found the flare nut on the vent bulkhead fitting is slathered in a thick coat of ProSeal already. This tells me I'll never get a wrench on those flats without cleaning the sealant off first, and especially trying to do laparoscopic surgery through the sender hole with tank attached to wing. Also suggests that sealant application over the nut either wasn't done properly or won't help even if it is.

I've been dealing with this up till now by anticipatory fuel load management, never parking the plane for more than a few hours with the offending tank over half-full. It's worked fine until a recent scrubbed X/C before which I topped off both sides to the brim. The leak rate is about a quart a day - significant.

I know the proper, permanent way to address this is to pull the tank and go in through the rear baffle and do what needs to be done. I'm looking for a temporary kludge to stop the leak until I'm sufficiently psyched to undertake the correct fix. The leak as far as I can determine is inside the vent tube, not wicking down the outside. It looks easy enough to re-route the vent line into the slipstream through the top of the wing root instead of the bottom, and bend/orient the open end forward into the slipstream. Other that creating a possible trip hazard for boarding passengers and a bit of an unsightly appearance, the "Cessna approach" seems to have merit, even if out of place on a low-wing aircraft. I could carry this out by drilling one new hole in the wing root closure skin and bending and re-clockcking the existing drain line 180 degrees. 20 minutes of work v. 20 hours.

Anyone see a safety or bad physics issue with this approach?

IF the leak is coming from the tubing inside the tank (i.e. fuel is coming out of the vent line and not the fitting/skin interface), then I would run the vent line into the cabin, go up about an inch or two above the top height of the tank and then back out of the fuse and to it's original exit. This will keep the fuel from draining out of the vent (gravity can no longer do it's work). same concept, but in reverse, as a P trap under every sink in your house. This will create no adverse effect on drawing fuel from the tank and no need for slipstream positive pressure. This is the method vans used on the smaller models to prevent fuel from leaking out of the vent line, though they had a 1-2 foot rise. Have no idea why they didn't do it for the 10, though I suppose it was just too messy to get the tube into the fuse and the raised floor would create a maintenance challenge.

pointing the vent upward is going to put a lot of dust, debris and water (if flying in rain) into your fuel system

[Bill Boyd]

Temporary (likely to become permanent during my ownership) kludge to deal with vent line drip when over half-full. Seemed to perform fine in flight testing yesterday. Probably adds back as much drag and ugliness as one of the many antennas I hid inside the canopy versus sticking into the slipstream. For now, I'll take it...