Hi Guys,
EDIT: DRAWING REVISIONS (ONX-G01) HAVE MOVED THE LOCATION FOR THE MAIN FUEL OUTLET TO THE BOTTOM OF THE SUMP.
Years ago I had a Sonex. After about a year the plane developed a slow leak around the fuel shut off valve. I don't know if it was the fitting or if the fuel valve needed tightening. It really didn't make a difference because I was afraid to touch it fearing I would make the situation worse.
So, under the heading of "Known Problem, Known Solution", today was Oops fitting day.
David Amsler provided some excellent tools to help with the process. However, there is one thing that makes the Onex different from a Sonex. The sump does not have a sloped face at the main fuel outlet. That posses access problems as shown in these pics.
Can't get a straight shot with a large chuck drill.
My solution was to use a uni-bit extension I happen to have. To complete the drilling solution I had to source a uni-bit with a 1" maximum hole size. I couldn't find many but at least the one I did find was short and so did not have to have the tip lopped off.
The solution to sanding the inside of the large hole was to fashion a tool similar (but inferior) to what David supplied that would fit my 1/4" chuck air drill. The tool was made from "stuff" I had on hand, the mandrel from a die grinder, a backing washer (standard AN stuff), and a washer of 1" outer diameter and proper hole size to fit the mandrel made from 1/8" steel plate.
Here are the two tools side by side:
The drilling worked best at high speed with light to moderate pressure. Every thing went pretty smooth. At one point the `1" bit did quit cutting. After a brief panic attack I pulled the drill out and saw why.
Cleared the bit and continued to drill through. Then the next problem. The drilling leaves a nasty burr inside the tank and I couldn't pull the drill back through. Also, the hole is deep enough that I no longer had access to the set screw that held the bit in the extension. The first thought that went through my mind was to send the tank with bit inside and extension hanging out back to Sonex and tell them I received a defective tank. The thought faded quickly :-). I had to reach in beside the bit with an exacto and cut the burr to remove the bit.
There is one more Onex specific thing. The nut on the large fitting had to have to corners ground off to clear the tank. Further, the side of the nut toward the tank had to be more aggressively ground to clear the fillet where the sump meets the tank.
David supplied good instructions. Read them when you get the tools and once again right before you start and take heed. The only problems I had were due to not re-reading the instructions right before starting.
Anyway, it went pretty well. I'm going to order plugs tonight so I can leak check the tank. If that test passes, I will be ready to return to tools.
Thank you to David and Stan for their help.
Wes