Green Cub Pilot
Member
I have a question for any of you out there that are familiar with fixing a slow leak in a wing tank...without removing the wing anc cutting fabric;
I had my L-4 rebuilt back in 2010 and a brand new 12 gallon wing tank was installed in the left wing. The tank installation is (of course) an incredibly difficult process, but the guy that rebuilt my Cub did a wonderful job. The Cub was test flown in January of 2011 and the wing tank had worked just fine since ..until about 8 months ago. Then, it developed a very small leak on the lower leading edge in the middle (most likely from a bad weld spot). The leak is every so slight, but it does begin to accumulate in flight and fuel starts running down the inside of the wing and out the drain holes on the lower aft side. I was able to locate the leak using a bore-scope, and cut an inspection hole just under that location. I then used PRC 1440B1/2 and sealed the leak really well. It is (as I said) on the lower leading edge side of the tank, so getting to it means having to squeeze the spatula in between the main spar and the tank to apply the PRC.
That worked for a few months, but I am starting to see dampness along the underside of the PRC patch, and fuel is starting to leak out of the tank in flight again (and seep out of the new inspection cover and back to the trailing edge drain holes again). RATS!!
I realize the inevitability of the leak to just get worse, but I am hoping there is another idea out there other than removing all the old PRC and try to re-patch it reapply again after M.E.K.ing the surface of the tank again or .. Removing the wing, cutting the fabric, yanking to old tank out and put a new on in.
The tank manufacturer has offered to replace the tank due to the bad weld, but removing the wing and doing all the fabric cutting, removing all the flight control cables that run through the tunnels, removing and then reinstalling, then making some kind of patch is really not an option I would like to have to do.
I use my Cub to do my job, and it flies about 3 days a week, so I really cant afford to pull it off the flight schedule for that long, nor do I really want to destroy the beautiful fabric finish to make a patch or large aluminum rectangular patch on the top.
So gang .any other options out there?
I have considered applying the PRC to the INSIDE of the tank through the tanks filler hole, which will be tricky to say the least, but would seal the inside as well as the outside. I have seen some tank repair materials that appear to be a spray-in, but I dont think they are legal for anything but experimental aircraft.
Any good ideas on how to seal it better other than replacing the tank??
Thanks in advance and feel free to reply offline if you want.
Jon
I had my L-4 rebuilt back in 2010 and a brand new 12 gallon wing tank was installed in the left wing. The tank installation is (of course) an incredibly difficult process, but the guy that rebuilt my Cub did a wonderful job. The Cub was test flown in January of 2011 and the wing tank had worked just fine since ..until about 8 months ago. Then, it developed a very small leak on the lower leading edge in the middle (most likely from a bad weld spot). The leak is every so slight, but it does begin to accumulate in flight and fuel starts running down the inside of the wing and out the drain holes on the lower aft side. I was able to locate the leak using a bore-scope, and cut an inspection hole just under that location. I then used PRC 1440B1/2 and sealed the leak really well. It is (as I said) on the lower leading edge side of the tank, so getting to it means having to squeeze the spatula in between the main spar and the tank to apply the PRC.
That worked for a few months, but I am starting to see dampness along the underside of the PRC patch, and fuel is starting to leak out of the tank in flight again (and seep out of the new inspection cover and back to the trailing edge drain holes again). RATS!!
I realize the inevitability of the leak to just get worse, but I am hoping there is another idea out there other than removing all the old PRC and try to re-patch it reapply again after M.E.K.ing the surface of the tank again or .. Removing the wing, cutting the fabric, yanking to old tank out and put a new on in.
The tank manufacturer has offered to replace the tank due to the bad weld, but removing the wing and doing all the fabric cutting, removing all the flight control cables that run through the tunnels, removing and then reinstalling, then making some kind of patch is really not an option I would like to have to do.
I use my Cub to do my job, and it flies about 3 days a week, so I really cant afford to pull it off the flight schedule for that long, nor do I really want to destroy the beautiful fabric finish to make a patch or large aluminum rectangular patch on the top.
So gang .any other options out there?
I have considered applying the PRC to the INSIDE of the tank through the tanks filler hole, which will be tricky to say the least, but would seal the inside as well as the outside. I have seen some tank repair materials that appear to be a spray-in, but I dont think they are legal for anything but experimental aircraft.
Any good ideas on how to seal it better other than replacing the tank??
Thanks in advance and feel free to reply offline if you want.
Jon
