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Zenith CruZer & Sonex Logs
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Date:  2-1-2018
Number of Hours:  2.00
Manual Reference:  C75-TA-2
Brief Description:  Rework Trim Tab Operation

No pics.

After I installed the trim tab servo, with the actuator arm set EXACTLY to 116mm as per plans, I of course riveted it all up.

And of course, the trim tab didn't work to the angles it was supposed to reach. *argh*

Up deflection (forcing elevator down, which drops the nose) was supposed to be 20 degrees. It was about 12. Down deflection (forcing elevator up, dropping the tail and raising the nose) was supposed to be 40 degrees; it was at 45. The motor didn't seem to bind, but the motor ran for a second or so after full down deflection was reached.

So, today I un-riveted the 8 servo access cover rivets and the 4 rivets holding the servo in place, removed the servo, and lengthened the actuator threaded rod. This took about 4 trial-and error attempts; I was in the ballpark, but wanted to get as close to 20/40 as I could. Zenith tech support said it was better to have more down trim than up, so I settled on 18 up and 42 down.

Tigtened all adjustment rod nuts, riveted the servo back in position, but put only 1 rivet in the access cover - just in case, but I also wanted to keep the cover where I could find it.

Once that was done, I riveted all trim tab holes to the trim tab hinge, which was riveted to the elevator yesterday. Fortunately, I did not rivet the tab itself until after I tested it.
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