David=2C
There are always exceptions. When I was hit by lightning=2C or call it elec
trical discharge=2C in clear skies=2C it entered via the tailpipe and exite
d via the radiators. Apart from some melted metal there was no damage. I al
so have nav lights on the wing tips.It just illustrates that just staying a
way from cu nims is no guarantee for avoiding a strike.Karl
Date: Fri=2C 14 Nov 2014 10:49:26 +0000
From: davidjoyce@doctors.org.uk
Subject: Re: Europa-List: Re: Electrical bonding
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John & Ira =2C With the greatest of respect for your professional electrica
l & aeroengineering backgrounds=2C I think there are two rather different i
ssues here:
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For certified commercial aircraft lightning protection standards se
ek to enclose all passengers and key aircraft components in a Faraday cage
conducting system that will cope with the fairly frequent strikes affecting
commercial operations without any significant damage. To bring composite a
ircraft to that standard clearly involves incorporating some conducting mat
erial in the entire surface of the plane and this is a nonstarter (or at le
ast a non retrospective mod option) for a plane like ours.
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The other issue is the possibility of minimising any damage to a pla
ne like ours in the event of a lightning strike=2C ( absolutely going along
with the assertion that it is much preferable to avoid it). There are thre
e good accounts of fibreglass small aircraft strikes that I have come acros
s and in every case lightning went from wingtip to wing tip causing signifi
cant damage. These cases are the UK glider=2C previously mentioned (www.aai
b.gov.uk/cms_resources/dft_avsafety_pdf_500699.pdf ) =2C another glider re
ferred to in that AAIB report of the first glider and the Europa strike suf
fered by Paul McAlister (www.sarangan.org/europa_forum/2004-08/msg00094.htm
l ). In each case the pilot thought he was well clear of threatening clouds
it seems. The gliders had the strike track along the aileron control rods
whereas with the Europa it tracked along the wing tip lights wiring killing
a number of the avionics in passing. I would strongly recommend folk readi
ng all these reports. Having personally done so I cannot avoid the conclusi
ons that :
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1. Getting struck by lightning is a real possibility for any sensible=2C ca
utious pilot let alone someone contemplating flying through the ITCZ where
rapidly developing massive Cu Nims are endemic
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2. Lightning can and will pass from wingtip to wing tip along the most avai
lable conducting track
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3. More debateable perhaps but my third conclusion was that there is much t
o be said for offering a track that steers clear of vital structures=2C and
in the light of this I had (in 2006) planned laying expanded aluminium mes
h in the wing close outs connected to aluminium foil over the wing tip and
to the rear lift pins/connecting rod. Nowadays I would no doubt use Alumini
um Microgrid obtainable at modest cost from Aircraft Spruce. I would not f
or a moment want to suggest that this would give commercial plane standard
immunity to damage=2C but that it would improve the chances of avoiding eit
her the wing exploding or the loss of avionics or other key electrical syst
ems. I had toyed with the idea of static diffusers but without a system of
conducting static from other parts of the aircraft I was not convinced this
was workable ( and I guess that this non conductance of static is what sav
es us from sparking when we touch ground - we are only discharging the imme
diate area of contact.
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Regards=2C David Joyce=2C G-XSDJ
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On 2014-11-14 08:42=2C John Wighton wrote:
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Ira=2C=0A
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You echo may own opinion on this subject. Fortunately my Europa does not s
eem to generate a lot of static (of a kind that can be detected at least).
There is not a lot that could be done if it did collect static whilst airb
ourne. =0A
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I had concerns about static build up and discharge on the ground=2C particu
larly whilst fuelling. I adopt the standard procedure of grounding everyth
ing to the same potential by touch=2C relying on terra firma to act as a gr
ound. So far there has never been the hint of a discharge even after a vig
orous polishing session.=0A
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Being involved in aircraft certification myself l am aware of the often hea
vy and costly solutions on larger aircraft. I am a structures signatory on
the A350=2C this has a high level of composites content and poses new issu
es and solutions on many fronts=2C including bonding and lightning protecti
on.=0A
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--------=0A
John Wighton=0A
Europa XS trigear G-IPOD=0A
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Read this topic online here:=0A
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http://forums.matronics.com/viewtopic.php?p=433644#433644=0A
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ectric.com=0A
">www.buildersbooks.com=0A
builthelp.com=0A
lotstore.com=0A
m=0A
.matronics.com/contribution=0A
ttp://www.matronics.com/Navigator?Europa-List=0A
ics.com=0A
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