My Autopilot Issues

[JimJab]

Hi All,

I am having issues with my MGL EFIS/Autopilot in my Jabiru 430 that has Trio Gold Servos

Background to the issue.

My pitch servo wants to disengage very often, I think it's from the servo slipping.

If I remove the pitch servo from the EFIS settings, the EFIS/autopilot will fly a GPS track just using the bank/roll servo without issue.

So I am thinking my issue could be with the EFIS pitch servo settings and or my aircraft's trim setup is not correctly setup with the right amount of frication on the trim lever.

Any advice would be greatly appreciated, as I would like to think I could get my plane's autopilot to fly my vertical heights as selected in my EFIS.

Cheers
JimJab

[David 8]

Jim the Trio's have a clutch which can be adjusted.

[JimJab]

Thanks David 8,

I googled again in earnest last night and finally found some information about the servo clutch. It was in the manual for one of the complete Trio Autopilot System around page 76.

Yesterday I had a good look at the Jabiru trim and spring system set up on the tail of the Jabiru. It seemed to be very stiff, so I took it apart, cleaned out the wet lube that had gummed it up and put some dry graphite on the shaft etc. and the system now works with about 100% less frication.

With the trim disconnected from the elevator, I could see how much friction the elevator and servo system had. I put some dry graphite on the elevator hinges and the cable sheaths ends for both the elevator and servo cable, this made a small amount of different with the elevator slowly dropping down on its own weight.

I then tried the pitch servo, I could hear it working, but the servo was only moving the servo arm the smallest amount of movement. Inside the servo it look to be all good with no missing teeth etc. but the servo arm was still not moving in proportion to the final gear movement.

David, I reckon you have hit the nail on the head with my servo problem, I will try tightening the clutch up today and see what happens.

Thank you very much.

Cheers
JimJab

[David 8]

Let me know how you get on ,Im not familiar with the Jab but I know can call a friend, who is familiar with Jabs and Trios ,if required.
Regards David 8

[JimJab]

Thanks David 8,

Please ask your friend, any advice would be gratefully received on what to expect from a Jabiru autopilot.

I have now tried tightening the pitch servo clutch to stop the servo from slipping. But I could not adjusted the clutch up any tighter. So I am thinking the servo needs to be pulled out for a better look at the clutch.

I have done some major googling and have read lots of different stuff being said about Jabiru autopilots.

It does seems the elevator/trim set up on a Jabiru is not good, for when you are trying to have your EFIS/autopilot fly height changes as this places so much back pressure on the pitch servo.

From what I have read, the best I can expect from a well set up EFIS/Autopilot of any type with a well maintained Jabiru elevator/trim system (with regards to friction), is to manually fly to your selected EFIS height, trim the aircraft and then engage the autopilot to hold the altitude and heading.

Since purchasing my Jabiru, even when it's trimmed at the selected altitude, my EFIS has always disengaged the autopilot very quickly that times due to the pitch servo slippage, so I stopped trying to use the autopilot.

Recently I removed the pitch servo from the EFIS autopilot settings and found the autopilot with just the roll servo would now remain engaged and could easily fly my selected track and fly to any new changes in headings to the track.

If anyone has their Jabiru/EFIS flying their changes in height, I would be very interested in hearing about this.

Cheers
JimJab

[David 8]

PM sent
David 8