IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM

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Air data but no baro alt

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=2631
Printed Date: 17 May 2024 at 7:19am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: Air data but no baro alt

Posted By: paulr
Subject: Air data but no baro alt
Date Posted: 14 Feb 2024 at 6:54pm

I am probably missing something super simple.

My IFD440 is wired to an Aspen display through an Aspen ACU.

I get the Aspen wind vector block, and I see OAT, IAS, and TAS on the IFD (including on config page 5).

What I *don't* see is baro altitude. More specifically, I still get "manual sequence required" when I fly a missed like the ILS 18 KMDQ, and I don't see B ALT or D ALT data on config page 5.

Any idea what the missing ingredient here is?

Replies:

Posted By: eallevato
Date Posted: 15 Feb 2024 at 10:37am

That is because it is not wired properly.

In order to get Baro altitude, the ARINC 429 data to the IFD must come from pins 26 and 27 on the EFD itself and not from the ACU.

Gene

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Gene

Posted By: paulr
Date Posted: 15 Feb 2024 at 10:52am

Ouch. Is the ACU stripping that 429 label or something? I didn't see this explicitly called out in the IFD install manual, just a note that the Aspen is an approved airdata source. I need something I can show my installer (who's not an Avidyne dealer, grrr) to get them to fix this properly.

Posted By: eallevato
Date Posted: 15 Feb 2024 at 11:28am

Yes, the ACU strips the Labels out.

See Note 2 on Figure 9-28A on the install manual.

Gene

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Gene

Posted By: paulr
Date Posted: 15 Feb 2024 at 1:06pm

Thanks, Gene! That's exactly what I needed.