Brittain servo?

[eman1200]

my brittain ap has slowly went from decent enough to starting to wander a bit.  I popped the pilot side cowl panel off and there was one tube that was old and brittle so I replaced it.  oddly enough it was like one of those flimsy flexible tubes heroin users use to tie up their arms with.  not that I really know about that but I watch tv.  visual inspections of the other tubes nearby didn't yield anything that looked out of the ordinary.  anyways, after replacing that one tube, the right side seems pretty solid.  when I turn the accutrak knob to the right it makes a swift standard rate turn, no delay, no complaints.  when I turn it to the left it sloooooooowly starts to turn and never gets to full standard rate.  did I mention it was sloooooow to respond?  I did a visual inspection of the tube starting a couple of inspection panels prior to the servo and up to it, it seems pretty solid.  don't see/feel any cracks, looks ok to me.  I compared the two servos just by pushing on them a little bit, the one on the left def seems a little 'squishier' than the other, but not by any significant amount.  I'm leaning towards trying to replace that servo, unless there are other suggestions to try first.  

 

so if anyone has a solid, working, good condition servo taking up room in their hangar they'd like to get rid of, please hit me up.  all other suggestions welcome as well.  thanks!

 

[Shadrach]

29 minutes ago, eman1200 said:

my brittain ap has slowly went from decent enough to starting to wander a bit.  I popped the pilot side cowl panel off and there was one tube that was old and brittle so I replaced it.  oddly enough it was like one of those flimsy flexible tubes heroin users use to tie up their arms with.  not that I really know about that but I watch tv.  visual inspections of the other tubes nearby didn't yield anything that looked out of the ordinary.  anyways, after replacing that one tube, the right side seems pretty solid.  when I turn the accutrak knob to the right it makes a swift standard rate turn, no delay, no complaints.  when I turn it to the left it sloooooooowly starts to turn and never gets to full standard rate.  did I mention it was sloooooow to respond?  I did a visual inspection of the tube starting a couple of inspection panels prior to the servo and up to it, it seems pretty solid.  don't see/feel any cracks, looks ok to me.  I compared the two servos just by pushing on them a little bit, the one on the left def seems a little 'squishier' than the other, but not by any significant amount.  I'm leaning towards trying to replace that servo, unless there are other suggestions to try first.  

 

so if anyone has a solid, working, good condition servo taking up room in their hangar they'd like to get rid of, please hit me up.  all other suggestions welcome as well.  thanks!

 

Maybe put vacuum to the system before tearing into servos. It could be the head unit, which is likely serviceable by https://www.porterstrait.com

@Kevin Westbrook

[eman1200]

7 minutes ago, Shadrach said:

Maybe put vacuum to the system before tearing into servos. It could be the head unit, which is likely serviceable by https://www.porterstrait.com

@Kevin Westbrook

yeah, I know there are some documents on how to do that, I'll read thru them and figure out how to do that, thanks.

[N201MKTurbo]

My redneck servo troubleshooting method. 
 

There are two plastic tubes that terminate under the panel on the left side. They are red and green. 
 

Take the rubber hose off them one at a time so you don’t mix them up. Put another rubber hose onto the tubes about 2 feet long. 
 

Stick the hose in your mouth and suck as hard as you can until you cannot suck any more air out of the hose. (Your airplane will love you for it) The yoke will turn.

Then stick your tongue on the hose. If the suction persists, your servos are good. If the suction bleeds off, you have leaky servos.

Some suggest using one of those hand operated vacuum pumps from the auto parts store. It will work too, but it is wasted money.

[eman1200]

19 minutes ago, N201MKTurbo said:

My redneck servo troubleshooting method. 
 

There are two plastic tubes that terminate under the panel on the left side. They are red and green. 
 

Take the rubber hose off them one at a time so you don’t mix them up. Put another rubber hose onto the tubes about 2 feet long. 
 

Stick the hose in your mouth and suck as hard as you can until you cannot suck any more air out of the hose. (Your airplane will love you for it) The yoke will turn.

Then stick your tongue on the hose. If the suction persists, your servos are good. If the suction bleeds off, you have leaky servos.

Some suggest using one of those hand operated vacuum pumps from the auto parts store. It will work too, but it is wasted money.

thank you for this.  just to clarify, I'm taking the red tube in the horrible screenshot below, removing it from the connection inside the cowl (which is basically right behind that bundle of white wires), attaching another tube to that tube and sucking?  

 

 

so like this, where the darker red is the additional attached tubing?

 

[N201MKTurbo]

41 minutes ago, eman1200 said:

thank you for this.  just to clarify, I'm taking the red tube in the horrible screenshot below, removing it from the connection inside the cowl (which is basically right behind that bundle of white wires), attaching another tube to that tube and sucking?  

 

 

so like this, where the darker red is the additional attached tubing?

 

Its easier to suck from inside the plane.

 

There is usually black rubber tubing hooked to the plastic tubing. 
 

Unless you have the older system with the gyro in the tail, then you will need to do the suckage in the tail cone.

[N204TA]

If the airplane turns right but not left, the possible vacuum leak is in the green (right wing) side.  The servo pulls the aileron down.

My system recently and suddenly started doing the same thing.  I found the tape sealing the servo boot was dry and coming off.  I wrapped a new piece of black electrical tape around the lip of the boot and I was back in business.

[eman1200]

24 minutes ago, N204TA said:

If the airplane turns right but not left, the possible vacuum leak is in the green (right wing) side.  The servo pulls the aileron down.

My system recently and suddenly started doing the same thing.  I found the tape sealing the servo boot was dry and coming off.  I wrapped a new piece of black electrical tape around the lip of the boot and I was back in business.

it's interesting you say that because I noticed the tape on the LEFT wing looked like it was coming off.  the right side didn't even appear to have tape on it.  might just try to re-wrap both sides. 

[N201MKTurbo]

 My method for wrapping servos with tape.

Get yourself a steel rod, about 1/8 inch in diameter and about 8 inches long. Wrap one end with electrical tape till it is about 7/16 in diameter. Use this tape dispenser to tape up the servos. It will get into tight places and you can put good tension on the tape. You cannot do that with a roll of tape.

[Kevin Westbrook]

Plz call me Kevin Westbrook 539-292-0474 I worked at Brittain lcan trouble shoot and repair your system....I don't think it's a servo it's the servo control valve ty

[eman1200]

here's my servo suckage test

 

[eman1200]

15 minutes ago, Kevin Westbrook said:

Plz call me Kevin Westbrook 539-292-0474 I worked at Brittain lcan trouble shoot and repair your system....I don't think it's a servo it's the servo control valve ty

wow that's generous, I just might do that, thank you.  but you'll have to talk to me like I don't know a single part of the brittain autopilot system because, well, I mostly don't lol

[eman1200]

21 minutes ago, Kevin Westbrook said:

Plz call me Kevin Westbrook 539-292-0474 I worked at Brittain lcan trouble shoot and repair your system....I don't think it's a servo it's the servo control valve ty

so I see this thingamajiggy.....

 

 

is there anything I can do to the unit or does it need a pro to rebuild or something?  I'll try to locate where mine is located over the weekend.

 

[Shadrach]

28 minutes ago, eman1200 said:

wow that's generous, I just might do that, thank you.  but you'll have to talk to me like I don't know a single part of the brittain autopilot system because, well, I mostly don't lol

Kevin is a great resource. I would definitely call him. He will be able to diagnose your problem and get things back in order for a reasonable price. 

[DCarlton]

On 7/25/2024 at 4:35 PM, N201MKTurbo said:

My redneck servo troubleshooting method. 
 

There are two plastic tubes that terminate under the panel on the left side. They are red and green. 
 

Take the rubber hose off them one at a time so you don’t mix them up. Put another rubber hose onto the tubes about 2 feet long. 
 

Stick the hose in your mouth and suck as hard as you can until you cannot suck any more air out of the hose. (Your airplane will love you for it) The yoke will turn.

Then stick your tongue on the hose. If the suction persists, your servos are good. If the suction bleeds off, you have leaky servos.

Some suggest using one of those hand operated vacuum pumps from the auto parts store. It will work too, but it is wasted money.

I thought this thing was great.  Easy to work with and see laying under the panel.  You can pull 6" vacuum and hold it to check for slow leaks; then it has an easy relief valve trigger.  A bit of a luxury but it made the job easier especially if you're working by yourself.    

 https://www.harborfreight.com/mityvac-vacuum-pump-39522.html

[eman1200]

1 minute ago, DCarlton said:

I thought this thing was great.  Easy to work with and see laying under the panel.  You can pull 6" vacuum and hold it to check for slow leaks; then it has an easy relief valve trigger.  A bit of a luxury but it made the job easier especially if you're working by yourself.    

 https://www.harborfreight.com/mityvac-vacuum-pump-39522.html

my .02, which is worth about that, is there is absolutely no need for that or anything mechanical or anything that costs money.  pull tube off, suck on it.  doesn't get any easier.  I was worried about how much suckage it would take.  not much at all.  

[DCarlton]

1 hour ago, eman1200 said:

my .02, which is worth about that, is there is absolutely no need for that or anything mechanical or anything that costs money.  pull tube off, suck on it.  doesn't get any easier.  I was worried about how much suckage it would take.  not much at all.  

It’s the test engineer in me that appreciated being able to pull 6” exactly and hold it.  Why make it easy when you can nuke it.  Would have needed an extension tube anyway to reach the back of the turn coordinator with my organic sucker.  It was a lot easier than building a test rig with a vacuum gage to mimic the Brittain test procedures which I think requires holding a vacuum for an extended period.  And I like tools …  and data.  

[tony]

12 hours ago, Kevin Westbrook said:

Plz call me Kevin Westbrook 539-292-0474 I worked at Brittain lcan trouble shoot and repair your system....I don't think it's a servo it's the servo control valve ty

Kevin,  thank you for offering to help.  That's very nice that you are willing to share your expertise.  What ever happen to the company?  The last time I talked to Cici (years ago), she told me a buyer bought the company and was going to set up somewhere in the carolina's.  I guess that never happened.....