REFLECTOR: Grounding Point

Sun Oct 24 17:56:11 CDT 2004

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
> > >_______________________________________________
> > >To change your email address, visit
> > >http://www.tvbf.org/mailman/listinfo/reflector
> > >
> > >Visit the gallery!  www.tvbf.org/gallery
> > >user:pw = tvbf:jamaicangoose
> > >Check new archives: www.tvbf.org/pipermail
> > >Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> >
> > _______________________________________________
> > To change your email address, visit
> > http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery!  www.tvbf.org/gallery
> > user:pw = tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> > _______________________________________________
> > To change your email address, visit
> > http://www.tvbf.org/mailman/listinfo/reflector
> >
> > Visit the gallery!  www.tvbf.org/gallery
> > user:pw = tvbf:jamaicangoose
> > Check new archives: www.tvbf.org/pipermail
> > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
> >
>
>
>=====
>James F. Agnew
>Jim_Agnew_2 at Yahoo.Com
>Tampa, FL
>Velocity 173 Elite Aircraft Completed & Flying
>_______________________________________________
>To change your email address, visit
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery!  www.tvbf.org/gallery
>user:pw = tvbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>_______________________________________________
>To change your email address, visit 
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery!  www.tvbf.org/gallery
>user:pw = tvbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html

"Those who sacrifice freedom to get security, deserve neither."
- Benjamin Franklin