GTN650 + G5 + KFC150 : G5 does not function on NAV Mode

[N177MC]

My new-to-me Mooney MSE came equipped with GTN650 + G5 HSI + KFC150.

The problem I have is the G5 HSI will play with the GTN & KFC 150 AP in Heading mode and in GPSS mode, but not in NAV mode.

The course info is displayed on the G5  but the AP does not operate when NAV mode is engaged.

Any ideas ?

[Pinecone]

You should not be using NAV mode.  GPSS is better and sends heading info to AP, so you use Heading mode.

My original Aspen/KAP-150 operated that way.

[kortopates]

If you’re also new to the KFC-150, using NAV mode, make sure you first use heading to put you on a heading to intercept the NAV course. Then once intercepted it should track it fine if it’s working.

Eventhough GPSS is preferred i assume Approach mode won’t work either if NAV doesn’t and you’ll need that to follow a GS or GP.


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[rklems]

I have a guess here... this is a somewhat common installation failure in the G5 replacing a KCS55/KI525 King system. The nav tracking comes from the GTN, which was usually wired through the KI525 and then to the KC19X head. Since the G5 installation manuals do not show this connection, more inexperienced installers do not reroute the nav signals directly from the GTN to the KC19X. The G5+GAD29D only provides course and heading error signals to the KC19X, it doesn't generate any nav signals (which is why there is the limitation that a G5 can be interfaced to only one navigator when installed with a 3rd party autopilot). So the analog +L/+R, +Up/+Down and +/- GS Flag signals must be connected from the GTN directly to the KC19X head. Using Nav/Apr is of course the only way to do a coupled approach with the KFC, you can navigate laterally with GPSS, but it doesn't go in to higher tracking mode, nor will it be able to couple vertically.

[N177MC]

RKLEMS nailed it !

I pulled the GTN650 and the KC1900 and sure enough the pinouts didn't ring out .

Hard to believe a fairly reputable shop made this install ...

Thanks RKLEMS !

 

[kortopates]

So it never worked!


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[N177MC]

10 minutes ago, kortopates said:

So it never worked!


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Nope, confirmed by the ex-owner.