Trio Avionics EZ-1 EZ-2 EZ-3 altitude hold servo installation

22 Oct 2006 Trio Avionics EZ-1 EZ-2 EZ-3 altitude hold servo installation

Just getting started with the installation of the Trio Avionics EZ-1/EZ-2/EZ-3 altitude hold servo. http://www.trioavionics.com/ The reason I listed all three current models because I don’t yet know which version I plan to use. I have only purchased the servo so far, which is basically the same for all of the models. Actually, there is an optional automatic trim adjustment system that you can get for the servo, and I have this option – just in case.

Installing the servo is normally extremely easy, but since I installed my batteries just behind the baggage compartment, the perfect location for the trim servo is gone. So, I need to find another place for it. There really is only one place that can work, just behind the elevator belcrank. There is plenty of room there, but there is no supporting structure to mount the servo. I’ll need to make something.

Here is my first attempt at some structure for the servo. The problem with this configuration is that the bulkhead where I was planning to attach this is too flexible. Everything back there is very flexible, and you really don’t want the servo to move at all, for two reasons. 1) the servo will not be as precise, since it has to try to figure out how much the structure is moving in addition to the elevator. Not good. 2) any kind of flexing of the bulkhead will eventually cause stress fractures. Also not good.

The only thing I could figure out to do is to extend the angle that is used to create the belcrank mount. Here’s what I’ve got so far. This is fabricated from a piece of 0.125x1x1.25 aluminium angle.

Of course, I had to drill out the original angle. That was not too difficult physically, but mentally it felt strange removing something that had been installed as part of the quickbuild. I believe this will be a good solution, and it is actually lighter than my original idea, with the lightening holes.

I’ll try to get this installed next weekend and see what we’ve got. It might be a bit long, so I may want to shorten it.