There are several solutions to this hazard, varying from very simple and
reasonably safe, to pretty complex but very safe.
1. - Very Simple - As Graham points out, a hazard only exists when a low
resistance to ground permits a charge on the aircraft to discharge rapidly
and create a spark. The high resistance to earth can be provided by the
pilot/refueller on removing the fuel cap. Simply roll the fingers around
the edge of the rim to touch the aluminium filler. If there is a local
charge, then there is a very good chance it will be dissipated by your body.
(You will also have the benefit of seeing if there was one too).
2. Not so simple - run a wire from the filler neck to the undercarriage.
The monowheel of the Europa has a 70k ohm resistance to ground because the
tyre contains carbon. This method has the advantage of NOT requiring an
earth clip on the exhaust.
3. Pain in the Arse - apply an area of conducting paint, or carbon fibre
veil, around 250mm radius around the filler neck. This will collect local
charge, via a high resistance from charged areas of the aircraft. Connect
this, via the filler to the U/C or engine mount or both.
I did some work on charge collection on composites (in flight) some time ago
and have the figures if anyone's interested.
Dave Simpson
-----Original Message-----
From: Jeff Heath <jheath@siliconlogic.com>
<peterlert@montrose.net>; Tennant@t-online.de <Tennant@t-online.de>;
europa@avnet.co.uk <europa@avnet.co.uk>
Date: 17 May 2000 18:13
Subject: Re: AW: aircraft destroyed
>113-23@auswaertiges-amt.de wrote:
>
>> Another shock went through the Europa community. Any of our beloved
planes
>> could melt in front of our eyes - just because a spark formed.
>>
>> Here is a mail I received from Kim Prout many months ago - reproduced
>> without
>> permission. (Kim, may I ?).
>>
>>
>> Hello Thomas!
>> Although never a problem on N111EU regarding fueling, I am considering
>> attaching a ground wire to the metal fill neck and running it to engine
>> ground so that when attaching ground wire to exhaust pipe it is indeed
>> carried from the nozzle at fill neck to ground. Keeping the nozzle
firmly
>> against the metal neck should help anyway, the problems come when there
is a
>> potential with un-contacted surfaces building a static charge. I'm sure
>> there are others out there who can tell you all the science of this, but
>> practically speaking this is my experience (and idea based on fire
>> department stuff).
>> kp
>>
>>
>> Makes sense to me - avoid any opposed electrical potentials to form
>> in the first place by keeping the nozzle in touch with the filler neck.
>>
>> Sincerely,
>>
>> <Thomas, N81EU>
>>
>
>What about connecting the fuel line itself to engine ground ?
>If then grounding to the exhaust stack to the fuel truck (or fuel can)
>you would then be safe.
>
>
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