Remove central vacuum filter and plumbing

[KB68M20F]

Fellow Mooney owners, I am installing 2 G5s to replace the vacuum driven attitude indicator(AI) and directional gyro(DG). While pondering the parts manual diagrams and other documents, it appears that the central vacuum filter will no longer be necessary, and can be removed. After this install there will be only the Brittain turn coordinator/PC system and retractable step left on the vacuum system. The turn coordinator has two filters attached to it. I assume that one is for the PC servo air and one for the vacuum portion of the turn coordinator, although I have no diagrams or documents to substantiate this. Cecilia from Brittain Industries sent me some very informative docs but none which explain the inner workings/plumbing  of the turn coordinator itself. An overhaul manual would probably have this information if anyone has one. If the turn coordinator filters it’s own air, and the PC system has no airflow, only negative pressure, the central vacuum filter is unnecessary. On my aircraft (68F), the 2 connections that come off the vacuum regulator go to the AI and DG, with a T connection in both of those lines in which one goes to the pilot valve, the other to the primary vacuum bib of the turn coordinator. When the G5s are installed I intend, unless otherwise enlightened, to remove all plumbing associated with the AI/DG including the lines that go from those instruments to the central vacuum filter. Then the pilot valve and turn coordinator primary vacuum lines will be connected one each to the 2 bibs on the vacuum regulator. Since this install involves other radios I don’t feel this is the time to put in an upgraded autopilot, and the PC system is actually working good. Does anyone have any comments positive or negative? I have searched the forum and not found anything on this particular issue, although I may have missed it. Thanks for your time!

[carusoam]

When going to the next level, there is an electric alternative for the step as well... See Takair for info on that...

question, isn’t the TC electric for being a back-up to the old vac instruments?

The part of this special TC that is vacuum, is driving the PC...

Earlier Mooneys, like the 65C had an additional gyro in the tail to drive the PC.  The modified panel mount TC came later...the 65C had a smallish TnB indicator, so a TC was quite an upgrade...

Best regards,

-a-

[KB68M20F]

Cecilia from Brittain sent me the overhaul manual for my PC/turn coordinator which does state that the TC is both electric and vacuum powered. She also mentioned that the 2 filters it has, p/n 123-002-002, are actually a Fram G12 fuel filter with the bib cut off. Interesting...They are currently unavailable from Brittain while they undergo reorganization. Thanks for the electric step info!

KB

[carusoam]

Cecilia has been a great resource for the Brittain customers... they lost a key person in their small business recently... but, it looks like Cecilia might be able to hold the reigns...

Best regards,

-a-

[Ragsf15e]

Interesting that your 68F has a retractable step... my 68F has a fixed step.  Sn 68-0164.  2xG5s would mean my vacuum sys is gone completely.

[M20F-1968]

My 68F also has a retractable step.

John Breda

[Ragsf15e]

Huh, wouldn’t have thought they would change that mid year, but don’t think mine has been mod’d.  Guess they did what they want, when they wanted to!