PC gyro, need advice on servicing

[Joshua Blackh4t]

So while I wait for my prop overhaul, I'm taking another go at my PC system.

I have read a lot of the literature and manuals on here, so I know I should be approaching it with a vacuum guage and vacuum source, but for now I just want to see if I can make it work and then fine tune it later.

The vacuum system works because the roll trim works, its just the gyro won't spin up. Its the remote head version so no instrument to check the gyro.

So here are my questions:

Should the gyro by lubricated? Last time I tried to get it working i put some acf 50 on the bearing, maybe it has too much resistance?

Is it possible that its the disconnect switch? I know there is some vaccum there because i can feel it on the air filter intake, but maybe not enough flow.

The filter was disconnected when I bought the plane, so maybe dirt or insects got in. Can the switch be blown out with compressed air?

I plan to connect it to a vaccum cleaner and see if it spins. Then clean up the bearings and see if it spins faster. Then put it back together and hope for the best. 

 

Thanks,

Joshua

 

[takair]

22 minutes ago, Joshua Blackh4t said:

So while I wait for my prop overhaul, I'm taking another go at my PC system.

I have read a lot of the literature and manuals on here, so I know I should be approaching it with a vacuum guage and vacuum source, but for now I just want to see if I can make it work and then fine tune it later.

The vacuum system works because the roll trim works, its just the gyro won't spin up. Its the remote head version so no instrument to check the gyro.

So here are my questions:

Should the gyro by lubricated? Last time I tried to get it working i put some acf 50 on the bearing, maybe it has too much resistance?

Is it possible that its the disconnect switch? I know there is some vaccum there because i can feel it on the air filter intake, but maybe not enough flow.

The filter was disconnected when I bought the plane, so maybe dirt or insects got in. Can the switch be blown out with compressed air?

I plan to connect it to a vaccum cleaner and see if it spins. Then clean up the bearings and see if it spins faster. Then put it back together and hope for the best. 

 

Thanks,

Joshua

 

Kevin Westbrook from Brittain recently overhauled mine for a very reasonable price.  I would not lube it…myself.  You don’t want lube moving to the vacuum pump.  Which gyro do you have, remote or panel mount?  PM me if you need Kevin’s number.  Regarding the switch, it depends which variation you have.  Do you have the pneumatic switch or electric solenoid?  They both have their own failure modes.

[Joshua Blackh4t]

Thanks, too far to send from Australia, especially since i'm considering a trutrak.

Remote gyro (so if it fails nothing is affected) and pneumatic switch.

Good point with the vacuum pump and lube

[0TreeLemur]

16 minutes ago, Joshua Blackh4t said:

Thanks, too far to send from Australia, especially since i'm considering a trutrak.

Remote gyro (so if it fails nothing is affected) and pneumatic switch.

Good point with the vacuum pump and lube

Why not ship it?   Pack it well and send it through the post.   When I lived in Australia, I'd get letters from the States with only domestic postage within a week.  Everything goes by air. 

[MBDiagMan]

Can’t remember the name of the shop in Tulsa that did mine, but it was “xxxx and Strait.”  They did a great job and it wasn’t crazy expensive.

[Jcmtl]

1 hour ago, Joshua Blackh4t said:

Thanks, too far to send from Australia, especially since i'm considering a trutrak.

Remote gyro (so if it fails nothing is affected) and pneumatic switch.

Good point with the vacuum pump and lube

Do you mean the gyro in the turn coordinator that drives the PC?   If so, i have one i just took off my plane i can send you, you just pay the shipping.  it was working perfectly.

[David Lloyd]

If a remote gyro for the PC, it must be a 1965 model, all other years use a T&B made for use with the PC.  Helpful to know the year and s/n.

Make sure the gyro is getting vacuum.  If it is, is the gyro spinning?  Seems like the Service Manual has a step-by-step trouble shooting guide.

[DCarlton]

5 hours ago, MBDiagMan said:

Can’t remember the name of the shop in Tulsa that did mine, but it was “xxxx and Strait.”  They did a great job and it wasn’t crazy expensive.

http://www.porterstrait.com

[Joshua Blackh4t]

5 hours ago, Jcmtl said:

Do you mean the gyro in the turn coordinator that drives the PC?   If so, i have one i just took off my plane i can send you, you just pay the shipping.  it was working perfectly.

Thanks, its the earlier version with a separate gyro so that wouldn't help me. Much appreciated though.

[Joshua Blackh4t]

Its a 1965 M20E.

So the thing is that "Make sure the gyro is getting vacuum" isn't as easy as it sounds. I need the engine running to check anything and that gets dangerous.

There is only the disconnect switch between the gyro and the vacuum line that drives everything. So if the switch isn't blocked, then its getting vacuum.

The gyro vacuum isnt disconnected by the switch (as far as I know) so it shouldn't be a switch problem.

I don't want to ground the plane for long enough to send things overseas. I'm not too worried about it, long term plan is an autopilot.

The other option is look for another remote gyro and switch, there should be a few of them around.

I just wondered if anyone had any experience with servicing the gyro. There is nothing to them so I thought someone might have done it. 

 

[takair]

7 hours ago, MBDiagMan said:

Can’t remember the name of the shop in Tulsa that did mine, but it was “xxxx and Strait.”  They did a great job and it wasn’t crazy expensive.

Kevin Westbrook does their Brittain stuff…

[takair]

55 minutes ago, Joshua Blackh4t said:

Its a 1965 M20E.

So the thing is that "Make sure the gyro is getting vacuum" isn't as easy as it sounds. I need the engine running to check anything and that gets dangerous.

There is only the disconnect switch between the gyro and the vacuum line that drives everything. So if the switch isn't blocked, then its getting vacuum.

The gyro vacuum isnt disconnected by the switch (as far as I know) so it shouldn't be a switch problem.

I don't want to ground the plane for long enough to send things overseas. I'm not too worried about it, long term plan is an autopilot.

The other option is look for another remote gyro and switch, there should be a few of them around.

I just wondered if anyone had any experience with servicing the gyro. There is nothing to them so I thought someone might have done it. 

 

I’ve made an attempt to get one going before going to Kevin.  It would not spin up. In my case he had to replace the impeller with one he had on the shelf.  There is an adjustment on the inlet line that changes the flow.  You set it up with a differential pressure gage.  What I found was that it is set and forget, so if it needs adjustment something is likely bad…like the bearings.  They are very reliable so an option might be to get a used one off of eBay…perhaps there is one closer to you.  

[Joshua Blackh4t]

3 minutes ago, takair said:

I’ve made an attempt to get one going before going to Kevin.  It would not spin up. In my case he had to replace the impeller with one he had on the shelf.  There is an adjustment on the inlet line that changes the flow.  You set it up with a differential pressure gage.  What I found was that it is set and forget, so if it needs adjustment something is likely bad…like the bearings.  They are very reliable so an option might be to get a used one off of eBay…perhaps there is one closer to you.  

Thanks,

Yeah, I was thinking it would be set right, so just freeing up what is blocked or not working.

It was sitting for a long time before I bought it. When I pulled it apart the first time, the gyro was very stiff (in gyro terms, not in normal terms) but the bearings feel good. It turns, but not fast enough.

My main question is whether it should be lubricated or not. Maybe the small amount of acf 50 is enough to stop it spinning.

I've been keeping an ear open for any, but haven't seen one for sale.

I'd email the service centre, but I don't want to bother a shop that I don't intend to buy anything off. Thats unfair on them.

[takair]

12 minutes ago, Joshua Blackh4t said:

Thanks,

Yeah, I was thinking it would be set right, so just freeing up what is blocked or not working.

It was sitting for a long time before I bought it. When I pulled it apart the first time, the gyro was very stiff (in gyro terms, not in normal terms) but the bearings feel good. It turns, but not fast enough.

My main question is whether it should be lubricated or not. Maybe the small amount of acf 50 is enough to stop it spinning.

I've been keeping an ear open for any, but haven't seen one for sale.

I'd email the service centre, but I don't want to bother a shop that I don't intend to buy anything off. Thats unfair on them.

I suspect (but can not confirm) they use a fine watch oil in the bearings, very small amount.  As I recall, the indication of a good one is a a spin down of over two minutes.  As a test, you can open up the rate adjustment (count the turns) and see if it is better.  I think there is also an adjustment of the “jet”.  This is simply the inlet tube and how close it comes to the impeller.   As you indicated, the switch should not have an affect on the gyro spool.  

[Guest]

3 hours ago, Joshua Blackh4t said:

Thanks,

Yeah, I was thinking it would be set right, so just freeing up what is blocked or not working.

It was sitting for a long time before I bought it. When I pulled it apart the first time, the gyro was very stiff (in gyro terms, not in normal terms) but the bearings feel good. It turns, but not fast enough.

My main question is whether it should be lubricated or not. Maybe the small amount of acf 50 is enough to stop it spinning.

I've been keeping an ear open for any, but haven't seen one for sale.

I'd email the service centre, but I don't want to bother a shop that I don't intend to buy anything off. Thats unfair on them.

I believe that I have a few of these in a box at my shop.  I can see if they spin up when I get back to work next week.

[McMooney]

5 hours ago, takair said:

Kevin Westbrook does their Brittain stuff…

Kevin is awesome, btw.  talked me thru a number of pc problems.

[Joshua Blackh4t]

Thanks for all help and offers, if I have no luck I will be asking to buy things.

Here's the update:

So, for a vacuum source i used.... a vacuum cleaner. To measure its suction i attached a bit of clear tube and put it into water. The vacuum sucked it up about a foot (only a battery powered vacuum) so by my calculations just under an inch of mercury.

The plane runs at about 5 inches, so 1 inch is low but it should make it work.

Connected it and it couldn't make it spin.

Pulled it all apart, cleaned it all with carb cleaner, and put it back together. I assembled it looser than I 'normally' would and no lube.

Connected it and....... it started spinning.

Not only spinning but if i tilted it, the p.c. valve was moving. Yay.

On approx 1 inch of mercury it took over 2 minutes to spin down, so here's hoping

Now I'll need a rubber band to hold down the p.c. button..... cheapest part on the plane.

Will update it when i get my prop back and can test it out.

Thanks again

[David Lloyd]

Vacuum cleaner?  I won't laugh.  Did the same thing over 40 years ago.  My home vacuum would only pull 3" also.

[gmonnig]

I'll be removing my gyro and valves out of my '65 M20E in the next month (it's a working unit). If you don't have any luck, let me know and I can send you some parts... 

[carusoam]

Note:

My 65C also had the gyro in the tail…

It worked…

You could tell it was working… by listening as you got out of the plane after shut-down….

That and the TnB gyro are very loud…

I sent my TnB in for service when I first got the plane…. They sent it back with a note and no charge….   
 

Best regards,

-a-

[gmonnig]

On 8/11/2022 at 5:00 AM, Joshua Blackh4t said:

Thanks for all help and offers, if I have no luck I will be asking to buy things.

Here's the update:

So, for a vacuum source i used.... a vacuum cleaner. To measure its suction i attached a bit of clear tube and put it into water. The vacuum sucked it up about a foot (only a battery powered vacuum) so by my calculations just under an inch of mercury.

The plane runs at about 5 inches, so 1 inch is low but it should make it work.

Connected it and it couldn't make it spin.

Pulled it all apart, cleaned it all with carb cleaner, and put it back together. I assembled it looser than I 'normally' would and no lube.

Connected it and....... it started spinning.

Not only spinning but if i tilted it, the p.c. valve was moving. Yay.

On approx 1 inch of mercury it took over 2 minutes to spin down, so here's hoping

Now I'll need a rubber band to hold down the p.c. button..... cheapest part on the plane.

Will update it when i get my prop back and can test it out.

Thanks again

Any luck on your autopilot? I have the entire system out of my plane now and will have it listed on here as soon as it'll let me post an ad (I donated to Mooneyspace but can't post yet). I was hoping to post it here before letting it go on eBay. I have the BI-805 servo control valve, the gyro, four bellows, heading computer and all connectors. It was working well and connected to my Garmin 650. 

[Joshua Blackh4t]

40 minutes ago, gmonnig said:

Any luck on your autopilot? I have the entire system out of my plane now and will have it listed on here as soon as it'll let me post an ad (I donated to Mooneyspace but can't post yet). I was hoping to post it here before letting it go on eBay. I have the BI-805 servo control valve, the gyro, four bellows, heading computer and all connectors. It was working well and connected to my Garmin 650. 

Thank,

I got it working, I only had a chance to test it this weekend and all seemed to work.

However.... the thought of adding a heading control is amazing.

How much do you want for it? Can you post pics of what head unit it is?

Also, what did you replace it with?

 

[gmonnig]

Honestly, I'm not sure what it'll all go for. I want to sell it all together because the 65' Mooney autopilot is a unique beast. I removed it in preparation for the Garmin GFC500. That process is starting next month with my first round of avionics. The bellows work great with no leaks too. Here's some pics.

[carusoam]

1 hour ago, gmonnig said:

will have it listed on here as soon as it'll let me post an ad (I donated to Mooneyspace but can't post yet)

Looks like you have access…. Because, I can see your supporter badge shining away!

The access usually takes time, because it is a manual process….

The full Brittain system is greatly appreciated by many…

Its amazing how well it works…

Best regards,

-a-

[gmonnig]

Here it was in the center stack before everything started to get taken out.