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I know nothing about Brittain autopilot but a friend has these parts for sale.

I’ve been a big fan of of the PC with Accu-Trak and AccuFlite, but lately have been tempted by one of the new autopilots coming to market. Both, the Accu-Trak and Accu-Flite just seemed a little sloppy in holding headings and track. I convinced myself that this is the way it always was. After annual, where I did the yoke shaft AD, it seemed a little worse. This past week, the system seemed exceptionally lazy for much of the flight, at times not even leveling the wings. This weekend I removed and cleaned the vacuum pilot valve....no real findings there. I started tracing things back, applying light vacuum to look for leaks and found the yoke disengage line was leaky. Pulling the yoke cover off, first thing I noticed was I had put the line on the wrong tube, it belongs on the innermost tube, however, I still had a leak. Focusing on the button, a visual inspection at the o rings revealed no obvious issues, however putting the button into the yoke revealed that the large (1/4”I’d x 1/16”) o ring was loose in the hole. Replaced it with a new one and it sealed up nicely. Test flight today in bumpy conditions and what a surprise. The system worked fantastic, has not performed this well in years...if ever. Instant response in wing level mode and held heading and track perfectly. It seems that a partial leak in the yoke button will allow the shuttle in the pilot valve to move part way....allowing some semblance of functionality, but not optimal functionality. In summary, sloppy wing leveler, check the o rings on the button. As a side note, in another thread I suggested removing the button if you want to disable the wing leveler for training or other reasons. Turns out, this likely wears the o ring in question, causing this issue. Otherwise this o ring remains static. Hope this saves someone a few $$.

Brittain PC & AP Documents View File These were provided to me by Brittain in 2017. Submitter moontownMooney Submitted 09/12/2018 Category Avionics

I have a 66 E, so the wing leveler is different for the models done after 66, but I don't know what the problem is. My plane drifts to the right always. I have to turn my adjuster knob all the way left and it sometimes doesn't go right, but usually still drifts. If I turn it right, it makes a standard rate turn right. I have replaced the servos in all four locations. I have vacuum tested the sevos and the tubing with no leaks. I have vacuum tested the lines coming from the adjustment knob and they pass with flying colors. I then sent my controller back to britton and got a new one, because that had to be the reason. Well it didn't change anything. Still does the same thing. I then had the rigging checked on the plane and it was perfectly rigged. I changed the tubing to see if the system would switch and pull left, well that didn't work either, when I adjusted to the left (remember it is now opposite) it made a standard rate turn right and when I did the opposite, it just went straight. I did a vacuum test of the knob controller and it acts exactly the same depending of the way i adjust, so it seems to be working fine. So every component has been checked and is operating correctly. so it seems. The only thing i didn't do was switch the servos on both wings, because that is a bigger job than I wanted to do. I am of the opinion it is not a wing leveler problem, but somehow mechanical on my plane, but I don't know. I don't know how many hours I have spent on this, and all I get is more questions. Thanks for your guys help. Mark

Hi All, In changing out a servo in the tail today I noticed that the cable that connects it (the forward servo) to the rudder control rod was slightly frayed. It looks like part number # 1890-18.5. any idea where to get one? I sent Mooney an email, any ideas? Thanks, Jim

There are several iterations of the Basic Brittain wing leveler, or PC. The one in my '74 C model is very different from others I have seen, though it seems to work pretty much the same. My question pertains to PC's of my PC's vintage. I would like to switch out the basic pneumatic control valve which is mounted on the interior side of the firewall with the BI-805 electric control valve . Has anyone here on Mooneyspace made this switch? Was it a worthwhile modification? Do you have any pictures of the installation? Where did you locate the BI-805? Where did you put the "disconnect" switch? Any other advice?