hose for Brittain TC and servo valve?

[AJ88V]

The hoses on the servovalve and related components of my Brittain positive control system are disintegrating.  They look like regular black soft rubber vacuum line and are dry rotted.

Looking at my Brittain manual (Mooney Positive Control Operation and Service Instructions, 11968, Issue C), all the hoses appear to be labeled as 3/8" OD Poly-Flo tubing or 3/16" OD plastic tubing.  None of it appears to be soft rubber vacuum line that's been installed in my place ever since I've owned it.

I'm thinking a prior owner or mechanic just swapped in the rubber tubing.

Anybody have experience with this?   Thanks, AJ

[Echo]

The hard plastic is in wings and sides from tail to cabin.  The rubber is correct on the Brittain turn coordinator.  Itis windshield washer hose and can be purchased on amazon.  I have a photo of it in my Mooney love affair thread with the part number.  It is inexpensive.

Edited Monday at 10:07 PM by Echo

[cliffy]

I was told by Brittian that they use regular  auto vacuum hose from the local PMA isle at Auto Zone

Now mind you this was 20 years ago. 

[AJ88V]

Thanks, gents.  My A&P/IA wanted to get the right stuff, but thought the hard plastic Poly-Flow hose would be a PITA to work with under the panel.  I did say I might go down to the auto parts store and get some regular vacuum hose, and now it sound like that is what I should do.

[Shadrach]

1 hour ago, AJ88V said:

Thanks, gents.  My A&P/IA wanted to get the right stuff, but thought the hard plastic Poly-Flow hose would be a PITA to work with under the panel.  I did say I might go down to the auto parts store and get some regular vacuum hose, and now it sound like that is what I should do.

I was advised by a Brittain employee to use Gates 27073 1/4” ID.  The surgical tube style tubing that I used to buy from LASAR would dry rot inside of five years. It never failed mind you, but it looked terrible. I’m two years into the gates tubing and it’s holding up very well.

[DCarlton]

2 hours ago, Shadrach said:

I was advised by a Brittain employee to use Gates 27073 1/4” ID.  The surgical tube style tubing that I used to buy from LASAR would dry rot inside of five years. It never failed mind you, but it looked terrible. I’m two years into the gates tubing and it’s holding up very well.

I was told Gates 27043 vacuum tubing.  7/32”.  I have a 50 foot spool in the garage.  I’ll admit it seems a touch small, but it doesn’t come off the barbs.  Hard to get on the filters.  

[Shadrach]

10 hours ago, DCarlton said:

I was told Gates 27043 vacuum tubing.  7/32”.  I have a 50 foot spool in the garage.  I’ll admit it seems a touch small, but it doesn’t come off the barbs.  Hard to get on the filters.  

My PC is INOP right now after being trouble free for years. I sent out the T&B for overhaul and replaced all hoses with 27073. It worked ok when returned to service but seemed to favor left turns. It gradually become worse and worse so I disabled it. Perhaps the whole problem is that there was a misfire on the correct tubing. I’m going to replace it all with  27043 this weekend and see if that clears up the problem. You may have just helped me solve the mystery.

[AJ88V]

1 hour ago, Shadrach said:

My PC is INOP right now after being trouble free for years. I sent out the T&B for overhaul and replaced all hoses with 27073. It worked ok when returned to service but seemed to favor left turns. It gradually become worse and worse so I disabled it. Perhaps the whole problem is that there was a misfire on the correct tubing. I’m going to replace it all with  27043 this weekend and see if that clears up the problem. You may have just helped me solve the mystery.

I wonder if this also could be due to the servo valve 'favoring' on direction.

When last working, I had a pretty strong knob setting to the right on mine. Will report back after replacing the hoses.

Thanks all!

[DCarlton]

1 hour ago, Shadrach said:

My PC is INOP right now after being trouble free for years. I sent out the T&B for overhaul and replaced all hoses with 27073. It worked ok when returned to service but seemed to favor left turns. It gradually become worse and worse so I disabled it. Perhaps the whole problem is that there was a misfire on the correct tubing. I’m going to replace it all with  27043 this weekend and see if that clears up the problem. You may have just helped me solve the mystery.

I doubt it's the tubing unless you have a small leak.  There's not much airflow and in my case from the T&B to the green/red junction it's a short run.  Mine seems to have more authority in one direction than the other too (but I can't tell you which way at the moment).  When that happened previously I had a pin hole leak in a rudder servo that became worse with the bellows extended (I think).  I'll ping Kevin and try to verify the hose spec.  I have 27043 written in my many notes.   [I've wondered if P factor has something to do with turn bias. Just grasping for ideas.]

[Echo]

Hmmmm.  My pilot trim on yoke is biased to left.  PC functions great, but The yoke control is NOT centered it has right bias that requires full left rotation of yoke knob.  I just bought a Accu-Flite, Accu-Trak BI-818 D.G. Adapter P/N:280-003-500.  Along with BI-805 (One listed now on Ebay) you could have a functioning directional control with a heading bug dg...I love mine.  Price to good not to buy.

[DCarlton]

10 minutes ago, Echo said:

Hmmmm.  My pilot trim on yoke is biased to left.  PC functions great, but The yoke control is NOT centered it has right bias that requires full left rotation of yoke knob.  I just bought a Accu-Flite, Accu-Trak BI-818 D.G. Adapter P/N:280-003-500.  Along with BI-805 (One listed now on Ebay) you could have a functioning directional control with a heading bug dg...I love mine.  Price to good not to buy.

DG adapters are hard to find!  I'd like to pick up a few spares too.  DG Adapter, Pilot Valve, TC, Servos.  I missed out on the group buy for the servo seals.  Curious if you done a leak test?  

[Echo]

3 minutes ago, DCarlton said:

DG adapters are hard to find!  I'd like to pick up a few spares too.  DG Adapter, Pilot Valve, TC, Servos.  I missed out on the group buy for the servo seals.  Curious if you done a leak test?  

Naw because system works.

[Shadrach]

18 minutes ago, DCarlton said:

I doubt it's the tubing unless you have a small leak.  There's not much airflow and in my case from the T&B to the green/red junction it's a short run.  Mine seems to have more authority in one direction than the other too (but I can't tell you which way at the moment).  When that happened previously I had a pin hole leak in a rudder servo that became worse with the bellows extended (I think).  I'll ping Kevin and try to verify the hose spec.  I have 27043 written in my many notes.   [I've wondered if P factor has something to do with turn bias. Just grasping for ideas.]

I think it may be leaking at higher vacuum levels. It seemed to operate fine on the ground prior to being disabled. In the air I needed full, right roll trim to sustain level flight. 

[DCarlton]

6 minutes ago, Echo said:

Naw because system works.

Full rotation of the knob sounds like you might have something going on.  But if it works, it works. Mine degraded over about two years before I found the leak.  

[DCarlton]

6 minutes ago, Shadrach said:

I think it may be leaking at higher vacuum levels. It seemed to operate fine on the ground prior to being disabled. In the air I needed full, right roll trim to sustain level flight. 

Symptoms sound similar to mine.  I got lucky.  There was a hole in the rudder servo (the one near the battery).  It's fairly easy to isolate and leak test without removal.  

[Echo]

52 minutes ago, DCarlton said:

Full rotation of the knob sounds like you might have something going on.  But if it works, it works. Mine degraded over about two years before I found the leak.  

I will go leak hunting when the system no longer functions.

Edited Tuesday at 04:02 PM by Echo

[Kevin Westbrook]

AJ Kevin Westbrook here what everyone saying about Gates 27023 is correct it's a good replacement for the old latex. It is stiffer than the latex.I worked at Brittain for 40 years if you need to call me 539-292-0474 !

[Echo]

23 hours ago, DCarlton said:

Symptoms sound similar to mine.  I got lucky.  There was a hole in the rudder servo (the one near the battery).  It's fairly easy to isolate and leak test without removal.  

What procedure did you use?  My response was flippant.  I apologize.

[DCarlton]

3 hours ago, Echo said:

What procedure did you use?  My response was flippant.  I apologize.

Not at all.  I did the same thing.  

Procedure:  Pulled the hoses off the Brittain turn coordinator and applied suction to the left and then right vacuum lines (the ones that go to the red and green hard lines that run along the pilot side fuselage).  I used a vacuum pump from Harbor Freight with a built in gage and quick release valve.  Connecting the pump to the hose has to be leak proof; the slightest leak and you'll never pull and hold a 5-6" vacuum.  Tape the connection with electrical tape.  One of my lines leaked and one pulled a steady vacuum without any additional pumping (I think my right one leaked and the right rudder servo is the one by the battery; would have to look it up to verify right or left).  If you identify which side is leaking, you still haven't isolated whether it's a T in the line (T between rudder and wing), a hole in a line, a fitting or a servo seal.  In my case, the rudder servo near the battery was easier to access and test than the wing, so it was tested next.  Plugged the hoses at the turn coordinator; pulled a vacuum first on the rudder servo near the servo.  Got lucky; it was leaking and had a hole in the seal.  Sent it to Kevin to get the seal replaced.  New seals are hard to come by now; they can sometimes be repaired with a rubber patch.  Also, if it's not obvious, when you break the vacuum line connection at the rudder servo, while plugging the hoses at the turn coordinator, you can test the line forward to the T fitting, and wing servo from the same location.  

Just FYI, if you go to the Gates web site, the 27073 hose doesn't appear to exist any longer.  27043 is still a good P/N.  Specs are all over the place on the internet and the various auto parts web sites; IDs, ODs, nipple sizes, some in inches; some in mm.  Plenty of sources for errors and confusion.  

[AJ88V]

Anybody have thoughts on using silicone hosing?  

[AJ88V]

18 hours ago, Kevin Westbrook said:

AJ Kevin Westbrook here what everyone saying about Gates 27023 is correct it's a good replacement for the old latex. It is stiffer than the latex.I worked at Brittain for 40 years if you need to call me 539-292-0474 !

Thanks, Kevin. Very good of you.  Just found the Gates tubing locally.

Question:  My tubes do NOT have clamps on them.  Are they needed?

[DCarlton]

2 hours ago, AJ88V said:

Anybody have thoughts on using silicone hosing?  

The blue stuff with the black liner?  It won't stay on the barbs reliably.  Just FYI, mine doesn't have clamps; with the 7/32 hose, it stays on the barbs very well.  I'm curious about the text book answer too though.  As a data point, Brittain overhauled my system in Tulsa on the ramp when they were still in business.  Although it's been 10-15 years, I don't recall ever seeing clamps on the rubber hose at the turn coordinator.  I think there are spring clamps on the poly tubing along the fuselage.  Would have to look again to be sure.  Again I'm no expert; just an owner of an ole Mooney.  

[AJ88V]

2 hours ago, DCarlton said:

The blue stuff with the black liner?  It won't stay on the barbs reliably.  Just FYI, mine doesn't have clamps; with the 7/32 hose, it stays on the barbs very well.  I'm curious about the text book answer too though.  As a data point, Brittain overhauled my system in Tulsa on the ramp when they were still in business.  Although it's been 10-15 years, I don't recall ever seeing clamps on the rubber hose at the turn coordinator.  I think there are spring clamps on the poly tubing along the fuselage.  Would have to look again to be sure.  Again I'm no expert; just an owner of an ole Mooney.  

I was thinking of the orange solid silicone tubing from Gates, but had the exact same concern that it would slip off the hose barbs.

FWIW, the Brittain manual calls out A-10 and A6 Corbin clamps, which are like the spring hose clamps Chrysler and other car makers use on water lines.  Representative pic below from the Brittain service manual:

[DCarlton]

2 hours ago, AJ88V said:

I was thinking of the orange solid silicone tubing from Gates, but had the exact same concern that it would slip off the hose barbs.

FWIW, the Brittain manual calls out A-10 and A6 Corbin clamps, which are like the spring hose clamps Chrysler and other car makers use on water lines.  Representative pic below from the Brittain service manual:

For clarification, when I said mine had no clamps, I was only talking about the rubber hoses that go to the back of my Brittain TC100EVT turn coordinator; not any of the other hoses.  

[AJ88V]

12 hours ago, DCarlton said:

For clarification, when I said mine had no clamps, I was only talking about the rubber hoses that go to the back of my Brittain TC100EVT turn coordinator; not any of the other hoses.  

Hope to dig into it today.  I only looked from beneath the panel, not from the top through the avionics access panels on the cowling.  Hopefully it will be way easier to get to from the top!!!