[newt]

Does the Garmin G3X Touch autopilot disconnect and red-X the AFCS system if the aircraft is out of roll trim?

A few weeks ago I got an uncommanded disconnect. I was out of roll trim, so the aircraft kicked into a left roll and I needed to apply right pressure on the stick to keep the wings level. I used aileron trim to neutralize the stick forces and power-cycled the autopilot breaker, and engaged it after it initialized, and everything was fine for the rest of the flight, and every flight since.

I think it kicked off because it was out of trim. But I don't recall reading about that behavior in the manuals, so I'm asking here.

(failing that, I'll go for another flight and apply full left trim, put the AP in HDG mode and see what happens. But I'm in my lounge room now instead of the cockpit, and maybe posting a thread here can produce instant gratification

- mark

(ping @g3xpert ?)

 

[mburch]

Does the Garmin G3X Touch autopilot disconnect and red-X the AFCS system if the aircraft is out of roll trim?

No, an out-of-trim condition cannot cause an autopilot fault.

The system records AFCS fault information in data log files, and displays historic fault information via the AFCS Diagnostics page. Start there.

 

[newt]

Wilco, mission for my next hangar visit. Thanks.

- mark

 

[lr172]

it will disconnect if you hit the trim button. this has happened to me several times when i accidentilly hit the trim button. i did not get a red X, so maybe that wasn't your case.

 

[newt]

The system records AFCS fault information in data log files, and displays historic fault information via the AFCS Diagnostics page. Start there.

Thanks, Matt.

My data log files have been uploaded to Savvy since this event, and I don't have originals anymore. If it happens again, I guess I'll know...

The AFCS diagnostics page said there was a roll servo hardware fault on 26 April. None before, none since.

GSA 28 s/n 2PG012102, system software 006-B1626-22 5.80, boot block 006-B1626-BA 2.20.

One thing I can extract from the Savvy flight log is AP Roll Torque %. Here's the event from Savvy's charting system, annotated:



Unsure why it needed so much torque. Conditions were light chop, nil wind. Nothing to write home about. The airplane kicked into a bit of a roll when it disconnected, but no dramas with recovering.

Any ideas?

- mark

 

[georgemohr]

it will disconnect if you hit the trim button. this has happened to me several times when i accidentilly hit the trim button. i did not get a red X, so maybe that wasn't your case.

Same. This will not result in a red X, but it is confusing when its your passenger that bumps the trim and you don't notice

 

[georgemohr]

Remember that the torque data is delivered from the servo, so if the servo is failing, the metrics might be wrong.

 

[mburch]

My data log files have been uploaded to Savvy since this event, and I don't have originals anymore.

FYI, you can always download the original .csv file from the Savvy website.

The AFCS diagnostics page said there was a roll servo hardware fault on 26 April.

GSA 28 s/n 2PG012102

Your servo falls within the affected range for Service Bulletin 23038... if you are seeing any kind of hardware fault I'd take advantage of the free replacement. I need to do this on my airplane too but I'm waiting for the end of the flying season.

 

[newt]

That's the most perfect answer I've ever seen

- mark