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Air data but no baro alt |
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paulr ![]() Senior Member ![]() Joined: 24 Jan 2014 Status: Offline Points: 558 |
![]() ![]() ![]() ![]() ![]() 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?
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eallevato ![]() Groupie ![]() Joined: 04 Apr 2018 Location: Northridge, CA Status: Offline Points: 69 |
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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
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paulr ![]() Senior Member ![]() Joined: 24 Jan 2014 Status: Offline Points: 558 |
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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.
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eallevato ![]() Groupie ![]() Joined: 04 Apr 2018 Location: Northridge, CA Status: Offline Points: 69 |
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Yes, the ACU strips the Labels out.
See Note 2 on Figure 9-28A on the install manual. Gene
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Gene
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paulr ![]() Senior Member ![]() Joined: 24 Jan 2014 Status: Offline Points: 558 |
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Thanks, Gene! That's exactly what I needed.
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