I don=99t think that this photo is a lightning strike!!!
Ivan
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Pete
Lawless
Sent: 12 November 2014 17:42
Subject: Re: Europa-List: Re: Electrical bonding
Hi Guys
I sobering pic of lightning damage to a fully bonded all metal aeroplane
- I suspect in a Europa it would ruin your whole day!
Plus an interesting Boeing article.
http://www.boeing.com/commercial/aeromagazine/articles/2012_q4/4/
Regards
Pete
G-RMAC #109
On 12/11/14 17:24, davidjoyce@doctors.org.uk wrote:
Peter, Thanks - absolutely no apologies needed - it is very pertinent! I
had pored over this in great detail when preparing my Oz trip! Both in
this and in the other GRP glider strike quoted the lightning ran from
wing tip to wing tip, with arcing causing enough heating/shock wave to
break open or delaminate the wing. It was very much because of this
report that I hoped to provide a more attractive (both to me and the
lightning) path running essentially outside the wing. Regards, David
On 2014-11-12 16:07, PETER MORGANS wrote:
Hi David,
Apologies for diving in on this topic.
You may be interested to read AAIB Bulletin 12/99 (attached pdf)
regarding the disintegration of Schleicher ASK21 over Dunstable. Back in
my gliding days in the late 1960's it was mandatory for all gliders
which held a B.G.A cloud flying category to have electrical bonding. I
think the answer is to stay away from large Cu unless you have a
parachute.
The following link, ref. this accident, also shows photographs of
damage:- www.pas.rochester.edu/~cline/.../ASK%20accident%20report.htm
It's sobering to look at the damage to fittings.
Regards
Peter Morgans G-CFKZ Trigear XS
_____
From: <mailto:davidjoyce@doctors.org.uk> "davidjoyce@doctors.org.uk"
<mailto:davidjoyce@doctors.org.uk> <davidjoyce@doctors.org.uk>
Sent: Wednesday, 12 November 2014, 14:00
Subject: Re: Europa-List: Re: Electrical bonding
Ira, You may well be right and I am quite prepared to accept your
superior electrical training, but talking to British Aerospce engineers
involved in lightning protection for the Airbus series did not produce
clear answers and my memory of the Europa lightning strike account is
that there were burn marks at each wing tip and the strike had travelled
across the plane. That being the case, it seems to me to be a better
idea to have a path other than the aileron controls or wing light wiring
to conduct it. Having been in a tram struck by lightning in my youth and
lost a neighbour to a lightning strike, I am not at all keen to go
anywhere near a cu nim, but a large proportion of those flying 'VMC'
---From UK to Australia have been unintentionally caught in electrical
storms. I did not imagine I could make my plane immune to damage but
just to lessen the likelihood of control run welding or instrument burn
out.
Regards, David G-XSDJ
On 2014-11-12 13:17, rampil wrote:
Bonding together small bits of metal inside a sea of plastic insulator
will
accomplish nothing except add weight to your airframe unless you
have an array of static discharge wicks. No Europas I am aware off have
them. The best thing for a builder to do regarding lightning strikes
is to make sure there are no voids in the layups where water can
infiltrate.
The water will turn to steam and explode. Aside from that, Do not
fly near Cu. If Cu are unavoidable, just remember: Flying IS avoidable.
In this I respectfully disagree with David. As a former electrical
engineer, I would also have to say, I can not see any benefit to bonding
wingtip to
wingtip, etc. The goal can not be to conduct a strike - you can not!
Rather,
the goal of bonding to discharge wicks is to bleed off areas of air
friction
static charge back to the atmosphere, thus avoiding being an attractive
nuisance for lightning.
There is no such this as "earth" on a composite airplane. The only
ground
is the negative battery terminal. That's it.
It's not a house! There's no neutral (white wire) and earth ground
(green
wire) dichotomy. Just make all grounds short, fat and tight.
--------
Ira N224XS
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