REFLECTOR: Grounding Point

Sun Oct 24 19:53:03 CDT 2004

the fuel itself is non conductive, it is the charge that is stripped from
the surface of the flowing fuel that builds up on the surface of the skin
and metal parts that causes the problem, the metal chain in the fuel trick
is not effective, since there is not any way for the charge to pass to the
chain.

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of Scott Derrick
Sent: Sunday, October 24, 2004 4:56 PM
To: Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: Grounding Point

If an airplane has capacitive fuel sensors,  Doesn't that provide a ground
path from the fuel in the tank to the exhaust pipe?

Scott

At 02:16 PM 10/24/2004, you wrote:
>We are talking retrofit here.  My plane has been flying (and refueling) for
>4 years and I only clip the grounding cable to the nozzle for lack of a
>better grounding point.  However I like the screen bit.  Would it work if
>one was to shape a cylindrical screen that could be inserted in the fuel
cap
>opening at every fuel stop.  This cylinder could reach the bottom of the
>tank and have a flange that would barely touch the top strake around the
>fuel tank opening. The fuel nozzle would then  flow through that screen.
>The only draw back would be to carry (and store ) this contraption to have
>it on hand at every refueling stop.
>Gilles
>
>-----Original Message-----
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
>Behalf Of Jim Agnew
>Sent: 24 octobre 2004 14:43
>To: Velocity Aircraft Owners and Builders list
>Subject: RE: REFLECTOR: Grounding Point
>
>
>The concept of a fire screen has been proven for many years in miners
lamps.
>A
>fine mesh screen tube surrounding the filler inlet that goes to the bottom
>of
>the tank will prevent the passage of the flame front into the fuel tank
even
>if
>the fuel vapors inside the fire screen tube ignite.  This screen does not
>depend on grounding.
>
>Jim
>
>
>--- Chuck Jensen <cjensen at dts9000.com> wrote:
>
> > Mmmmmm. Alex's idea of first checking for continuity between the fueler
>ring
> > and the exhaust pipe is a good one.  If there is continuity, then
>executing
> > Al's idea of a drooping chain from the cap down into the fuel seems to
> > assure there is a fuel-chain-exhaust-refueling stating ground (all this
> > assuming there is fuel ring to exhaust continuity).  Richard's method,
>from
> > a Very Large Aerospace Company, appears to do the same thing, just
better
> > and with a higher degree of certainty.  Of course, if there's not
> > continuity, then its back to the drawing board.  It's somewhat
comforting
>to
> > know that the incidence of Velos going off like Roman Candles is rare,
but
> > I'd hate to be the first data point.
> >
> > Chuck
> >
> > -----Original Message-----
> > From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> > Behalf Of Richard Riley
> > Sent: Sunday, October 24, 2004 11:44 AM
> > To: Velocity Aircraft Owners and Builders list
> > Subject: RE: REFLECTOR: Grounding Point
> >
> >
> > We went around and round on this topic on one of the canard mailing
lists
>a
> > few months ago.  Following all the suggestions, I talked with a fuel
>system
> > designer at the Very Large Aerospace Company where I work and came up
with
> > the following for my plane...
> >
> > The fuel cap ring is attached to a coarse brass screen, shaped in a
tube,
> > that goes from the fuel cap ring to bottom of the tank.  It is attached
by
> > a brass ball chain to the fuel drain, and to a brass bolt in the
outboard
> > fuel bulkhead.  That bolt is then attached by a wire to the engine, and
> > therefor to the exhaust pipes.
> >
> > Most of the static charge in refueling is created by the fuel falling
from
> > the nozzle to the surface of fuel in the tank.  The brass screens strips
> > that away.  No matter what the level of the fuel, it's pierced by the
>chain
> > going to the fuel drain.  And then the whole thing is electrically
bonded
> > to the engine block.  If the fuel truck attaches the ground strap to the
> > exhaust pipe, all the potential is equalized.
> >
> >
> > At 09:21 AM 10/24/04, Al Gietzen wrote:
> > >I guess there are different views on this, but I see little relation
(as
> > >in maybe "none") between grounding the exhaust pipe, and refueling
> > >safety.  The static charge buildup is between the nozzle and the fuel
> > >(surface); or the nozzle and the potential existing static charge on
the
> > >surface of the strake due air friction.  So have a metal chain or cable
> > >from the cap ring hanging into the fuel, and keep the nozzle against
the
> > >ring; and, if you have just landed, wipe the surface of the strake with
a
> > >damp cloth before contacting the nozzle to the ring.
> > >
> > >Anyway, that's my take; but I've been wrong once before in my lifeJ.
> > >
> > >Al
> > >Subject: REFLECTOR: Grounding Point
> > >
> > >I didn't find a direct reference in the archives, so I was still
>wondering
> > >if the exhaust pipes is an adequate grounding point when refueling?  I
> > >always assumed it was but I'd hate this to be a FireBall Falacy.
> > >
> > >Chuck
> > >_______________________________________________
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>
>
>=====
>James F. Agnew
>Jim_Agnew_2 at Yahoo.Com
>Tampa, FL
>Velocity 173 Elite Aircraft Completed & Flying
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