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Another data path error 2 years after using contact cleaner on my G1000 LRU's. I was on an Angel Flight with two cancer patients from Atlanta to Memphis. 30 minutes into the mission, I got the error and AP disconnects with a red AFCS warning at the top left of PFD. Previously I could cycle the AFCS breaker or Avionics bus and regain AP. Not this time. I tried those, then pulled each of the GIA63W breakers. As I was on an instrument plan above a solid cloud deck, I did not go to the extreme of shutting anything else down in flight and had to hand fly the next two hours. Once I landed, I borrowed a can of contact cleaner from the local shop, removed and sprayed the GIA's and GDL69, and everything worked fine for the trip home.
My question is about a more aggressive inflight reset of the entire avionics system. If I'm in VMC, theoretically I could turn off ALT and BAT masters to bring everything down. With standard mags, the IO-360 should continue unaffected, correct? Once I switch masters back on, the AHRS reference gets reset. But as long as I'm keeping the aircraft straight and level, the G1000 should come back online normally, right? I'm not aching to try this, but if this happened somewhere impractical to land quickly (ie over water to the Bahamas), or having to come down through tough IMC conditions, I'd want to know my options.

Yep, turning off the master and alt switch in flight works as you describe. I inadvertently did this once on a cross country flight when I bumped the switch with my knee. It did surprised my wife when the panel suddenly went dark. I calmly reached over than turned it back on and said "Nothing to worry about, I was just testing something..."

The one thing you do loose and have to re-enter is your active flight plan.

I suppose many of us have stories of accidentally shutting down the plane's electrical system in flight.

Years ago I was in cruise on an IFR flight from San Diego to Davis, CA in our DA42 with my student-pilot daughter sitting left seat. She dropped something on the cockpit floor, reached down, and accidentally hit the Electric Master switch to OFF. The Austro engines didn't skip a beat (utilizing backup ECU batteries), and when the G1000 came back up, it retained radio frequencies so we were still communicating with the same ATC controller. Fortunately ATC didn't try to reach us while the systems were restarting.

Unlike newer G1000 NXi flight decks, the DA42's Legacy G1000 retained the original transponder code after restart. But I did have to scramble to reload the flight plan GPS waypoints while maintaining our original heading.

MarkA wrote: ↑Sat Mar 25, 2023 6:05 pm The one thing you do loose and have to re-enter is your active flight plan.

Good reason to store a complex flight plan so you can quickly reload.

dmloftus wrote: ↑Sun Mar 26, 2023 12:11 am

MarkA wrote: ↑Sat Mar 25, 2023 6:05 pm The one thing you do loose and have to re-enter is your active flight plan.

Good reason to store a complex flight plan so you can quickly reload.

Or with FS210/510 and Foreflight synced to the panel, the current flight plan is always in Foreflight and can be transferred to the panel.

Today during some moderate turbulence I had the dreaded FAILED PATH with the AFCS disconnect and warning in the top left. I cycled the AFCS breaker and it went away and behaved normally the remainder of the flight. I had a similar event many months ago as well. Do these LRU contacts really get "dirty" or corroded such that they would cause the failure, or is it more likely that there is a shoddy connection somewhere else and simply rebooting is what has fixed it for most folks? While it is easy to reseat the LRU's, as someone noted, the pins are very fragile and easy to get messed up, while being a PITA to repair if they are accidentally bend or push in.

For me, it took removal and reinsertion to fix the problem. I could occasionally reboot and get it to come back up temporarily. But I believe the contacts get oxidized, which increases resistance. A good spray has solved the problem for 1-2 years.

My turn to get this one. A few minutes after reaching cruise at 10k the AP started an uncommanded pitch up with alerting sound. I disconnected immediately. Reviewing the situation, the AFCS red warning indicator was lit, and there was a FAILED DATA PATH alert. The A/P button no longer responded after this. I considered cycling the CB but instead hand flew it for an hour or so back to BFI. On the continuing flight home to PAE the A/P passed all startup tests and worked as expected in flight.

I'm hoping to fly cross country in a month or so and will not go without a reliable autopilot, so I'm hoping some contact cleaner will do the job.

As far as turbulence goes, the takeoff on the error flight was pretty bumpy, but I also had a VERY bumpy flight a month or so ago, so I guess something could have gotten loose. That being said, the flight from BFI to PAE was extremely bumpy and had no issue.

Yes my failures were sporadic at first, then became more frequent before I cleaned the LRU contacts. If you only get the AFCS error, the safest way to reset in flight is pulling and resetting the AFCS breaker. The balance of your systems are unaffected. Many times that fixed my error. Once it didn't, I resorted to cleaning the contacts. As stated earlier in the thread, you can start pulling other breakers, even cycling the master switch, but of course those steps affect more or all of your systems.

I had the FAILED PATH advisory message in my DA62 yesterday afternoon on an Angel Flight from El Paso to Houston. Turbulence for the first 2/3 of the flight was continuous light and occasional moderate, with the A/P kicking off multiple times (at 11,000'). Didn't get the AFCS warning but got a "GCU1 FAIL - GCU1 is inoperative" message which as far as I can tell, appeared with the data path message although I can't swear to it. Aircraft has just over 100 hours on it and went in for the 100 hour service a few days prior. No other errors apparent, everything was operating normally. A GCU is a "control unit," as I understand it, which can be either the standalone GCU 475 that is installed above the PFD to control it (which we don't have in our planes typically), or the keypad in the center console (which I have but rarely use), or perhaps something else. After reviewing this thread, I think I'll first see whether this continues to show up and if so, will contact Premier to check it under the warranty (after checking to see if the keypad is inop, as I didn't figure out the possible connection until after I got back).

I was curious, however, if anyone else had gotten the GCU1 FAIL message, either in conjunction with the data path failure or otherwise. I'm assuming they are connected but they might be separate too.

Thanks!