Positive Control rolls the airplane

[zaitcev]

Apparently, nobody used PC on my airplane for many years. The valve button on the yoke is held down by a little flip bracket. Yesterday, I decided to test what's going to happen if I turn it on by releasing the button. The result is, airplane rolls to the right gradually. I only had the cookies to let it roll to about 45 degrees, but it showed no signs of stopping. The T&B indicated a turn properly.

Is this something that I should ask my mechanic to investigate, or should I identify a specialist option? In an older thread on the topic someone suggested contacting Brittain of all people.

[Yetti]

probably a leaking line to the servo or leaking servo

one of these could help trouble shoot.  You are looking for Green red and blue tubing

 

[Yetti]

There is a test sequence for on the ground.  Do you have the POH supplement?

[Ron McBride]

Test on the ground, the yoke will turn the opposite direction as the plane is turning.

You probably need the servos repaired/replaced.   Lasar will have them.

Ron

 

[rakesb]

Did the roll-trim knob/valve have any effect on the roll? Had the PC system on my C rebuilt when I bought it in 2013. Really like it. Try this link for a manual (not sure if it's the correct version for you):

http://67m20e.com/Manual No. 11990 Mooney PC Operation and Service Instructions.pdf

[Guitarmaster]

It will probably be a fairly easy and reasonably inexpensive fix . I rebuilt my entire PC system for about $370. It's a little bit time consuming running all of the new tubing, but well worth the time
The folks at Brittian Industries are outstanding! Don't be afraid to call them and ask them questions . they're very reasonably priced and very willing to help!

Sent from my XT1585 using Tapatalk

[Hank]

1 hour ago, N803RM said:

Test on the ground, the yoke will turn the opposite direction as the plane is turning.

You probably need the servos repaired/replaced.   Lasar will have them.

Ron

 

Brittain rebuilt a leaky with good servo for  example in 2010 for $124 plus shipping. They are great people, and very easy to work with.

Before pulling a servo or checking for leaks, did you turn the adjustmental knob on your Turn Coordinator?

[HRM]

Somewhere here in the Mooney Space I posted my story of a fabled, revered master-Mooney-A&P/IA replacing an aileron servo on my PC on the tarmac in front of his maintenance hangar at KGGG.

Not something i would want to do, but most likely what is wrong with your system. With patience and skill, a relatively easy fix for something that you will love having. I recall a CFI saying to me after we had been in the air for an hour, "You have remarkable rudder skills." It wasn't me, it was the PC 

[Yetti]

The story from Brittain is that the left (red) tubing seems to go away faster than the right (green)wing tubing

[MyNameIsNobody]

Call Brittain. They will be able to give guidance on trouble shooting. It is their system and their servos. I do not know why you would call Laser when you have the specialist on these systems in Tulsa. Get that fixed. Should not cost a lot even if replacing all servos

[Andy95W]

10 minutes ago, MyNameIsNobody said:

Call Brittain. They will be able to give guidance on trouble shooting. It is their system and their servos. I do not know why you would call Laser when you have the specialist on these systems in Tulsa. Get that fixed. Should not cost a lot even if replacing all servos

+1.

LASAR is great, but in this case Brittain will be a bigger help.

[carusoam]

Zaitcev,  Expect some confusion going forwards... 

1) Prepare to get good support from Britain...

2) not pay a lot

3) have a wing leveler that works

4) have a system that is capable of upgrades

5) look for things like a panel mounted switch to keep from holding the button down.

6) look for the other boxes that allow for following a heading or nav radio...

7) expect to buy some tubing and tape to get over most issues.  Some rubber parts may be a bit more tricky...

You may want to become familiar with the usual box part numbers and names...

Britain has a website..  

http://www.brittainautopilots.com/products-services.html

Siri constantly respells the company name, apparently incorrectly...

Best regards,

-a-

Edited June 5, 2017 by carusoam

[Heloman]

Mine didn't work when I bought it, found a hose on the turn coordinater had worn  out and got loose on the fitting. Pulled it off, cut an inch off, put it back on and works great! Start by doing a look over, might be something simple.

[Bob_Belville]

+1 to all the above. The Brittain PC is great and the repair costs resemble lawn mower repair shops more than aviation.

As I understand it, Mooney added the PC system quite early on (1965?) because our relatively sleek birds can get away from us in a hurry compared to the Cherokees and Skyhawks pilots were coming out of.

[Dream to fly]

Not hijacking the thread but would like to know what controls would I need to have the Brittan PC fly headings?  I have one with new servos but I never use it.  I keep the button held in.  I'd like to upgrade it.

[Bob_Belville]

1 hour ago, Dream to fly said:

Not hijacking the thread but would like to know what controls would I need to have the Brittan PC fly headings?  I have one with new servos but I never use it.  I keep the button held in.  I'd like to upgrade it.

IMNSHO, you need to give the PC a chance. Fly a heading? Just roll to the heading and let go. If it drifts use the trim knob to trim. You'll have to keep an eye on the heading and adjust from time to time but it is far better than nothing and you can look away for 30 seconds w/o finding yourself in a 30 degree bank.

But the heading system upgrade Brittain made is called Accu-Flite.

http://www.brittainautopilots.com/heading-pre-select.html

 

[Shadrach]

On June 4, 2017 at 6:49 PM, zaitcev said:

Apparently, nobody used PC on my airplane for many years. The valve button on the yoke is held down by a little flip bracket. Yesterday, I decided to test what's going to happen if I turn it on by releasing the button. The result is, airplane rolls to the right gradually. I only had the cookies to let it roll to about 45 degrees, but it showed no signs of stopping. The T&B indicated a turn properly.

Is this something that I should ask my mechanic to investigate, or should I identify a specialist option? In an older thread on the topic someone suggested contacting Brittain of all people.

It is leaking somewhere, no one here can tell you where.  Before you start making calls and involving folks that aren't able to put their eyes and hands on your plane, check all of the hoses. Yes the hoses that run through the airframe are red and green, but there are vacuum hoses behind panel that could cause your symptoms and they are not color coded. Start at the rear of your TC and work your way through the system.  On a side note, these hoses rarely get checked by none Mooney specific shops. They are a bitch to get to, but it's only two hour job to replace them at the most.  They will continue to hold vacuum even when in horrendous shape, until they fail.  I've seen them in such bad shape that when stretched slightly they look like a black rubber band with chunks of dirt stuck to it. The hard lines (green and red) rarely fail unless damaged during mx.

Edited June 10, 2017 by Shadrach

[Yetti]

4 hours ago, Dream to fly said:

Not hijacking the thread but would like to know what controls would I need to have the Brittan PC fly headings?  I have one with new servos but I never use it.  I keep the button held in.  I'd like to upgrade it.

Accutrac II and 2 wires to the CDI or HDI with heading bug and +- 5volt output

[zaitcev]

7 hours ago, Shadrach said:

It is leaking somewhere, no one here can tell you where. (...) Start at the rear of your TC and work your way through the system.

I was afraid that would be the answer. I presume I cannot just go to the nearest AutoZone and cut 20 ft off a spool of vacuum hose?

[Shadrach]

57 minutes ago, zaitcev said:

I was afraid that would be the answer. I presume I cannot just go to the nearest AutoZone and cut 20 ft off a spool of vacuum hose?

Call LASAR, they have it and it is inexpensive.

LASAR Parts
(Parts orders only)
(707) 263-0581 or
(800) 954-5619