Vacuum Pump issues or AI/DG ?

[Indiana_Pilot]

My Attitude indicator has developed an issue where it will show a bank to the left (just a bit less than 5 degrees)and then it will seem to right itself.

The DG seems to show precession a little easier than it should sometimes. the DG has always been touchy but within limits of what I would call normal even in the bumps..

The Attitude Indicator is a Sigmatek 23501-06-09 (B5000B series)

The vacuum pump always reads within limits.. before i have it checked out, would you think a vacuum pump or line leak or the actual Attitude Gyro ?

 

[Capt. Geoffrey Thorpe]

Vacuum is not a good indicator of actual flow. When was the filter last changed?


Note: I ain't no A&P so obviously, I am wrong.

 

[gismo]

My Attitude indicator has developed an issue where it will show a bank to the left (just a bit less than 5 degrees)and then it will seem to right itself.

The DG seems to show precession a little easier than it should sometimes. the DG has always been touchy but within limits of what I would call normal even in the bumps..
The Attitude Indicator is a Sigmatek 23501-06-09 (B5000B series)

The vacuum pump always reads within limits.. before i have it checked out, would you think a vacuum pump or line leak or the actual Attitude Gyro ?

Depends on how it's plumbed. Some vacuum systems use a common filter with a gauge that reads the pressure delta across the gyros and in that case if the gauge is reading within limits the only thing that could be blocking airflow would be a kinked and/or collapsed hose. OTOH if the gauge reads the system pressure referenced to ambient (cabin air pressure) a plugged filter would likely make the gauge read slightly higher than normal while the gyros receive less than normal airflow.

 

[Indiana_Pilot]

I am guessing the filter is something I can't replace myself ? I looked through the logs and didn't see anything where it has been replaced previously. (I'll double check) maybe that is all it is..


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[gismo]

I am guessing the filter is something I can't replace myself ? I looked through the logs and didn't see anything where it has been replaced previously. (I'll double check) maybe that is all it is..


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You can legally replace any filter but you should have your mechanic show you how to do it (including the required logbook entry). BTW if you have a pressure system there are two filters, one on the pump intake and one between the pump and the gyros. But with a pressure system it's unlikely the gauge would read OK when a clogged filter was inhibiting adequate airflow in the gyros. OTOH, a kinked or leaking hose could cause your symptoms.