GFC 500 in a PA28-181 - New install problems

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Michael Rellinger

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Michael60614
Recently purchased a PA28-181 with all new just installed Garmin panel - GTN 750, (2) G5's,
GTX 345, GMA 345 and finally a GFC 500.

Everything is terrific except the performance of the GFC 500. It cannot hold an altitude ( Alt hold mode) as it just oscillates +/- 200' of the intended hold altitude in addition when I am in Nav mode and I dial in a course that its 90 degrees or more from my present heading, the plane goes into a steep bank of 30 degrees or more and then over shoots the intended course by 20 - 30 degrees and then turns back it the opposite direction to capture the intended source.
My avionics shop has had the plane in for numerous adjustments without much success in fixing these issues.

My concerns are many but I will limit it to a few here.

#1 - I don't believe that in altitude hold that the plane should oscillate by +/-200'. Do you think this is acceptable?
#2 - A plus 30 degree bank is fine for a pilot but my passengers get a little nervous when this happens. Is this be acceptable to you?

If you have a similar set up and you have any comments or similar experience please comment!

Thank you!

Michael Rellinger
 
No, those things are not normal. In smooth air it should hold the altitude perfectly. @WannFly just had one installed and said it held altitude within 30 feet in quite a bit of turbulence.

If your avionics shop can't figure it out, find a better shop.

Also, be sure the plane is rigged properly, that's a very common source of problems with autopilots that has nothing to do with the autopilot itself.
 
Regarding altitude holding, make sure your controls are well lubed with no binding, the 500 servos aren’t that strong, and binding will result in behavior you’re describing.


Tom
 
Agree, my 20 yr old venture 2000 did better that’s what you are describing. Alt hold in GFC 500 is to the spot in smooth air, 30 feet off from what I have tested in howling winds at 550 AGL or so. I haven’t seen a 30 degree bank, ever. All turns are standard rate turns, doesn’t matter how much and how fast I twist the heading knob. Haven’t seen any S turns either to capture and overshoot magenta line.

Find another shop.

B/w was this archer listed on controller sometime back? I took that price to get my hull value adjusted
 
Bw apart from the audio panel, I have exact same setup.
 
Nope found it on my home field! Former owners lost there medical!
WannFly said:
Agree, my 20 yr old venture 2000 did better that’s what you are describing. Alt hold in GFC 500 is to the spot in smooth air, 30 feet off from what I have tested in howling winds at 550 AGL or so. I haven’t seen a 30 degree bank, ever. All turns are standard rate turns, doesn’t matter how much and how fast I twist the heading knob. Haven’t seen any S turns either to capture and overshoot magenta line.

Find another shop.

B/w was this archer listed on controller sometime back? I took that price to get my hull value adjusted
Click to expand...
 
You have this setup on a Piper Archer as well and don’t have any of these issues???
 
How does the plane do when you're hand flying? Does it trim out fine and maintain altitude? What do you see when George is turned off and you're trying to fly hands off?

My point is, if the plane doesn't trim out and fly straight and level hands off, the autopilot will have no choice but to chase the setting.

Right?
 
MooneyDriver78 said:
Regarding altitude holding, make sure your controls are well lubed with no binding, the 500 servos aren’t that strong, and binding will result in behavior you’re describing.


Tom
Click to expand...
Controls are well lubed
Ravioli said:
How does the plane do when you're hand flying? Does it trim out fine and maintain altitude? What do you see when George is turned off and you're trying to fly hands off?

My point is, if the plane doesn't trim out and fly straight and level hands off, the autopilot will have no choice but to chase the setting.

Right?
Click to expand...
 
These plane flys fine by hand and has been flown by another pilot both with me and without to confirm these issues!
 
Michael Rellinger said:
You have this setup on a Piper Archer as well and don’t have any of these issues???
Click to expand...

That is correct, recently I did a review of the AP on the forum under avionics and upgrades, details are there.
 
Just a thought, would a static leak cause an issue like this? Something similar had happened to my century 2000 long time ago and it was due to a linked hose. Now there are no hoses that goes to GFC, but it gets all instructions from G5, wondering if it’s wonky at the source. That still despot explains the overshooting and excessive banks. Have you flown a hold? Does the AP overshoot the hold?
 
If OP comes back, I am willing to take pictures of the GFC config on the G5 and post
 
I am still not sure what you are saying?
What does a poster have to do with the Garmin GFC500?
 
You. The original person to post the question.
 
Michael Rellinger said:
I don’t understand, what is OP??
Click to expand...

That was Ron Howard's character in The Andy Griffith Show.

But in this case, we here at PoA often refer to the person who initiated a thread as the "Original Poster" and we're all too lazy to type it out we write OP.

This will all seem normal before long.
 
I must be dense as I still don’t understand the statement
“ If OP comes back, I am willing to take pictures of the GFC config on the G5 and post”

If I am the OP, where am I coming back from???
 
Michael Rellinger said:
If I am the OP, where am I coming back from???
Click to expand...

Many times noobs create 1 thread and disappear into the interwebs.

In this case, @WannFly was basically saying if you continue to participate in the thread he will bust you a solid and share the settings on his for you to cross check. Wouldn't be the first time there was a hit-n-run thread that people reply to and OP never participated in again. (aka trolling)

And while we're talking, the plane hand flying fine and the plane flying straight and level hands off are by no means the same thing. Sometimes we don't even notice we are "correcting" for trim issues with our hand because it's automatic. Just like when our cars a little out of alignment and we correct for it without noticing. Hands off on the car also identifies it, right?
 
I am going to take some picture this evening and post back so that Michael can cross check
 
Ok, thanks! I am new to blogs and didn’t understand what Wanafly was saying!
I am in need of some good advice as I have this new plane with an all new panel and the Autopilot is not performing up to what I believe is a standard !
I will answer all the questions anyone asks of me and will stay on this blog if it will help get it to a normal state of operation!
 
As you’ll see all over this board, when it comes to troubleshooting start with the simple (inexpensive troubleshooting) and work your way toward the complex (more expensive). Looking forward to the moment you post how the problem is discovered and fixed. Your autopilot should and will perform better!
 
@Michael Rellinger

you can access the G5 config pictures here.
there are also couple of crappy videos i shot, one is holding altitude (in all fairness it was pretty smooth today)
another video where is make a 90 degree heading change, fairly fast on the GMC mode controller. you will see initially the AP banks to about 20 degrees for few seconds, then come inside the standard rate turn mark. i was flying at 110 kts TAS or so, so my standard rate turn would be roughly 17 degrees
 
Thanks for the pictures, I have not accessed my set up screens nor do I know how. Since I am not a AP mech, I would be nervous changing any of these settings, it is my understanding that each setup is based on the plane make and model as well as the installed equipment onboard!
As to your video, I noticed you are using your G5 to set your heading using the HDG mode on the AP. I can do that as well with no issues on my plane.
It is when I set a course on my GTN750 with the AP in NAV mode that I bank over 30 degrees and pass through my intended course by 20-30 degrees and bank back in the opposite direction to capture it!
I also have a video of the issue but am unsure how to post it!
 
No need to change any set up, you can go to the config mode in G5, press the knob n the right side and put the power on , just to compare settings, if you would like. Your and my setup should be exactly the same since they are same make and model - PA-28-181.

I didn’t get a chance to fly a course and intercept, will do when I have a chance, but what you described doesn’t happen in my setup and I have flown a crap ton of approaches VFR intercepting courses from all diff places.

If the AP is good with capturing heading but only overshoots while capturing the magenta line, I would think some course correction angle error or some kind. I am not sure. It happened with my old century 2000 and there was a gain setting in the G5 that helped a lot, but these setup is different, G5 doesn’t send a heading error to the AP, it’s all digital. Someone more familiar and more knowledgeable probably can help troubleshoot. All I can tell you, something very winky is going on with your set up. Does your AP hold altitude in smooth air?
 
If you want to post the video, either put in on YouTube and post the link from there or put in in file sharing app/cloud provider and share it with a link that can be accessed by anyone and post the link here
 
Need to make your video public if you want any input. Also it would be good to show the screen on the 750 when you do the switch from heading to nav you mentioned in the earlier post. Lastly, where is your installer in all this? From all reports, this is a rock solid autopilot. If the problems are with the unit or the install vs. operator error, you should either have the original installer make it right or seek out someone who can.

Where are you based? Perhaps there is someone nearby on POA who can give you a recommendation.
 
Video is now public! This is the first time I have posted to YouTube!
WannFly said:
No need to change any set up, you can go to the config mode in G5, press the knob n the right side and put the power on , just to compare settings, if you would like. Your and my setup should be exactly the same since they are same make and model - PA-28-181.

I didn’t get a chance to fly a course and intercept, will do when I have a chance, but what you described doesn’t happen in my setup and I have flown a crap ton of approaches VFR intercepting courses from all diff places.

If the AP is good with capturing heading but only overshoots while capturing the magenta line, I would think some course correction angle error or some kind. I am not sure. It happened with my old century 2000 and there was a gain setting in the G5 that helped a lot, but these setup is different, G5 doesn’t send a heading error to the AP, it’s all digital. Someone more familiar and more knowledgeable probably can help troubleshoot. All I can tell you, something very winky is going on with your set up. Does your AP hold altitude in smooth air?
Click to expand...
 
Altitude hold is one of my problems,
In smooth air that plane oscillates +/- 200’.
It is in a constant up and down motion.
 
Michael Rellinger said:
Altitude hold is one of my problems,
In smooth air that plane oscillates +/- 200’.
It is in a constant up and down motion.
Click to expand...

That’s like a porpoise in the air. I had a problem like that with my century 2000 which ended up being a kink in the static line. Not normal as you can see from my video there is almost no movement in altitude when straight and level.
 
Michael Rellinger said:
Here is a video of the bank and turning issues!
https://youtu.be/OuHZXOFRjL8
Click to expand...

Yeah, something is seriously wrong with it.

The autopilot should be following the flight director darn near perfectly. You can view the flight director as what the autopilot is "thinking". It looks to me as if it's being followed at first, and it's clearly commanding a greater than standard rate turn for some reason.

However, later on it also seems to continue banking after the flight director is commanding a level off, and it's a bit pitched up near the end compared to what the FD is asking for.

I think you have a combination of multiple problems. It wouldn't surprise me if your plane is somewhat out of rig and/or one or both of the pitch/roll servos were not properly installed, and I wouldn't be surprised if you find the setup is different from what @WannFly posted either.

If you want to get into this yourself, you can look at the GFC 500 maintenance manual and run the tests starting on Page 31.

Sadly, since it's multiple errors, I think you have a badly botched install. If it was just one, maybe you got a bad servo or something from Garmin, but I think this one is on the installer. I would give them a chance to make it right, free of charge, and if they won't or can't do that, I would get Garmin involved, starting by contacting their aviation support department.
 
I have given them many chances to fix these issues and they are scratching there heads.
I don't know if I mentioned this but prior to purchasing the plane, during a pre purchase flight the G5 was tell me that the autopilot was inop due to the servos. When I inquired about it the Avionics shop told me the Garmin had a service bulletin on all (3) servos and replaced them after I purchased the plane.
The autopilot has not worked properly since.
I would think that if it was my rigging or static port issues, they would be up to speed the failures on this AP and advise me......but they don't know seem to know how to fix this issue.
 
Where are you based? You need a new avionics shop. That’s likely the best help this group can give you. It shouldn’t be that difficult to diagnose.
 
The problem is that the Avionics are still under warranty and I am trying to get Garmin involved with the shop to get this resolved.
They are a Garmin dealer
 
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