 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
f.kyle(at)sympatico.ca
Guest
|
 Posted: Fri Jan 11, 2013 7:25 am Post subject: Grounding & Fuelling |
 |
|
Bud,
Thanks for clarifying your rules for fuelling - vital review!
I have a question related to same. My Europa has a 2inch aluminium fuelling inlet (‘cobra’ I think is a term), all the way from the fuelling cap to the tank inlet. I want to ground the aircraft for fuelling of course and the other components, but am not sure if there isn’t a grounding route already established.
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? Would there be a static disparity twixt that and the aircraft ground structure?
Cheers, Ferg
[quote][b]
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
 |
frans(at)privatepilots.nl
Guest
|
| Posted: Fri Jan 11, 2013 9:39 am Post subject: Grounding & Fuelling |
|
|
On 01/11/2013 04:26 PM, f.kyle(at)sympatico.ca wrote:
| Quote: | 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
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
budyerly(at)msn.com
Guest
|
| Posted: Fri Jan 11, 2013 7:40 pm Post subject: Grounding & Fuelling |
|
|
<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Ferg,
Gary Leinberger may have the best photo's of how I do it. Gary wanted the fuelling inlet to be grounded well so I put a small screw into his aluminum inlet filler neck and a wire down and around the Cobra to the main battery ground. My aircraft are normally fitted with an external jack for recharging and jumping near the battery. The Anderson Power Products plugs I use are in contact with the exterior skin so the skin, fuel filler neck and engine are all on the same plane. When fuelling, the grounding cable is attached to the tail pipe.
So with an aluminum cobra, just wrap a wire around that or a #4 = 40 screw tapped in the neck and Redux sealed, the run a bit of #18 wire to the ground of the aircraft should do it quite cheaply, easy and soundly.
Regards,
Bud
[quote] ---
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
budyerly(at)msn.com
Guest
|
| Posted: Sat Jan 12, 2013 5:03 pm Post subject: Grounding & Fuelling |
|
|
<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> 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
[quote] ---
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
frans(at)privatepilots.nl
Guest
|
| Posted: Sun Jan 13, 2013 2:15 am Post subject: Grounding & Fuelling |
|
|
On 01/13/2013 02:02 AM, Bud Yerly wrote:
| Quote: | 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.
|
You seem to assume (know?) that fuel is conductive. I'm pretty sure
however that fuel is quite a good isolator, just like the rest of the
carbohydrate family members. So, various components in contact with the
fuel may carry a different electrical charge and will not relieve
themselves via the fuel. It is entirely possible that the skin around
the fuel filler opening has a neutral electrical charge, while the
aluminium elbow carries a static charge. Now you think since you have
grounded the skin, engine, fuel nozzle/can and your body that nothing
can happen, but at the moment you insert a long fuel nozzle deeply and
it gets far enough to get close to the elbow the static charge of the
elbow might relieve itself to the fuel nozzle with a spark.
Ok, so grounding the aluminium elbow sounds like a good idea?
Unfortunately this creates a new problem:
Fuel itself may become electrically charged due to sloshing and friction
within the plastic tank. Imagine what will happen when you pour fresh
fuel in and the fuel level of the electrically charged fuel starts
rising, slowly approaching the grounded elbow...
I think you can't really solve this problem in a plastic aircraft with a
plastic fuel tank carrying non-conductive fluids. It looks to me that
you either should try to ground every individual component in contact
with the fuel and run a metal wire through the tank so all the fuel
molecules frequently run into the wire and discharge themselves before
they reach the sparking level potential, or, to accept that the whole
system may carry a charge but as long as it has nowhere to go there is
no sparking risk, i.e. do not ground anything in contact with the fuel.
Except for the fuel filler opening, but since it is plastic just a wipe
with a wet rag accomplishes this task. Never insert a hose or something
deeply inside the fuel filler opening. Although it sounds scary: The
fuel itself is not conductive so you can pour neutral fuel from a
grounded nozzle into a static charged tank without a problem, as long as
there are no grounded objects (like the elbow) to cause sparks when the
fuel level starts rising.
| Quote: | Problem is with the trailered aircraft.
|
We carry our Europa home after every local flight and we always refuel
at the local gas station while trailering to the airfield. We think it
is nearly impossible to refuel without making contact with the trailer,
various aircraft parts, the fuel opening and the fuel nozzle. It is
usually my wife who climbs onto the trailer (her belly is flatter than
mine so she just squeezes herself between the wing and the fuselage) to
reach the fuel opening and by the time she is in position I step on the
fender of the trailer and hand over the fuel nozzle over the wing flap,
my next task is holding on to the fuel hose to keep it from pulling on
the nozzle while reading out the liters on the display so my wife knows
when to stop. It would be very hard to accomplish the refueling
procedure without making solid contact with all the aircraft, trailer,
fuel nozzle, etc parts. Also keep in mind that we live in a very "wet"
country with high humidity levels being the norm, and static charge is
quite unlikely to build up on vehicles (except for rubbing certain
clothes against the upholstery while sitting in the car, but this
usually relieves itself while getting out of the car -ouch- before you
can even approach the fuel related objects)
When we fly to drier climates we usually leave the trailer behind as it
is too heavy to keep it strapped to the aircraft.  so we never find
ourselves in a situation where we have to refuel a trailered Europa in a
very dry environment.
| Quote: | 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.
|
In the Netherlands (but probably entire Europe) you can't lock the fuel
nozzle in the open position. You have to keep squeezing until the tank
if full. This ensures the person stays in contact with the fuel nozzle
all the time. Of course you can walk away but this would be pointless
because the fuel flow stops the very moment you loose contact with the
thing.
| Quote: | Your wet rag idea is great, if you have really dry hands or are messy
like me.
|
I have to add that the "wet rag" is usually not purposedly wetted, but
we always carry a rag in the airplane which we use to dry the airplane
from condensation in the morning, and to clean the windshield from bugs.
The rag usually stays wet during the entire multiple day travel,
especially because we keep the rag in a plastic bag to keep the interior
as dry as possible. Usually it is much more difficult to find a dry rag
than to find a wet rag. We use the very same rag to wipe off the
skin around the fuel opening before opening it.
Frans
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
grahamsingleton(at)btinte
Guest
|
| Posted: Sun Jan 13, 2013 1:13 pm Post subject: Grounding & Fuelling |
|
|
Bud & Frans
I still believe the urethane breather tube is a static generator, especially the 1/4" dia. one because air and fuel droplets are rushing
up it during refueling, the vapour and droplets of fuel are charged up when the exit the breather. Nearest relief point to ground is your hand.
I always fitted a 3/8" D aluminum breather which makes refueling easier too.
Graham
From: Bud Yerly <budyerly(at)msn.com>
To: europa-list(at)matronics.com
Sent: Sunday, 13 January 2013, 1:02
Subject: Re: Europa-List: Grounding & Fuelling
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
[quote] ---
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
budyerly(at)msn.com
Guest
|
| Posted: Sun Jan 13, 2013 4:51 pm Post subject: Grounding & Fuelling |
|
|
<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--><?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Frans,
Speaking from the US, the additives to the fuel here makes it a low conductivity fluid. I don't recommend it, but aviation fuel conductivity it is so low that you can hook a bulb with an attached bare wire submerged in the fuel and then approach the bulb with the ground wire and there will be no jump of electrical arc until virtual contact. At 12 volts, it isn't a problem, but in 250 volt power fuel storage it can arc.
Your point on the elbow is in error if the elbow is in contact with the aluminum fuel cap ring as I understood the hookup was. The cap/aluminum cobra neck will ground to earth through the wire to the aircraft ground system. However you are exactly right if the plastic cobra is installed and only the aluminum elbow connects the plastic cobra to the plastic tank. Why do that at all? Now the nozzle has a path to arc if it hasn't already as you indicated. Your are correct, it helps nothing and can be a potential hazard...
Flowing and sloshing fuel would cause an electrical charge buildup while fuel flows in during fuelling or sloshing, so when fuelling keep yourself in contact with the aircraft skin and nozzle. As for sparking with the nozzle in, if you have fuel flowing or not, if you leave the handle and vehicle without re-grounding, you will potentially be creating a discharge hazard.
My experience comes from an accident investigation of a fuelling accident. The fuels engineers talked over my head (not hard to do) and in a nutshell, JP-4 is a wide cut gasoline and had virtually nil conductivity just like gasoline. However, moving to JP-8 the conductivity jumped considerably screwing up all our fuel senders, and in a shorted imbedded fuel pump, it was found that it would conduct over a small distance (1/4 inch) and jump a spark at 250 volts. Normally there was no damage even if it arced because of the imbedding of the pump into the fuel and a virtual nil oxygen environment even at low fuel levels... However with fuel sloshing (low fuel in the bulk tank), it was enough to jump a spark. The spark arced a pin hole leak into a corroding tank bottom near the pump (added iron sulfides was what they found aided the arc). The pin hole leak provided a path for a discharge from the short through the fuel stream to the ground, so that was their cause... I still think it was the young airman and his cold weather nylon coat that was the ignition source.
Later when the FAA was approving the STC of gasoline in aviation engines, again we were fine until in California they had interesting required additives for emissions. One was an iron carbide molecule that with tolulene and other ionized cleaning additives screwed up the capacitance probes, resistive senders and in tank fuel pumps shourted out internally left and right. Then they required added ethanol (the plague) and again, we had another measured jump in conductivity by a factor of two, and the FAA stopped all auto fuel use in aircraft until investigated. These government mandated changes in fuel caused small increases in conductivity, but enough to cause the industry to change its fuel refining requirements for California. We all know that the difference in conductivity is enough to prevent capacitance systems from maintaining their accuracy when changing from one fuel to another, or simply one brand to another, but they no longer kill capacitance probes any longer as in the 80's. The good news is SO CAL Transportation Dept forced its own state government to cease further development of new additives unless stringent tests were conducted and quality of the fuel produced be monitored and tested carefully. As all our systems require a very low conductivity to allow safe operation of submerged pumps, fuel level senders etc. those of us pushing for auto fuel in our old low octane aircraft engines, were pleased. Too bad ethanol is still with us here in the States and ethanol free fuel is somewhat scarce.
So, do you have to run a wire anywhere inside the tank to ground our fuel system...Like we both said...NO. I only stated that if the metal ring on the outside of the aircraft fuel tank inlet, had a wire running to ground, and the tailpipe is grounded to earth, the outside of the aircraft should have the charge on the outside of the aircraft dissipated to earth. Is it just as effective as putting ones ungloved hand on the earth contacted fuel can and the aircraft using our somewhat low conductivity body as a ground wire.
You know that the static electricity stays on the outside of a vessel, and if a spark is going to jump it will most probably be caused by static discharge to a ground such as a fuel nozzle from the outer skin of the aircraft. The vapor around an open fuel tank then becomes a hazard.
I agree that fuelling on a trailer is not a major concern except for the guy in rubber soles being handed a fuel nozzle via gloved hand while standing on the trailer in winter rubber boots in a cold weather environment. Sparks will occur. Don't jump through hoops changing the airplane, just be aware and dissipate your static charge before opening the cap and putting the fuel nozzle to the filler neck...
Regards,
Bud
[quote] ---
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
budyerly(at)msn.com
Guest
|
| Posted: Sun Jan 13, 2013 4:57 pm Post subject: Grounding & Fuelling |
|
|
<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Graham,
You may be correct as flowing fluids make for a static source, but still, the static should be discharged through the person fuelling to ground provided he has made earth contact and contact with the aircraft. If he loses contact during fuelling, he may build charge and has a spark potential. Again, a self inflicted problem.
The larger breather vent is a good idea, especially in a tail dragger or you will get wet on a rapid fuelling attempt.
Regards,
Bud
[quote] ---
| | - The Matronics Europa-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
