GFC-500 "hunting" during dead calm flight / How does gain adjustment work?

Salty

Salty

Touchdown! Greaser!
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Salty
Ok, so during the day with even very mild turbulence I don't notice it, but on a night flight with dead calm there was a mild bank left, bank right, bank left. It's about 2 seconds between switches. It only banks a degree, maybe 2 at most.

First question is, is this normal and I just have to deal? It's not really that big a deal, but it's very noticeable. I think my wife will get sea-sick from it.

Second question, assuming it's not normal is, which way do you think I should adjust the gain if I try to tune it out? Is it too sensitive and overshooting, or is it lagging? My guess is to reduce the gain because it's probably a little too sensitive.

Third question is, how much of an adjustment should I make for this situation? I'm assuming it would be a very small adjustment considering the mildness of the symptom.
 
Oh man, gain adjustments are never ending. It's sickening. In this day and age I cannot understand why we have to mess with such rudimentary settings at all. Seriously, it should be possible for a computer to interpret an EFIS and choose how much force is necessary to smoothly adjust stick controls on its own.

Make sure you don't have deadband, then trial and error...
 
Salty said:
How do you do that?
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Look at where the roll servo arm connects to the aileron pushrod or bellcrank. Push it back and forth and look for slop. Post pics of your servo installation. Which hole on the servo arm is connected to the pushrod? Distal hole is better if it may be used. What plane is this in?
 
It's a mooney. I don't think there's room to get a picture. It's pretty tight in there.
 
Salty said:
It's a mooney. I don't think there's room to get a picture. It's pretty tight in there.
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I would guess most of those installations would have good performance with similar or the same gain settings as their installation should be the same. If you adjust the gain, I would try lowering the roll servo gain by trial and error until you get better results.
 
It's hooked directly to the bell crank, so I doubt there's any play, but I'll open up the hatch and see if I can see anything at all.
 
Take pics of your settings before messing with them so you may go back if you aren't happy with the results.
 
I fixed the link
 
ok, I looked at the link. I have only done installs with pushrods, but I believe that may be the source of your issues. I would check into that with mooney guys and installers for that autopilot in mooneys.
 
It’s not normal with that AP, I can confirm that
 
I called my installer and the guy that knows what he’s doing is out with COVID….
 
Is there a fuel imbalance it's trying to compensate for?
 
Haven't had a chance. Hoping to have them look at it this week.

You working on IR again?
 
Salty said:
You working on IR again?
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not yet, just doing my usual VFR practice approaches. Might start back up this month / January. Getting out of LZU and getting FF is darn near impossible at the time I usually fly with ATL. That is my biggest driver to get IR now lol
 
Installer agrees the play is the problem. They had it as tight as they could get it with the unmodified mounting hardware. They are working on it right now to modify it to tighten it up.
 
I forgot to mention I did test it in heading mode and it was no better, worse if anything.
 
Good to hear! I’ve flown a couple different planes with the GFC 500 and they were amazingly precise! Glad you got it figured out!
 
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