How to “Use” Brittain Autopilot

[Nukemzzz]

Ok, so since buying my 66’ E In December I’ve only been able to fly it for 10hrs and I’ve not had much time to play with all the knobs. The 10hrs was mostly training and it’s been down for a couple of months now as the engine gets rebuilt. See my other thread on that one. While waiting on the engine I’m sorting other things. See my other posts on the flap pump and instrument panel overhaul. 

Next on my list is Autopilot. A couple of times I flipped switches and turned knobs and nothing happened so I put and InOp sticker on it and noted it for future investigations. The PC system is also inop  

I’d like to start with something I can’t find anywhere on the intertubes, including here... how in the heck to you operate this system?  It looks to me like I have a well equipped version and it’s worth saving. It’s an Accutrak 1... I’ve established that. However, next to it I have strange knobs that indicate pitch and altitude. I think they are vacuum pull switches, I’ve not seen this on other’s panels. 

What am I looking at here?  What does those knobs do?  What is the glass with two lines on the right of those knobs?  What can it do and how do I do it?  Is this likely connected to my King VOR?  My Narco HSI?  I don’t have GPS yet, but apparently it can connect when I do.  

Lastly, the wing leveler seems too evasive time me. I’d very much like a switch on the dash that disables it, once I actually get it working. Anyone else do this?  I don’t like the idea of having to remember to hold down that button down on the yoke while slipping on landing and such . I also worry about what it will do during a stall (lead to a spin maybe). My version has the remote gyro BTW. Not the TC type. 

Help me to be excited about fixing this thing so I can motivate myself. Lol 

[RLCarter]

Pretty sure I have the manuals for the Brittian stuff at the house, will check when I get home this evening. 

[Matt Ward]

I've got the same altitude hold on mine.  You pull the top one on and then adjust the pitch trim with the bottom.  The two lines are sort of "in balance" indicators - that is how I think of it at least.  I don't love it because it requires so much nose up trim in my plane; I may have failing servos.  Mine holds me +-500 feet, enough to get ATC' attention.  I don't use it since I can trim it out much better.  I've got the manuals too if you need them, I can scan them I suppose.

I have the PC disconnect on my yoke.  I almost never touch it.  When I first started flying it, I did combinations of velcroing it down, rubber banding it down, and holding it down with my thumb.  It doesn't matter at all to me now - I just let it do its thing - it's very easy to overpower.  If I'm landing in something really nasty, I might squeeze it with my thumb, but not likely.  You can also pull it straight up and out if you like that.

The heading track should be great.  It works as advertised - it will follow the track on your NAV1 (Narco?) or NAV2 (KX155?).  It may be wired to follow a GPS track - mine is - but that's installation dependent and not something that will auto-magically work when you add a GPS.  The High/Low sensitivity is a mystery in planes I've flown with it - that is one I've never truly been able to figure out.  The AP in mine requires the PC to be operative, FWIW.

[Hank]

The Brittain applies corrections using the PC servos, so that has to be fixed first. 

Overpowering the PC is fairly simple and won't hurt anything. The extra resistance reminds me to not overbank in the pattern. It's not a stall or spin risk that I've noticed in 13 years of ownership. 

[Nukemzzz]

20 minutes ago, Matt Ward said:

I've got the same altitude hold on mine.  You pull the top one on and then adjust the pitch trim with the bottom.  The two lines are sort of "in balance" indicators - that is how I think of it at least.  I don't love it because it requires so much nose up trim in my plane; I may have failing servos.  Mine holds me +-500 feet, enough to get ATC' attention.  I don't use it since I can trim it out much better.  I've got the manuals too if you need them, I can scan them I suppose.

I have the PC disconnect on my yoke.  I almost never touch it.  When I first started flying it, I did combinations of velcroing it down, rubber banding it down, and holding it down with my thumb.  It doesn't matter at all to me now - I just let it do its thing - it's very easy to overpower.  If I'm landing in something really nasty, I might squeeze it with my thumb, but not likely.  You can also pull it straight up and out if you like that.

The heading track should be great.  It works as advertised - it will follow the track on your NAV1 (Narco?) or NAV2 (KX155?).  It may be wired to follow a GPS track - mine is - but that's installation dependent and not something that will auto-magically work when you add a GPS.  The High/Low sensitivity is a mystery in planes I've flown with it - that is one I've never truly been able to figure out.  The AP in mine requires the PC to be operative, FWIW.

Very good info.  Thanks!

I assumed that the sight glass would show vacuum bias and indicate when trim was needed but then this "Pitch" knob confused me.  

From what I've read other places, the Accutrak should be connected to my 290 VOR (or maybe the HSI) output and it's used to follow whatever the CDI is tracking.  So it seems if I pair the GPS with the right one, it should just work with the GPS setting tweaks.  

I've only found 4 servos and its my understanding the PC system has Aileron and Rudder servos.  So if I have ALT Hold it seems there should be two more servos somewhere?  Two I've found are below the battery box in the tails section. They don't look so hot but they are hard to see without significant work.  I think I need to get a vacuum pump and start testing stuff.

For science:  Does the leveler try to to "level" a stall?  My Mooney already wings over hard on stall, having a system try to level it with ailerons seems like a bad idea to me.  Maybe the fact that it has rudder servos addresses this because it coordinates?

[Nukemzzz]

22 minutes ago, Matt Ward said:

"You can also pull it straight up and out if you like that."

If I can just slide the button out and disable it that would be great and I've heard this was the case, but I can't seem to get mine to come out.  66' E by the way.  Maybe varies by year?

[Nukemzzz]

Last question for the moment....

Does  the PC or Autopilot system put the other vacuum driven gages at risk?  Seems it is prone to letting air in and killing vacuum. How does a busted boot not cause the AI or DG to stop?  

[Hank]

14 minutes ago, Nukemzzz said:

If I can just slide the button out and disable it that would be great and I've heard this was the case, but I can't seem to get mine to come out.  66' E by the way.  Maybe varies by year?

You need to.partially remove the button. Pry gently with a key or screwdriver, it should ease out. There's a little bitty o-ring on the bottom inside the yoke, too.

Previous disabling ideas involved 35mm film cannisters over the yoke, or broccoli rubber bands to hold the button down (but you'd better like broccoli, rubber bands have short lives when stretched).

Just be aware that disabling the PC is dine by creating a vacuum leak, which will also disable your Brittain AP. Just saying, word to the wise and all that.

Love my Brittain!

[Lawyerpilot]

Hi guys, I am very interested in this topic because I am in an annual on my 1965 m20c and my PC is INOP and I am determined to get it going.  I see the red and green hoses are disconnected and not attached to anything near the firewall behind the panel.  I have opened all of the access panels and can verify the servos are installed and intact and tomorrow I am buying a pressure tester and testing the system for leaks.  Once I verify there are no leaks or repair any leaks, I am not sure how to reconnect the system and once I do I have no idea how to operate it.  I was able to download a maintenance manual for the PC system so I am confident I can test the system and troubleshoot leaks, but I cannot find an operators manual for a Brittain BI-603 controller.  (See picture).  I have a magnetic sensor in the tail cone, but I do not see a remote gyro in the tail cone.  This leads me to believe that the PC must have been driven by hoses connected to a turn coordinator, but the turn coordinator in the aircraft is electric and must be a replacement, or maybe it was attached to a DG that has been since replaced?  Can I now use a Brittain DG if I want to?  Do I need to buy a Turn Coordinator first and connect it to that?  I called Brittain today and left a message, but they didn’t call back.  Just wondering if anyone has any experience with either the PC as I have described, or the Brittain controller?  Thanks for any information.

Edited July 2, 2020 by Lawyerpilot

[Lawyerpilot]

[RLCarter]

Sorry for getting back so late, I couldn’t find the manual but have sent a txt to someone that might, will get back as soon as I know something 

[Guest]

5 hours ago, Lawyerpilot said:

Hi guys, I am very interested in this topic because I am in an annual on my 1965 m20c and my PC is INOP and I am determined to get it going.  I see the red and green hoses are disconnected and not attached to anything near the firewall behind the panel.  I have opened all of the access panels and can verify the servos are installed and intact and tomorrow I am buying a pressure tester and testing the system for leaks.  Once I verify there are no leaks or repair any leaks, I am not sure how to reconnect the system and once I do I have no idea how to operate it.  I was able to download a maintenance manual for the PC system so I am confident I can test the system and troubleshoot leaks, but I cannot find an operators manual for a Brittain BI-603 controller.  (See picture).  I have a magnetic sensor in the tail cone, but I do not see a remote gyro in the tail cone.  This leads me to believe that the PC must have been driven by hoses connected to a turn coordinator, but the turn coordinator in the aircraft is electric and must be a replacement, or maybe it was attached to a DG that has been since replaced?  Can I now use a Brittain DG if I want to?  Do I need to buy a Turn Coordinator first and connect it to that?  I called Brittain today and left a message, but they didn’t call back.  Just wondering if anyone has any experience with either the PC as I have described, or the Brittain controller?  Thanks for any information.

From the IPC, there are a number of different installations depending on model year.

Clarence

[Yetti]

I believe all the manuals are in the download section.  You should also have a flight supplement in your plane.   There are some extensive threads on fixing these.   BIGman had one.   You can also contact the Brittian and will send you manuals.   They should also be close to getting back up and going.

[Nukemzzz]

I have picture #1 above (remote gyro) for PC with Accurak and altitude hold added.  What's strange is I don't see any elevator servos.  Shouldn't they also be in the tail section?

[Yetti]

in wings about 2 ribs in

[Lawyerpilot]

58 minutes ago, Yetti said:

I believe all the manuals are in the download section.  You should also have a flight supplement in your plane.   There are some extensive threads on fixing these.   BIGman had one.   You can also contact the Brittian and will send you manuals.   They should also be close to getting back up and going.

Thank you very much for replying I am excited to get any info! 

[geoffb]

Yes, elevator servos are in the tail cone.  The drawing from the IPC shows the basic PC installation.  The B6 autopilot with heading and nav coupling was an option.  Pitch control, which would add the elevator servos, was an option to the B6.  Speaking in my 65-66 terms.  I think in 67 they went away from the stand alone PC gyro.

[Lawyerpilot]

Thankyou, that makes sense as an option.  Do you know what instrument the B6 would have been connected to.  I see the magnetic sensor in the tail cone.  Does that suggest that a DG or a Turn Coordinator would have been connected to the B6 rather than the remote gyro that would have been standard equipment as the PC without the auto pilot option?  You are really helping me sort the mystery out folks!

 

[carusoam]

Welcome aboard LP...

The 65C was the first for many things... PC included...

Its gyro is in the tail cone...  you may hear it when exiting the plane...

Its not the quietest gyro in the world when spinning down...

It is possible that your system may have been updated over the years... read your logs for that...

Best regards,

-a-

[Lawyerpilot]

Thanks for the warm welcome, are you familiar with the B6 autopilot?  I can’t seem to find any publications on it.  There is no knob for any kind of roll trim control.  My hunch is that the roll trim control must have received the input from another knob on the turn coordinator or other instrument attached to the system.  I really can’t find any PC system that didn’t have some ability for roll trim control.  Thanks

2 hours ago, carusoam said:

Welcome aboard LP...

The 65C was the first for many things... PC included...

Its gyro is in the tail cone...  you may hear it when exiting the plane...

Its not the quietest gyro in the world when spinning down...

It is possible that your system may have been updated over the years... read your logs for that...

Best regards,

-a-

 

[Lawyerpilot]

12 hours ago, Yetti said:

I believe all the manuals are in the download section.  You should also have a flight supplement in your plane.   There are some extensive threads on fixing these.   BIGman had one.   You can also contact the Brittian and will send you manuals.   They should also be close to getting back up and going.

Thanks for this advice, I searched for BIGman but nothing came up, would you know of a link?  Thanks

[Yetti]

Best way to search mooneyspace is Google.    Put mooneyspace and Brittian.  In and you will have hours of reading fun

[Hank]

The B6 unit is altitude control only. The other Brittain units control flight path--one by heading bug, the other by nav signal (VOR or GPS).

[Lawyerpilot]

Thanks Hank, I am confused, if you look at my picture of the B6 you will see that there is a HDG, CAP, TRK, LOC selection switch and the altitude hold and pitch trim knobs are not even installed and I don't see any servos installed in the tail for pitch control.  These is a magnetic sensor installed which suggests the opposite, that it has at least HDG control,  The knobs and the ability to dial in a heading are consistent with direction control, but no altitude.  Are you familiar with any B6 publications?  Do you know if the Brittain parts are interchangeable?  Like could I hook up a Brittain DG and that would manage the system instead of a remote gyro?  Lee 

[Guest]

2 hours ago, Lawyerpilot said:

Thanks Hank, I am confused, if you look at my picture of the B6 you will see that there is a HDG, CAP, TRK, LOC selection switch and the altitude hold and pitch trim knobs are not even installed and I don't see any servos installed in the tail for pitch control.  These is a magnetic sensor installed which suggests the opposite, that it has at least HDG control,  The knobs and the ability to dial in a heading are consistent with direction control, but no altitude.  Are you familiar with any B6 publications?  Do you know if the Brittain parts are interchangeable?  Like could I hook up a Brittain DG and that would manage the system instead of a remote gyro?  Lee 

Pretty sure that if you’re in Heading mode you select the heading you wish to fly by turning the knob in ht eB6 control head.  Yours doesn’t appear to have the Altitude hold add on.  You should have 4 vacuum servos in the plane, one in each wing to control ailerons and 2 in the tailcone to control the rudder.

Clarence