REFLECTOR: Grounding Point
Jim Sower
canarder at frontiernet.net
Fri Oct 29 00:01:31 CDT 2004
Didn't hear about that one. Wonder what the particulars are.
Cessna has rubber bladder tanks IIRC. RV (and everyone else) is all
metal. I'm questioning the assertion that grounding my chain (which
goes over the metal fuel orifice into the tank bottom) won't work
because there's no adequate path to ground (while implying that the
screen WILL provide an adequate path). My setup has at least as good a
path than any spam can, since they don't even have a chain and make no
attempt to ground the fuel streaming out of the nozzle (which is said to
be the source of static charge). This screen seems more effective than
my chain, but my chain is more effective than 99% of GA aircraft
(dramatically more effective than Cessnas with bladders) and is dirt
simple, practically free, and 90% installed before you even start
thinking about static discharge.
Alex Balic 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: 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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