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From: "Steven W. Boese" <SBoese@uwyo.edu>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Date: Sun, 22 Nov 2009 10:45:41 -0700
Subject: RE: [FlyRotary] Ground isn't ground
Thread-Topic: [FlyRotary] Ground isn't ground
Thread-Index: Acprisj8iVcA6oRhThGMN16AqHLp1gADBNvu
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Steve,

Thank you for posting the information on the solution for the spark problem=
.  The results are of particular interest to me since the routing of my gro=
und to the starter sounds like it is identical to yours.  The test I made t=
hat showed similar symptoms was based on the possibility that the EC2 and t=
he CAS return were grounded in two different places and that noise generate=
d in the ground between these two locations was degrading the CAS signal.  =
If I understand correctly, the noise generated due to the starter current p=
assing through the engine assembly is being injected into the CAS signals e=
ven though the CAS circuits and the engine block are electrically isolated.=
   =20

Benefiting from your troubles, I am fabricating a longer ground cable for i=
nstallation in my plane.  My inclination is to add this cable to the starte=
r and retain the original one to the front cover.  Removing the cable to th=
e front cover would result in the ground for alternator passing through the=
 big Oreo cookie.   Although the alternator currents are not as large as th=
e starter current, they are still significant, noisy, and more likely to ca=
use problems during normal operation rather than just during starting.

Steve Boese
 =