Brittain autopilot, how does it work?

FredFenster

FredFenster

Pre-takeoff checklist
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Apr 18, 2013
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Manitowoc, WI
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Greg L
I've never used or even flown in anything with an autopilot before, so bear with me. I've got a Brittain Nav Flite II autopilot. No idea if it works or not, but I did verify all the servos are at least installed and hooked up so I'd like to at least give it a shot. Previous owner of 20 years said he never used it so that's no help. Brittain was kind enough to send me the operational manuals, but I'm still lost. How does it "turn on" for lack of a better description? My first guess was the vacuum "Pull on" knob. Should I see a change at all in the vacuum gauge when it does turn on? There's also a King display on the left side of the picture below (says off, n1, hld, n2). Can't seem to get this to turn on or display anything. All of the other radio equipment is working, even the Loran powers up before having an error :D. The toggle switch above the Brittain doesn't seem to do anything that I can notice either.

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ah, the old "I never used it", which translates to "it doesn't work". but coupl'a suggestions....1) post this over on mooneyspace, there are quite a few brittain pros over there, 2) I have a similar toggle switch as yours but I have no vacuum pull on switch. I'd get in a little bank then flip the toggle switch, both with and without the vacuum switch (most likely with) and see if it levels the wings. when I use my toggle switch it engages just the basic wing leveler. I have the accu trak and accu flight, both of which are significantly different from your control module so I really don't have any suggestions there.
 
FredFenster said:
How does it "turn on" for lack of a better description? My first guess was the vacuum "Pull on" knob. Should I see a change at all in the vacuum gauge when it does turn on? There's also a King display on the left side of the picture below (says off, n1, hld, n2). Can't seem to get this to turn on or display anything. All of the other radio equipment is working, even the Loran powers up before having an error :D. The toggle switch above the Brittain doesn't seem to do anything that I can notice either.
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The King display doohickey is a KN-62 DME that’s remote channeled to either Nav 1 or 2. The switches and labeling for the A/P do seem kinda sketchy, but it does appear that the “vacuum - pull on” switch would turn on the A/P. I’m guessing the Nav 1/Nav 2 switch above it selects the appropriate VOR for autopilot nav tracking.

Basic A/P operation should be; when switched to MAN, you’d be in wing leveler mode. Use the center turn knob to command or stop turns. Switch to HDG mode and use the goofy looking “heading bug” on the right to fly a compass heading. The CAP, TRK and APP modes are for VOR tracking. And be ready to turn that thing back off if it starts acting weird...
 
Thanks, I'll try turning it on while banked and see what happens. I was playing with it trimmed out straight and level and couldn't tell anything, never thought to turn it on while in a turn. Been reading on Mooneyspace all morning trying to get more info too.

DME, interesting! I tested the nav radios to make sure they worked and the glideslope indicators worked but turned them off after. Probably explains why nothing showed up there if the nav radios were off. Looks like I would've had a state of the art IFR panel 40 years ago.
 
What does your direction gyro look like?

I wouldn't care about anything else other than making the heading hold work.

Pull the "Pull On" master valve and switch the control head to HDG mode and see what happens. I'm not sure the "Pull on valve is labeled correctly, if its an autopilot valve it should be labeled "Autopilot Master" or something like that.
 
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DG - Nothing fancy, no heading bug. Attitude indicator does have a roll trim knob. Weather looks good on Saturday so I should be able to go out and play with it.

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bnt83 said:
What does your direction gyro look like?

I wouldn't care about anything else other than making the heading hold work.

Pull the "Pull On" master valve and switch the control head to HDG mode and see what happens. I'm not sure the "Pull on valve is labeled correctly, if its an autopilot valve it should be labeled "Autopilot Master" or something like that.
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heading hold would be controlled using the cheesy dial on the brittain panel
 
Ask the previous owner?
 
Salty said:
heading hold would be controlled using the cheesy dial on the brittain panel
Click to expand...

That sure adds some complexity to the system. Mine tracks a heading bug on a gyro through DG amplifier.

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How long do you plan on having the plane, and do you see yourself using/needing an autopilot? If so, maybe have the autopilot pulled and replaced with something made in this century (and pull the Loran as well).
 
If it went unused that long, odds are pretty high that at least one of the servo boots is rotted and not functional. They can be replaced, but it's expensive for Stone Age tech.
 
Fred, I have a Brittan B6 which is somewhat similar but has a few more functions. The entire system works off the Vacuum so its not electrical. The way you turn it on is to pull the button that says (pull on) next to the vacuum placard. If the button stays out it should work. To see if it works fly straight and level make sure the compass type dial on the unit is set to the same heading that you are flying. Turn the big knob to HDG and it should hold heading. To turn the plane turn the dial on the Brittan unit to the heading that you want to fly. I see it says alt hold but I don't see an alt hold button. If it has one press it and see how it does. It may descend and then level off so give it sometime. Its not spectacular in rough air. These things go bad when the rubber components ( diaphragms tubing etc. starts to dry out and crack) The tubing is pretty much just surgical tubing and the filters are actually fuel filters that were identical to the one I had in my Honda. Sadly their main tech tied several years ago and I don't think they support the autopilot anymore. I was lucky and we had ours overhauled ( for less than 1K if you can believe it) not long ago just before the tech died and it works pretty well. Good luck.
 
Hello, Fred. Neat old unit you have there. What a find! Vacuum-powered. These are dinosaurs. And I say that as the owner of a very old autopilot also, the Altimatic III. But even my old unit is a modern marvel compared to the Brittain.

The chance of this randomly working for you after two plus decades of inactivity are only barely above the nonzero plane. But give it a shot. You just never know, eh?

It's just my opinion, but in the event it's nonfunctional, there's no benefit to investing in getting this working again. Assuming it does not, in fact, work, it needs to be placarded inop, disconnected or deactivated, and an entry should be placed in the maintenance log for continued legal operation of this aircraft.
 
Good news for me, it works! Set the heading on the small dial, pulled the vacuum knob out, turned the other knob to HDG and that’s the heading it flew! Adjusted the heading knob and it adjusted course. It didn’t do anything for altitude but I only saw 4 servos for it. I’ll have to read up on the other settings, they seemed to either do nothing or put the plane into a never ending right turn.

The DME indicator might be toast, couldn’t get anything to show on the display. Tuned a nav radio to a vor and could hear the ID on that radio but just buzzing on the dme button on the audio panel.
 
Well, capture and track are going to be dependent on you having a VOR tuned in. If your VOR wasn't getting a signal, or you were far to the left of the radial tuned in, it might seem like a never ending right turn.
 
Yeah, that's one in a million! If it tracks the heading bug and nothing else, you're still ahead of the game. Maybe you can get other components to work.
 
I pulled together a bunch of Brittain info here.

There is one tweak for the TRK mode - put both the OBS and the Brittain heading bug on the desired heading.

I can’t paste a link as I have fewer than 5 posts.

go to “windfield.farm” and click on Brittain Autopilot.
 
My neighbor has one of these Brittain Pneumatic autopilots in his Wing Deringer. He says it works just fine. I've not had a chance to fly in it yet.
 
Just an update on this - Had some avionics work done. Added a GPS, replaced a faulty nav indicator, and they figured out what the unlabeled switch above the autopilot was for. It'll now track a heading set on the small heading indicator, capture and follow the magenta line on the GPS, or follow a VOR from the nav radio. Using it almost feels like cheating :D
 
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