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pitot system leak check

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Flyer68

Well Known Member
I am testing the pitot as instructed in the production check list.
I am getting a time of 2-3 seconds between the air speeds. The instructions say
"max allowable pitot leak rate is 10 kt in 1 minute. "
Has anyone else done this test and where would the most likely place be for leaks?
 
Mine was tight. The most likely source is the slip joint between the metal probe and the nylon instrument line.
 
Another possible leak source......

When builders drill the pitot tube for the anti-rotation screw, occasionally they go a little too far and fully penetrate the tube slightly. This causes a leak path that can be hard to find unless you disassemble the pitot tube.
Check all of the other (easier) connections first.
 
Check the splice behind the instrument panel where the pitot line from the tail cone is connected to the line from the pitot tube. Mine had a leak there that a had quite a problem getting stopped.
 
Static system leaks

I had two bad leaks when I checked mime. One was from the edges of the glass on the VSI, I sealed that with clear epoxy. The other leak came from air speed ind., it was leaking from the static side and out the pitot tube. I had to purchase a new air speed gauge. Now it is sealed up tight.
 
Where was the leak?

Hi Bill, Wondering where your pitot leak was and how you repaired it, as I have the same issue.
 
9Driver said:
Check the splice behind the instrument panel where the pitot line from the tail cone is connected to the line from the pitot tube. Mine had a leak there that a had quite a problem getting stopped.
Click to expand...

Ditto. This is where mine leaked as well.
 
I finally stopped my leak by wrapping each end of the splice with two turns of .032 safety wire and twisting the ends enough to compress the outer tube. This stopped the leak and has stayed leak free through two required xpndr cks where they have to pump the system. Others may not agree with the method, but it worked.
 
That double wrap safety wire technique works great, even on the 3mm tubing we use on R/C jet air gear actuator lines. I did the same on all my pitot/static vinyl line connections in the system when I recently upgraded to dual ADHRS and heated pitot. Woody

9Driver said:
I finally stopped my leak by wrapping each end of the splice with two turns of .032 safety wire and twisting the ends enough to compress the outer tube. This stopped the leak and has stayed leak free through two required xpndr cks where they have to pump the system. Others may not agree with the method, but it worked.
Click to expand...
 
In my Navy days we used to varnish over suspected leaking connections in vacuum systems. Something to keep in mind.
 
That Worked

Thank You, the double wrap safety wire worked great. I also rtved the splice. My only problem now is there seems to be no leak. In order to measure the time to lose 10 knots might take 2 hours. It took 12 minutes to lose 1/2 knot.
Now to the next problem. When I do,the static port test, it seems I have a vacuum. To ensure there was no problem with a blockage in the tubing, I removed the fitting from the ADHARS and hooked the syringe up directly. When I pull the syringe I have a vacuum and no indication of any change on the Dynon for altitude. Any ideas?
 
D&M Dan said:
Thank You, the double wrap safety wire worked great. I also rtved the splice. My only problem now is there seems to be no leak. In order to measure the time to lose 10 knots might take 2 hours. It took 12 minutes to lose 1/2 knot.
Now to the next problem. When I do,the static port test, it seems I have a vacuum. To ensure there was no problem with a blockage in the tubing, I removed the fitting from the ADHARS and hooked the syringe up directly. When I pull the syringe I have a vacuum and no indication of any change on the Dynon for altitude. Any ideas?
Click to expand...

For the pitot test, the time vs speed loss is a maximum allowed. As long as the speed indication doesn't change by more than the maximum you are good. If there is zero change, you are very good.

No alt change when testing the static system could be only two things....

- You have a huge leak somewhere.

-The static system is not plumbed properly and you have no connection the ADAHRS.
 
When I pull the syringe there is a vacuum. I have removed the fitting going directly into the ADAHRS and have hooked the syringe directly to the static port with the same results. Is there possibly an issue with the ADAHRS?
 
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