Mailing List lml@lancaironline.net Message #16121
From: Gary Casey <glcasey@adelphia.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: S-TEC autopilots
Date: Fri, 08 Nov 2002 14:09:41 -0500
To: <lml>
<<I had a "Hard up" command from my STec Controller while IMC climbing out
of Camarillo, CA>>

Thanks for recovering before you hit my house!  For several years I flew
behind a S-TEC 60 and would often get a runaway trim event shortly after
engaging pitch control.  Finally tracked it down to the "clutch" in the
servo, which is actually a solenoid that rotates gears into alignment.  If
the gears happen to hit tooth-to-tooth the servo will jam, but only if the
torque is in a specific direction and stays there.  The controller would try
to move the controls, sense the torque, and start trimming.  Once the motor
torque reverses the gear will drop into place and work normally.  The cure
was simply to give the controls a little bump right after engaging.

Gary Casey
ES


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