Finishing up trim motor and rudder cable
TLDR
- Improved anti-chaffing on the rudder cable
- Rigged the trim motor movement range
Details
Anti-chaffing rudder cable
Since I last installed the two little plastic plates on the rudder cable, I just wasn’t happy with the design a the rudder cable will eat through the plastic really quick.
So I asked on the facebook builder group, and of course someone has thought about this before. They suggested that I can wrap the cable in a pneumatic line similar to the pitot tube, then the entire steel cable will rub on the plastic tube evenly instead. I liked this idea much better. I happen to have extra tubes from building the pitot/static lines, so I just cut a piece and sliced it open, then wrapped it on the rudder cable.
Adjust trim movement range
Then I spend a few hours to adjust the trim motor movement range.
The maintenance manual has steps on how to adjust the trim range. The only tricky part is that the trim is connected to RayAllen T2-7A actuator through a hard pushrod. So I cannot move it by hand.
I looked up the wire diagram and figured out that I needed to supply power to tail harness pin #7 and #8. Swapping the polarity would swap the movement direction.
So I connected the 2 pins to a 12v power generator. I first made the trim stay even with the elevator to zero the angle scale. Then I moved the trim motor full down to reach the 25 degree down range, then all the way up.
The manual said the range should be -25/+5, with +/- 3 degrees. But I could not get within range. My motor just didn’t want to move 30 degrees full range. I sent a question to Sling Technical, and they said I should follow the range on POH, which has +/- 5. So I redid the adjustment, got to -20/+2, both directions within range.
