Fuel Pick-up Tube Service Bulletin
December 16-18, 2006
I finally decided to tackle the fuel pick-up tube service bulletin issued by Van's. When Van's had put out the service bulletin, I went back to check my photos and builders log to see if I had Prosealed the nut that attaches the fuel pickup tube to the bulkhead that carries through the fuel tank access plate. I decided that if I had Prosealed this sufficiently, I would not take the tanks apart to safety wire, figuring that the Proseal would be adequate to keep the nut from working loose. Well, I had no specific reference in the log book or any clear cut pictures of the pickup tube assembly that I had taken prior to sealing the tank. This was enough for me to decide to take the tanks apart and safety wire per the service bulletin.
Since I do not have my wings mounted to the fuselage, now would be the best time to complete the task. I laid the wing (one at a time) on table to get easy access to the tank access plate. ( I am using the capacitance senders so my access plates are a little different from the float senders that are commonly used). I began by removing all the screws holding the plate on the tank. I had place a dab of Proseal on each screw before installing them. They came loose relatively easy. The next task was not such a joy. Breaking loose the seal between the access plate and the tank was difficult because I used the cork gasket supplied with the wing kit and Prosealed both sides of the gasket. My philosophy at the time was "This baby WON'T leak if I use the gasket AND Proseal".
I purchased a set of plastic putty knives thinking that I could get under the access plate and work the putty knife around the plate to lift it up without scratching the surfaces. WRONG! Cured Proseal is some tough sh*t. I could barely even get the putty knife started under the plate. They were not stiff enough or sharp enough to cut through the Proseal. What I ended up doing to cut through the Proseal was to cut some .025 aluminum strips about 3/4" in width by about 3 inches long and bend them 90 degrees in the middle. I beveled and sharpened one end around the three sides and gripped the other angled end with some vice-grips. I carefully forced the sharpened edge under the access plate and slowly and painstakingly worked it around the plate trying not to scratch or mar up either surface. Eventually, I was able to cut the Proseal all the way around and lift off the access plate. I did put some scratches in the plate and on the tank but I'll scotchbrite it up to smooth it out before reassembly.
To my surprise, there was not too much residual Proseal left on either surface. Most of it was on both sides of what remained of the gasket. I was disappointed to see that I had indeed Prosealed the nut to the pickup tube and bulkhead fitting. Had I known that earlier, you wouldn't be reading this now.
The safety wiring aspect of this task was the easy part. I just had to be careful not to drill the hole through the nut in such a way as to put a hole through the inside. I also was not going to disturb the Proseal that was already in place on the nut, bulkhead fitting, pickup tube and anti-rotation bracket.
All of the old excess Proseal came off very easily with MEK. I polished up the surfaces of the plates and end tank ribs with a scotchbrite pad to smooth out some of the scratches caused from removing the plates. There were a lot of Proseal "crumbs" that ended up inside the tank. I made sure to clean it all out prior to reassembly.
I purchased new gaskets, screws and Proseal in preparation for the task. Reinstallation was pretty easy but I have yet to leak test the tanks again. I'll post leak test results at the appropriate time.
Some final thoughts. Just like anticipating the construction of the tanks and using Proseal for the first time, there was a bit of unknown going into this task. Would I create leaks where there were none previously? Would I damage the tank by trying to remove the access plate? My recommendation is to take it slow and meticulously as you would with other phases of the construction process. I will say that it must be much more difficult to perform this task with the wings installed because trying to remove the access plate with less than 3 inches of clearance from the tank end would be a big challenge if even possible at all. I'm sure others have done it. As with building the tanks the first time, I'm just glad to be past this point.