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Well, I’m looking for advice, experience, and anyone who has had an issue with their blade under the wing. I am working closely with my avionics shop and Garmin to find a solution to an ongoing problem with my static system.
Here’s the issue. I had a new Garmin GFC 500 autopilot installed back in January. Everything is perfect, except when I level out in cruise, I get a 20-50’ oscillation up and down. Ascending or descending there isn’t any problem, coupled approaches are perfect. Opening the alternate static port in the cabin eliminates the oscillation at cruise.
Here is what has been done. The system has been checked several times now and all leaks have been eliminated from the instruments all the way out to the hard lines in the wing at the blade. We have zero leaks and the issue persists. The blade was dropped down and checked for any blockages, we found a little debris in the pitot side, cleaned it out, but nothing on the static side. Reinstalled the blade and the problem still persists.
We removed the (new) rubber hose from the hard line on the static side in the wing at the blade and the oscillation is gone. There have never been any fluctuations in any of the instruments prior to the installation or now, all needles are solid. The internal plumbing has been checked and replaced as needed. All things point to the blade...
Our next plan of attack are to check the blade for any cross leaks, but we are skeptical there is a problem, so I ask, has anyone had an issue like this? We know that S-Tech used to install their own static ports for their autopilots because of an oscillation issue. Is there something about having a 3 blade prop causing turbulence out there? Really just throwing darts at this point...Help?
Thanks,
Dave
Here’s the issue. I had a new Garmin GFC 500 autopilot installed back in January. Everything is perfect, except when I level out in cruise, I get a 20-50’ oscillation up and down. Ascending or descending there isn’t any problem, coupled approaches are perfect. Opening the alternate static port in the cabin eliminates the oscillation at cruise.
Here is what has been done. The system has been checked several times now and all leaks have been eliminated from the instruments all the way out to the hard lines in the wing at the blade. We have zero leaks and the issue persists. The blade was dropped down and checked for any blockages, we found a little debris in the pitot side, cleaned it out, but nothing on the static side. Reinstalled the blade and the problem still persists.
We removed the (new) rubber hose from the hard line on the static side in the wing at the blade and the oscillation is gone. There have never been any fluctuations in any of the instruments prior to the installation or now, all needles are solid. The internal plumbing has been checked and replaced as needed. All things point to the blade...
Our next plan of attack are to check the blade for any cross leaks, but we are skeptical there is a problem, so I ask, has anyone had an issue like this? We know that S-Tech used to install their own static ports for their autopilots because of an oscillation issue. Is there something about having a 3 blade prop causing turbulence out there? Really just throwing darts at this point...Help?
Thanks,
Dave
