Confusion with my KFC-150, G5 HSI, GI-275 and a 530W

[skyfarer]

So I have the above avionics, and I can get the KFC-150 to track a heading set on the G5. I can change the GPSS on the G5 and it'll track courses loaded up in the 530, no problem too. Even flies holds beautifully.  But what I can't figure out is how to get it to track a VOR, or a Localizer. The KFC-150 has an approach mode too, and the manual in my POH says it'll couple an approach, of course this was back before someone installed the G5's and the GI-275.  I can press the FD button and see a Flight Director appear on the GI-275, but I have no clue what it gets the information to feed the the flight director. Doesn't appear to be valid when I setup an approach in the 530, I get a good GS and localizer on the G5 when I shoot RNAV approaches. FWIW, there is also a KX-155 and a VOR head for NAV2.

I can find nothing in the POH supplements about the G5's, or the GI-275. There are logbook entries where all this was installed by Crystal Avionics in TX. A call to them didn't get returned.

So, does anyone have any ideas how this stuff might be wired up, and how I might test for possible configurations? 

Attached is a photo of the panel.  The altitude preselector below the turn coordinator does nothing far as I can tell.  Jimmy swapped it out for a known working one before I bought the plane, so neither of us could tell if it's just not wired up at all to the above collection of stuff.The KFC-150 will altitude hold perfectly, and I can command climbs/descents with the KFC-150 UP/DOWN buttons.  Selecting altitudes on the GI-275 doesn't seem to do anything either.

Cheers,

Jeremy

 

Edited January 27, 2023 by skyfarer
spelling

[skyfarer]

@LANCECASPER I think a lot of these glass upgrades were made after you owned it, if I'm not mistaken.

[LANCECASPER]

3 hours ago, skyfarer said:

@LANCECASPER I think a lot of these glass upgrades were made after you owned it, if I'm not mistaken.

You are correct! I did minimal upgrades back in December of 2006 (Garmin 496 panel dock, Bose interfaces, Aero Comfort leather Yokes & had the interior panels covered.

If Crystal Avionics in New Braunfels did the work, Jimmy may have been the one to have the work done when he had it for sale. With the Garmin G5s and a GI275 and the King KFC150 and pre-select, it can become a Franken-panel and I can see how the button-ology in getting all of that to work would be confusing.

Since the GI-275 is talking to the KFC150 I would want that as my primary attitude and might even add Synthetic Vision. I would also then want a GI-275 as the HSI so you are looking at the same presentation. One of the G-5s could be probably  be used as a backup, maybe in place of the turn coordinator. The KAS-297B should still work to pre-select the altitude if it was wired correctly.

[PT20J]

The GI 275 FD commands will come directly from the KC 192 (the controller for the KFC 150). Does the FD operate correctly in basic modes such as heading and pitch?

The autopilot seems to work fine in HDG mode following the G5 HSI heading bug or the GPS when in GPSS. Does the FD work correctly when using GPSS?

When you have the 530 set to a VOR or localizer, I assume you switch it to VLOC since you said that the needles display correctly on the G5 HSI. Are you putting the autopilot in NAV mode to have it track the VLOC output from the 530 through the G5? If you are on an ILS are you putting the autopilot in APR mode to enable the GS capture?

Skip

 

 

[Bolter]

Just some tidbit from a similar panel in my previous Mooney 201 (430W, KAP 150, G5 HSI).  I just had to set the 430W to VLOC and then the G5 HSI displayed and fed the AP the VOR path instead of the GPS path.  The AP was in NAV mode for both GPS and VOR tracking.

For the G5 in GPSS mode, the AP had to be in HDG mode, not NAV.  

-dan

[hais]

55 minutes ago, Bolter said:

Just some tidbit from a similar panel in my previous Mooney 201 (430W, KAP 150, G5 HSI).  I just had to set the 430W to VLOC and then the G5 HSI displayed and fed the AP the VOR path instead of the GPS path.  The AP was in NAV mode for both GPS and VOR tracking.

For the G5 in GPSS mode, the AP had to be in HDG mode, not NAV.  

-dan

I think that’s how it is supposed to work. @skyfarer, what happens when you set the CDI on the 530 to VLOC, the KFC150 to HDG, and G5 to GPSS?

[N231BN]

Not to be harsh, but your airplane is not airworthy with those instruments installed and no AFMS. Furthermore, if the GI-275 is providing attitude to your autopilot, it must be installed in the primary location.

My recommendation would be either sell the G5 HSI, move the G5 ADI to the TC position, and add a base GI-275 as HSI; or sell both G5s and get a GI-275 ADAHRS with backup battery as an HSI/MFD Standby.

Edited January 28, 2023 by N231BN
Added image

[Pinecone]

12 hours ago, LANCECASPER said:

The KAS-297B should still work to pre-select the altitude if it was wired correctly.

As I understand it, the KAS-297B gets its altitude data from the encoding altimeter.

[jlunseth]

Well, you can have all the AFMSs in the world but if you don’t know what is connected to what you are still going to be lost. The AFMSs are written by a manufacturer who does not know what the actual installation will be. I had one 275 installed as a backup AI, and then got a second one to replace the old King instruments that were driving my KFC200. The two I were installed in dual reversionary mode replacing the old AI/Flight Director and HSI.  I have the AFMSs and all the manuals, but I have still made many, probably ten test flights of a couple of hours each to try to figure out what is directing what, and when I have to push what button, and I am still not completely satisfied that I know all of it. I have run into some unique quirks along the way, nothing dramatic that would bring the plane down in IMC, but things that do not act as expected. There are passages in the AFSMs I got that are short and obtuse and you don’t really understand their meaning until you have run into it in the air. The original system was installed, manuals written, and approved as a system. Now you have paid to have a completely different set of nifty components installed in its place but no one writes a manual or AFSM for that unique system. You just have to get in the air, definitely VFR, put it through its paces and learn what it does and what its foibles are.

I am going to take a guess at what is going on, and it’s just a guess because I am not an avionics installer and I don’t know what is connected to what in your panel. The G5 as I understand it is not fully compatible with non-Garmin AP’s. You need a 275 for that, and that is probably why it is there, to run the AP. The puzzle is what the 530 is connected to. It should be connected to the 275 in order to feed approach information to the 275 so the 275 can drive the AP, but if you are getting Glideslopes, etc. on the G5 my guess is that the 530 is connected to the G5s and that the G5s are just displays, that is, they do not drive the AP for an approach they just display how the approach is progressing so you can hand fly??? Probably the system could be connected to display information on the G5 and also provide information to the 275, but maybe the connection to the 275 is not there? GPSS is a little bit of a different thing, at least in my plane. I have an Icarus SAM and it is connected so it can drive a navigation course but not an approach. The 275 needs to be getting the approach info from the 530 in order for it to drive the AP, and maybe it is not getting that info.

Is there a Nav switch somewhere on the panel maybe, like a Nav1/Nav2 toggle switch that would direct the nav signal to the 275?

[skyfarer]

So few of you asked about this, and I can confirm:  To track a GPS course that's programmed in the 530, I set the AP to HDG mode, and switch the G5 to GPSS. 

Also, in HDG mode and GPSS as above, switching the 530 to VLOC and tuning in a VOR, it doesn't appear to track the VOR. Although I do get a good display of the VOR CDI on the G5. Similarly, I get good indications of GS and Localizer on the G5 when flying ILS approaches.

I'm going to fly today and try to get the KFC-150 to track a VOR again. Also I'll make sure I'm hitting the AP ENG button, after pressing HDG, that's an easy one to forget!

[LANCECASPER]

1 hour ago, Pinecone said:

As I understand it, the KAS-297B gets its altitude data from the encoding altimeter.

Yes,  in gray code from the KEA130A, which is still present. The KAS-297B also has it's own unique button pushing.

https://www.dropbox.com/s/mcixf7xlr4ecral/KFC 150 Pilots Guide.pdf?dl=0

 

[PT20J]

1 hour ago, skyfarer said:

So few of you asked about this, and I can confirm:  To track a GPS course that's programmed in the 530, I set the AP to HDG mode, and switch the G5 to GPSS. 

Also, in HDG mode and GPSS as above, switching the 530 to VLOC and tuning in a VOR, it doesn't appear to track the VOR. Although I do get a good display of the VOR CDI on the G5. Similarly, I get good indications of GS and Localizer on the G5 when flying ILS approaches.

I'm going to fly today and try to get the KFC-150 to track a VOR again. Also I'll make sure I'm hitting the AP ENG button, after pressing HDG, that's an easy one to forget!

The KFC 150 predated GPS roll steering. GPSS is a workaround to have the autopilot follow the 530’s GPS roll commands using HDG mode. To track a VOR or Localizer, the 530 must be in VLOC and the KFC 150 in NAV or APR. It will only capture a GS if it is in APR.

Ssip

[Pinecone]

40 minutes ago, LANCECASPER said:

Yes,  in gray code from the KEA130A, which is still present. The KAS-297B also has it's own unique button pushing.

https://www.dropbox.com/s/mcixf7xlr4ecral/KFC 150 Pilots Guide.pdf?dl=0

 

YES.

It took me a while to figure out it will only capture an altitude ONLY if you had set the climb/descent rate on it first.

[skyfarer]

48 minutes ago, PT20J said:

The KFC 150 predated GPS roll steering. GPSS is a workaround to have the autopilot follow the 530’s GPS roll commands using HDG mode. To track a VOR or Localizer, the 530 must be in VLOC and the KFC 150 in NAV or APR. It will only capture a GS if it is in APR.

Ssip

Ah, I see. I'm heading out flying today, I'm going to try this.  I was trying to track a VOR with the AP in HDG mode thinking the AP was getting roll steering from the G5 the same way it does on a GPS course. But today I will try it the way you describe and see what I get. 

[skyfarer]

15 hours ago, LANCECASPER said:

You are correct! I did minimal upgrades back in December of 2006 (Garmin 496 panel dock, Bose interfaces, Aero Comfort leather Yokes & had the interior panels covered.

If Crystal Avionics in New Braunfels did the work, Jimmy may have been the one to have the work done when he had it for sale. With the Garmin G5s and a GI275 and the King KFC150 and pre-select, it can become a Franken-panel and I can see how the button-ology in getting all of that to work would be confusing.

Since the GI-275 is talking to the KFC150 I would want that as my primary attitude and might even add Synthetic Vision. I would also then want a GI-275 as the HSI so you are looking at the same presentation. One of the G-5s could be probably  be used as a backup, maybe in place of the turn coordinator. The KAS-297B should still work to pre-select the altitude if it was wired correctly.

I have to say when I first got interested in the plane, I thought the 496 would be the first thing I was going to remove and replace. Obsolete and old, right?  Nope!  I updated it's terrain and nav databases from Garmin, activated the Sirius XM weather and music on it, and can't imagine flying without it! It's a bit clumsy with it's user interface, but now that I'm proficient with it, I LOVE that thing. Maybe someday I'll still pick up a GDL92, but for now a Stratux, my iPad and that 496 gives me multiple redundant weather streams, plus tunes in my headset for long XC trips!    

[PT20J]

3 hours ago, N231BN said:

Not to be harsh, but your airplane is not airworthy with those instruments installed and no AFMS. Furthermore, if the GI-275 is providing attitude to your autopilot, it must be installed in the primary location.

My recommendation would be either sell the G5 HSI, move the G5 ADI to the TC position, and add a base GI-275 as HSI; or sell both G5s and get a GI-275 ADAHRS with backup battery as an HSI/MFD Standby.

Agreed. This is kind of a goofy configuration. I had something similar. The previous owner installed a GNS 430W and an Aspen PFD. The KG 258 for the KAP 150 autopilot was retained and moved down to the lower right of the panel where @skyfarer's GI 275 is located. This was OK, because the KG 258 became a standby instrument and didn't have a flight director. So, what I suspect happened here is that someone relocated the KFC 150's KI 256 and installed the two G5s and then later replaced the KI 256 with a GI 275. But that instrument should really be primary since it has the flight director.

As far as the AFMS, yes you should have copies of those in the POH because they include limitations. The installer should have provided the owner with the AFMSs, the STCs and 337s, wiring diagrams showing the configuration (most installers annotate the appropriate drawings from the Installation manual), and tables showing how the units were configured (from either the Maintenance Manual or Installation Manual). You can download the AFMS, Pilot's Guides and Maintenance Manuals from Garmin's website. Installation Manuals for some equipment is on the website, but many are only available to Garmin dealers.

Skip

[jaylw314]

I was going to point out the same thing @N231BN pointed out.  I had researched putting in a G5 and came to the conclusion you'd have have an ADI with the flight director in the primary position.

The KFC-150 and KAS-297B combo is something you REALLY want to understand the buttonology about before you go flying it.  For example, I found out the hard way (fortunately while in VFR) that the combo with my 530W is NOT capable of GPSS, even though some configurations are.  Made doing a procedure turn very...interesting.

I'm pretty sure the KAS-297B is connected to the AP because if it is not connected, I THINK it shows dashes on the display as an error message.

The workflow with the KAS-297B is to set your desired altitude, then set your desired vertical speed, then arm VS and ALT.  It will not do anything until you press VS.  If you are in HDG or NAV mode but manually pitched for a climb/descent, pressing ALT will capture your desired altitude when you hit it without changing your current climb/descent.

You can find the user guides for them online to familiarize yourself, but it's hard to imagine you don't (or shouldn't) have them in your AFMS section in your POH.

And not to encourage you to spend more money, but dang, that Bravo panel is really hurting for a primary engine monitor.  Those gauges take up SO much space! 

Edited January 28, 2023 by jaylw314

[skyfarer]

The AFMS for the KFC-150, the 530W, and the KAS-297B are in the POH. The GI-275 and G5 supplements are easily found online and I have those, BUT... what I really need is to get from Crystal Avionics, the AFMS they should have provided that contain specifics to my airframe installation.

I'm close to finishing my instrument rating, so I only fly this plane VFR at present. But, soon I'll be rated and want all this documentation in order so that I understand all the limitations and operation of the setup.

[PT20J]

5 minutes ago, skyfarer said:

The AFMS for the KFC-150, the 530W, and the KAS-297B are in the POH. The GI-275 and G5 supplements are easily found online and I have those, BUT... what I really need is to get from Crystal Avionics, the AFMS they should have provided that contain specifics to my airframe installation.

I'm close to finishing my instrument rating, so I only fly this plane VFR at present. But, soon I'll be rated and want all this documentation in order so that I understand all the limitations and operation of the setup.

Actually, if you sit with the generic G5/GI AFMS' and go through each option and figure out which box to check, it will provide you with a great deal of understanding of your system.

[jlunseth]

I think Skip and I are agreeing with each other. The primary instrument driving the AP needs to be the 275, so it needs to be connected to the 530 for any approach information to get to the AP (which will happen through the 275, not the G5's). I have the KFC200 so it is the same but not quite. In my aircraft, to fly an ILS, the 530 needs to be switched to VLOC just before the final approach course of an ILS. That's the first thing. Normally, when you put the ILS into the 530, it will put the LOC frequency in the standby (bottom) slot of the Nav radio frequency display. The pilot must switch that to the top (active) frequency manually. If the pilot makes that switch, then the 530 normally will switch automatically to VLOC at some point during the approach. The AP then needs to be switched to APCH mode, it should not be in Nav or HDG. So if you have all those things done correctly, (1) the correct frequency is in the active window, (2) the 530 is in VLOC, and (3) the AP is in APCH, then the AP will capture the GS and fly down it, and will also capture the Loc for horizontal position. If you are still in HDG on the final approach course you will get no GS. The correct ADI will be the 275, not the G5's, although they can be used as a reference. 

A couple of words of caution. First, the autoswitch in the 530 that switches the unit from GPS to VLOC is a setting, it must be set in the menus of the 530 to autoswitch. If it is not, the pilot must manually make the switch to VLOC. Bear in mind that if, for some reason, the autoswitch does not happen, the pilot can always manually switch to VLOC. Second, you can't make the switch to VLOC and APCH too soon. You can use HDG and GPSS to fly the backcourse and the procedure turn but you should not switch to APCH until you are right at the final approach course, and same with the switch to VLOC, that should happen there also. If they happen before you are on the final approach course the 530 will get confused and fly you somewhere weird. I have made that mistake in IMC, not to be repeated. 

Probably more than you want to know but here goes. The 150 and 200 are analog AP's. What they were originally designed for was to use the HDG bug to fly the outbound course and the procedure turn in an ILS, and if the aircraft is put into APCH mode before the ILS or VOR final approach course, the AP will fly to the HDG bug and use the rate of approach to the final approach course in the computations it makes about when to switch from ARMED to CPLD in APCH mode. At that point, APCH mode takes over from HDG mode and flies the approach. Only APCH mode has the capability to capture the GS, so if the AP is not in APCH, or it never switches from ARMED to CPLD, then it won't capture the GS. Now we have brought in electronic instruments, including a GPSS, that converts the digital signal from the GPS into an analog signal for the AP. That is fed in through the HDG bug to fool the AP into flying the course the GPS dictates when GPSS is "On". However, ILS or VOR approaches need to be flown in VLOC and with the AP in APCH mode, or the approach won't work. When that switch is made, the AP is operating completely in an analog mode, just as it did before GPSs came around, except for one thing. The RWY## waypoint is fed to APCH mode to use that as an endpoint to the approach. Otherwise, as far as capturing the GS and holding the LOC are concerned, that is being done in analog mode in the AP and it must have the LOC/ILS frequency tuned in and the 530 must be transmitting that signal to the AP. Same applies for a VOR approach except the AP won't give you a glideslope on a VOR. 

There is another, GPS way of flying a VOR that is fairly new, and that will give you a GS in the same way that the GPS provides a GS for an RNAV, that is, it is a GS calculated by the GPS, not a GS coming from an ILS-type signal (which isn't there in a VOR approach). I guess the new type overlay approach is legal as long as you monitor on an actual VOR frequency and indicator.

[jlunseth]

PS all that assumes that the 275 is getting information from the 530 in your aircraft. If it is not hooked up that way then I don't see a way to fly an approach from the 530. I am assuming that was the reason the 275 went in. Maybe someone installed the G5's thinking they were compatible with the AP and they only sort of are.

[hais]

1 hour ago, jlunseth said:

I think Skip and I are agreeing with each other. The primary instrument driving the AP needs to be the 275, so it needs to be connected to the 530 for any approach information to get to the AP (which will happen through the 275, not the G5's). I have the KFC200 so it is the same but not quite. In my aircraft, to fly an ILS, the 530 needs to be switched to VLOC just before the final approach course of an ILS. That's the first thing. Normally, when you put the ILS into the 530, it will put the LOC frequency in the standby (bottom) slot of the Nav radio frequency display. The pilot must switch that to the top (active) frequency manually. If the pilot makes that switch, then the 530 normally will switch automatically to VLOC at some point during the approach. The AP then needs to be switched to APCH mode, it should not be in Nav or HDG. So if you have all those things done correctly, (1) the correct frequency is in the active window, (2) the 530 is in VLOC, and (3) the AP is in APCH, then the AP will capture the GS and fly down it, and will also capture the Loc for horizontal position. If you are still in HDG on the final approach course you will get no GS. The correct ADI will be the 275, not the G5's, although they can be used as a reference. 

A couple of words of caution. First, the autoswitch in the 530 that switches the unit from GPS to VLOC is a setting, it must be set in the menus of the 530 to autoswitch. If it is not, the pilot must manually make the switch to VLOC. Bear in mind that if, for some reason, the autoswitch does not happen, the pilot can always manually switch to VLOC. Second, you can't make the switch to VLOC and APCH too soon. You can use HDG and GPSS to fly the backcourse and the procedure turn but you should not switch to APCH until you are right at the final approach course, and same with the switch to VLOC, that should happen there also. If they happen before you are on the final approach course the 530 will get confused and fly you somewhere weird. I have made that mistake in IMC, not to be repeated. 

Probably more than you want to know but here goes. The 150 and 200 are analog AP's. What they were originally designed for was to use the HDG bug to fly the outbound course and the procedure turn in an ILS, and if the aircraft is put into APCH mode before the ILS or VOR final approach course, the AP will fly to the HDG bug and use the rate of approach to the final approach course in the computations it makes about when to switch from ARMED to CPLD in APCH mode. At that point, APCH mode takes over from HDG mode and flies the approach. Only APCH mode has the capability to capture the GS, so if the AP is not in APCH, or it never switches from ARMED to CPLD, then it won't capture the GS. Now we have brought in electronic instruments, including a GPSS, that converts the digital signal from the GPS into an analog signal for the AP. That is fed in through the HDG bug to fool the AP into flying the course the GPS dictates when GPSS is "On". However, ILS or VOR approaches need to be flown in VLOC and with the AP in APCH mode, or the approach won't work. When that switch is made, the AP is operating completely in an analog mode, just as it did before GPSs came around, except for one thing. The RWY## waypoint is fed to APCH mode to use that as an endpoint to the approach. Otherwise, as far as capturing the GS and holding the LOC are concerned, that is being done in analog mode in the AP and it must have the LOC/ILS frequency tuned in and the 530 must be transmitting that signal to the AP. Same applies for a VOR approach except the AP won't give you a glideslope on a VOR. 

There is another, GPS way of flying a VOR that is fairly new, and that will give you a GS in the same way that the GPS provides a GS for an RNAV, that is, it is a GS calculated by the GPS, not a GS coming from an ILS-type signal (which isn't there in a VOR approach). I guess the new type overlay approach is legal as long as you monitor on an actual VOR frequency and indicator.

Thank you for taking the time to write a detailed description. 

[skyfarer]

6 hours ago, N231BN said:

Not to be harsh, but your airplane is not airworthy with those instruments installed and no AFMS. Furthermore, if the GI-275 is providing attitude to your autopilot, it must be installed in the primary location.

My recommendation would be either sell the G5 HSI, move the G5 ADI to the TC position, and add a base GI-275 as HSI; or sell both G5s and get a GI-275 ADAHRS with backup battery as an HSI/MFD Standby.

Thanks, this is interesting. Can you also provide the STC No. you have here? I see in the logs where the G5's were installed and the KI256 moved, I'll review these STC's. Then about 13 months later, the GI-275 ADAHRS/AP was installed, replacing the KI256. I also have an A&P/IA that I trust looking over all this, plus another avionics guy who is the go to autopilot guy around here. Hopefully we'll get this figured out and make sure I'm airworthy and safe for flight into IMC.

[skyfarer]

2 hours ago, jlunseth said:

I think Skip and I are agreeing with each other. The primary instrument driving the AP needs to be the 275, so it needs to be connected to the 530 for any approach information to get to the AP (which will happen through the 275, not the G5's). I have the KFC200 so it is the same but not quite. In my aircraft, to fly an ILS, the 530 needs to be switched to VLOC just before the final approach course of an ILS. That's the first thing. Normally, when you put the ILS into the 530, it will put the LOC frequency in the standby (bottom) slot of the Nav radio frequency display. The pilot must switch that to the top (active) frequency manually. If the pilot makes that switch, then the 530 normally will switch automatically to VLOC at some point during the approach. The AP then needs to be switched to APCH mode, it should not be in Nav or HDG. So if you have all those things done correctly, (1) the correct frequency is in the active window, (2) the 530 is in VLOC, and (3) the AP is in APCH, then the AP will capture the GS and fly down it, and will also capture the Loc for horizontal position. If you are still in HDG on the final approach course you will get no GS. The correct ADI will be the 275, not the G5's, although they can be used as a reference. 

A couple of words of caution. First, the autoswitch in the 530 that switches the unit from GPS to VLOC is a setting, it must be set in the menus of the 530 to autoswitch. If it is not, the pilot must manually make the switch to VLOC. Bear in mind that if, for some reason, the autoswitch does not happen, the pilot can always manually switch to VLOC. Second, you can't make the switch to VLOC and APCH too soon. You can use HDG and GPSS to fly the backcourse and the procedure turn but you should not switch to APCH until you are right at the final approach course, and same with the switch to VLOC, that should happen there also. If they happen before you are on the final approach course the 530 will get confused and fly you somewhere weird. I have made that mistake in IMC, not to be repeated. 

Probably more than you want to know but here goes. The 150 and 200 are analog AP's. What they were originally designed for was to use the HDG bug to fly the outbound course and the procedure turn in an ILS, and if the aircraft is put into APCH mode before the ILS or VOR final approach course, the AP will fly to the HDG bug and use the rate of approach to the final approach course in the computations it makes about when to switch from ARMED to CPLD in APCH mode. At that point, APCH mode takes over from HDG mode and flies the approach. Only APCH mode has the capability to capture the GS, so if the AP is not in APCH, or it never switches from ARMED to CPLD, then it won't capture the GS. Now we have brought in electronic instruments, including a GPSS, that converts the digital signal from the GPS into an analog signal for the AP. That is fed in through the HDG bug to fool the AP into flying the course the GPS dictates when GPSS is "On". However, ILS or VOR approaches need to be flown in VLOC and with the AP in APCH mode, or the approach won't work. When that switch is made, the AP is operating completely in an analog mode, just as it did before GPSs came around, except for one thing. The RWY## waypoint is fed to APCH mode to use that as an endpoint to the approach. Otherwise, as far as capturing the GS and holding the LOC are concerned, that is being done in analog mode in the AP and it must have the LOC/ILS frequency tuned in and the 530 must be transmitting that signal to the AP. Same applies for a VOR approach except the AP won't give you a glideslope on a VOR. 

There is another, GPS way of flying a VOR that is fairly new, and that will give you a GS in the same way that the GPS provides a GS for an RNAV, that is, it is a GS calculated by the GPS, not a GS coming from an ILS-type signal (which isn't there in a VOR approach). I guess the new type overlay approach is legal as long as you monitor on an actual VOR frequency and indicator.

Thank you for taking the time to write all this up! Also, definitely not "more than I want to know", the more knowledge I have the better off I am. This is why I'm on MS!

[PT20J]

There seems to be a little bit of confusion about how these devices play together. It might help to start with the original KFC-150 configuration.

Attitude is fed to the autopilot from the KI 256 and the autopilot drives the KI 256 flight director command bars. There is no connection between the KI 256 and the other avionics.

Lateral information (heading, course deviation) is fed to the autopilot from the KI 525A HSI. Not shown is that the nav radios drive the CDI and GS needles. This information is also fed to autopilot.

In the current installation, the GI 275 substitutes for the KI 256 and the G5 HSI substitutes for the KI 525A. It’s really that simple 

The only new feature added is GPSS that allows the autopilot to follow GPS roll steering commands (to allow such features as turn anticipation, procedure turn, holding patterns, DME arcs). This adds a slight complexity because the autopilot now uses NAV for VORs and HDG for GPS nav, and you have to turn GPSS off in order to have HDG follow the G5 heading bug.

Skip