GFC 500 pitch oscillations by Mooney model

[Rick Junkin]

During my research into this oscillation issue I came across this Garmin service bulletin for gain adjustments on SR22 GFC500 installations, the details of which can only be accessed by an authorized Garmin dealer/installer. Cirrus pilots were reporting oscillations similar to what we're seeing and this SB addresses pitch performance. While it wouldn't be legal within the STC specifications to use this data for our Mooney installations it may be enlightening to know what fix Garmin put in place for the SR22. You can ask your installer if they'll take a look at it for you and share what's in it.

December 08, 2022 :  (2022) Service Bulletin 22113 Rev A: Approval of an updated maximum autopilot engagement speed and new gains for Cirrus SR22 aircraft

 

Cheers,
Rick

[Rick Junkin]

Looks like Garmin will have an indirect opportunity to address the pitch oscillation issue as part of the answer to this proposed AD.

https://www.avweb.com/aviation-news/ad-mandates-garmin-autopilot-software-fix/?MailingID=1527

Cheers,
Rick

[ArtVandelay]

That software has been available since January. AD is yesterday’s news.

[kortopates]

That software has been available since January. AD is yesterday’s news.

Maybe, but the new news is the need to get a sign off for complying with this new AD; even though you may have installed the update.


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[PT20J]

2 hours ago, kortopates said:

Maybe, but the new news is the need to get a sign off for complying with this new AD; even though you may have installed the update.


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Good point. I think a lot of people might miss that. There was an AD a while back on McCauley governors for a bad batch of bearings. I got documentation from the shop that overhauled mine showing that it used a PMA bearing rather than the affected McCauley part. So I wrote up a log entry stating that as the method of compliance with the AD and my IA signed it.