Tuesday, April 17, 2018

Section: 23
Hours: 5

I worked on the aileron actuator today. The belcrank rides on a brass bushing which is captured between 2 brackets that bolt to the main spar. I had installed the belcrank some time ago but not torqued it to final values. Today I measured 15 inch pounds of drag on the lock nut and the specs call for 85 inch pounds of torque combined for 100 inch pounds. When I applied that much torque, the belcrank no longer rotated freely. I spent much of the day adjusting, pulling the belcrank and bushing apart and trying to figure out what was wrong. I determined that with that much torque applied, the bushing had deformed on the ends which caused it to bind inside the belcrank tube. I tried to file down the bushing with out any luck. I wish I had a lathe about now...

I ordered a new bushing from Van's and moved on to the second wing. In reading the blogs about installing the belcrank several builders had commented about the lack of a washer between the bushing and the bracket, potentially causing wear between the bracket and the bushing end. This time I added a washer between the bushing and the bracket and lowered the torque to 90 inch pounds. The second belcrank freely moves. I think the combination of the washer and lower torque helped.

I'll have to wait for the replacement bushing before completing the other wing.

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