Frans,
I agree. I believe that the wet rag idea is the same as touching with
your bare hand and then touching your grounded Jerry Can or filling
station nozzle completes the neutralization of the static charge
difference.
Since auto's with plastic tanks have the fuel grounded to the vehicle
ground via the fuel pumps, and the capacitance probe, injectors, fuel
regulators, etc. Your point of ground of the whole fuel system is
already accomplished by the engine fuel systems in our aircraft, just as
in the autos. I too did not make an electrical connection between my
cap and the ground system because we are just a big plastic tank with
static electricity around the outside, and the fuel in the tank is
grounded to the engine and the ground of the aircraft. Sparks jumping
should be easily controlled by grounding the frame of the engine (the
fuel itself) to the earth and then earthing yourself (via your wet hand)
to the side of the aircraft and then to the Jerry Can which is setting
on the ground. All components and yourself are now at an equal charge
state, or close enough, to not jump a spark.
Problem is with the trailered aircraft. When moving the nozzle from one
vehicle to another you have lost contact with the vehicle and trailer,
so one must reestablish the neutral charge by touching the trailer with
a hand, then the plane to the trailer. It is an academic exercise to
assume that the vehicle, trailer and yourself are of the same charge
state (grounded) unless a metal strap was attached to the frame and
drags on the ground and the plane is grounded to the trailer. The
National Transportation directives have been changed years ago deleting
the grounding of fuelling vehicles with chains hanging on the ground.
Re-fuelling vehicles use grounding cables to accomplish this.
Background:
Gas Stations use valves with cutoffs to allow the grounded fuel line to
be placed into a vehicles open hole by a woman wearing a static
generating outfit in reasonable safety providing she stays in contact
with the nozzle at all times... The person can not lose contact with
the nozzle and vehicle skin during the fuelling. If they do, one can
expect upon return to the nozzle, there is a high probability of a spark
being generated (as in those U-Tube videos). The operation is only safe
because the act of the person contacting the hose nozzle grounds the
person to the fuel pump and earth, the fuel door is opened and the
nozzle is placed into the vehicle fuel receptacle (neutralizing the
charge) then the fuel trigger is pulled. The vapor exiting the vehicle
during fuelling has no source of ignition (unless the person loses
contact with the vehicle and nozzle). Back to the aircraft on the
trailer, if the re-fuel person was inattentive, doing the fuelling and
the fuel nozzle was removed from the tow vehicle, say after fuelling the
car, then the person jumped up on the trailer to fuel the plane, as long
as he touched the trailer by hand and then the aircraft to open the cap,
while holding the fuel nozzle, he again has neutralized the ground and
has reasonable expectations of safe fuelling.
Bottom line: Use your body as a conduit when fuelling from a Jerry Can.
Never fuel the can in the vehicle (as Graham pointed out, it develops
its own charge due to the fuel movement, sliding in the boot, etc.), put
the can on the ground then open it and then grab the fuel nozzle and
begin fuelling the can. To fuel the aircraft, remove the can from the
transport vehicle and put the can on the ground, put your hand on the
can and plane and open the aircraft fuel cap, touch the aircraft and the
can and lift to fuel or use your hand pump now to transfer fuel
safely...
Your wet rag idea is great, if you have really dry hands or are messy
like me.
Regards,
Bud
----- Original Message -----
From: Frans Veldman<mailto:frans@privatepilots.nl>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Friday, January 11, 2013 12:38 PM
Subject: Re: Europa-List: Grounding & Fuelling
<frans@privatepilots.nl<mailto:frans@privatepilots.nl>>
On 01/11/2013 04:26 PM,
f.kyle@sympatico.ca<mailto:f.kyle@sympatico.ca> wrote:
> Can I install a grounding bib on the outside of the
> fuselage, well away from but electrically connected to the 2inch
tube in
> addition to any previous route?
If you start grounding components in direct contact with fuel, you
have
to ground them ALL. Otherwise a non-grounded metal piece (in contact
with the fuel) will discharge itself to the grounded piece, sparking
inside the fuel enclosure.
So, do not ground anything in contact with the fuel, or, if you do,
then
ground everything in contact with the fuel. (This includes the fuel
vents, which may become electrically charged and try to relieve
themselves via the fuel to your grounded cobra).
Probably safest would be a metal wire inside the tank, running from
the
inlet to the outlet, making contact with all metal parts in between,
have one side connected to the engine and the other side to the fuel
filler opening.
Or just don't ground anything, so if there is an electric charge, it
won't find a path to ground via the fuel related components.
This is what I do: I have not grounded anything connected to the fuel.
Before I refill, I use a wet rag (or my bare hands) to wipe off the
fuel
filler opening, then I place one hand on the wetted surface, and in
the
other hand I have the fuel nozzle, and with both hands connected I
bring
the fuel nozzle in contact with the fuel filler opening.
If there is any electrical charge between the nozzle and the fuel
filler
opening, it will relieve itself via my body instead of via the fuel.
As the aircraft is made of non-conductive material, any grounding
efforts are bound to fail. Electrical charge will easily build up near
the fuel filler opening, despite any efforts to ground individual
parts.
The only way to get rid of local charges on a non-conductive material
is
to wipe it off with something conductive; wet rags or body parts
suffice.
Frans
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