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 Technical Info
 Avionics/Panel Installations
 Pitot static placement
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Tim06A

USA
6 Posts

Posted - 10/07/2011 :  06:38:15  Show Profile  Reply
Hey Gang,
We recently bought an older T-18 (N312LL). The VSI, Altimeter and Airspeed indicator seem to be very erratic. The static ports are on the pitot tube. I'm thinking that is not the correct placement. Where has everyone found to be the best spot for the static port.
Thanks
Tim

Rich Brazell

USA
911 Posts

Posted - 10/07/2011 :  11:36:58  Show Profile  Reply
Are you sure about the static port being on the pitot tube ? Some folks just vent from the back of the panel and that can cause "erratic" readings. If it is on the pitot tube I would also check the connections all the way to the instruments. There may be a common "T" than has a leak ? Doesn't take much.

I placed my flush static ports on the sides of the A/C. One on the left for the instruments and one on the right for the autopilot.

RB

Edited by - admin on 11/07/2011 11:00:00
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Ryan Allen

USA
150 Posts

Posted - 10/07/2011 :  17:56:59  Show Profile  Reply
I just chased a static leak for several hours before I switched the "T" out on the back of the instrument because I had run out of ideas of where the leak was coming from. It solved the problem. I still cant figure how it was leaking but it sure stopped it once I switched it out.

Edited by - Ryan Allen on 10/07/2011 17:58:45
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Tim06A

USA
6 Posts

Posted - 10/07/2011 :  18:44:52  Show Profile  Reply
Yep thought about leaks too. I ran across an article that Lee sent me a while ago & re-read it. It was from the '80s and in reference to our plane specifically. It talked about the same problems we're still having. Makes me think the placement has been wrong from the beginning. I was thinking that side of fuse would be best. Just need to figure out exactly where.

Edited by - admin on 11/07/2011 11:00:00
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Rich Brazell

USA
911 Posts

Posted - 10/07/2011 :  19:34:52  Show Profile  Reply
Now that I think back when I did my pitot static system leak check (using a balloon/modeling clay and a large syringe) I did find (2) leaks on the back of 2 instruments where the nylon fittings screwed in. I applied a little EZ turn to the threads and problem solved. When I had the pitot/static system ground checked for the transponder Mode C, he ran a leak check using one of those very expensive black boxes and it was a very tight system.

RB

Edited by - admin on 11/07/2011 11:00:00
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Rich Brazell

USA
911 Posts

Posted - 10/08/2011 :  08:27:33  Show Profile  Reply
Try the Thorplist Archives and search static port location.

RB

Edited by - admin on 11/07/2011 11:00:00
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hurant

USA
34 Posts

Posted - 10/08/2011 :  17:48:48  Show Profile  Reply
The side mounted static lines are supposed to be connected to balance out side slips, etc.

Edited by - admin on 11/07/2011 11:00:00
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bfinney

USA
87 Posts

Posted - 10/09/2011 :  11:13:32  Show Profile  Visit bfinney's Homepage  Reply
According to my news letter index the following have articales on the static ports (news letter-page no.):
19-3, 44-4, 61-5, 91-9, 100-17, 105-10

Of this list I only have 91, it has a drawing on how to position the static ports on the side of the fuselage. I have not verified it but I believe my static ports are farther aft than what is shown in the drawing.

Bruce Finney
N18JF T-18C #262
Auburn, WA USA

Edited by - admin on 11/07/2011 11:00:00
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stug

Australia
13 Posts

Posted - 10/09/2011 :  13:07:26  Show Profile  Reply
A few Australian T18s have their static ports located further aft than the position indicated in the newsletters with apparent good results. My other post on the topic of side skins had a drawing showing the static location.
Stuart

Edited by - admin on 11/07/2011 11:00:00
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