Mailing List flyrotary@lancaironline.net Message #21300
From: Charlie England <ceengland@bellsouth.net>
Subject: Re: [FlyRotary] Re: To Fuse or not to Fuse
Date: Mon, 02 May 2005 21:05:48 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Bill Dube wrote:



Here is Bob K's and his well reasoned  argument  FOR fuses

<http://www.aeroelectric.com/articles/Rev9/ch10-9.pdf>http://www.aeroelectric.com/articles/Rev9/ch10-9.pdf

The keystone of Bob's endorsement of fuses:


When the failure manifests itself by opening the breaker or
fuse likelihood of recovering the system by replacing a
fuse or pushing in a breaker is very, very small.

        Beneath it all, this is what all the fuse versus circuit breaker discussions hinge on.  It is an incorrect assumption, in my experience.

        A very large percentage (but by no means all) of electrical problems in vehicles are intermittent in nature. You can very often reset the breaker and restore the critical system long enough to safely land the aircraft. A fuse does not give you this option, at least not in a timely manner.

To be realistic, don't most of the multi-reset stories start in old/poorly maintained/poorly designed/etc aircraft?

I really think that the cornerstone(s) of his endorsement is more along the lines of 1. you don't have to have a 50 year old design &  'aircraft (poor) quality' factory electrical system in a homebuilt and 2. you can design critical-to-flight systems  to have automatic or flip-a-switch backups. The reality is (as he's stated many times) *nothing* is failure proof. His philosophy is that you design the system with redundancy to trump any single failure.

Everyone's got to make their own choices but it helps to start with the right assumptions.

Charlie
(I'll make the decision when it's time to pull wire.)


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