I went out to the airport this morning to remove snow from in front of the hangar. You have to keep on top of the snow, or risk having it turn to ice from the heat of the sun bouncing off the hangar door.

While I was there I attacked the fuel tank screws that I had drilled the heads off when I was removing the tank. I had been worrying about this since the day I removed the tank, and had come up with several alternate fixes - two ways to hopefully remove the screws, and a couple of fall-back schemes to replace the nut plates if I couldn’t get the screws out. Replacing some of the nut plates would be difficult, as they were in very difficult to reach areas. I had hopes of using dental floss to pull the new nut plates in place so I could rivet them in place with blind rivets.

Several of the screws were in an easy to access area, where the outboard edge of the fuel tank was secured to the upper wing skin. Here I used acorn nuts threaded on the protruding end of the screw to unscrew the screw a bit so I could grab the end with Vice Grips.


For the other screws, where I could not easily reach the end inside the wing, I used Alden Micro Grabit screw extractors. I found these guys at Lee Valley Tools - I knew if Lee Valley carried them that they would be good quality. They are a two ended tool, with a short left hand drill bit on one end, and a tapered left hand thread on the other end. The drill bit is left hand, so that it will tend to unscrew the screw remnant. After drilling the hole, you reverse the tool in the drill, put the tapered thread in the hole you just drilled, and slowly unscrew the fastener. The M4 size works well with #8 screws, as long as you drill the hole close to the centre of the screw. I was lucky in that the Phillips heads of the screws naturally centred the drill when I drilled the heads off, and the end of the drill bit left a depression in the centre of the screw shaft that helped guide my drilling efforts today.


I have tried many different kinds of screw extractors in the past when I had broken off bolts, but the Micro Grabits are the best of the bunch. I had bought two of them, as I have invariably broken off a screw extractor in the past. But today, these things worked like magic, and I had all the offending screw ends removed in about 30 minutes. I’ll sleep a lot better tonight knowing that this part of the fuel tank issue has been resolved.