Mailing List lml@lancaironline.net Message #26136
From: <edechazal@comcast.net>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: S-TEC 50 Problem - LNC2
Date: Sun, 17 Oct 2004 09:29:00 -0400
To: <lml@lancaironline.net>
I've got an S-TEC 50 autopilot installed in my 360.  Altitude hold no longer works properly.  A few months ago some of you gave me advice on looking at the pitch servo and possibly the pressure transducer.  The pitch servo meets factory specs, I was able to determine.  The pressure transducer, however, appears flaky.  Probing the back of the connector indicates an open circuit in the signal path in the transducer.  Although this could be the contact inside the connector too, since I was only able to probe the harness side.  The transducer seemed to work on the bench (signal moved properly with pressure change, but my setup could not rule out intermittencies). I removed the connector and attached the leads directly to the male pins on the transducer with higher quality female contacts.  Result seemed better than before, but a full down command still occurred, and the system hunted excessively (50 foot excursions up and down).
 
I'm going to wire it so that I can monitor the output signal during flight and during commanded excursions to try to catch the culprit in the act. 
 
Do any of you have an S-TEC pressure transducer you are not using (you switched to Tru-Trak) that you'd be willing to part with?
 
Thanks,
Ed de Chazal
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