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static drain for Instruments SI 20-43


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I have a '67C  which does not have a static drain for the static Instruments installed.  living in the PNW  we see a lot of rain and I have noticed my static instrument mainly Altimeter's hundredth needle oscillate  several hundred feet bouncing up and down while the 2 G5's are rock solid. I a little concern installing a  static sump since I have heard of horror stories were valve didn't shut off  causing  a leak. I was wondering what others thought on this ? 

I did not see where in the SI  where to locate the static drain. does any one know where I might find this information?

Thanks in advance,

 

James  '67C

 

Edited by jamesm
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James,

Two things...

1) You have a dead leg in the static system in the tail, if it is filled with water... a drain is an excellent idea...

2) There are drains for both the static and pitot systems... they can be copied directly from other more modern Mooneys...

 

Like everything else... some maintenance, cleaning and lubricating keeps the parts working really well...

Indoor storage helps a lot too...

PP thoughts only,

Best regards,

-a-

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1 hour ago, jamesm said:

I have a '67C  which does not have a static drain for the static Instruments installed.  living in the PNW  we see a lot of rain and I have noticed my static instrument mainly Altimeter's hundredth needle oscillate  several hundred feet bouncing up and down while the 2 G5's are rock solid. I a little concern installing a  static sump since I have heard of horror stories were valve didn't shut off  causing  a leak. I was wondering what others thought on this ? 

I did see where in the SI  where to locate the static drain. does any one know where I might find this information?

Thanks in advance,

 

James  '67C

 

Think of it this way--if you install a static drain, and it leaks, you will could have a small error in you altimeter and a small error in your wallet when you do your IFR cert at the shop.  If you have water in your static system, you could have a large error in your altimeter, and a large error in your life insurance after flying through IMC. :unsure:

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38 minutes ago, jaylw314 said:

Think of it this way--if you install a static drain, and it leaks, you will could have a small error in you altimeter and a small error in your wallet when you do your IFR cert at the shop.  If you have water in your static system, you could have a large error in your altimeter, and a large error in your life insurance after flying through IMC. :unsure:

Up until now I have been flying VFR  and every so often get a vfr cert done on the static system. I have been considering getting my IFR ticket .  This is my reasoning for asking the question about static line drain.  I have bad luck when it comes to IFR cert on pitot static system as maintenance cost goes. During my ADS-B  install  several years  ago the Avionics shop charged me per instrument what most shops (I'm told) charge more of a flat rate structure for the IFR cert need less to I was not happy.    that other thing is that I cringe that water could freeze  in static line gives uneasy feeling.

James '67C

 

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James I can give you some good advice with this, a better understanding of the two systems and the connection between the two goes a long way. I would begin by obtaining an accurate diagram of them, and any modifications need to be assessed. Single, or additional static system for the G5's, this should be documented by the installer and included in the paperwork package required to be provided to you.

Trivia question: what altitude change would be seen when opening the static drain in flight?

Bob Weber

WebairConsulting.com  616 822 1999

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You are correct, @jamesm, the SI does not mention location of the drain valve.  As I read the SI, moving the location of the tee is sufficient to prevent water from being trapped in the static system.  Oddly enough, I can't see any mention of a sump drain valve, but seems to show something like it.  

The problem I would have with installing a sump drain valve is that in cold climates, undrained water will freeze and damage the valve.

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11 hours ago, jamesm said:

Up until now I have been flying VFR  and every so often get a vfr cert done on the static system. I have been considering getting my IFR ticket .  This is my reasoning for asking the question about static line drain.  I have bad luck when it comes to IFR cert on pitot static system as maintenance cost goes. During my ADS-B  install  several years  ago the Avionics shop charged me per instrument what most shops (I'm told) charge more of a flat rate structure for the IFR cert need less to I was not happy.    that other thing is that I cringe that water could freeze  in static line gives uneasy feeling.

James '67C

 

The IFR cert is usually a flat rate, seems to run between $300-450.  ADS-B installs typically require a static system check.  The added cost would be any leaks they have to troubleshoot :wacko:

IIRC, the IFR cert requires the rate of leakage from the static system to be less than 100 fpm? 

Realistically, a static line leak is not going to be a huge error--think of what happens when you're in a plane and open the alternate static source.  That's basically a massive leak into the static line from the cabin air, and that's often only an error of less than a couple hundred feet.

Edited by jaylw314
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6 hours ago, Bob Weber said:

James I can give you some good advice with this, a better understanding of the two systems and the connection between the two goes a long way. I would begin by obtaining an accurate diagram of them, and any modifications need to be assessed. Single, or additional static system for the G5's, this should be documented by the installer and included in the paperwork package required to be provided to you.

Trivia question: what altitude change would be seen when opening the static drain in flight?

Bob Weber

WebairConsulting.com  616 822 1999

It depends on the plane. I believe mine goes up by about 200 ft at cruise. It would be somewhat speed dependent. A leak at the static drain in the tail cone would probably be a pretty small error the leak would be at a similar position to the static ports.

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My bird has no static drain.  The alternate static source on when we acquired her was a push/pull valve installed on the back of the VSI.   It was impossible to get to in flight.  

We installed an alternate static switch in the panel https://www.aircraftspruce.com/catalog/elpages/togglevalve11-12168.php?clickkey=9489

Any time I open the alternate static valve in flight there is a slight deviation indicated on the VSI, and a twitch of the altimeter that quickly goes away.

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So Where I was seeing this happening is usually Less than 3500 ft and about  120 to 110 mph it doesn't happen on all flights just some. The Hundredth needle probably+/- 300 ft bounce.

I don't have static drain currently installed.  I was suspecting that water was in the static line  would/could displacing  causing needle to bounce.  Then again I could be way off it was just a hunch on my part. 

It is a dual static ports while a single line running to  front of the airplane  probably  1ft above the pilot's knee, it  has pneumatic  multiport adapter that feeds all the static interments (G5's, Altimeter, VSI, ASI, encoding altimeter) same for the pitot system. I am pretty sure that it is original  pitot and static lines. The Pitot & Static systems was switched over to the pneumatic  PTC (Push to connect)  style  connectors. I couldn't find anything  in the  AC 43-13 to telling me explicitly which pneumatic  connectors to use  nor was there anything  explicitly saying  what type static line(s) to use. The experimental  guys use connectors must be good. ;-).    I have ask IA's  and they  seem agree that there is  not real  guidance on which pneumatic  connectors and  pneumatic lines, and pneumatic fittings to use for "approve" and or "acceptable" installations. So as I understand it you could go to Lowes Aerospace or your local aviation aisle  in Home Depot   or Napa store  to get your pneumatic fittings.

 

James

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Be looking for the dead leg...

It resides between the two static ports in the tail...

Probably a four way intersection...left side, right side, dead leg to collect water, and then the tube that goes to the static instruments up front...

It is quite possible, somebody didn’t know why the dead leg was there...

Find the official drawing to see what it is supposed to look like...

Water getting up to the instruments is bad... and should be avoided...

Most often the drains are completely empty... checked every flying day...

A good sideways rain, can fill the static system with a lot of water...

PP thoughts only,

-a-

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In an F it is right below the battery in the battery access area in the rear.  Some have a pitot in the wing on the lower leading edge by the wing root.   For lots of water the drain won't really get it out.   You have to disconnect the tube and blow it out.  Once side at a time.  Only blowing to the rear as not to damage instruments.  Then you have to get retested.

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