Any issues with Garmin glass and KFC 150?

[shawnd]

I am looking at installing a G3X with a GI-275 (ADAHRS + AP) and retaining my existing KFC-150 which has been working just fine w/ the stock Bendix 6-pack. Wondering if folks have observed any unexpected behaviors from the Garmin units + King AP combination. From other threads, I see there are sometimes issues like unable to intercept nav, oscillations, etc., but many of them were purely Garmin setup on Mooneys. Wondering if anyone with the Garmin + King KFC or KAP setup has seen any of these? What were the mitigations? Did servos need rebuilding? 

I am trying to avoid GFC500 installation to keep my already insane avionics upgrade expense down. Appreciate any help.

 

I tried searching on MooneySpace directly but no search results pop for "KFC 150" Google pointed me to this thread on the topic:

 

[shawnd]

If things are working great, would be good to know as well :-)

[ArtVandelay]

As a general rule, if you want the GFC500, get the G3X, any other autopilot get the G500 which has better support of OEM products.

[shawnd]

Thanks @ArtVandelay Yeah the G500 specs page explicitly calls out the features in the interfaces page. G3X just says AP support but has this disclaimer in the fine print:
 

"¹G3X Touch will not support display of flight director (FD), autopilot modes or annunciations for non-Garmin autopilots. Consult your Authorized Garmin Dealer for more details."

Waiting for estimates and will then see how this changes the game. Do you know since the GI-275 is acting as the middle man, if the limitations are still valid?

[PT20J]

The G3X and GFC 500 are part of a system. Most of the autopilot software is actually in the G3X. It’s a completely different architecture than a KFC 150. 

Garmin’s solution for legacy autopilots is the G500TXi or a pair of GI 275s.

[Fly Boomer]

4 minutes ago, PT20J said:

Garmin’s solution for legacy autopilots is the G500TXi or a pair of GI 275s.

How are each of the GI-275s configured in that setup?  I don't know much about it, but I think the GI-275 can wear a variety of different hats.

[PT20J]

1 minute ago, Fly Boomer said:

How are each of the GI-275s configured in that setup?  I don't know much about it, but I think the GI-275 can wear a variety of different hats.

One as an attitude indicator and one as a HSI. 

[shawnd]

My plan was to have a G3X with two GI-275: have ADAHRS+AP and ADAHRS units.  Question is can the Garmins interoperate enough and have the 275s drive the King with full feature functionality. 
 

In case of system failure I am okay to go to minimal AP support. 
 

if that can be supported, I would be saving about 11 AMU is my guess (diff between G3X and G500).

[LANCECASPER]

6 hours ago, shawnd said:

I am looking at installing a G3X with a GI-275 (ADAHRS + AP) and retaining my existing KFC-150 which has been working just fine w/ the stock Bendix 6-pack. Wondering if folks have observed any unexpected behaviors from the Garmin units + King AP combination. From other threads, I see there are sometimes issues like unable to intercept nav, oscillations, etc., but many of them were purely Garmin setup on Mooneys. Wondering if anyone with the Garmin + King KFC or KAP setup has seen any of these? What were the mitigations? Did servos need rebuilding? 

I am trying to avoid GFC500 installation to keep my already insane avionics upgrade expense down. Appreciate any help.

 

I tried searching on MooneySpace directly but no search results pop for "KFC 150" Google pointed me to this thread on the topic:

 

I'm not a fan of removing things that are perfectly functional plus the KFC150 was the best GA autopilot of its time.

However, although it may be working very well now, the truth is it's close to 40 years old. At this stage, spending good money on an extra GI-275 plus all of the additional labor to interface Garmin equipment to the King a/p would be much better spent toward a GFC500. The first time you need to have your King A/P repaired you will kick yourself for not doing it all together.

[shawnd]

Unfortunately, I had MidCo IRAN the KFC 150 in 2022 and I already own 3 GI-275s thanks to a snafu with Garmin avionics installer at my home airport. This is why I am trying to find a way to move forward and have a good IFR solution, hopefully with a G3X. Cost of installing a G500 over G3X is 11 AMU but a new AP labor would be significantly more. 
 

I am in a crappy situation, trying to make the best of it without spending 70+ AMU. 

[ArtVandelay]

My plan was to have a G3X with two GI-275: have ADAHRS+AP and ADAHRS units.  Question is can the Garmins interoperate enough and have the 275s drive the King with full feature functionality. 
 
if that can be supported, I would be saving about 11 AMU is my guess (diff between G3X and G500).

It’s 4 AMUs difference unless something changed in the last 3 years.
I had quotes for both G3X and G500 before going with G3X.

And adding the 2 275s would eat the difference up.

[Ragsf15e]

GI-275s would be primary attitude source for the autopilot while g3x would be pfd.  G3x wouldn’t have inputs to the autopilot except maybe heading.  I think it would feel kludged together.  I don’t think I’d go this route.  Maybe just put in a couple gi-275s instead of the g3x.

[ArtVandelay]

Unfortunately, I had MidCo IRAN the KFC 150 in 2022 and I already own 3 GI-275s thanks to a snafu with Garmin avionics installer at my home airport. This is why I am trying to find a way to move forward and have a good IFR solution, hopefully with a G3X. Cost of installing a G500 over G3X is 11 AMU but a new AP labor would be significantly more. 
 
I am in a crappy situation, trying to make the best of it without spending 70+ AMU. 

You can get the G3X, GFC500, and G5 as backup…cut a whole new panel….sell the old equipment and only be out less than half that: $35 AMUs.

I’m assuming you already have a Garmin GTN GPS.

[shawnd]

@ArtVandelay you are right. The difference between a G500 and G3X is about 5AMU now. Sarasota Avionics provides a nice worksheet that breaks down the details. I am assuming the local guy provided a rough estimate based on the most expensive LRU kit for the G500 which runs about 9 AMU.

Worksheets for both G3X Touch and G500 TXi: https://www.sarasotaavionics.com/worksheet

I am waiting on estimates from two shops this week. That should give me a good idea on the cost of interfacing with the KFC and also I can evaluate the two PFD options with them.

However, one takeaway is that I believe other than KFC being an old unit, once interfaced with say a Garmin PFD, no one has seen any issues with it. 5 AMU might be worth the cost of getting all the features when working with the KFC.

[Flash]

3 hours ago, shawnd said:

Unfortunately, I had MidCo IRAN the KFC 150 in 2022 and I already own 3 GI-275s thanks to a snafu with Garmin avionics installer at my home airport. This is why I am trying to find a way to move forward and have a good IFR solution, hopefully with a G3X. Cost of installing a G500 over G3X is 11 AMU but a new AP labor would be significantly more. 
 

I am in a crappy situation, trying to make the best of it without spending 70+ AMU.

Dual GI275s work great with a KFC150. It's like they were made for each other. It's not difficult to operate. You get GPSS by toggling GPSS on and hitting HDG on the KFC150. The KFC150 flies LPV approaches as if they were ILS approaches; it's none the wiser that the glideslope it captures is from a WAAS GPS. That setup doesn't cost anywhere near 70+ AMU.

[LANCECASPER]

8 hours ago, Ragsf15e said:

GI-275s would be primary attitude source for the autopilot while g3x would be pfd.  G3x wouldn’t have inputs to the autopilot except maybe heading.  I think it would feel kludged together.  I don’t think I’d go this route.  Maybe just put in a couple gi-275s instead of the g3x.

@shawnd It makes complete sense to build your panel around your autopilot. Since you’re going to stick with the KFC150, I agree with @Ragsf15e 100% on just putting in the GI-275s, since you own them already and they are designed for people who want to keep their existing autopilot.

The G3X has been around a long time in aviation terms and is due to be updated and won’t really do anything for you that the GI-275s can’t. If you don’t have one, put a Aera 760 on the yoke, which you can probably buy for what the sales tax would be to do a G3X and a new panel. Once the next greatest thing comes out then consider a new panel and maybe by that time you’ll be ready for whatever imrovements they’ve made to the GFC autopilot by then.

[Fly Boomer]

6 hours ago, Flash said:

Dual GI275s work great with a KFC150. It's like they were made for each other. It's not difficult to operate. You get GPSS by toggling GPSS on and hitting HDG on the KFC150.

What device is providing the GPSS?  There have been several over the years.

[Pinecone]

AFAIK the 275 provides the GPSS steering.   It translates the GPS info into headings for the AP.  That is why you want the AP in Heading mode, NOT NAV mode.

[shawnd]

2 hours ago, LANCECASPER said:

@shawnd It makes complete sense to build your panel around your autopilot. Since you’re going to stick with the KFC150, I agree with @Ragsf15e 100% on just putting in the GI-275s, since you own them already and they are designed for people who want to keep their existing autopilot.

The G3X has been around a long time in aviation terms and is due to be updated and won’t really do anything for you that the GI-275s can’t. If you don’t have one, put a Aera 760 on the yoke, which you can probably buy for what the sales tax would be to do a G3X and a new panel. Once the next greatest thing comes out then consider a new panel and maybe by that time you’ll be ready for whatever imrovements they’ve made to the GFC autopilot by then.

@LANCECASPER that was exactly my plan for the install in 2023 . I wanted to wait as well and just get the basics upgraded before IFR training. After the snafu, I am consulting with another avionics shop in the area and they are thinking the labor to identify the previous mess and correct it might be close to just doing a new panel. And would be a good time to do the glass upgrade for the older 6 pack.

Let me see what the estimates look like and I am planning on digging deeper to find the best option for now. Thank you!

[Ryan ORL]

I echo the above comments about dumping the KFC150 and maybe selling a couple of the GI-275s to recoup some cost.  Just do the GFC500.

I absolutely love my G3X w/ EIS plus GFC500/GTN650 combo panel.  I just cannot see dumping that many AMUs into a halfway solution.  Once a G3X is involved, you're at least cutting a whole new panel and hopefully tearing out a ton of the old wiring.  Why not just get it done with?  You know the GFC500 will be will supported for years to come, and you can dump all the old wiring.  And I certainly can't see spending more money to get into a G500 setup just to keep the King autopilot.  Plus you're getting a modern digital autopilot that supports VNAV and all the other vertical modes you would expect.

My airplane had an Aspen and KAP150 when I bought it... and I had to have it repaired at one point also.  Sarasota Avionics has basically one old guy in his 70s who used to work for BK and is their "King autopilot guy".  It was super expensive, a lot of money was wasted debugging it, and in the end, I never felt confident we wouldn't be working on it again very soon.  One of the biggest motivators for dumping all my money on avionics was to just be rid of the old stuff and not have to be stuck dealing with a (decreasing) handful of shops that are willing to work on that stuff.

Fwiw, I sold my old KAP150 head unit and BK servos on eBay and I got at least $3500 out of the lot of it.

If you don't go that route, I also echo the other posters and say, pass on the G3X or G500, just do 3x GI-275s.  (Attitude/HSI/EIS)  The install will be much simpler... I wouldn't rip up my whole panel to keep a bunch of legacy stuff around.

[Flash]

4 hours ago, Fly Boomer said:

What device is providing the GPSS?  There have been several over the years.

In my case, the 275 gets the GPS signal from an IFD 540. But I would imagine that the KFC150 is oblivious to what GPS is upstream of the 275, and the 275 can take GPS input from (most?) GPS receivers.

[PT20J]

Most well integrated panel: G3X, GFC 500, GTN Xi (G5 is designed as a standby for G3X, but Garmin has recently updated GI 275 to make it better integrated. There may still be some limitations, so check). This requires a major rip and replace and if you are going to do this, it's ultimately less expensive to replace everything you might eventually want to replace which increases the cost. Mine cost about $80K.

Keep KFC 150 option: G500TXi, GI 275 standby. You can add a GFC 500 later if the KFC becomes troublesome because the GI 275 has the GFC software and will drive the TXi FD which doesn't work with the G3X.

Lowest cost: Replace the King AI and HSI with GI 275s. You can add a GFC 500 later as described above. If you have a GTX 345 transponder, you can Bluetooth pair it to an iPad and get GPS, AHRS, and ADS-B In using ForeFlight or Garmin Pilot. There are probably a lot of other options for getting data to an iPad. So, this panel, while not quite as sexy as having a big screen will give you most of the functionality at a much lower cost.

All the dealers pay the same for the hardware (less some end of year rebates depending on how much they sell). Cost and quality of installation varies widely. I would get several estimates for each option. And always remember, shops are in the business of selling stuff. 

[shawnd]

Thanks @PT20J and others as well. Yep makes sense on the approaches. Now just waiting for the estimates to roll in. Did reach out to the Avionics Shop at KTIW as well.  

[wombat]

I've got a KFC 150 and G500 (Older) and while I recognize it lacks some features of the GFC 500, I really don't understand why people think it's worth $30k to upgrade.

If I was dead set on a glass panel, I'd get a the G500 TXi and keep the KFC 150 for now.    If I didn't absolutely have to have glass, I'd do as many others suggested and use 2 of the GI-275's.   

The additional features of the GFC 500

• Vertical nav enroute
• Altitude preselect
• Vertical speed
• S&L Button
• TOGA button (remote)
• Stability protection
• Airspeed protection
• Smart Glide

For the amount of money it takes just to upgrade the autopilot, you can buy and keep a brand new Subaru Crosstrek at your most common destination airport.

[shawnd]

More and more I am leaning towards the "Keep the KFC option" with G500TXi.

On a separate note, regarding the straight and level button, the KFCs can do the same operation I think in 4 button pushes.

1. Heading button press to align bug to current heading
2. Hit the ALT button on KFC
3. Hit the HDG button KFC
4. Hit the AP button on KFC.

Haven't had an opportunity to try it out but should get your plane to S&L condition. Or are there envelopes beyond which KFC won't engage vs a GFC 500 would?