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Empennage

Electric trim assembly

The girls went shopping today so the boys went to the shed. I did a “once over” on the elevator and found that the electric trim assembly had yet to be done. I started by assembling the servo and mounting brackets, then fixing the servo cover plate to the elevator skin. I placed the servo assembly onto the cover plate and checked for fit.

The servo motor clashed with the cover plate doubler so I marked the areas where it clashed with a Sharpie.

I also found that the edges of the plate nuts protruded into the opening and were clashing with the servo. I used a Dremmel tool with a small cutting wheel and shaved off the edges of the plate nuts that were clashing with the servo motor. I also cut out notches in the cover plate doubler and finished off with my micro files to smooth the edges and round the corners. I checked for fit and made a few minor adjustments until I could pass the servo motor assembly through the opening.

I then had to figure out where the servo brackets needed to be match drilled to the cover plate. Firstly, I attached the cover plate using a couple of bolts and screwed these into the plate nuts.

I then placed the servo assembly on the inside face of the cover plate and checked for alignment and clearance to the edges of the opening. I then used a Sharpie to mark the position of the brackets on the cover plate.

In order to be able to mark out the holes on the cover plate, I removed the servo and attached back onto the brackets upside down. This allowed the brackets to be in the correct position, but gave access underneath the servo motor so I could get a Sharpie in to mark the forward holes.

Once I had the forward hold marked, I removed the servo, got the father-in-law to hold the brackets into the correct position, and then marked the remaining holes. I also marked the area where one of the servo brackets extended into the servo rod channel.

I used my trims to so a straight diagonal cut on the servo bracket so that it wouldn’t extend. I didn’t see the point in spending the extra time and effort in making a round cut when it has to benefit structurally, and either method will remove the offending bracket from sight. I then rounded all the corners, broke all the edges and deburred all the holes.

I then cleaned all the elevator parts with PreKoat in preparation for priming. Nothing exciting to see so I didn’t take any photos.

Build time 4 hours (2 hrs trim servo and 2 hrs cleaning elevator parts).

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About gstrack

Husband and father of 2. Control & Instrumentation Engineer. Flying nut. Gadget geek.

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