Brittain autopilot equipment list

[jager3]

I own an M20C that was never equipped with an autopilot. I would appreciate information on installing an old (approved) Brittain autopilot as my first.

I would like information as follows: 1) equipment list, ie. servos, control head, etc. 2) additional flight system, ie. gyros, sensors, etc. 3  )obtaining certification by FAA

4) instillation tips and user operation instructions

I realize this is an old system, but I know it has already had approval and Tru-Trak and others are either not fully approved or have priced themselves our of my range.  I've hand flown my aircraft for over 3 decades and realize the latest "whiz bang" unit would be idea, but after experiencing my 2nd major overhaul, I am woefully short of pocket change to buy the "latest".

[Echo]

In avionics section NOT in selling area an owner had listed a complete Brittain system.  Not recommending, just pointing out for you to take a look.  Photos show all components.

Edited August 27 by Echo

[JoeM]

I have a complete Brittain system in my '65 E model, with altitude hold and pitch control. For 4 years I have tried to keep it working, buying parts Others were selling, rebuilding servos, sending parts to Kevin in Tulsa, and doing extensive testing myself. You probably know there are very few people who will work on them, and even fewer who are FAA certified. The company is essentially out of business. Jimmy Garrison says that it would add $2000 to the value of your airplane, assuming it worked. It probably won't. It would definitely cost more than that to install, troubleshoot, and attempt to repair. I am getting ready to take mine out and install an aerocruze 100 aka trutrak. Cost is about $7,000 for a good autopilot, admittedly not as good as Garmin. If you are so inclined, you can install it yourself under supervision. If it were me, I would not waste money on a Brittain system.

[jager3]

Thank you for the replies, information, and advice. Also, I wasn't sure the aerocruze 100 was approved for the M20C; it looks like a much more practical way to go for the money.

[MarquezJC]

I believe the Aeorcruze 100 STC for the C, D, E and F models are still being finalized by Duncan.  Last rumor I saw was maybe sometime  late this year.  You can also get a field approval from the FAA which I believe some have done. 

[hammdo]

Mine goes in this month for the AeroCruze. No issue with the current STC from Duncan…

-Don

[DCarlton]

28 minutes ago, hammdo said:

Mine goes in this month for the AeroCruze. No issue with the current STC from Duncan…

-Don

Please post pics and let us know how it installs / performs.  I haven't kept up with AeroCruze development.  

[cliffy]

I have the Aerocruze 100 in my D model and it is working fine. I did have to adjust one parameter to calm down the pitch oscillating slightly in ALT Hold. 

I will say you will need to be very sure your airplane flies hands off (NOW before you install it) straight and level and doesn't fall off on one side or the other. It has to be in near perfect trim before you install the A/P otherwise it will wander back and forth across the course as the out of trim condition pulls it one way and the A/P tries to bring it back .

Many Mooneys are not in good trim laterally! Many many of them, but it can be done. 

That is the only issue I have found.  Pay real close attention  to the wiring diagrams (especially the caution on reversing the pitch feed wires to the pitch servo) and all should go well.  

It takes some use to get to know the "buttonology" of the control head. No worse than learning a Garmin EFIS.

[0TreeLemur]

On 8/26/2025 at 11:49 AM, jager3 said:

I own an M20C that was never equipped with an autopilot. I would appreciate information on installing an old (approved) Brittain autopilot as my first.

I would like information as follows: 1) equipment list, ie. servos, control head, etc. 2) additional flight system, ie. gyros, sensors, etc. 3  )obtaining certification by FAA

4) instillation tips and user operation instructions

I realize this is an old system, but I know it has already had approval and Tru-Trak and others are either not fully approved or have priced themselves our of my range.  I've hand flown my aircraft for over 3 decades and realize the latest "whiz bang" unit would be idea, but after experiencing my 2nd major overhaul, I am woefully short of pocket change to buy the "latest".

Is your C equipped with a PC system?   If so, Is it working?    Adding an Accutrak II to a working PC system is relatively straightforward.     My C model had a working PC system when I bought it.  I added Accutrak II (NAV mode), Accuflite II (HDG mode) and PC-AH (altitude hold).  The Accuflite and PC-AH parts are damn near unobtanium.   I've got spare parts for the Accutrak II left over.  Others might have more parts.   If you don't have an installed PC system, then doing any of this would probably not make sense.

[jeremyc209]

9 hours ago, cliffy said:

I will say you will need to be very sure your airplane flies hands off (NOW before you install it) straight and level and doesn't fall off on one side or the other. It has to be in near perfect trim before you install the A/P otherwise it will wander back and forth across the course as the out of trim condition pulls it one way and the A/P tries to bring it back .

Many Mooneys are not in good trim laterally! Many many of them, but it can be done. 

Mine rolls slightly to the right, and appears to be slightly uncoordinated (ball on the right) when I'm in straight and level flight unless I rest my foot on the pedal. Fixing the PC system compensated for the roll but not the uncoordinated straight flight. My AP (just the Accutrak, testing on VORs) hunts but I don't think it's set up properly, it will bank well beyond a standard rate turn. It seems like it has a slow reaction time, then overcorrects.

Everything appears correct on rigging, yoke positions are normal etc. The service manual outlines the bending of aileron trailing edges (the left edge down in my case) and the rudder trim tab but I haven't gone that far yet.

[cliffy]

I caution on bending control edges. Too much chance of going too far and pulling a rivet. For roll (If its close) I use a 1/4 to 1/2 turn on the flap up stop bolt. 

Nothing works well until the airplane is rigged WITH trim boards correctly. You have  to get the throws correct. Just like rigging the gear you can't start in he middle of the procedure and expect to have good results. 

One can check to see if the airplane is even near correct by aligning one aileron counter weight with the top of the wing skin (tape it there) and then looking at the other to see how close it is to being flush with its top wing skin. The inboard ends of the aileron should be right next to the outboard ends of the flaps in this position . As old as our airplanes are, when in flight and with a load on them- the ailerons MAY be above the flap trailing edges. If the ailerons are rerigged by putting a simulated load UP on them and then rigging them to be flush the flaps can then be rigged to match them WITH the simulated load.  This assumes the right flap is not twisted by 50 years of people standing on it by mistake. 

When ever the lateral trim is worked on the control wheels have to be locked level in place with an aluminum angle and straps. 

If the ball is not centered then it will roll off or wander back and forth with the autopilot. Make sure it is centered on level ground before you determine that it needs  rudder tab adjustment.

[jeremyc209]

Thanks for the advice, I'll check those out. Where do I put a bubble level when leveling the plane laterally? Seat rails? I assume playing with the tire pressure will do the trick. Does the TC twist or adjust in some way if it's out of wack and the plane is level?

The PC system is really nice, and I have a GPS + Garmin 106 going in soon so it'd be nice if the AP could follow the magenta line well. 

[cliffy]

The Accutrak will only follow an old style nav deviation with millivolts out ( I think 5 millivolts =full scale)

If the GPS output is a digital signal it won't work. We're talking crystal radio to a main frame here. 

There are ways to get a Brittian A/P working but almost all radio shops have no idea or interest in doing so.-

let alone most of us who just fly the thing. As touchy as the FAA is on the autopilot issue right now (think Boeing) 

we are now into an area that at the least requires the proper manual to refer to and an A&P to sign off what is done.

I strongly suggest you work along those lines.  Leveling the airplane and the T/C are basic tasks for an A&P with the proper  manuals. Your local A&P would be the one to talk to about doing this kind of work. 

After flying my Accutrak for years and pulling it out for an Aerocruze 100 I'd never go back. BTW I have almost 2 complete Accutraks on the shelf that will go up for sale shortly. 

[jeremyc209]

Yeah I'll have the shop correct anything with the TC but it would be nice to at least verify whether it's the TC that needs adjustment or the rigging. The avionics shop also shares a hangar with a mechanic. 

He said it'll work as the 375 can output the analog mv left/right signals. Current upgrade budget is going into new audio/com1 (par200b), CDI, and GPS so I can get my IR training done. If I can get it to follow a GPS course that'll do for now. 

Still looking for an Accuflite...