Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Fri, 07 Jun 2002 08:41:17 -0400
Message-ID: <redirect-1285556@logan.com>
From: "Marc F. Clemente" <marc@mclemente.net>
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Subject: Re: Sandel HSI
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I am not sure about the King, I think it requires an external compass as 
well.  For the Sandel, the external compass source can be a remote 
compass system (what I have in the tail of the plane), or it can be a 
separate DG or HSI (vacuum or electric) with bootstrap output.  But the 
broken EDO-Aire (Cessna) HSI that came out of the panel when the Sandel 
went in was a vacuum instrument.

In my opinion, the Sandel HSI with a remote gyro is more reliable than 
the vacuum HSI which broke.  The overhaul shop wanted $2500 to 
repair/overhaul the old HSI.  They said that all the bearings, flags and 
needles were sticking, and the belt which moves the compass card was 
worn.  All the problems were associated with moving parts, and there 
were a lot of them in there.  The Sandel has only one moving part (the 
cooling fan).  The remote compass system which supplies heading 
information to the Sandel also has only one moving part (the gyro).

Of course, if I have a total electrical failure, all I have left is the 
wet compass, attitude indicator and altimeter.  I can accept that.

I wrote:
>> Advantages:
>> No vacuum required

John Kleber answered:
> I didn't realize vaccuum was required for the King HSI........


Marc Clemente