My Wooden Airplane
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4/25/2013 - 4/30/2013

5th Bearing Revisited

Back in December, when fitting the propeller, I decided to check the runout of the face of the prop hub. William Wynne recommends that anything greater than .001 warrants removal of the hub to see if any contaminants might be in the way. Mine was .006, so off it came.

Unfortunately, when I removed the prop hub, the 5th bearing came out with it! I tried to put it back in, but it wasn't going smoothly. I decided to wait until Sun-N-Fun, where I could speak to William and/or Dan Weseman. It turns out, mine was not the first bearing to come out with the hub. Dan thinks it might be a slight misalignment of the Safety Shaft causing the hub to mate with the bearing at a slight angle, which is causing them to jam together. So I went back home, tried one more time to get the bearing back in, and discovered that the jaws on the back of the bearing were now deformed, and were preventing me from reinstalling the bearing correctly. I sent the picture below to Dan, and he confirmed that the jaws were ruined (they should be completely smooth, without that ridge), so he sent me a new set. Of course, this meant that I had to remove the front cover so I could adjust the new set of jaws again. Fortunately, I was able to return everything to their proper settings and get the bearing runout back to within .0005. But to put the front cover back on (and ensure that there were no oil leaks), I had to remove and replace the oil pan.

Once that was taken care of, I put the prop hub back on, and checked the runout again.
It was still .006! After reporting back to Dan with my results, he suggested that .006 was not enough to worry about (especially with a wooden propeller), since prop bolt torque could have a far greater impact on prop alignment than hub runout. Who knows? I may even be able to use that .006 to my advantage when aligning the prop later.

Total Time: 6.0 hrs.