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Digitrak ALT hold / Shear Screw

jetempleton

I'm New Here
I acquired my RV7 in May. Just before my trip from UT to Oshkosh, the ALT hold failed. I flew there and back with just lateral nav. Not that big a deal.

I removed the baggage bulkhead and saw immediately what the problem was: the center screw holding the actuator arm had fallen out. I found a screw and replaced it using blue locktite. I attached the arm at "twelve o'clock".

On a recent trip to Palm Springs, engaging the ALT ARM on my EFIS, it trimmed the nose way high, even though a 500 VS was selected on the EFIS. I turned the VERT ARM off and just waited until I was at altitude and then re-engaged the alt hold. It worked OK except had a constant barber pole on the TS display.

On the way home, I flew through some cloud. I believe that's when the ALT hold went out. This weekend I took another look, and this time the shear screw had been sheared. I had a spare and replaced it. This time I assembled the linkage arm at "six o'clock". I have not flight tested the autopilot yet.

I am not the builder of this airplane, and therefore my thinking is that the link arm needs to be in some correct position.

Any help? Also on how to correctly sequence the "button-ology" to properly engage the altitude seek and hold capabilities. I have an Advanced Flight Systems 3500 EFIS.
 
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