G3X & GFC500 Flight data

[Davidv]

I'm trying to troubleshoot something with my autopilot and was wondering if anyone with the G3X & GFC500 setup would be willing to share one of their flight data files with me (preferably one that has cruise for around an hour in relatively smooth air).  I'm still getting a bit of vertical speed movements in altitude hold mode and want to compare my data to another Bravo or long body to see what's normal.  Feel free to PM if you would like to exchange data files.

David

[mike_elliott]

David, @DonKaye has close to this setup in his 93 ish Bravo. Also @kortopates Paul Kortopates may have some files he could share from Saavy clients.

 

[Davidv]

Thanks Mike, unfortunately Paul has told me in the past they don’t share any data (even blind).  Kind of ironic when everyone shares their data with them to help build their algorithms! 
 

Maybe they can re-evaluate? I can’t see the harm in sharing anonymous data (take out n numbers, airports, Lats and longs).

[PilotX]

I don't have exactly the same setup but with GI275/GFC500. If you want to go through four hours of logs or two hours of logs let me know. Just PM me with an e-mail if interested.

[Tom 4536]

13 hours ago, Davidv said:

I'm trying to troubleshoot something with my autopilot and was wondering if anyone with the G3X & GFC500 setup would be willing to share one of their flight data files with me (preferably one that has cruise for around an hour in relatively smooth air).  I'm still getting a bit of vertical speed movements in altitude hold mode and want to compare my data to another Bravo or long body to see what's normal.  Feel free to PM if you would like to exchange data files.

David

Not sure if your concern is the same as mine, but my new GFC500 & GI275 in ALT hold continuously oscillates the pitch (slightly) in smooth air. I don't have the date but it is strange seeing the horizon constantly (slowly) going up & down. The altitude is not deviating more than =/- 25ft. My avionics shop said it is not suppose to do that, but getting Garmin's help has been a struggle. I have an M20K-231.

[Davidv]

7 minutes ago, Tom 4536 said:

Not sure if your concern is the same as mine, but my new GFC500 & GI275 in ALT hold continuously oscillates the pitch (slightly) in smooth air. I don't have the date but it is strange seeing the horizon constantly (slowly) going up & down. The altitude is not deviating more than =/- 25ft. My avionics shop said it is not suppose to do that, but getting Garmin's help has been a struggle. I have an M20K-231.

Yes, that's been my issue and Garmin hasn't been any help either.  They just tell me to talk to my avionics shop and all my avionics shop says is "well we installed it correctly so I don't know what to tell you".  To their credit, they said they would look at it again but I'm not sure what they will do differently that they didn't do the first time they looked at it.  I'm going to send my data files to @TrekLawler and with all of the data they should be able to tell what's causing this issue given it records everything including servo movements.

[Tom 4536]

13 minutes ago, Davidv said:

Yes, that's been my issue and Garmin hasn't been any help either.  They just tell me to talk to my avionics shop and all my avionics shop says is "well we installed it correctly so I don't know what to tell you".  To their credit, they said they would look at it again but I'm not sure what they will do differently that they didn't do the first time they looked at it.  I'm going to send my data files to @TrekLawler and with all of the data they should be able to tell what's causing this issue given it records everything including servo movements.

My avionics shop said that Garmin won't tell them how the GFC500 works, making it impossible to troubleshoot the AP. They say that Garmin support has not been very responsive or helpful. My plane has been in the avionics shop over 2 weeks and still no resolution in sight.

[kortopates]

There has been a number of posts on this topic in the past. The resolution for many has been to eliminate all friction in the elevator and trim system from yoke back to elevator and make sure its well lubed. Any area its sticking can cause these symptoms. A few people with the pitch oscillation issues reported that doing that 100% solved their problem. Since its an easy fix, its definetly well worth trying that first and is a Mooney specific issue too. 

[Niko182]

PM sent

[Davidv]

2 hours ago, kortopates said:

There has been a number of posts on this topic in the past. The resolution for many has been to eliminate all friction in the elevator and trim system from yoke back to elevator and make sure its well lubed. Any area its sticking can cause these symptoms. A few people with the pitch oscillation issues reported that doing that 100% solved their problem. Since its an easy fix, its definetly well worth trying that first and is a Mooney specific issue too. 

Yes, I've been through all the fixes with three different mechanics who have fixed this before.  I'm not getting big up and down pitches but I guess I expected perfection given that it's a digital autopilot.  I'm thinking Garmin can look at my data to see if the pitch and trim torque are consistent with the inputs.

[kortopates]

Yes, I've been through all the fixes with three different mechanics who have fixed this before.  I'm not getting big up and down pitches but I guess I expected perfection given that it's a digital autopilot.  I'm thinking Garmin can look at my data to see if the pitch and trim torque are consistent with the inputs.

I would expect perfection as well. Agreed though on approaching Garmin with data and a video showing attitude and out the window.


Sent from my iPhone using Tapatalk

[HXG]

It sounds like you’ve already tried lubricating the yoke shafts. But, I highly recommend this as the first do it yourself fix attempt for any GFC-500 slight altitude deviations/porpoise.

My Bravo GFC 500 began a +- 10-20 feet altitude hold porpoise a few weeks ago.  I wiped down the yoke shafts with a small amount of silicone lubricant applied to a cloth. Problem solved and GFC500 is back on rails. There was no perceptible yoke shaft friction prior to lubrication, but it was noticeably smoother after.  

This may not help in your case, but has been a welcome easy and cheap fix for several pilots with Pipers, Bonanzas, & Mooneys. 

[Davidv]

5 minutes ago, HXG said:

It sounds like you’ve already tried lubricating the yoke shafts. But, I highly recommend this as the first do it yourself fix attempt for any GFC-500 slight altitude deviations/porpoise.

My Bravo GFC 500 began a +- 10-20 feet altitude hold porpoise a few weeks ago.  I wiped down the yoke shafts with a small amount of silicone lubricant applied to a cloth. Problem solved and GFC500 is back on rails. There was no perceptible yoke shaft friction prior to lubrication, but it was noticeably smoother after.  

This may not help in your case, but has been a welcome easy and cheap fix for several pilots with Pipers, Bonanzas, & Mooneys. 

Thanks, even though several people have looked at this it’s always worth a try! What lubricant specifically did you buy? Did you go behind the panel or just pull them all the way back?

[HXG]

46 minutes ago, Davidv said:

Thanks, even though several people have looked at this it’s always worth a try! What lubricant specifically did you buy? Did you go behind the panel or just pull them all the way back?

I don’t recall the brand. But, it was a simple silicone lubricant spray (without grease or other additives) I picked up at home depot. I sprayed a small amount on a cloth (slightly damp, don’t soak it) and applied it to the exposed yoke shafts after pulling the yokes back. I didn’t remove anything. I just wiped the visible yoke shafts. This was suggested by a mechanic and avionics guy I use. Fortunately, It actually worked in my case. 

[PMcClure]

I do not know how to share data files, but if you tell me, I can try. I can say that perfection is the best description for the ride on my G3X/GFC 500. I do not detect any oscillations in pitch or bank. 

[Davidv]

Just now, PMcClure said:

I do not know how to share data files, but if you tell me, I can try. I can say that perfection is the best description for the ride on my G3X/GFC 500. I do not detect any oscillations in pitch or bank. 

That’s great, so if you’re in an IAS climb it holds it pretty much to the knot? There should be an SD card in your G3x that you can pull to download the flights to your computer.  They are just simple Csv files but contain a ton of data.

[PMcClure]

Well..... I do not use IAS mode much. Mostly I use VS mode. I have noticed some hunting for air speed some in IAS, but I just have not used it much.  When I have used IAS, it seems to hold within +/- 3-5 knots. VS mode is dead on. IAS not as much, but not what I would say is a problem or defect. 

Going in for annual tomorrow and I do have to update the card. But if you can wait, I should be flying it next Sat and can do some tests in IAS and VS for comparison. 

[Davidv]

5 hours ago, PMcClure said:

Well..... I do not use IAS mode much. Mostly I use VS mode. I have noticed some hunting for air speed some in IAS, but I just have not used it much.  When I have used IAS, it seems to hold within +/- 3-5 knots. VS mode is dead on. IAS not as much, but not what I would say is a problem or defect. 

Going in for annual tomorrow and I do have to update the card. But if you can wait, I should be flying it next Sat and can do some tests in IAS and VS for comparison. 

Thanks, good to know on VS speed. Whenever you get a chance to get the data is fine with me!

[PMcClure]

On 6/28/2021 at 4:26 AM, Davidv said:

Thanks, good to know on VS speed. Whenever you get a chance to get the data is fine with me!

Pm sent with a few data files. Let me know if you need anything else.