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GFC700 autopilot coupled missed approach

Anyone know why the G58 with Nxi upgrade does not allow the AP to remain engaged when pressing the GA button? Is there a software upgrade that enables this? Seems that most airplanes with GFC600/700 are capable of coupled missed approaches. Is it a certification issue with height loss?

Model: Baron G58
Posted 11/20/2023 - 3 months ago
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Not sure about the 600 but the 500 goes to TOGO mode when the button is pushed. You get pitch and roll until you re-engage the proper mode = NAV or HDG. Hit TOGO, firewall, gear flaps up engage NAV and it will fly the missed. Granted ALT is set.

Posted 11/20/2023 - 3 months ago
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The a/p should stay engaged, albeit with pressing the GA button it will revert to pitch & roll modes and the application of throttle should command the pitch to go to approximate climb attitude of ~7°. I found no GFC-700 A/P manuals published at the garmin.com website, however, from the GFC 600 A/P Pilots Guide 190-01488-00_h, page 37 (available for download from garmin.com …page 37 attached below):

Go Around mode is a coupled pitch and roll mode and is annunciated as both the vertical and lateral modes when active. The GA button installed in the cockpit is used to activate Go Around mode. Pressing the GA button while in the air allows the execution of a missed approach or a go around without disconnecting the autopilot (i.e., Coupled Go Around). Go Around mode arms Selected Altitude Capture mode automatically, and any attempts to modify the aircraft attitude (i.e., with the CWS button or the NOSE UP/DN wheel) result in reversion to Pitch and Roll Hold modes.

Also, from Section 2.3 “Vertical Modes”, “Commands a constant nose-up pitch attitude and also commands zero bank angle” (i.e.: roll mode), control – GA button, annunciation – GA. As Keith points out above, to get out of roll mode (read “zero bank angle”) you must engage another roll mode such as NAV or HDG as you desire.

Jim
ABS Technical Advisor
BPPP Instructor & Ambassador
CFII/MEI, A&P/I-A

attachment

Go Around Mode.pdf - 95.1 KB

Posted 11/21/2023 - 3 months ago
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Enhanced AFCS rolled into the Textron STC SA01830WI at NXi Phase 2 (GIA 64W) and was not backwards compatible to Phase 1 (GDU 1050/1055 display update only). All the NXi field upgrades to this point are to NXi Phase 1 status (GDU upgrade + retain GIA 63W) and would not have E-AFCS like a factory aircraft at NXi Phase 2 or later. This remains true under Garmin's duplicate STC SA01945WI which exists for field support of those upgrade installations.

E-AFCS is a requirement for coupled GA.

Posted 11/21/2023 - 3 months ago
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That sounds like the issue. Thanks Matt! This is a 2016 G58 that was upgraded to Nxi. So to simplify - Nxi upgrade = no ESP or coupled GA while Factory installed Nxi (post 2016) = ESP and coupled GA capability. And there is no upgrade path for older Nxi systems. Is that all correct?

Posted 11/21/2023 - 3 months ago
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In reply to: Phil Cohen | 11/21/2023 - 3 months ago

That sounds like the issue. Thanks Matt! This is a 2016 G58 that was upgraded to Nxi. So to simplify - Nxi upgrade = no ESP or coupled GA while Factory installed Nxi (post 2016) = ESP and coupled GA capability. And there is no upgrade path for older Nxi systems. Is that all correct?

Mostly correct. Like I mentioned, NXi has been implemented in phases. The initial factory airplanes had NXi Phase 1, similar feature set to the upgrades, and this serialized in at TH-2476 (early 2017).

NXi Phase 2 added GIA 64W, GMA 1360, GWX 75, and enabled E-AFCS, beginning at S/N TH-2515 (early 2019).

NXi Phase 3 represents the current production G58, which while largely a component obsolescence project on the GIFD, added the GI 275 standby and CO Guardian. Phase 3 serialized in at TH-2538 and on (late 2022).

The only upgrade path for Phase 1 airplanes to get E-AFCS would be for Garmin to add support to their duplicate STC, but this will require GIA 64W to be installed at significant hardware cost. TxtAv is not planning a service bulletin against our STC at this time to update Phase 1 to Phase 2. Updating either to Phase 3 would be extremely involved due to structural changes to the instrument panel and Garmin equipment racks to support the standby relocation.

That being said, I think Baron's are selling into late 2025 now.

Posted 11/22/2023 - 3 months ago
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GFC700 autopilot coupled missed approach