Artificial Horizon Precess Errors

5 Replies

Artificial Horizon Precess Errors

Posted by Michael Walpole on Jul 8, 2018 8:21 pm

In climbs or descents the artificial horizon in our Warrior (PA28-151) indicates a left bank even with the wings level.  Vacuum Gauge is showing 5 psi and is in the middle of the green.  Today while climbing to 6500, it got progressively worse to the point it showed the plane in a 20* bank while the wings were level.  Then it took about 10 minutes for it to level out after going into level flight.  What would cause this?
Mike W
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Re: Artificial Horizon Precess Errors

Posted by Ronald Levy on Jul 9, 2018 7:36 am

Most likely worn-out bearings in the AI, which would mean time for replacement or overhaul.  But first ask your mechanic to check for a loose fitting or blockage in the lines.

Re: Artificial Horizon Precess Errors

Posted by William Hemme on Jul 9, 2018 11:33 am

Either the air filter for that AH gyro is getting plugged up or the gyro itself is wearing out.

Re: Artificial Horizon Precess Errors

Posted by Edward Pataky on Jul 9, 2018 12:30 pm

Worn bearings.  Attitude Indicators and Head Indicators are precision instruments, with VERY tight tolerances.  They only last 400 hours... maybe a bit more until an overhaul is needed.

I would bet the farm plus 10% that the bearings re going out on your AI, and an overhaul is in order.

Good luck!

Ed

Re: Artificial Horizon Precess Errors

Posted by Michael Walpole on Jul 9, 2018 4:33 pm

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It progressively got worse during climb and took 10 minutes to straighten out after level off at 6500
Mike W

Re: Artificial Horizon Precess Errors

Posted by Ronald Levy on Jul 9, 2018 5:41 pm

Michael Walpole:
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It progressively got worse during climb and took 10 minutes to straighten out after level off at 6500

Doesn't change my analysis.  Either there's a loose/blocked line to the AI or the AI has worn out.