On 11/15/2023 4:55 PM, k...@bouyea.net wrote:
A recent [Pilot Workshops.com] newsletter asked a good question;
Grounding While Fueling? Their link to the article is:
https://pilotworkshop.com/tips/grounding-while-fueling
Spoiler Alert: it should be at a point that grounds the fuel tank(s)
to eliminate the spark potential between it and the fueling system.
Okay, that’s great. Hmmn, like probably most of us, N133RM has a
composite tank sitting on rubber cushion strips further isolating it
from any grounding exposure. And the fuel line going to the firewall
bulkhead fitting? Yeah that’s rubber too. So the question really asks
us to seek the answer for our airplanes. So just what IS metal in the
fuel tank?
The finger screen is brass and it’s held in place by a metal AN
fitting that has a metal On-Off fuel valve.
I plan to install a grounding lug on the outside of the AN fitting to
an engine-connected ground. Then I CAN clip the fueling system to the
exhaust stub sticking below the cowl. Now I’ll be grounded!
PS for extra points, are the fuel cap threads isolated (or insulated)
from the composite tank material? Mine are not. Read the article for a
suggestion on what to do with the fueling system nozzle…
John Bouyea / OR81/ Hillsboro, OR
N133RM KR-2S – imported, fixed & flying
www.bouyea.net/N133RM <http://www.bouyea.net/N133RM>
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
The few times I purchased fuel for 211LF from a truck or ground based
fuel system I always made the attendant feel more comfortable by
hooking their ground cable to my exhaust stack. In reality that
accomplished absolutely nothing as that in no way removed any electrical
potential from the aircraft, especially from the composite wing with a
composite tank that had zero electrical conductivity. It is amazing
what an electrical charge can be created by flowing fluids or
particles. I learned that working on office equipment for 33 years and
vacuuming toner or developer grains from the machines. I have on
numerous occasions drew arcs that cracked so loud it caught the
attention of others near by. Fortunately my body was never a part of
the circuit.
I'll give a web post to one of the better solutions I've heard that you
can try.
https://generalaviationnews.com/2006/12/01/how-to-ground-a-composite-aircraft/
My procedure in the past, whether it worked or not or maybe I was just
lucky, was before opening the cap I'd place my hand flat on the wing
near the cap and then hold the metal nozzle of the filler hose. That in
theory made equal any electrical charge on the wing equal to the the
filler hose so no spark would occur as my body was a very high
resistance conductor. When filling the tank I was very careful to
always keep the metal nozzle in contact with the filler neck / wing
surface so as to never make a gap for any charge that might build to
jump and make an arc.
The web article above has a simple solution that I had not considered.
The only thing I would add as I didn't see it suggested in the article
would be to add a wire to the metal strip with a clamp that could be
connected to the metal filler nozzle so as to always keep the nozzle at
the same potential as the fuel being dispensed in to the tank and
building a charge.
Any electrical engineers see a problem with any of this?
Larry Flesner
--
KRnet mailing list
KRnet@list.krnet.org
https://list.krnet.org/mailman/listinfo/krnet
