REFLECTOR: Grounding Point

[Scott Derrick]

Still no first hand evidence.

Just hearsay...

At 05:07 PM 10/28/2004, you wrote:
>Hey Jim-
>
>As I recall, several/a few years ago, a Velocity was lost due to a 
>refueling fire- can't remember who it was, but it generated a lot of 
>interest on the reflector at the time-
>As far as a Cessna, or an RV having problems, I would guess that they 
>generally do not since you can ground(equalize) the entire airframe very 
>easily to the fuel truck through the ground cable, as long as you attach 
>it to somewhere on the airframe since the airframe itself is conductive 
>all of the way to the fuel cap rings.   The problem that we, lancair, 
>Glassair ect have is that it is difficult to ground the refueling point 
>through other areas of the aircraft.
>
>Alex
>-----Original Message-----
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On 
>Behalf Of Jim Sower
>Sent: Thursday, October 28, 2004 4:12 PM
>To: alex157 at direcway.com; Velocity Aircraft Owners and Builders list
>Subject: Re: REFLECTOR: Grounding Point
>
><...not any way for the charge to pass to the chain ...>
>So how does it get go ground on a Cessna or RV?
>
>BTW, in the interest of perspective or context, does anyone on this list 
>have first-hand (saw it happen) or second-hand (personally knows a 
>reliable first-hand witness) of a refueling fire caused by static charge 
>on ANY airplane?  Or automobile, for that matter?
>
>Inquiring minds need to know ... Jim S.
>
>Alex Balic wrote:
>>
>>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: <mailto:reflector-bounces at tvbf.org>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: <mailto:reflector-bounces at tvbf.org>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 <mailto:cjensen at dts9000.com><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: <mailto:reflector-bounces at tvbf.org>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


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