From: Sky2high@aol.com
Message-ID: <108.83664d9.291d47a6@aol.com>
Date: Fri, 9 Nov 2001 09:52:22 EST
Subject: Re: Relay Problem
To: lancair.list@olsusa.com
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Reply-To: lancair.list@olsusa.com

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Rick,

If your master switch or its circuit to ground has resistance or poor 
connections, the juice used to initially pull in the relay may not be enough 
to hold it during the startup current draw of the newly energized entire 
master circuit (lights, pumps, etc) -- this may be exacerbated each time by 
carbon buildup on the master relay contacts which might require a few closure 
hammerings before good enough contact is made.

If replacing the master relay does not change the situation one iota, 
carefully check the master switch and its circuit.  Also, check the 
battery/engine ground connection.

The basis is as follows:

My friend Arnie had a similar problem recently, the master relay contacts 
would not make until the master switch was snapped on several times, and 
replacing the master relay corrected the symptom (carbon clogged contacts), 
but not the cause.

My Cessna Skymaster had similar problems where the master switch had some 
resistance in it which meant the holding current/voltage for the master relay 
was reduced and allowed the contacts to bounce during turbulence, thus arcing 
and building carbon which ultimately reduced the current/voltage available on 
the master circuit leading to difficulty in starting the first engine and 
reducing the ability of the battery to act as a EMF noise ballast.  This was 
combined with unavoidable corrosion buildup at the aircraft frame ground.  
After cleaning the aircraft/engine ground (should be done each annual), using 
a new switch and relay all power/noise problems were cured.

Another Lancair owner was recently having problems with VM1000 readouts and 
after cleaning up his ground connection to the engine, all the problems went 
away.

Scott Krueger
LNC2 N92EX (Just cleaned my ground at 365 Tach Hours)
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