GFC 500 Abnormal Disconnect

manac

manac

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Manac
Is it normal/acceptable for a GFC 500 to disconnect in moderate to heavy turbulence?
AP was really nice on a long turbulent flight. It did well and my shoulders weren’t in knots after the flight. Once though after a good upset the ap disconnected with the abnormal disconnect indication. It was a non issue and reengaged right away. There’s nothing in the fms about what will trip an abnormal disconnect.
I had to disconnect once when it took me to the yellow arc trying to hold altitude, in turbulence.
Just getting to know it’s capabilities and limitations.
 
Most APs do that and disconnect if you try to over power it as well.
You should have gotten an annunciation.
 
I did get an annunciation/indication for abnormal disconnect.
It would be nice to know what will cause a disconnect.
The fms doesn’t mention if loss of pitot pressure will cause a disconnect. I assume it will but I don’t like assuming things.
 
Assuming you have G5s, insert a mini sdcard and turn on logging.
When problem occurs again I think you’ll have what you need to debug the problem, or send the log to Garmin service.
 
2 X GI275’s. They all ready sample at 1 Hz, don’t know if that is fast enough to pick up the event. Not even sure if it’s a problem.
I’ll call Garmin next week.
 
manac said:
Is it normal/acceptable for a GFC 500 to disconnect in moderate to heavy turbulence?
AP was really nice on a long turbulent flight. It did well and my shoulders weren’t in knots after the flight. Once though after a good upset the ap disconnected with the abnormal disconnect indication. It was a non issue and reengaged right away. There’s nothing in the fms about what will trip an abnormal disconnect.
I had to disconnect once when it took me to the yellow arc trying to hold altitude, in turbulence.
Just getting to know it’s capabilities and limitations.
Click to expand...

You have a good question, there might not be anything wrong with it like you said. It would be interesting to hear what your garmin dealer has to say about it.

I have put 700+ hrs on my gfc500 with 2 G5s. After about 400 hrs and just over 2 years every once in while it would give me 3 beeps and shut off. I don't remember seeing any abnormal disconnect message? After about the third time it happened with months in between it quit working. Took the plane over the local shop that installed it to find out the roll servo was bad. I was past the 2 year warranty and I had to pay for a new servo.
After they ordered me one they installed it while I waited and it has been good since. They charged me for the part and did the labor very cheap.

But I don't think you are having the same issue. It sounds like you were in big time turbulence.
 
Talked to a cs rep at Garmin.

If the AHRS resets the AP will disconnect, probably what happened when I found that big bump.
Gary - has your ap ever disconnected in turbulence?

George doesn’t know that there is turbulence. Will point the nose down to maintain selected altitude until you hit the yellow arc. They suggested pulling the throttle but I was already cursing at maneuvering speed. I’ll try that next time but I could see George diving even at idle. Disconnecting the ap might be simpler.

Not a big deal but I don’t like that you can’t run just lateral or just altitude mode.
 
manac said:
Talked to a cs rep at Garmin.

If the AHRS resets the AP will disconnect, probably what happened when I found that big bump.
Gary - has your ap ever disconnected in turbulence?
Click to expand...

No it hasn't yet.

I wonder why the AHRS reset? I don't think that has ever happened during any of my flights?

I am pretty much a "flatlander" flyer I was thinking. It seems to handle turbulence just fine but I bet I haven't been in any big time turbulence?

I did fly over Clingman dome at 8600'...once! lol
IMG_8002.JPG
 
Chase why AHRS would disconnect, if that was the cause of the 500 disconnecting. You should try to eliminate the “probably” in your sentence, for safety. I know you likely know that, just giving that little annoying dude on your shoulder some back-up...
 
“Chase why AHRS would disconnect”, would if I could.

No system diagram. No idea what the inputs required for ap function are and a poor answer from Garmin. Thinking about Garmin’s response the AHRS didn’t go offline, I never got that message.

Flew 3.5 hours in smoooooth air yesterday no issues.
I like how the setup works, just the Garmin documentation and support are weak.
 
manac said:
“Chase why AHRS would disconnect”, would if I could.

No system diagram. No idea what the inputs required for ap function are and a poor answer from Garmin. Thinking about Garmin’s response the AHRS didn’t go offline, I never got that message.

Flew 3.5 hours in smoooooth air yesterday no issues.
I like how the setup works, just the Garmin documentation and support are weak.
Click to expand...

Garmin depends on their dealers for support.

Cincinnati Avionics installed all my Garmin and has been absolutely great as far as support goes.
 
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