IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM - DFC90 AP not accurate after installation of dual I

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DFC90 AP not accurate after installation of dual I

Printed From: Avidyne
Category: Avidyne General
Forum Name: IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
Forum Description: Topics on Avidyne's IFD 5 Series and IFD 4 Series Touch Screen GPS/NAV/COM
URL: http://forums.avidyne.com/forum_posts.asp?TID=772
Printed Date: 09 May 2024 at 1:41pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: DFC90 AP not accurate after installation of dual I

Posted By: pat@werigi.com
Subject: DFC90 AP not accurate after installation of dual I
Date Posted: 02 Aug 2015 at 8:44pm

2007 Cirrus W/Avidyne MFD,PFD & DFC90 dual IFD440

Not sure if this is just an installation issue but wanted to see if anyone has the same results.

After the installation of dual IFD440's my DFC90 performs like the Stec 55X that I swapped it out for. Sot several RNAV approaches today and my AP "hunted" for the final approach course. My AP was super accurate prior to the install.

Any thoughts?

Thanks

Pat

Replies:

Posted By: AviSimpson
Date Posted: 05 Aug 2015 at 2:33pm

This is odd. There shouldn't have been a change going from the 430 to 440 in regards to autopilot control. Was there any changes to the PFD? Are you getting "Servo Limit" CAS messages on you PFD?

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Simpson Bennett
Avidyne Corporation
Product Manager

Posted By: bdevault
Date Posted: 07 Sep 2015 at 11:03pm

Wow, I thought I was the first one to have *that* problem. I bet we aren't the only ones who have it though given that DFC90 Cirri with Entegra and 440s can't be a rare combo.

LPV approaches couple the DFC90 in "NAV APPR" mode just like an ILS, track the GS perfectly but then proceed to fly the last 1000' or so down to the DH very sloppily on lateral guidance just like the S-TEC it replaced. The DFC 90 also continuously performs S-turns when tracking garden-variety VOR signals and can't ever quite seem to find a stable course.

Here's the weird thing: the DFC 90 *still* flies ILS's perfectly, indeed so well you can leave it engaged until you're over the numbers (that is, when it will even tune the ILS signal at all, which is another issue I'm fighting with my two new 440's, in which ILS/LOC signal acquisition seems occur at random, but that's a whole other rant...).

I called support when I noticed this and they seem as confused as I am about the whole thing. I've now sent them my logs.

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Bryan

Posted By: AviJake
Date Posted: 08 Sep 2015 at 12:14pm

Looking forward to seeing those logs. I've personally flown hundreds of GPS approaches with dual IFD and DFC90 configuration to DH and lower and have never seen this. Nor do we have any other reports of this kind of behavior.

Would like to hear the other rant too since I've also never had the slightest issue with tuning of the ILS signal. In fact, I can't remember the last time I've manually tuned a localizer frequency.

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Steve Jacobson
sjacobson@avidyne.com

Posted By: AviJake
Date Posted: 09 Sep 2015 at 7:57pm

Flew a coupled RNAV approach down to about 30' AGL in VFR conditions today and the airplane never budged off of dead center glideslope and glidepath.

Looking forward to seeing your logs.

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Steve Jacobson
sjacobson@avidyne.com