Problem with Brittain autopilot, Part xx

[drapo]

So for some times, I've had some problems with the Brittain Accutrak autopilot and would do some troubleshooting on my free times but not intensively since I hand-fly most of the time and I was going to replace it with the TT/BK soon to be released () digital autopilot.

This week, while I was inspecting the battery compartment and the ELT, I decided to have a look at the gyro and, lo and behold, found a tubing that was almost completely gone! That tubing goes from the gyro to a filter in a dead end. For those who are familiar with the system, could that single tubing be the cause of the problems?

[takair]

One of the filters is for the gyro inlet and the other is for the servos.  If some of the rubber got into either, it could be a problem.  If not, you are sucking unfiltered air through the system.

[carusoam]

Wherever one tube is gone... there may be a few just like it closer to the servos...

See how much tubing you can inspect...

Or... preferentially find the connections at The Servo... to see if everything is connected properly... while looking at connections check the electrical tape on the servos themselves...

Sounds like a full inspection of the system probably requires the openness of the annual...
 

PP musings only, not even full ideas...

Best regards,

-a- 

[drapo]

Or.... I could wait for TT/BK...

[carusoam]

Patience... How much do you have?

If we were patient people... would we still fly Mooneys..?

Speed

Efficiency

Safety

Quality of build

Go Mooney!

-a- 

[drapo]

14 minutes ago, carusoam said:

Patience... How much do you have?

If we were patient people... would we still fly Mooneys..?

Speed

Efficiency

Safety

Quality of build

Go Mooney!

-a- 

Lots of patience, been with the same lady for almost 40 years, still can’t handfly her and could use an autopilot 

 

[Yetti]

probably should pick up some Fram G12 filters to replace that filter and some vacuum tubing from the same store.

[Hector]

So when you say you are having problems with the AP can you describe the issue? Is your wing leveler working and you are just having trouble with the Accutrack? If only the Accutrack is having issues what is it doing?


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[drapo]

Everything seems to work Ok, including the PC and the manual Turn control. When it is on Accutrak, it will leave the selected track on a left turn after a a few minutes, as if the servo or the input gets tired of figtiing the stronger right side.  

I was planning on recalibrating the servo control valve at next annual but found this damaged tubing and was wondering if it had anything to do with it.

[SSimpson77]

7 hours ago, drapo said:

Everything seems to work Ok, including the PC and the manual Turn control. When it is on Accutrak, it will leave the selected track on a left turn after a a few minutes, as if the servo or the input gets tired of figtiing the stronger right side.  

I was planning on recalibrating the servo control valve at next annual but found this damaged tubing and was wondering if it had anything to do with it.

Sounds like the same issue I’m having with my accutrak. I also found the same hose cracks along the servo lines and gyro lines. It’s hard to find the exact size hose. Chief aircraft had some stuff, thinner wall but snug fit to fittings. National aviation parts association had some small vacuum line that felt like it would collapse under 5” of vacuum. Went with the Chief stuff. I figured it’s something in my rigging that I need to correct before checking gyro. When I press the DC button on yoke, my plane has a slight tendency to bank/turn left. 
 

[MBDiagMan]

On 8/3/2020 at 8:38 PM, drapo said:

Or.... I could wait for TT/BK...

I hope you’re young.  I’m 71 years old and my family has a history of living to the age of 90.  If I make it that long, it won’t be long enough to see the TT approved.

[Hector]

Everything seems to work Ok, including the PC and the manual Turn control. When it is on Accutrak, it will leave the selected track on a left turn after a a few minutes, as if the servo or the input gets tired of figtiing the stronger right side.  

I was planning on recalibrating the servo control valve at next annual but found this damaged tubing and was wondering if it had anything to do with it.

Check all the hoses and replace them but it does sound like the servo control valve may need overhaul.


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[MBDiagMan]

If the unit needs overhaul there’s an outfit in Tulsa, Pierce and Strait I think is their name that does a great job.  You can look them up or call Britain for contact information.

[outermarker]

Sounds like a leak either in the opposite servo or line.