Explain the "typical" Autopilots found in a Vintage M20

[Mr. T]

Still on the hunt for the perfect M20 (E / F / J) and have found numerous autopilots in the older planes that I'm not familiar with (The STEC A/P's I understand - mostly).  I "grew up" in a Grumman AA5 with no autopilot and fussy "trim tabs" (extensions on the aileron that you had to bend by hand), and while I did my entire Instrument training in that plane, I hated flying in IMC, as you couldn't relax your scan for more than an instant without it wandering off one way or the other. I'm not doing that anymore. So now, 16 years later, I've had a little bit of experience with an STEC in the club 182 - GPSS, approach coupled, vertical speed hold, automatic elevator trim -- it's pretty sweet. And I'm pretty sure I need most of that same functionality in my M20.

Could someone give me a brief rundown of the various types, capabilities of each and whether I should steer clear of any of them in particular? What I've seen so far, I think:

* "PC" - Seems like a rudimentary wing leveler. What else can it do?
* Brittain "AccuTrack" and/or "AccuFlight" - Sounds like maybe an add-on to the PC?
* Century I, II, IIIB, etc.?
* Am I missing any?

In particular, I'm trying to understand which of these can:

* Track a heading bug
* Track a CDI
* Be upgraded for GPSS (I probably already know that answer)
* Be fully approach-coupled (I think I know that answer also...)

Can any of the components (servos in particular) be re-used if upgrading to a more modern autopilot?

I see some folks advocating for de-prioritizing the A/P on a purchase and instead planning to install one of the newly available (or soon to come) autopilots. Any ideas on installed cost for any of the newer systems? I'm guessing $15-20AMU?

[TTaylor]

Astronautics Corp Of America Pathfinder Autopilot Systems were in many from the early to mid 70's.  The M2/P2 was most common (2-axis)  but I think there were  some M3/P3.

 

 

[Oldguy]

18 minutes ago, Mr. T said:

Could someone give me a brief rundown of the various types, capabilities of each and whether I should steer clear of any of them in particular? What I've seen so far, I think:

* "PC" - Seems like a rudimentary wing leveler. What else can it do?
* Brittain "AccuTrack" and/or "AccuFlight" - Sounds like maybe an add-on to the PC?
* Century I, II, IIIB, etc.?
* Am I missing any?

In particular, I'm trying to understand which of these can:

* Track a heading bug
* Track a CDI
* Be upgraded for GPSS (I probably already know that answer)
* Be fully approach-coupled (I think I know that answer also...)

Can any of the components (servos in particular) be re-used if upgrading to a more modern autopilot?

While I cannot speak to the ones you listed, you left out the King KAP/KFC 100/150 autopilots. KAP vs. KFC is without (KAP) or with (KFC) Flight Director capabilities. 100 vs. 150 is 1-axis (100) or 2-axis (150) autopilot. A yaw damper can also be added for control of an additional axis.

I fly a 1984 M20 J with an Aspen connected to my KAP 150. Earlier this year, I added a KAS 297B Altitude Pre-select/Vert. Speed Select to my panel. I now have the ability to set desired altitude, the rate at which to climb - or descend - to it, GPSS capability from the Aspen, and fully coupled flight and approach capability. The combination of KAS 297B, GNS 430W, Aspen 1000 PFD Pro, KAP 150, and KEA 346 (encoding altimeter for KAS 297B) give me as much capability as I believe I will ever need for the current type of flying I do. 

Rumor is King will have their KFC 230 AeroCruze digital autopilot released...soon... and can replace the KAP 150 and KAS 297B. They say the servos are reusable, but until I see the final announcement and someone installs it, I am reserving my belief in re-usability.

I know there are likely other models (KFC 225?), but I have no information or experience with them. Hope this helps some.

[Bob_Belville]

The PC System was built for Mooney by Brittain Industries. It is a full time wing leveler with a trim knob. A button on the yoke is held down to disengage the system while in a turn. 

Brittain offered a pretty broad line of autopilots which can be seen in the photo gallery here:

http://www.brittainautopilots.com/photo-gallery.html

Jerry Walters died a year or 2 ago. We learned recently that the stock of the company has been bought and the new owners plan to resurrect the product line and support. Jerry's sister is going to continue to be involved.

[Hank]

1 hour ago, Mr. T said:

Still on the hunt for the perfect M20 (E / F / J) and have found numerous autopilots in the older planes that I'm not familiar with (The STEC A/P's I understand - mostly).  I "grew up" in a Grumman AA5 with no autopilot and fussy "trim tabs" (extensions on the aileron that you had to bend by hand), and while I did my entire Instrument training in that plane, I hated flying in IMC, as you couldn't relax your scan for more than an instant without it wandering off one way or the other. I'm not doing that anymore. So now, 16 years later, I've had a little bit of experience with an STEC in the club 182 - GPSS, approach coupled, vertical speed hold, automatic elevator trim -- it's pretty sweet. And I'm pretty sure I need most of that same functionality in my M20.

Could someone give me a brief rundown of the various types, capabilities of each and whether I should steer clear of any of them in particular? What I've seen so far, I think:

* "PC" - Seems like a rudimentary wing leveler. What else can it do?
* Brittain "AccuTrack" and/or "AccuFlight" - Sounds like maybe an add-on to the PC?
* Century I, II, IIIB, etc.?
* Am I missing any?

In particular, I'm trying to understand which of these can:

* Track a heading bug
* Track a CDI
* Be upgraded for GPSS (I probably already know that answer)
* Be fully approach-coupled (I think I know that answer also...)

Can any of the components (servos in particular) be re-used if upgrading to a more modern autopilot?

I see some folks advocating for de-prioritizing the A/P on a purchase and instead planning to install one of the newly available (or soon to come) autopilots. Any ideas on installed cost for any of the newer systems? I'm guessing $15-20AMU?

The PC system is a wing leveler, and does a good job flying a straight line in whatever direction you point the plane.

The Brittain AccuTrack flies your heading bug, wherever you spin it to is the direction you go. Adjust the bug as needed for crosswind correction.

AccuFlight is a Brittain add-on and can be slaved to either a GPS or a VOR head [mine has a 3-way switch--430/OFF/Nav2]. When set to the GPS, it will fly a very nice approach pattern, but it does nothing for altitude, that is all on me. So is airspeed and vertical speed.

Brittain also makes a separate altitude add-on, the B6, but I can't speak to it as I don't have one . . .

[jaylw314]

1 hour ago, Mr. T said:

Still on the hunt for the perfect M20 (E / F / J) and have found numerous autopilots in the older planes that I'm not familiar with (The STEC A/P's I understand - mostly).  I "grew up" in a Grumman AA5 with no autopilot and fussy "trim tabs" (extensions on the aileron that you had to bend by hand), and while I did my entire Instrument training in that plane, I hated flying in IMC, as you couldn't relax your scan for more than an instant without it wandering off one way or the other. I'm not doing that anymore. So now, 16 years later, I've had a little bit of experience with an STEC in the club 182 - GPSS, approach coupled, vertical speed hold, automatic elevator trim -- it's pretty sweet. And I'm pretty sure I need most of that same functionality in my M20.

At least in the M20J's, the Bendix-King AP's (the KAP and KFC series) seemed to be common factory options.  IIRC, the KFC150, 200 and 225 were digital AP's and have flight directors, while the KAP series was analog and have no flight director.

The KFC200 is capable of GPSS, but the KFC150 is not.  Both would be capable of all the other functionality you mentioned otherwise.

There is a consensus here that Bendix-King sucks as a company, so there are concerns about longevity with their AP's.  One of the limiting issues is that their AP's are attitude-based, so they require input from the AI.  Of course, this only works with their mechanical AI right now (KI256?), so if that goes you are stuck overhauling a mechanical AI ($$$$).  Likewise, you cannot simply replace it with a Garmin G5 or other AI because the AP will no longer work.  Supposedly, the G5 may have limited function soon (no flight director), but I don't know if that has happened yet or if anyone has done that.

For now, the KFC150 I have installed works very well and flies ILS approaches down to minimums very nicely, nor have I had any problems in the 3 years I've owned it

[LANCECASPER]

5 minutes ago, jaylw314 said:

At least in the M20J's, the Bendix-King AP's (the KAP and KFC series) seemed to be common factory options.  IIRC, the KFC150, 200 and 225 were digital AP's and have flight directors, while the KAP series was analog and have no flight director.

The KFC200 is capable of GPSS, but the KFC150 is not.  Both would be capable of all the other functionality you mentioned otherwise.

There is a consensus here that Bendix-King sucks as a company, so there are concerns about longevity with their AP's.  One of the limiting issues is that their AP's are attitude-based, so they require input from the AI.  Of course, this only works with their mechanical AI right now (KI256?), so if that goes you are stuck overhauling a mechanical AI ($$$$).  Likewise, you cannot simply replace it with a Garmin G5 or other AI because the AP will no longer work.  Supposedly, the G5 may have limited function soon (no flight director), but I don't know if that has happened yet or if anyone has done that.

For now, the KFC150 I have installed works very well and flies ILS approaches down to minimums very nicely, nor have I had any problems in the 3 years I've owned it

The KFC & KAP 150 and the KFC 225 were digital. The KFC 200 is analog. All are capable of GPSS with add-on aftermarket boxes (such as http://sarasotaavionics.com/avionics/gdc31-gpss) or an Aspen.

[carusoam]

If you get this far... 

Check the details on the age of the AP for how digital or analog they are... (Lance just filled in some detail)

The KFC was top of the line earlier than the KAP showed up...

The early 90s KAP150...

- holds altitude

- follows heading

- follows magenta line, gps

- follows non-magenta line, VOR

- can intercept one course from another...

- can intercept a VOR/ILS

- a few clicks, you can climb or descend at a rate you pick... 100fpm intervals...

- upgradable with gpss and altitude level-off... to minimize memory challenges...

- KAP does not have flight director skills, but does have CWS control wheel steering...?

Pretty powerful computer for 90s technology...

Best regards,

-a-

[jaylw314]

11 minutes ago, LANCECASPER said:

The KFC & KAP 150 and the KFC 225 were digital. The KFC 200 is analog. All are capable of GPSS with add-on aftermarket boxes (such as http://sarasotaavionics.com/avionics/gdc31-gpss) or an Aspen.

Wow.  I did not remember correctly at all!   And thanks for pointing out the 150's can do GPSS with an add on box.

[INA201]

I’ve got the Century 2b which is coupled to a G5 with GPSS and 750 for lateral guidance only. It does a good job following the direction of your flight plan, anticipating turns etc.  You can add an STEC 30 component for altitude but it’s like $6000 last I checked. Personally, I’m waiting for the right digital option for a sub $10k install price to modernize.  I’m happy overall as the Mooney holds altitude reasonably well and doesn’t add a lot to workload.

[Bravoman]

1 hour ago, Oldguy said:

While I cannot speak to the ones you listed, you left out the King KAP/KFC 100/150 autopilots. KAP vs. KFC is without (KAP) or with (KFC) Flight Director capabilities. 100 vs. 150 is 1-axis (100) or 2-axis (150) autopilot. A yaw damper can also be added for control of an additional axis.

I fly a 1984 M20 J with an Aspen connected to my KAP 150. Earlier this year, I added a KAS 297B Altitude Pre-select/Vert. Speed Select to my panel. I now have the ability to set desired altitude, the rate at which to climb - or descend - to it, GPSS capability from the Aspen, and fully coupled flight and approach capability. The combination of KAS 297B, GNS 430W, Aspen 1000 PFD Pro, KAP 150, and KEA 346 (encoding altimeter for KAS 297B) give me as much capability as I believe I will ever need for the current type of flying I do. 

Rumor is King will have their KFC 230 AeroCruze digital autopilot released...soon... and can replace the KAP 150 and KAS 297B. They say the servos are reusable, but until I see the final announcement and someone installs it, I am reserving my belief in re-usability.

I know there are likely other models (KFC 225?), but I have no information or experience with them. Hope this helps some.

I am interested in the Aerocruz and was particularly interested in it a couple of months back when I was having issues with my KFC 150 and before I spent about $3000 getting it back up to snuff.  I had contacted Bendix King directly early in the summer and was assured that it was going to be released in September. That did not occur. Everyone in the avionics business that I have spoken to says that given the history with Bendix King product announcements  there is no telling when it will actually come to market.  IMO It looks like it will be a great auto pilot replacement option for many of us if it  actually hits the market place. 

[LANCECASPER]

3 hours ago, Bravoman said:

I am interested in the Aerocruz and was particularly interested in it a couple of months back when I was having issues with my KFC 150 and before I spent about $3000 getting it back up to snuff.  I had contacted Bendix King directly early in the summer and was assured that it was going to be released in September. That did not occur. Everyone in the avionics business that I have spoken to says that given the history with Bendix King product announcements  there is no telling when it will actually come to market.  IMO It looks like it will be a great auto pilot replacement option for many of us if it  actually hits the market place. 

Looks like the Aerocruze autopilot is now FAA approved, now just the airframes that are going to get approved.

https://www.beechtalk.com/forums/viewtopic.php?f=21&t=159538

[gsxrpilot]

As long as you're still shopping... I wouldn't spend money on anything with a Brittain. The difference in price between an E with a wing leveler and one with an Stec30/altitude will be probably only $3K or $4K and might not even be that much. An E with an Stec gives you a very capable autopilot today, and the ability to upgrade to the Stec 3100 for a very reasonable price and then have a modern state of the art autopilot. I know Mooneys have done just fine for many years with the wing leveler and associated upgrades... but it doesn't mean I have to participate since there are other, better options out there. 

There are lots of autopilot options on the horizon... we just don't know how far out that horizon is.

If looking at a J, the KFC150 is a really nice autopilot. But while it integrates with my Aspen for lateral guidance and GPSS, it can't get vertical speed or altitude pre-select from the Aspen. For that reason, I'd probably prefer an Stec or Century autopilot if I was buying a plane today.

Just my $0.02

[MIm20c]

The newer AP’s will be in the 8-18k range installed and will be a big upgrade from anything available in the 80’s. However, even a stec 30/50/60/55 with gpss can provide a ton of functionality.  I find mine (stec 50 w/ aspen gpss) removes a lot of the workload. The 30 and 50 will not follow a glide slope but they do have altitude hold. 

[EricJ]

My J has the Century III that it left the factory with forty years ago.   I just spent a bunch of money on a panel/avionics upgrade, and I really wish the modern digital autopilots that are in the process of coming out were currently available for my airplane, but they're not yet.   So, instead, I spent WAY more than anticipated overhauling the Century III to get it to "work" again (and I use the term generously).  My suggestion to you would be to not do that, i.e., unless there's a modern autopilot in the airplane, it's not going to matter what's in it as they're not worth spending any money on.   In other words, whether it is a Century or a Brittain or (heresy!) an older King, it won't matter because if anything happens to them they're not worth spending any money fixing them.   Just wait and get a modern digital unit (of your own selection, to your own desires and tastes) when it comes time to spend some money on such upgrades, probably when installing some nice GPS and panel glass at the same time.

My Century III is now fully functional, just really lazy (in need of adjustment).   I just had it fly a DME arc yesterday, which it did reasonably well with a little help, and I'm still trying to figure out how to get it to (or whether it will) fly the glidepath on a GPS approach.  I think it tried to yesterday, but I turned off the ALT at the wrong moment, so I'll have to go try again.

That said, the money I spent overhauling it would have been much better spent on something modern, but it just isn't an option quite yet.

If you're looking at an airplane that has a "vintage" autopilot, any autopilot, and it works, it's probably not going to matter which one it is, as it won't be worth repairing the next time it breaks.

[drapo]

You should also have a look at the new generation digital autopilots. TruTrak should have an STC/PMA for Mooneys esrly next year while Trio is thinking about it.

[whiskytango]

2 hours ago, EricJ said:

My J has the Century III that it left the factory with forty years ago.   I just spent a bunch of money on a panel/avionics upgrade, and I really wish the modern digital autopilots that are in the process of coming out were currently available for my airplane, but they're not yet.   So, instead, I spent WAY more than anticipated overhauling the Century III to get it to "work" again (and I use the term generously).  My suggestion to you would be to not do that, i.e., unless there's a modern autopilot in the airplane, it's not going to matter what's in it as they're not worth spending any money on.   In other words, whether it is a Century or a Brittain or (heresy!) an older King, it won't matter because if anything happens to them they're not worth spending any money fixing them.   Just wait and get a modern digital unit (of your own selection, to your own desires and tastes) when it comes time to spend some money on such upgrades, probably when installing some nice GPS and panel glass at the same time.

My Century III is now fully functional, just really lazy (in need of adjustment).   I just had it fly a DME arc yesterday, which it did reasonably well with a little help, and I'm still trying to figure out how to get it to (or whether it will) fly the glidepath on a GPS approach.  I think it tried to yesterday, but I turned off the ALT at the wrong moment, so I'll have to go try again.

That said, the money I spent overhauling it would have been much better spent on something modern, but it just isn't an option quite yet.

If you're looking at an airplane that has a "vintage" autopilot, any autopilot, and it works, it's probably not going to matter which one it is, as it won't be worth repairing the next time it breaks.

+1 on not wasting any more money on Century legacy autopilots.  I have a C21 that will hold heading (except when it doesn't), track a course through a GPSS box (except when it doesn't) and hold altitude (except when it doesn't).  It has been "repaired" at the factory and the computer has been replaced.  I am looking forward to replacing it with a TruTrak.

[Mr. T]

Thanks for all the replies - I was hoping for more discussion of the "really old" stuff but think I understand the basics.

I guess the question comes down to this:

If you found a plane that had everything else you wanted *except* it had either the basic PC or one of the Brittain APs, would that make you reconsider the purchase? Would you offer less because of the AP? (Assuming you're like me and believe that an autopilot is an important bit to have...)

[kris_adams]

30 minutes ago, Mr. T said:

If you found a plane that had everything else you wanted *except* it had either the basic PC or one of the Brittain APs, would that make you reconsider the purchase? Would you offer less because of the AP? (Assuming you're like me and believe that an autopilot is an important bit to have...)

this is always a tough question.  At 40-50 years of age (mine is a 1979) our planes are now a story book of upgrades and/or repairs to paint, interior, avionics, engine, and mechanicals...different people care about different categories.  We have to find a plane that works or we can upgrade the components that are most important.  I almost think you have to be willing to open your wallet a bit for the plane that has exactly what you want...instead of deducting for one that doesn't...

I have a Century IIB with STEC 30 altitude hold installed by PO for ~$7K (the STEC piece).  It will track Nav sources as well as the bug (which is what I find I  use most of the time).  I don't have auto trim or vertical speed.  Even this basic setup is an amazing aid in single pilot IFR ops.

Good luck

[Marauder]

Thanks for all the replies - I was hoping for more discussion of the "really old" stuff but think I understand the basics.
I guess the question comes down to this:
If you found a plane that had everything else you wanted *except* it had either the basic PC or one of the Brittain APs, would that make you reconsider the purchase? Would you offer less because of the AP? (Assuming you're like me and believe that an autopilot is an important bit to have...)

Depends on your flying. If you are flying VFR most of the time, it’s a nice to have and the early stuff works well when it is working. Since Brittain seems to be coming back, there will be support.

If you are flying IFR, you’ll want something with a little more capability, although a basic Brittain will fill most of those needs.

I flew my Mooney IFR with a non-trustworthy PC system for 7 years. It made for more work especially during re-routes while in the soup. In 1998 I installed an STEC 60-2 and later added GPSS. When you fly a full function autopilot, you can become more of a flight manager. It lessens the workload In route and if you are flying a tough approach single pilot, helps either by keeping you fresh to hand fly it or allows you to monitor the approach while you are looking for the runway.


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[MIm20c]

1 hour ago, Mr. T said:

Thanks for all the replies - I was hoping for more discussion of the "really old" stuff but think I understand the basics.

I guess the question comes down to this:

If you found a plane that had everything else you wanted *except* it had either the basic PC or one of the Brittain APs, would that make you reconsider the purchase? Would you offer less because of the AP? (Assuming you're like me and believe that an autopilot is an important bit to have...)

If the plane had everything I wanted except a good autopilot I would not add anything for the existing system. However, it wouldn’t slow me down on going forward with the purchase. 

[Cyril Gibb]

16 hours ago, EricJ said:

...and I'm still trying to figure out how to get it to (or whether it will) fly the glidepath on a GPS approach.  I think it tried to yesterday, but I turned off the ALT at the wrong moment, so I'll have to go try again.

I have a Century 2000, so if the Century III operates differently ignore the following.

The GS flag/light should become active when intercepting the localizer.  Whether I'm in ALT or ATT(attitude) mode, the autopilot captures and follows the glideslope when intercepting the glideslope without any button pushing.

Does your autopilot capture an ILS glideslope?  If it captures an ILS but not a GPS glideslope it could be using the incorrect pin from the WAAS GPS.  In the case of a GNS430W, the ILS glideslope pinout has to be moved to the pin that activates the GS for both ILS and GPS.

[gsxrpilot]

2 hours ago, Mr. T said:

Thanks for all the replies - I was hoping for more discussion of the "really old" stuff but think I understand the basics.

I guess the question comes down to this:

If you found a plane that had everything else you wanted *except* it had either the basic PC or one of the Brittain APs, would that make you reconsider the purchase? Would you offer less because of the AP? (Assuming you're like me and believe that an autopilot is an important bit to have...)

Me?  I would not purchase the airplane. You've already said, "an autopilot is an important bit to have". And I agree with that. So I'd keep looking and find the plane that has one.

There are of course, many variables to consider. How long are you willing to keep looking. The total fleet of these planes is shrinking and its getting harder to find good ones. 

IF TrueTrax, Trio, etc... get their autopilots approved for Mooneys... that might be a decision factor. But they aren't available today.

[tigers2007]

How hard would it be to change out a Century IIb single axis for the two axis TT Vizion (after the STc comes out of course)? I hate my Century.


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[Bravoman]

21 hours ago, LANCECASPER said:

Looks like the Aerocruze autopilot is now FAA approved, now just the airframes that are going to get approved.

https://www.beechtalk.com/forums/viewtopic.php?f=21&t=159538

 If I am reading everything correctly that the Bendix King rep said on the Beech forum , looks like the Aerocruz will be available for the Bravo  and other long  bodies sometime mid to late next year.