I’m not condoning it I’m just merely mentioning that I know a guy who changed the gain Settings and it fix the problem. It is fixable. It seems that Garmin may be more Concerned about what looks proper than what actually works. It can be fixed, you do some more flight testing and you change the settings to where it doesn’t porpoise in cruise, and then you issue a service letter.
There’s a whole thread over on Beechtalk regarding a -3° down angle in cruise in a bonanza in level flight. And we all know that airplanes really don’t fly with a nose below the horizon…., and it’s the same thing a Garmon rep gets at all high and mighty and said you are illegal and you are breaking the law and your plane in Unairworthy if you reset the pitch to zero in Cruise even though every Aircraft Theyve ever flown including about six or eight jet transport airplanes also show +2 to +3 positive pitch in cruise. And that the attitude indicator they removed also had an adjustable Horizon bar to compensate for this. Anyway, I’ve seen this regarding other issues and although I appreciate their stuff should be documented and airworthy, the stuff ought to work especially when you’re spending several cubic yards of cash on it. You can have both but it takes manpower to do it. My opinion only