Disappearing CDI & VDI

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   I just got the airplane back from an upgrade and am having some issues that don't make sense to me.  Maybe I'm doing something wrong or it could be a wiring issue.  We just did the MAX upgrade to the Aspen PFD and added an MFD.  Upgraded the STEC 30 to a STEC 55X.  Replaced the AXP340 and SkyTrax 100 with an NGT 9000+ with TCAS and ATAS.  Replaced the Cessna fuel senders with CIES digital and moved the JPI to the left side of the panel.  Here it is now:

One of the problems I am experiencing is:

When I program in an approach ( LPV or LNAV) and use the autopilot, it will follow the approach perfectly, flying the procedure turn and descending to the DA or MDA.  Everything works as it should.

When I set it up to hand fly the approach, I still get the GPS (LNAV or LPV) indicator in the top right corner and also see the approach in the widget I have displayed on the IFD showing the approach in use.  No CDI, VDI, or even command bars ever shows up on the Aspen.  My upper right box on the IFD is set to show the fix navigating to and the one next down shows next fix.  When hand flying the approach, the fix navigating to never advances to the next fix.  There is a switch on the panel to change between FD and FD/Autopilot.  It doesn't matter which position it is in.

If I start the approach with the autopilot and then disconnect it, the CDI and VDI are still there and I can fly the approach.

Anyone have any thoughts on this?  The shop is going to come to me to fix that and some other issues but for now, I think this might have them stumped.

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Kentucky Captain Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 21 Mar 2015 Location: KBRY Status: Offline Points: 234	Post Options Post Reply Quote Kentucky Captain Report Post Thanks(0) Quote Reply Topic: Disappearing CDI & VDI Posted: 17 Aug 2020 at 6:13pm
	I just got the airplane back from an upgrade and am having some issues that don't make sense to me. Maybe I'm doing something wrong or it could be a wiring issue. We just did the MAX upgrade to the Aspen PFD and added an MFD. Upgraded the STEC 30 to a STEC 55X. Replaced the AXP340 and SkyTrax 100 with an NGT 9000+ with TCAS and ATAS. Replaced the Cessna fuel senders with CIES digital and moved the JPI to the left side of the panel. Here it is now: One of the problems I am experiencing is: When I program in an approach ( LPV or LNAV) and use the autopilot, it will follow the approach perfectly, flying the procedure turn and descending to the DA or MDA. Everything works as it should. When I set it up to hand fly the approach, I still get the GPS (LNAV or LPV) indicator in the top right corner and also see the approach in the widget I have displayed on the IFD showing the approach in use. No CDI, VDI, or even command bars ever shows up on the Aspen. My upper right box on the IFD is set to show the fix navigating to and the one next down shows next fix. When hand flying the approach, the fix navigating to never advances to the next fix. There is a switch on the panel to change between FD and FD/Autopilot. It doesn't matter which position it is in. If I start the approach with the autopilot and then disconnect it, the CDI and VDI are still there and I can fly the approach. Anyone have any thoughts on this? The shop is going to come to me to fix that and some other issues but for now, I think this might have them stumped.
	Woo Hoo!!!

paulr Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 24 Jan 2014 Status: Offline Points: 564	Post Options Post Reply Quote paulr Report Post Thanks(0) Quote Reply Posted: 18 Aug 2020 at 8:01am
	That is super weird. I don't even have an Aspen yet so I am certainly no expert, but the first question I'd ask is this: do you ever see a CDI/VDI on the Aspen when you're not flying an approach? That is, does the HSI function normally? I'm assuming that to hand-fly an approach, you're loading and activating it on the IFD (because you said you get the correct LNAV/LPV indicator). In that mode, I would still expect the IFD to output the same deviation outputs, although the sensitivity changes when at/inside the FAF. The fact that the AP is able to fly the approach tells me that it's getting deviation outputs from somewhere, so my first suspicion is either an Aspen bug or misconfiguration that is causing it to ignore the ARINC labels for deviation (117, 173, and 174). I can't find any reference indicating whether there's a discrete 429 label for "I am flying an approach right now" but I bet there is. Presumably you've already reached out to Avi & Aspen tech support already to see if they have any data collection suggestions to help you pin this down. Please do update us if you learn anything-- I love this kind of fascinating problem![1] [1] as long as it's not in my airplane, y'know

Kentucky Captain Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 21 Mar 2015 Location: KBRY Status: Offline Points: 234	Post Options Post Reply Quote Kentucky Captain Report Post Thanks(0) Quote Reply Posted: 26 Aug 2020 at 4:51am
	I've been flying the airplane regularly, testing the upgrades for issues for the shop to fix when they come up to my airport for the repairs. I did get a flight in yesterday where I hand flew the approach without ever having engaged the autopilot and I did get a CDI and VDI. Worked perfectly. I don't know what was with that last flight but I will be conducting some more testing. Autopilot coupled approaches work perfectly unless I forget to engage approach mode. I didn't have to do that with the STEC30 and it's not yet a natural movement of buttonology for me.
	Woo Hoo!!!