Autopilot going wild

[Tivec 3]

I was on a flight from ENBR to ENAL in the PC12, and was performing a pretty steep descent (2800fpm) at low torque. I'm using the F1 GTN 750 as my nav unit, and I had the autopilot set to NAV, and it was following the path quite perfectly, until all of a sudden it decided to bank sharply to the left, the FD showing a bank angle way past 30 degrees, and the autopilot happily obliged. Before I could react to this, the FD moved to show an equal bank over to the other side, causing the AP to turn happily that way.

After this, I couldn't get the autopilot to follow along in any way, even in heading mode the FD would oscillate left and right wildly. I switched off the autopilot and proceeded to land safely on manual controls.

I'm curious as to what could be causing this - this makes the aircraft very unpredictable to fly on autopilot.

[scottb613 1,188]

On ‎12‎/‎10‎/‎2017 at 6:09 AM, Tivec said:

I was on a flight from ENBR to ENAL in the PC12, and was performing a pretty steep descent (2800fpm) at low torque. I'm using the F1 GTN 750 as my nav unit, and I had the autopilot set to NAV, and it was following the path quite perfectly, until all of a sudden it decided to bank sharply to the left, the FD showing a bank angle way past 30 degrees, and the autopilot happily obliged. Before I could react to this, the FD moved to show an equal bank over to the other side, causing the AP to turn happily that way.

After this, I couldn't get the autopilot to follow along in any way, even in heading mode the FD would oscillate left and right wildly. I switched off the autopilot and proceeded to land safely on manual controls.

I'm curious as to what could be causing this - this makes the aircraft very unpredictable to fly on autopilot.

Hi Henrik,

I don't have this issue and I've been flying this aircraft a bunch...

If you don't have it - suggest you request the mod from Bert as it greatly improves operation of said aircraft...

Regards,
Scott

[Tivec 3]

I have, and it is working a lot better since I did. Haven't had the weird oscillation either, but I haven't got a lot of hours yet :)