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Garmin GFC 500 Autopilot issues


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I will be working through this with Garmin and avionics shop but wanted to post here to get and give info.

 

Normal IFR refresher training and AP kept disconnecting in level flight, as much as 10x on a 2 hr flight. I did receive the red PIT error on G5 and G3.  To be fair we were working through lots of VNAV scenarios, so I wanted to contribute it to not clearing flight plans or having incorrect one loaded , I don’t think that was it though. Though CFII confirmed several disconnections were just smooth and level. Though it was disconcerting it was a reminder to keep hand skills fresh not IMC approaches in this  event. I’ll post updates but any feed back or experience with other GFC owners would be great.

 

Thanks

 

Edited by chan65
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7 minutes ago, chan65 said:

I will be working through this with Garmin and avionics shop but wanted to post here to get and give info.

 

Normal IFR refresher training and AP kept disconnecting in level flight, as much as 10x on a 2 hr flight. I did receive the red PIT error on G5 and G3.  To be fair we were working through lots of VNAV scenarios, so I wanted to contribute it to not clearing flight plans or having incorrect one loaded , I don’t think that was it though. Though CFII confirmed several disconnections were just smooth and level. Though it was disconcerting it was a reminder to keep hand skills fresh not IMC approaches in this  event. I’ll post updates but any feed back or experience with other GFC owners would be great.

 

Thanks

 

Garmin should be able to tell what the fault is from data logs.  In my case, I was having the same failure modes due to YD disconnects... Still not fully resolved.  Are you flying a long body?

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Keep a data card in the G5 so Garmin can evaluate the data.  4 ways to disco AP. 1. AP disco on yoke 2. On GFC507 3. breaker, and 4 by engaging elec. trim. Your issue Is pitch servo or the elec. Trim Switch giving you issues.  

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15 hours ago, alextstone said:

Garmin should be able to tell what the fault is from data logs.  In my case, I was having the same failure modes due to YD disconnects... Still not fully resolved.  Are you flying a long body?

Med body J-  here is what the Avionics shop suggested today 

Good Morning Chan,

 

I have had some issues where the ap will disconnect now and then. I have replaced a yaw servo that was doing that. What I found when flying was that I would get a yaw light on my G5 and G3 on the V35 which then the ap would disconnect. I watched it happen a few times and that was my only light before disconnect. That being said I suspect maybe the pitch trim servo is seeing a fault or has one. What we can do is download data off the G5. If you have a small sd card that you can put in the G5 and just fly it some with it in then I can download that file n send to Garmin. If you don’t have a micro sd card let me know I can ship you one. Its like a 16g micro card.

 

Thank you

 

Bill

 

Ive ordered the mini SD- Ill fly this week and send the card in for evaluation 

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12 hours ago, KB4 said:

Keep a data card in the G5 so Garmin can evaluate the data.  4 ways to disco AP. 1. AP disco on yoke 2. On GFC507 3. breaker, and 4 by engaging elec. trim. Your issue Is pitch servo or the elec. Trim Switch giving you issues.  

thank you , i wasn't aware of the option for the mini SD, it may in fact have on  in it, will verify soon , if not have ordered one,  I bet your diagnoses is correct on 1-4  thank you for taking the time to respond!!

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just installed about 2 weeks ago had the GFC 500 autopilot with no Yaw dampener in  a short body C model. I have  GNC255 &GNC355 as my nav source and early stages in my instrument training.  While I have  virtual no auto pilot experience other than wing lever that failed about  3 years ago.  So I have been going up  in VFR conditions and the AutoPilot has kicked off on me twice. I  am  assuming it my lack unfamiliarity with the AutoPilot.  the other time I had Autopilot flying the holding pattern I may kicked rudder but don't know if that would  cause the AutoPilot to trip off.  I have been only able to get about 5 hrs on it so far.

James '67c

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30 minutes ago, DAVIDWH said:

In my case my disconnects turned out to be a defective servro.

Garmin replaced servo, still under warranty. Labor was my expense.

 

 

I hear Garmin has been replacing a LOT of servos. Any idea what’s up? I have committed to an $80K Garmin installation as soon as Garmin gets 10.6” G3X displays in stock. But now I’m hearing about GFC 500 servo issues and AHRS  issues and I’m starting to get cold feet. For an $80K upgrade to a $160K airframe to make sense the stuff needs to be rock solid. My objective is reliability. The only recent Garmin product I’ve purchased is a GTX 345 and it had to be replaced on warranty due to a faulty AHRS and Garmin support told me it’s the same AHRS used in their other products. 
 

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1 hour ago, PT20J said:

I hear Garmin has been replacing a LOT of servos. Any idea what’s up? I have committed to an $80K Garmin installation as soon as Garmin gets 10.6” G3X displays in stock. But now I’m hearing about GFC 500 servo issues and AHRS  issues and I’m starting to get cold feet. For an $80K upgrade to a $160K airframe to make sense the stuff needs to be rock solid. My objective is reliability. The only recent Garmin product I’ve purchased is a GTX 345 and it had to be replaced on warranty due to a faulty AHRS and Garmin support told me it’s the same AHRS used in their other products. 
 

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Personally I haven't had any servo issues thus far (knock on wood).  Installation completed last October.  Coming up on 120 hours in service since.

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Anyone know what is the stated warranty period on GFC500 hardware?  I'm seeing recent posts on other forums related to trim servo failures but realize you mostly hear about problems vs success which tends to inflate perceived risk of occurrence.  Still, getting a little worried about my pending install and might delay until more data.

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My one time experience with Garmin warranty service was very positive. They replaced my GTX 345 without question and my shop didn't charge me anything for installing the replacement unit. The fact that Garmin has gone to a LRU concept with no field maintenance below the LRU replacement level means that determination of a problem cause is limited to whatever diagnostics are built in and the troubleshooting expertise of the technician. If it is on warranty, busy shops would naturally opt for swapping a LRU rather than spend a lot of time troubleshooting which would likely result in swapping the LRU anyway. Ultimately, this is probably less expensive for the shop, Garmin and quicker turnaround for the customer. But, it can make it appear that a lot of LRUs are being replaced because, especially on new installations, the real problem may not be the LRU at all.

The automobile industry does the same thing. Dealers don't fix anything -- they just swap parts until the problem goes away. Radio would cut out on my Acura during warranty. Dealer swapped radio. Still broken. Dealer swapped rear window (contains embedded antenna). Still broken. Dealer swapped cable from radio to antenna. SUCCESS! If this happened a lot and someone was tracking parts replacements, they could mistakenly think that Acura had a lot of bad windows and radios.

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While I've heard of servo failures as well, I presume this is just because people typically only mention the problem, not the success.  I now have 2 years and 250 hours on my GFC-500 install and no issues at all, it has been flawless since day one.  I can say the same about all the Garmin gear that I've bought in the last 14 years.  The only repair issue I had was an almost 10 year old GTN-650 (I have it installed the first week they were shipping) that wouldn't hold the time so on boot up it was always searching the sky to download a current almanac.  The repair was quick and the unit came back looking like new.

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On 5/24/2021 at 7:12 AM, chan65 said:

I will be working through this with Garmin and avionics shop but wanted to post here to get and give info.

 

Normal IFR refresher training and AP kept disconnecting in level flight, as much as 10x on a 2 hr flight. I did receive the red PIT error on G5 and G3.  To be fair we were working through lots of VNAV scenarios, so I wanted to contribute it to not clearing flight plans or having incorrect one loaded , I don’t think that was it though. Though CFII confirmed several disconnections were just smooth and level. Though it was disconcerting it was a reminder to keep hand skills fresh not IMC approaches in this  event. I’ll post updates but any feed back or experience with other GFC owners would be great.

 

Thanks

 

Ran about 3 hours with SD card and sent in for data, it seems to be pointing to the pitch trim servo, the whole system is less than 2 years old , so it will be interesting to see what they come up with B2FC9AB6-5DB3-4E86-9546-733FAF303763.thumb.jpeg.bbe8567cf67b8abc2c948b5a34b70712.jpegA364A8BA-BE86-46C5-BCA2-28C5D4831236.thumb.jpeg.6b0094b71789b420062238486347cb28.jpeg

Edited by chan65
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  • 1 month later...

Update , before this AP problem , I had about 200 hrs on the system prior to this issue. Garmin did replace the servo. I flew it less than an hour without issue , plane went into annual ,  first flight after annual  the issues reappeared, Garmin requested a second data card reading , I sent it in last week and am waiting to here. It’s a bummer  

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