Jump to content

King KFC 225 and Garmin 750


M20R

Recommended Posts

Just replaced my non-WAAS Garmin 530/430 with a 750/650 with Flight Stream and a GTX 345 transponder. I also have a King KFC 225 digital autopilot. I was assured by the installer that he was aware of the extra wiring requirements (GPS Select) between the 750 and 225.

On the test flight, I checked out everything. GPS tracking and turn anticipation worked perfect. ILS also worked perfect. However, the glide slope capture on the 225 would not engage on the GPS LPV approach. The GS appears on the HSI (750) and CI 106 (650) and functions normally. The 225 tracked the lateral nav perfectly in the approach mode but no GS capture.

I am very familiar with the 225 and 750 in other aircraft so I know when and how to activate the approach mode. I verified that the 750 and 650 are set to “Prompt”.

I tried several different LPVs all with the same result, no GS capture. I even tried not enabling the outputs, no difference.

The installer assured me they added the correct wiring.

Is there anything I can try before bringing it back?

 

Link to comment
Share on other sites

4 minutes ago, M20R said:

Just replaced my non-WAAS Garmin 530/430 with a 750/650 with Flight Stream and a GTX 345 transponder. I also have a King KFC 225 digital autopilot. I was assured by the installer that he was aware of the extra wiring requirements (GPS Select) between the 750 and 225.

On the test flight, I checked out everything. GPS tracking and turn anticipation worked perfect. ILS also worked perfect. However, the glide slope capture on the 225 would not engage on the GPS LPV approach. The GS appears on the HSI (750) and CI 106 (650) and functions normally. The 225 tracked the lateral nav perfectly in the approach mode but no GS capture.

I am very familiar with the 225 and 750 in other aircraft so I know when and how to activate the approach mode. I verified that the 750 and 650 are set to “Prompt”.

I tried several different LPVs all with the same result, no GS capture. I even tried not enabling the outputs, no difference.

The installer assured me they added the correct wiring.

Is there anything I can try before bringing it back?

 

If it captures the ILS correctly, I would think the wiring is correct. Perhaps a setting in the 750. What does it do using the 650 on a LPV as a source if you have the AP set up to be able to use the 650 as a source also? You might try to PM TrekLawler here and see if there is anything on the Garmin side he is aware of.

  • Like 1
Link to comment
Share on other sites

I had the same problem in one of my 172's with a 750 and kap 140.  Like you said, there is a setting in the 750 to make the "enable apr output" prompt appear before the FAF.  There is also an additional wire that goes straight from the 750 to the autopilot.  I would get them to make sure both of those items are correct.  It will do the ILS just fine without that wire so that doesn't help.  

When I upgraded one of my 430's in the the mooney to WAAS they had to add that wire as well in order to make it fly LPV coupled approaches on the 225.

Hope this helps.

Link to comment
Share on other sites

  • 6 years later...
On 6/11/2016 at 6:30 PM, cl65fo said:

I had the same problem in one of my 172's with a 750 and kap 140.  Like you said, there is a setting in the 750 to make the "enable apr output" prompt appear before the FAF.  There is also an additional wire that goes straight from the 750 to the autopilot.  I would get them to make sure both of those items are correct.  It will do the ILS just fine without that wire so that doesn't help.  

When I upgraded one of my 430's in the the mooney to WAAS they had to add that wire as well in order to make it fly LPV coupled approaches on the 225.

Hope this helps.

It seems my 2000 Ovation with WAAS 430s and a KFC-225 isn't coupling to and tracking glide-slope on LPV approaches. At first, I thought it was because perhaps I'd armed the approach too late, having either been given late vectors onto final at the IF or high vectors, coming in above the GS. (In a couple of cases, both!) But now I'm not so sure...

On my most recent try, I was given very tight vectors onto final and was brought in high, but I did see the "GS arm" indication on the KFC-225. Would I see that indication if I was missing the above-described wire? Or does "GS arm" on the 225 indicate I have the wire and something else is up?

Thanks,

--Up, N194V.

Link to comment
Share on other sites

12 minutes ago, Jeff Uphoff said:

It seems my 2000 Ovation with WAAS 430s and a KFC-225 isn't coupling to and tracking glide-slope on LPV approaches. At first, I thought it was because perhaps I'd armed the approach too late, having either been given late vectors onto final at the IF or high vectors, coming in above the GS. (In a couple of cases, both!) But now I'm not so sure...

On my most recent try, I was given very tight vectors onto final and was brought in high, but I did see the "GS arm" indication on the KFC-225. Would I see that indication if I was missing the above-described wire? Or does "GS arm" on the 225 indicate I have the wire and something else is up?

Thanks,

--Up, N194V.

First off I think the 225 is an amazing AP but it can be a little finicky sometimes. Please reference this page for the proper procedure.  If you are not being prompted with this APR message your 430w will need to be configured for it.  An additional wire is necessary to trick the 225 for vertical LPV guidance and gpss steering as well IIRC (it has been well over a decade since we had that interface).  If you’re a BT member this LINK might be helpful.  If you need more help let me know!

 

6329987B-54AC-4E77-9508-DC638EC0D6FD.jpeg.bbf0a8025b84f48e85b00873bff83b37.jpeg

  • Like 1
Link to comment
Share on other sites

4 hours ago, Jeff Uphoff said:

It seems my 2000 Ovation with WAAS 430s and a KFC-225 isn't coupling to and tracking glide-slope on LPV approaches. At first, I thought it was because perhaps I'd armed the approach too late, having either been given late vectors onto final at the IF or high vectors, coming in above the GS. (In a couple of cases, both!) But now I'm not so sure...

On my most recent try, I was given very tight vectors onto final and was brought in high, but I did see the "GS arm" indication on the KFC-225. Would I see that indication if I was missing the above-described wire? Or does "GS arm" on the 225 indicate I have the wire and something else is up?

Thanks,

--Up, N194V.

If I remember correctly in 2000 all Ovations came with 430s and a KFC225 A/P so it should have been wired for the glide slope on the ILS.  You could upgrade to 530s. Maybe Ins 2006 or later when they upgraded the 430 to 430W the extra wiring needed to be put in, but II would think that would have been clearly documented when it came back from upgrade for the shop to follow, since they had to swap out the antenna, etc.

Link to comment
Share on other sites

I had the same problem on 2003 Olvation when I upgraded to WASS.  Initially the extra wire from the KING 225  the autopilot was not added. When that was corrected I found that if I waited to hit approach mode after being aligned on final the autopilot would capture the GS. It was not necessary to make any other inputs to 530.  I later found that if I activated the approach mode too early, the approach mode button on the 225 would begin to flash when when it saw the GS and I could just press the Approach button again and it would capture the GS. I have never had to enable autopilot outputs on the 530 to fly GPS approaches.

Link to comment
Share on other sites

57 minutes ago, LANCECASPER said:

If I remember correctly in 2000 all Ovations came with 430s and a KFC225 A/P so it should have been wired for the glide slope on the ILS.  You could upgrade to 530s. Maybe Ins 2006 or later when they upgraded the 430 to 430W the extra wiring needed to be put in, but II would think that would have been clearly documented when it came back from upgrade for the shop to follow, since they had to swap out the antenna, etc.

The wiring was correct for an ILS approach as delivered with the 430/430 and 530/430.  The extra wire was/needs to be added when the units were upgraded to waas so the 225 could utilize gpss. The garmin 430w/530w/650/750 boxes need to be programmed to prompt APR while transitioning to approach mode so the 225 can do a precision gps approach instead of an ILS.  I’m not sure if the garmin box just tricks the AP into thinking it’s doing an ILS during the LPV approach or something happens inside the 225. Again it works really well if the pilot uses the proper procedure at the correct time. 

  • Like 1
Link to comment
Share on other sites

On 3/31/2023 at 9:49 AM, MIm20c said:

First off I think the 225 is an amazing AP but it can be a little finicky sometimes. Please reference this page for the proper procedure.  If you are not being prompted with this APR message your 430w will need to be configured for it.  An additional wire is necessary to trick the 225 for vertical LPV guidance and gpss steering as well IIRC (it has been well over a decade since we had that interface).  If you’re a BT member this LINK might be helpful.  If you need more help let me know!

 

6329987B-54AC-4E77-9508-DC638EC0D6FD.jpeg.bbf0a8025b84f48e85b00873bff83b37.jpeg

This was the answer! Thank you!

I tested things out today on RNAV (GPS) Y 34 ROA (full procedure), and I kept checking the PROC screen between the IAF (MONAT) and the IF (ZIPAX). The "Enable A/P APR Outputs" remained grayed out for the IAF leg and didn't go live as an option until the turn toward the FAF began, at which point I could activate it and then APR on my KFC-225. Glide slope armed and captured correctly, just like an ILS. (The "APR Guidance Available Use PROC before A/P APR" prompt didn't show up until the option went live, so I beat it to the punch.)

--Up, N194V.

  • Like 1
Link to comment
Share on other sites

I have the IFD to 225 ap...if garmin or the avidyne is configured correctly ...as you are navigating to IAP fix in either heading mode (vectors to final )or own nav in nav mode and GPS aproach is activated you will get the prompt enable ap guidance.Once pressed..your ap is now off line...this is normal ..the apr and gs buttons must now be pushed to reingage the ap.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.