Positive Control Cutout??

[BillC]

Gentlemen,

A friend has a 1970 M20C. He is unhappy with the positive control. Most of his flying is maneuvering to local airports and the need to keep the button pressed is wearing on him. Especially when he would like to let the right seater fly without having to hold the button the whole time. He would like to keep the system operational so it can be used on the occasional cross country. I am unfamiliar with the system but am an A&P and would like to help him out.. Is there a way to disconnect the system temporarily without using the button? Maybe someone has added a valve to cut off the vacuum supply? I'm planning on flying the airplane this coming week and wanted to get a heads up before I go there.

Thanks for your input.

Bill

[takair]

There were two versions. The early ones, like my 64 used a vacuum relay. The button in the yoke simply created a leak to disable the system when you pushed it. To disable, you simply remove the button ( don't lose it though!!!). If you have the solenoid you may be able to wire in a master switch to do a similar thing. Old timers used to use a film canister over the button to keep it depressed, hard to come by these days. Perhaps a strip of Velcro would be a modern equivalent. I have personally just become accustomed to pushing it and remove the button if someone wants to fly from the right seat. The only awkward moments are when you want to hit the PTT at the same time, or worse yet, you push PTT instead....

[Hernan]

I used a thick rubber band to keep the bottom depressed, when I want to used the PC, I simply sliced the rubber band down. Simple and uncomplicated .

[Andy95W]

On my first Mooney (67 C) I installed a Bob Fields Inflatable Door seal pneumatic switch. Looks like a normal toggle switch and allows you to turn it on and off like it was electric, but when engaged the pushbutton on the yoke still works. Install it off the same line that goes to the yoke switch in series.

Not sure how legal that was, but it was a very elegant and effective solution.

[Seth]

I used a thick rubber band to keep the bottom depressed, when I want to used the PC, I simply sliced the rubber band down. Simple and uncomplicated .

Exactly what I did when I had my M20F.

You can indeed create a disconnect however - call Brittain in Oklahoma and they'll sell you the part needed and talk you through the install process. It was too expensive for me when all I needed was a few thick rubber bands. Always keep an extra rubber band should the primary one snap.

-Seth

[N601RX]

If you use a pneumatic valve, it has to be one that will disconnect the vac from the pc system and also vent the pc system. A simple on/off will not work. If I remember correctly, If you already have the Brittain electric solenoid then a normally on switch will accomplish what you want to do.

[yvesg]

Look at this picture. A small shaped metal flap is rotated ON the button to keep it depressed... works perfect.

Sorry picture is reversed.

Yves

[Marauder]

Look at this picture. A small shaped metal flap is rotated ON the button to keep it depressed... works perfect.

Sorry picture is reversed.

Yves

You acrobatic pilots...

[Hank]

I like the PC, and almost never hit the button [unless someone is flying from the right]. I almost always use one of the two Brittain autopilots, AccuTrac or AccuFlight [whichever one is driven from the DG]. The extra resistance in the pattern is my reminder to not overbank.

 

The rubber band trick works, too. Try a fat one like from a bunch of broccoli.

[BillC]

Thanks for the reponses. I told my friend about the elastic band option. He thought it was brilliant! I guess we have a winner.

Thanks for all your input.

Bill

[takair]

Thanks for the reponses. I told my friend about the elastic band option. He thought it was brilliant! I guess we have a winner.

Thanks for all your input.

Bill

He should be sure to find an expensive elastic band to stay in the spirit of aviation. A standard Walmart version just won't cut it. I wonder if there is a market for PMAd cut-off bands. :-)

[Marauder]

Thanks for the reponses. I told my friend about the elastic band option. He thought it was brilliant! I guess we have a winner.

Thanks for all your input.

Bill

The fat ones that you find on some vegetables are perfect...

[scottfromiowa]

The fat ones that you find on some vegetables are perfect...

and Broccoli for your Mark 21 maintenance

[BillC]

I just got a call from the owner. He tried the elastic band trick and loves it!! He used one from a bunch of broccolli as Hank suggested.

Thanks again,

Bill

[carusoam]

Go MooneySpace!

Good thing they still grow broccoli, because the 35mm film canister is getting harder to come by...

Best regards,

-a-

[Hank]

I just got a call from the owner. He tried the elastic band trick and loves it!! He used one from a bunch of broccolli as Hank suggested.

Thanks again,

Bill

That's about the best use I've found for broccoli!