DFC90/DFC100 Digital Autopilot - Can I have the Stec 55x back after DFC90 installed

Can I have the Stec 55x back after DFC90 installed

Printed From: Avidyne
Category: Avidyne General
Forum Name: DFC90/DFC100 Digital Autopilot
Forum Description: Topics on the Avidyne DFC Digital Autopilots
URL: https://avidynelive.com/forum_posts.asp?TID=2664
Printed Date: 26 Mar 2026 at 11:50am
Software Version: Web Wiz Forums 12.07 - https://www.webwizforums.com

Topic: Can I have the Stec 55x back after DFC90 installed

Posted By: icordoba
Subject: Can I have the Stec 55x back after DFC90 installed
Date Posted: 02 Jul 2024 at 10:55am

Hi,

I am having a false Autopilot Inop - AHRS Failure error in my PFD even though the AHRS is working OK. I had returned the PFD back to Avidyne for repair but after it came back to Europe with its Form 8130 of course, the problem persists (Avidyne reports they could not reproduce the problem). The autopilot is OK as my shop have test-installed another PFD from another Cirrus and everithing works ok... The DFC90 is installed in a Cirrus SR22 G2 with the flap cable wired. having said this... my question:

I am pretty frustrated wit this... Can I have my shop put back the Stec in my plane and reconfigure the PFD to use it and put the DFC90 aside in case I need to fly until I decide if I send the PFD back, again, to Avidyne USA (I'm in Europe)?

I ask this because having the flap cable wired, a voltage is injected into one of the pins of the autopilot. This is OK for the DFC90 but I am not sure if the STec 55x can be damaged by that voltage if I install it back. I don't want to damage my STec as I kept it as a backup auto pilot in case something like this happened.

thanks,

Ignacio

Replies:

Posted By: AviSteve
Date Posted: 08 Jul 2024 at 11:06am

I asked the tech support team about this. The short answer is yes, but you'll have to mess with wiring. Tech support is going to contact your shop.

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Steve Lindsley
Avidyne Engineering

Posted By: icordoba
Date Posted: 08 Jul 2024 at 1:15pm

Thanks.

The Flap cable is installed, does it means that to connect back Stec 55x the cable wire needs to be removed?

I don't intend to go permanently back to STec 55x but only temporarily so I am not willing to remove the cable. If that is the case, I think I would give app and forget about STec 55x for good, but it would help in my situation should I not be able to use the DFC90 with one of the available PFDs.

Thanks for any additional info. Honestly, i don't think my shop will help.

Ignacio