One of the minor squawks we have had on our RV-3 has been an intermittent left fuel sender. Well, it started out intermittent, then went from ?mostly dead? to ?all dead? after awhile. Since we use the extremely accurate totalizer for fuel management, this was just an annoyance that we wanted to fix before the paint shop, and with the week?s forecast calling for continued glop, Louise and I figured it was a good tie to tackle it.
The RV-3 wing design is a little different from its siblings. On later model RV?s, the inboard end of the tank is set out from the fuselage farther than the inboard wing rib after of the spar. This leaves a reasonable space in which to work between the tank and the fuselage. On the -3, the inboard end of the tank is co-planar with the inboard rib, so there is only about two and a half inches in which to work. I frankly was worried that we?d have to pull the tank to get the sender out. Working with the screws and proseal in that tiny space was not going to be fun. If we has to pull the tank, I wanted to do it before paint, obviously. But there was no harm in trying to get it out with the tank on the airplane, so off came the root fairing, and microsurgery began.
Getting the five screws that hold the sending unit removed was made a whole lot easier because we had used Allen-head screws instead of the stock pan-head Phillips. It was still tedious with an Allen wrench, but would have taken as long to go and buy the right Allen bit for our small right-angel ratchet driver. I was really worried about the proseal removal, but it turned out to be fairly simple using a razor blade and two Plexiglas scrapers we made from a canopy scrap. Once we got it broken loose, it took a little creative puzzle-solving to get the float sender out of the tiny gap, but once the old one was out, it was easy to see what had gone wrong.
The screw that holds the sense wire in place goes into a bras ?button? that is pressed into an insulator on the plate. The rheostat wire is soldered to this button. Because there was no room to use even a stubby driver to attach the wire, we did it with the mini ratchet and a screwdriver bit ? and the ratchet handle provided WAY more torque than a screwdriver would have ? when the screw got too tight, it spun the ?button?, breaking the solder joint on the wire. The moral of the story ? BE VERY CARFUL NOT TO TIGHTEN THAT SCREW TOO MUCH!! A star washer and a light touch should be sufficient?..
Installing the new unit was straightforward, if messy. Messy because we had to maneuver it into place, then apply the proseal using tongue depressors, working over our heads. It sure isn?t as neat as when it was done on the wing rack ? but it holds fuel. One thing I always do when using proseal is to mix more than I need, and use the extra on the mixing board as a ?test coupon?. When I think it has cured sufficiently, I section the coupon with a razor knife to make sure I am happy that it has set properly, and is ready for fuel.
This was the big ticket ?fix it? item on junior?s list before paint, so now we will just do some tinkering with fiberglass until it disappears into Grady?s GLO custom next month. I like to think that when it comes out of paint, it?s like driving a new car of the lot ? and it?s great to have everything working.
Paul
The RV-3 wing design is a little different from its siblings. On later model RV?s, the inboard end of the tank is set out from the fuselage farther than the inboard wing rib after of the spar. This leaves a reasonable space in which to work between the tank and the fuselage. On the -3, the inboard end of the tank is co-planar with the inboard rib, so there is only about two and a half inches in which to work. I frankly was worried that we?d have to pull the tank to get the sender out. Working with the screws and proseal in that tiny space was not going to be fun. If we has to pull the tank, I wanted to do it before paint, obviously. But there was no harm in trying to get it out with the tank on the airplane, so off came the root fairing, and microsurgery began.
Getting the five screws that hold the sending unit removed was made a whole lot easier because we had used Allen-head screws instead of the stock pan-head Phillips. It was still tedious with an Allen wrench, but would have taken as long to go and buy the right Allen bit for our small right-angel ratchet driver. I was really worried about the proseal removal, but it turned out to be fairly simple using a razor blade and two Plexiglas scrapers we made from a canopy scrap. Once we got it broken loose, it took a little creative puzzle-solving to get the float sender out of the tiny gap, but once the old one was out, it was easy to see what had gone wrong.
The screw that holds the sense wire in place goes into a bras ?button? that is pressed into an insulator on the plate. The rheostat wire is soldered to this button. Because there was no room to use even a stubby driver to attach the wire, we did it with the mini ratchet and a screwdriver bit ? and the ratchet handle provided WAY more torque than a screwdriver would have ? when the screw got too tight, it spun the ?button?, breaking the solder joint on the wire. The moral of the story ? BE VERY CARFUL NOT TO TIGHTEN THAT SCREW TOO MUCH!! A star washer and a light touch should be sufficient?..
Installing the new unit was straightforward, if messy. Messy because we had to maneuver it into place, then apply the proseal using tongue depressors, working over our heads. It sure isn?t as neat as when it was done on the wing rack ? but it holds fuel. One thing I always do when using proseal is to mix more than I need, and use the extra on the mixing board as a ?test coupon?. When I think it has cured sufficiently, I section the coupon with a razor knife to make sure I am happy that it has set properly, and is ready for fuel.
This was the big ticket ?fix it? item on junior?s list before paint, so now we will just do some tinkering with fiberglass until it disappears into Grady?s GLO custom next month. I like to think that when it comes out of paint, it?s like driving a new car of the lot ? and it?s great to have everything working.
Paul