What's the secret to using APR on the KFC 225 Autopilot?

[Max Clark]

I have a new (to me) M20R with an Avidyne IFD 540 + 440 stack.

I can load approaches fine in the IFD (RNAV and ILS), and when flying them the King HSI GS does work.

What I haven't been able to figure out is what the correct sequence of buttons (or timing) to push on the 225 to capture and fly the GS.

Any tips or tricks I should try in the plane?

[wombat]

Don't know about the 225, other than it's probably similar to the 150.

Basically you fly on heading or nav mode and as you are flying toward the approach course (from under the glide slope) you press the approach button (APR) and APR will blink.   When you get close to the course, APR will go solid and it will track the course (GPS, ILS, etc).    When you get close to the glide slope, GS will go solid  and ALT will go off.

The pilot's guide can be found here: https://www.bendixking.com/content/dam/bendixking/en/documents/downloads/006-18035-0000_1-KFC-225-KI-525A-Pilot-s-Guide.pdf

The front course ILS directions are on page 20 & 21 (Page 23 of the PDF)

[Max Clark]

8 minutes ago, wombat said:

Don't know about the 225, other than it's probably similar to the 150.

Basically you fly on heading or nav mode and as you are flying toward the approach course (from under the glide slope) you press the approach button (APR) and APR will blink.   When you get close to the course, APR will go solid and it will track the course (GPS, ILS, etc).    When you get close to the glide slope, GS will go solid  and ALT will go off.

The pilot's guide can be found here: https://www.bendixking.com/content/dam/bendixking/en/documents/downloads/006-18035-0000_1-KFC-225-KI-525A-Pilot-s-Guide.pdf

The front course ILS directions are on page 20 & 21 (Page 23 of the PDF)

Thanks - I'll try and record a video to share this coming weekend. APR was not capturing for us and the GS was not being tracked.

[Fritz1]

Capture the localizer outside the FAF at intercept altitude, fly towards FAF on final approach course on HDG or NAV, press APR, autopilot will track localizer inbound and intercept GS at FAF, if not something is not working, this is the procedure for an ILS, for a GPS approach there may be an additional step on the navigator to enable approach outputs

[EricJ]

This may go without saying, but with many/most autopilots the GS should be intercepted from below.    Many won't capture otherwise.

[rgpilot]

When flying an RNAV approach with autopilot (King 225) in APP mode, after passing INF the APP button will begin to flash. I push it two times and it then captures the GS.

When my Garmin 530 was updated to WASS they had to add a wire from the autopilot directly to the back of the 530. Before they added the wire I could not capture the GS.

Edited June 4, 2024 by rgpilot

[Tx_Aggie]

Don’t hit the apr button until the faf is the next waypoint. (In between iaf and faf.) you’ll lock on the gs every time thereafter. 

[Max Clark]

2 hours ago, rgpilot said:

When flying an RNAV approach with autopilot (King 225) in APP mode, after passing INF the APP button will begin to flash. I push it two times and it then captures the GS.

When my Garmin 530 was updated to WASS they had to add a wire from the autopilot directly to the back of the 530. Before they added the wire I could not capture the GS.

I've been reading about this wire - I need to figure out how to tell if it was done

[Max Clark]

1 hour ago, Tx_Aggie said:

Don’t hit the apr button until the faf is the next waypoint. (In between iaf and faf.) you’ll lock on the gs every time thereafter. 

I think we tried that - will test again

[LANCECASPER]

@Jake@BevanAviation

[Jake@BevanAviation]

I would double check the wiring to the KFC225, specifically the gps select and ILS/GPS approach.

[PT20J]

Agree with Jake. The ILS Energize input on B-K autopilots enables the GS. 

[Max Clark]

So basically hope that the original Avidyne install was done properly

Test it in the plane

Have it inspected and corrected if not

[PeteMc]

Just had another thought.  Are you Arming the Approach before you switch the IFD to VLOC (or it switches on it's own)?  Wondering if there's a "glitch" when switching from GPS to VLOC that's messing up the AP if you've already put it in the Approach mode?

[Max Clark]

18 hours ago, PeteMc said:

Just had another thought.  Are you Arming the Approach before you switch the IFD to VLOC (or it switches on it's own)?  Wondering if there's a "glitch" when switching from GPS to VLOC that's messing up the AP if you've already put it in the Approach mode?

Would it switch GPS to VLOC for an RNAV approach?

[PeteMc]

2 hours ago, Max Clark said:

Would it switch GPS to VLOC for an RNAV approach?

Sorry, missed it was both RNAV and ILS you were talking about.  Just remembered "GS" and thought it was an issue capturing the GS on an ILS.

[LANCECASPER]

3 hours ago, Max Clark said:

Would it switch GPS to VLOC for an RNAV approach?

VLOC is for VOR or Localizer. This might be helpful:

https://www.aopa.org/news-and-media/all-news/2014/may/05/when-to-switch-to-vloc-on-an-ils-or-vor-approach

[Max Clark]

This was not obvious or easy to figure out.

When flying the segment approaching the FAF you have to activate APR on the autopilot. The autopilot should indicate APR ARM, and GS ARM on it. This is the correct and normal indications before reaching the FAF. The problem I was having was pressing APR immediately switched the autopilot to APR mode without indicating GS ARM, or activating GS.

Here's the trick

The IFD with display and advisory in the lower right corner in blue "Enable A/P APR". When this comes up you can clear the advisory by pressing on the screen, and you'd believe that it's time to press APR on the autopilot. This is wrong. The correct procedure is to press the LSK soft key on the lower left side of the IFD next to "Enable A/P Approach" on the FPL page (it's not obvious, different color, flashing, anything, it's just sort of there), and then after that press APR on the autopilot. BTW documentation says that the LSK is available on the FPL page, I need to check if it's available on the MAP page as well. I also need to check if it it's available on the 440 as well, but I don't believe it is.

1. Activate the approach in the IFD
2. Fly the approach
3. When nearing the FAF the IFD advisory (blue box lower right screen) "Enable A/P APR" will display
4. From IFD FPL page press "Enable A/P Approach" LSK on lower left of IFD
5. Press APR on autopilot
6. Verify APR and GS are ARM

I'll try to make and post a video showing this

[wombat]

Glad you figured out how to make that work!   

That's a pretty complex series of steps required. 

[Max Clark]

It's easy when you know what you need to do - was annoying because I couldn't find this documented anywhere

FWIW the IFD + KFC flys the approach perfectly