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Re: Europa-List: Lightning bonding

Subject: Re: Europa-List: Lightning bonding
From: David Joyce <davidjoyce@doctors.org.uk>
Date: Tue, 10 Jun 2008 23:10:47

Fred & al, As I see it the problem with bonding aileron push rods is that 
they don't go to the end of the wings.Ideally I think you need a conductor 
that extends to the wing tips and also possibly one that is not inside the 
wing cavity. In the quoted glider incident (which happened in 1999 at 
Northall, just North of London, CAA occurrence no. 199902166) the heat 
generated by the lightning arcing through the wing surface to the control 
runs was thought to be enough to massively expand the contained air and blow 
the wing skins off. There is a caveat however to basing too much on that 
incident as investigation showed that the power of that particular lightning 
bolt was exceptional, in fact seven times higher than the power that 
certified aircraft are designed to withstand. Nevertheless I like the notion 
of a conductor that isn't connected to the bit I am holding, and feel there 
is a good chance of the aluminium mesh in the close out approach conducting 
lesser bolts straight through without giving me or my avionics a nasty 
shock!
        As an amusing postscript to the glider story the passenger in the 2 
seat glider was having a trial flight. As he hadn't had his money's worth 
the club offered him a free repeat, but he is said to have declined!
           Regards, David Joyce, G-XSDJ
----- Original Message ----- 
From: "Fred Klein" <fklein@orcasonline.com>
Sent: Tuesday, June 10, 2008 2:59 PM
Subject: Re: Europa-List: Lightning bonding


On Tuesday, Jun 10, 2008, at 04:43 US/Pacific, TELEDYNMCS@aol.com wrote:

> They used fairly heavy gauge braided jumpers made from tinned
> copper to tie everything metal together to prevent arcing.

Nice, thoughtful post John...thanks...If you locate a source for this
braided jumper material, spread it around...I've known there was a
reason I haven't closed my wings yet...Fred

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