Mailing List lml@lancaironline.net Message #44775
From: John Schroeder <jschroeder@perigee.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Design for Circuit Breakers & Fuses?
Date: Wed, 07 Nov 2007 15:11:16 -0500
To: <lml@lancaironline.net>
Colyn -

The vast majority of our fuses are in two busses on the panel. The fuses are accessible. On a recent flight the pitch trim quit working. I pulled the fuse in a matter of a minute and determined that it was good. We have two battery buss fuse panels that are located very near the batteries in the rear of the aircraft. These are hard to get to - even on the ground.

John


On Wed, 07 Nov 2007 09:46:33 -0500, Robert Pastusek <rpastusek@htii.com> wrote:

Colyn Case said:


The pro-fuse argument makes sense to me except for one thing:   A breaker
gives you a positive indication that it interrupted the circuit.  A fuse,
particularly a hidden fuse, gives you no indication.


I thought that would be bad because I'm left to diagnose a problem with
incomplete information.   e.g. my trim isn't working - is it something I can
do something about or is the trim servo toasted?


You fuse guys must have thought about this.  What's the counter-argument?


Colyn,

You have a good point if you intend/need to troubleshoot while still in the
air. As I noted in my original post, many years of doing this in military
fighters (as a weapon systems operator-with a well qualified pilot still
flying the jet and typically swearing because his xyz was not working)
convinced me that this was (in my experience) a totally pointless exercise.
I'm pretty sure I never recovered a system by resetting a CB, and I once
caused a fire in the cockpit, and killed a generator another time. Still,
I've heard that others have successfully recovered systems by resetting
CB's. So in the end, you make your own tradeoffs/decisions. Everything is a
compromise at some level.


Bob






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