Brittain Autopilot Systems

[carusoam]

@211º Ross is looking for you...^^^^

-a-

[Vance Harral]

Installation of altitude hold components varies by make and model.  There are actually three "boxes": the pitch damper, the altitude hold control unit, and the altitude reference chamber.  Often all three are bundled together such that they look like just one or two boxes, but they are three units.

In our 1976 M20F, the pitch damper and altitude hold control unit are in the front of the airplane, just behind the firewall with the avionics; but the altitude reference chamber is in the tail.  I'm not sure why ours is installed that way, might be as simple as lack of space.

[cliffy]

I was told by Jerry years ago that in Mooneys mounting the entire system in the tail can lead to oscillations because of fluctuating pressure in the tail cone. He much preferred mounting forward of the instrument panel.  

[carusoam]

Jerry Manthey?

A great resource.

Best regards,

-a-

[Browncbr1]

On 5/7/2019 at 9:54 PM, 211º said:

From talking to Jerry a long time ago, I think that the altitude chamber and trim chamber are the two black boxes that are stacked in the tail cone. Mine (and many) have CCW and CW marked on them. But alas, I do not know which is which.

In that same conversation, Jerry noted that the altitude hold sometimes wouldn’t work too well because pilots can still descend with the altitude hold on... just over power the system like we do when turning without pushing the yoke button. That descent without turning the altitude hold off stretches the two diaphragms.

After looking at the pictures it looks like the altitude hold is the one on the bottom.

The altitude reference chamber is not in this photo.  That is the brain box and the diaphragm box.   One of the tiny latex tubes from the brain box goes to the reference chamber.   The reference chamber is literally just a totally enclosed aluminum box that has a single hose fitting for the small latex tube to connect to.   You could literally make a reference chamber using pvc pipe with end caps and a hose connection.  Almost always, no one knows what it is or what it does, so usually it is not included when people are selling a ‘complete alt hold” setup.   99% of people selling alt hold setups don’t include this critical component.  

[Taifun]

Hello,

I just detected this topic, and hope that I can get some help from you

The TC100-12EVS in our M20C is inop since yesterday. And I'm searching for a spare part and or where I can get the device overhault ?

I already contact Brittain Industries in Tulsa, and LASAR, but I will be thankfull for every additional informations or hints.

Thank you in advance
Christoph

 

[carusoam]

Welcome aboard Christoph!

The turn coordinator can be OH’d...

Let’s see if there are any recommendations for who to use...

See if this helps any...

https://mooneyspace.com/search/?q=Tc100&quick=1

Best regards,

-a-

 

[takair]

Reviving this thread.  Recently came across a complete altitude hold system and will be installing in my old bird.  Does anybody have pictures of the aft elevator servo installation?  There are variations in the documents and I don’t have the referenced Mooney bracket.  Also, for those with the altitude modules all mounted in the back of the aircraft, how well does it work?  I don’t think I have room for another thing up front and there is some suggestion Above that It does not work as well n the tail cone.

[HRM]

5 hours ago, takair said:

Reviving this thread.  Recently came across a complete altitude hold system and will be installing in my old bird.  Does anybody have pictures of the aft elevator servo installation?  There are variations in the documents and I don’t have the referenced Mooney bracket.  Also, for those with the altitude modules all mounted in the back of the aircraft, how well does it work?  I don’t think I have room for another thing up front and there is some suggestion Above that It does not work as well n the tail cone.

I have a complete system installed in my E, but I am not near my hangar, so if you can wait I could send your pictures when I get back.

[takair]

43 minutes ago, HRM said:

I have a complete system installed in my E, but I am not near my hangar, so if you can wait I could send your pictures when I get back.

Thanks.  Not quite ready to start, so not a big rush.  

[Browncbr1]

On 8/8/2020 at 9:42 AM, takair said:

Reviving this thread.  Recently came across a complete altitude hold system and will be installing in my old bird.  Does anybody have pictures of the aft elevator servo installation?  There are variations in the documents and I don’t have the referenced Mooney bracket.  Also, for those with the altitude modules all mounted in the back of the aircraft, how well does it work?  I don’t think I have room for another thing up front and there is some suggestion Above that It does not work as well n the tail cone.

The bracket in the tail is basically a trapezoid that bolts to both sides where the elevator control shafts join.  The bottom of the bracket then attaches to the cables for the up servo and down servo.

The brain mounting bracket is basically a piece of sheet metal that is screwed to the side of the stack of two boxes.  The sheet metal is bent on the bottom so that it wraps around some of the steel tube cage and the top of the sheet is bent away from the boxes so that they can be screwed down to the angle aluminum bulkhead.  The mounting location is on the right side wall behind the panel as far forward and right as possible.  Rerouting scat is probably required.  Oem windshield/inspection panels make install easier to see and understand.   If you take the right inspection panel off and look straight down on the inside wall skin, you can see the angle aluminum bulkhead that the bracket screws to.  There is a hole in the top of the brain box that has a nylon flathead screw deep inside   This is the pitch adjustment that must be adjusted for installation error.  Trim the plane perfectly for straight and level cruise, engage the pitch plunger only  (do not pull the alt hold plunger yet)...   give it a minute or so.   It will command the pitch either up or down if it needs adjustment.   The desired result if the brain box is adjusted correctly is nothing..  it should remain perfectly in trim after pulling the pitch plunger.

 

Run a length of small latex tube to the tail along with the bigger nylon hoses so you can mount the altitude reference chamber back there on the bottom empennage skin.

the reason why many alt hold systems that are installed in the tail don’t work is because the brain box is not oriented correctly.   There is a pendulum in there that senses pitch.  If it is not installed in the correct orientation, then you can imagine the result.   Then, the pitch sensor fights the reference chamber/static sensor.  This is actually the case for the photos above..  the brain was installed on the shelf in the tail with the hose connections pointing forward instead of left.  

All of the hose connections on the brain box should be pointing left  (90 degrees from direction of flight toward pilot side).  The purpose of the adjustment screw at the top of the box is to fine Tune the inner parts as close to perfectly level on the horizon as possible.  If the box is mounted with too much pitch forward or backward, then there won’t be enough fine tube adjustment to compensate.   If you are making your own bracket, or mounting in the tail, I would level the plane, and install using a level on top of the box.

 

Edited August 14, 2020 by Browncbr1

[takair]

3 hours ago, Browncbr1 said:

The bracket in the tail is basically a trapezoid that bolts to both sides where the elevator control shafts join.  The bottom of the bracket then attaches to the cables for the up servo and down servo.

The brain mounting bracket is basically a piece of sheet metal that is screwed to the side of the stack of two boxes.  The sheet metal is bent on the bottom so that it wraps around some of the steel tube cage and the top of the sheet is bent away from the boxes so that they can be screwed down to the angle aluminum bulkhead.  The mounting location is on the right side wall behind the panel as far forward and right as possible.  Rerouting scat is probably required.  Oem windshield/inspection panels make install easier to see and understand.   If you take the right inspection panel off and look straight down on the inside wall skin, you can see the angle aluminum bulkhead that the bracket screws to.  There is a hole in the top of the brain box that has a nylon flathead screw deep inside   This is the pitch adjustment that must be adjusted for installation error.  Trim the plane perfectly for straight and level cruise, engage the pitch plunger only  (do not pull the alt hold plunger yet)...   give it a minute or so.   It will command the pitch either up or down if it needs adjustment.   The desired result if the brain box is adjusted correctly is nothing..  it should remain perfectly in trim after pulling the pitch plunger.

 

Run a length of small latex tube to the tail along with the bigger nylon hoses so you can mount the altitude reference chamber back there on the bottom empennage skin.

the reason why many alt hold systems that are installed in the tail don’t work is because the brain box is not oriented correctly.   There is a pendulum in there that senses pitch.  If it is not installed in the correct orientation, then you can imagine the result.   Then, the pitch sensor fights the reference chamber/static sensor.  This is actually the case for the photos above..  the brain was installed on the shelf in the tail with the hose connections pointing forward instead of left.  

All of the hose connections on the brain box should be pointing left  (90 degrees from direction of flight toward pilot side).  The purpose of the adjustment screw at the top of the box is to fine Tune the inner parts as close to perfectly level on the horizon as possible.  If the box is mounted with too much pitch forward or backward, then there won’t be enough fine tube adjustment to compensate.   If you are making your own bracket, or mounting in the tail, I would level the plane, and install using a level on top of the box.

 

Great info, especially on orientation, mine was going to end up pointing wrong!  I have the bracket that mounts the up units behind the panel, but I have no room and the STC for my plane has it in the back on the shelf.  I’ve made brackets for that already.  I was lucky enough to purchase a very complete Factory kit.  Likely one of the last poor Gerry assembled.  My last major dilemma is how to mount the aft servo itself.  Any chance you have a picture of that?  I have a factory sketch, but it does not give enough detail to reference the exact location....is it adjacent to the rudder bracket?  I have a stormscope antenna that may conflict with the location, the connector sticks up.  

[takair]

I’ve been told before, but the technology alludes me, how does one orient the pictures correctly from an iPad!?

[carusoam]

I usually just wait long enough...

Some hangar fairy comes along and orients them overnight....

Sometimes the HF doesn’t recognize which way gravity is pointing...

Most pics miss by 90° to the left... but sometimes the camera was rotated while getting the pic...

save, edit, rotate, save, upload...

Best regards,

-a-

[0TreeLemur]

1 hour ago, takair said:

Great info, especially on orientation, mine was going to end up pointing wrong!  I have the bracket that mounts the up units behind the panel, but I have no room and the STC for my plane has it in the back on the shelf.  I’ve made brackets for that already.  I was lucky enough to purchase a very complete Factory kit.  Likely one of the last poor Gerry assembled.  My last major dilemma is how to mount the aft servo itself.  Any chance you have a picture of that?  I have a factory sketch, but it does not give enough detail to reference the exact location....is it adjacent to the rudder bracket?  I have a stormscope antenna that may conflict with the location, the connector sticks up.  

 

Great to see that you are doing this.  I've assembled most of the pieces, except for the servos.  Are they the same model used on the ailerons?   Please post some photos when you get it installed and let us know how it works!   I love the PC system with the Accutrak II.  Are you in contact with Brittain?   Are they back in business?

Thanks,

-Fred

[Browncbr1]

Just now, 0TreeLemur said:

Great to see that you are doing this.  I've assembled most of the pieces, except for the servos.  Are they the same model used on the ailerons?   Please post some photos when you get it installed and let us know how it works!   I love the PC system with the Accutrak II.  Are you in contact with Brittain?   Are they back in business?

Thanks,

-Fred

No, the servos are much bigger and with much more travel than the aileron servos. 

[Browncbr1]

1 hour ago, takair said:

Great info, especially on orientation, mine was going to end up pointing wrong!  I have the bracket that mounts the up units behind the panel, but I have no room and the STC for my plane has it in the back on the shelf.  I’ve made brackets for that already.  I was lucky enough to purchase a very complete Factory kit.  Likely one of the last poor Gerry assembled.  My last major dilemma is how to mount the aft servo itself.  Any chance you have a picture of that?  I have a factory sketch, but it does not give enough detail to reference the exact location....is it adjacent to the rudder bracket?  I have a stormscope antenna that may conflict with the location, the connector sticks up.  

Is your installation going into a short body?   

In my F, the aft servo bolted right up to existing structure.  However, I think I may happen to have that aft bracket in your drawing on my parts shelf if you end up needing it.

Btw, I’d you don’t already know, if you climb or let down without having opened the plungers to let the vacuum out of the system, the diaphragms in the brain will stretch and will degrade its ability to hold altitude tightly.  I recommend adding a third plunger as a master pc system on/off unless you want to deal with the thumb button on the yoke.   I did so and used the hole on the yoke for my ptt.

Edited August 14, 2020 by Browncbr1

[takair]

33 minutes ago, Browncbr1 said:

Is your installation going into a short body?   

In my F, the aft servo bolted right up to existing structure.  However, I think I may happen to have that aft bracket in your drawing on my parts shelf if you end up needing it.

Btw, I’d you don’t already know, if you climb or let down without having opened the plungers to let the vacuum out of the system, the diaphragms in the brain will stretch and will degrade its ability to hold altitude tightly.  I recommend adding a third plunger as a master pc system on/off unless you want to deal with the thumb button on the yoke.   I did so and used the hole on the yoke for my ptt.

Yes, short body, E model.  If you have a spare bracket I would purchase from you.  Without drawings Im sure I would fabricate it three times to get one good one.  I had heard and forgotten about the pressure.  I think I will figure out a way to Add a master switch to the system.  The drawings don’t even show it tied to the PC pneumatic solenoid.  Thanks for the tips.  Kind of getting excited to install this now.  I guess I’m one of the few getting more reliant on my vacuum pump, but I really am mesmerized by this design.  For those not aware, there is not a single wire in this altitude hold system.

[takair]

48 minutes ago, 0TreeLemur said:

Great to see that you are doing this.  I've assembled most of the pieces, except for the servos.  Are they the same model used on the ailerons?   Please post some photos when you get it installed and let us know how it works!   I love the PC system with the Accutrak II.  Are you in contact with Brittain?   Are they back in business?

Thanks,

-Fred

Will try to remember pictures.  Feel free to ping me.  Already I can see I need to clean the tail cone, I live with the crud until I post a picture of my mess.  As Browncbr1  mentioned, the servos are very different.  They use more volume, makIng it harder to squeeze in.  Brittain is partially open Cecilia, Gerry’s sister, continues to provide what service she can.  Really first rate, in fact.  She provided written transfer and authorization to use the STC but indicated she could not sell parts at this point.  Really rooting for them.  

[Browncbr1]

3 hours ago, takair said:

Yes, short body, E model.  If you have a spare bracket I would purchase from you.  Without drawings Im sure I would fabricate it three times to get one good one.  I had heard and forgotten about the pressure.  I think I will figure out a way to Add a master switch to the system.  The drawings don’t even show it tied to the PC pneumatic solenoid.  Thanks for the tips.  Kind of getting excited to install this now.  I guess I’m one of the few getting more reliant on my vacuum pump, but I really am mesmerized by this design.  For those not aware, there is not a single wire in this altitude hold system.

Drawings don’t show it connected to pc because it doesn’t connect to the pc side.  The AH connects via a T fitting you will install on the vacuum line separate from PC.   

For the master switch, you can use the plumbing that goes to the yoke button or you could add a T fitting to the main vacuum line after the regulator that goes directly to a plunger valve.  

Edited August 15, 2020 by Browncbr1

[outermarker]

I saw this mounted to the down tube that is next to the nose wheel cavity. The photo needs to be rotated twice to the right so the the air vent is on top. It has a clear hose that is going to the Alternate Air valve via a tee. I have no idea what it is electrically tied to. Is this part of an altitude hold system?

[Andy95W]

That's your Mode C output to your transponder.

[carusoam]

OM,

Twice to the right... 

Hmmm... you have the original fabric side wall there.... I recognize the color...

Best regards,

-a-

[outermarker]

I saw this mounted to the down tube that is next to the nose wheel cavity. The photo needs to be rotated once to the right so the the air vent is on top. It has a clear hose that is going to the Alternate Air valve via a tee. I have no idea what it is electrically tied to. Is this part of an altitude hold system?

[Pasturepilot]

Just now, outermarker said:

I saw this mounted to the down tube that is next to the nose wheel cavity. The photo needs to be rotated once to the right so the the air vent is on top. It has a clear hose that is going to the Alternate Air valve via a tee. I have no idea what it is electrically tied to. Is this part of an altitude hold system?

I think @Andy95W got your answer. Looks like an altitude encoder. Chase that cable and see if it goes to your transponder.