Gas, Cans, & Bonding - Page 4

Sam Buchanan · #31 10-25-2018, 04:10 PM

The question for which I haven't seen the answer is "where should the ground wire be attached on the fueling rig?"

Does static need to be discharged at the pump or at the nozzle where gasoline enters the aircraft tank? It seems to me grounding should occur at the nozzle to eliminate static buildup as gasoline flows through the delivery hose post-pump. Is having the grounding cable at the pump leaving part of the system unprotected?

rv7charlie · #32 10-25-2018, 06:15 PM

Before anything else, I should say that a good friend of mine actually had a fuel fire while fueling his -6A from cans. He was fortunate; it did no damage. He had fire around the filler neck (quickly extinguished by dropping the cap into the fill neck), and a small fire on the ground due to spilling some of the can's contents as he recoiled from the fire. He will no longer fuel his plane except from an airport pump.

With that out of the way...

If I'm not mistaken, commercial pump hoses are bonded from nozzle to pump. Having said that, I suspect that if you fail to attach the ground line to the plane, and hold the nozzle over/in the fill neck without actually touching the neck, you could still get static buildup. I think this because it's my understanding that the fuel's flow through the hose can generate static charge buildup, similar to rubbing your shoes on carpet.

Having said all that, I'm pretty sure that plastic gas cans are impregnated with enough conductive material to bleed off any static charge, as long as they are in contact with ground or the source/destination of the fuel. And if you can believe the Gubmnt, metal is no help. See the last sentence in the 2nd paragraph. Also note the recommended procedure to minimize risk while transferring fuel in either direction.
https://www.cdc.gov/niosh/docs/98-111/default.html

Last, IIRC, the reason I was told to hook up the ground lead before getting the hose at the fuel farm was because the plane itself has the potential (pardon the pun) to build up a static charge in flight (think static wicks on high/fast planes), and there's a risk it could retain that charge as you approach it with the grounded fuel hose.

I continue to fuel from plastic gas cans; I just try to incorporate whatever new info I learn as time goes by.

Charlie

edit: Should have added: Touching the can to something metal on the plane before opening either fuel container should dissipate any static charge differences between the fuel and the plane.

RFSchaller · #33 10-25-2018, 08:53 PM

Any static spark would occur at the first contact point. If the component that makes that contact is grounded to any part of the airframe it should be at the same electric potential so know spark would occur. So it doesn?t matter where you pick on the airframe to connect the ground wire as long as it?s not insulated from the airframe. In practical terms that means don?t pick a painted or nonconductive surface, but exhaust pipes, unpainted tiedown rings or unpainted nosewheel forks are good choices. The other end should have a conducting path to the fuel nozzle.

Sam Buchanan · #34 10-25-2018, 09:00 PM

Quote:

Originally Posted by Sam Buchanan

The question for which I haven't seen the answer is "where should the ground wire be attached on the fueling rig?"

Does static need to be discharged at the pump or at the nozzle where gasoline enters the aircraft tank? It seems to me grounding should occur at the nozzle to eliminate static buildup as gasoline flows through the delivery hose post-pump. Is having the grounding cable at the pump leaving part of the system unprotected?

I was not as clear as I should have been. By "fueling rig", I'm referring to the ones that have appeared in this thread with either electric or hand-crank pumps. The aircraft end of a grounding scheme should obviously be connected to a conductive surface, but where should we connect the other end of a ground cable. To the plastic can, or a probe in the fuel, or the pump, or at the nozzle? Is it sufficient to have a conductive nozzle that is in contact with the metallic aircraft tank?

I am inclined to think the metallic nozzle would bleed off any charge created by movement of fuel in the system, but am wondering if I am overlooking something.

MVPILOT · #35 08-11-2019, 09:17 AM

The only airport I could but high octane non ethanol fuel quit selling it for lack of volume. (Arlington Flight Services KAWO) As far as I know the nearest on airport fuel is over 200 miles away and so same problem. I can purchase from a Cenex gas station about 10 miles away. What a hassle.

N804RV · #36 08-11-2019, 09:54 AM

Quote:

Originally Posted by MVPILOT

The only airport I could but high octane non ethanol fuel quit selling it for lack of volume. (Arlington Flight Services KAWO) As far as I know the nearest on airport fuel is over 200 miles away and so same problem. I can purchase from a Cenex gas station about 10 miles away. What a hassle.

I'm at AWO. I run 0-E in my Sonerai. Nelson's is about 1.5 miles from AWO, and they have 92 octane 0-E. And, its cheaper than what AFS was selling it for on the field. Also, River Rock Smoke Shop, on Smokey Point BLVD has 89 octane 0-E.

For those of you that haven't discovered it yet, check out https://www.pure-gas.org.

Also, for those of you that can hoist a gas can and don't like the one-gallon-per-minute gas pump rigs, nor the "Safety-can" style ****, you can still buy the old utility jug used by dirt-bikers for years.

https://www.amazon.com/VP-Racing-Squ...gateway&sr=8-3

Touching airplane and jug before and during fueling, never had a static issue.

bobg56 · #37 08-11-2019, 10:21 AM

I have a wire cable with alligator clamps at each end. I attach it to my tail tie down ring and the other end I either let lay on the ground or attach it to a tie down point if near one. That should discharge any built up charge and keep it attached while fueling using plastic jugs...works for me.

Bob Y · #38 08-11-2019, 02:01 PM

Don?t want to insult anyone by stating this, but the purpose for the BONDING cable is to bond the airframe to the fuel dispensing nozzle. Fuel flowing through the hose and nozzle can develop a static charge. Electrical current flows from high to low potential. If both the airframe and nozzle are at the same potential (via the bonding cable), voltage won?t build up between the nozzle and filler neck, thus no static discharge. The hose on the fuel truck, or airport stationary fueling pump, has an internal bonding wire that connects the nozzle to the chassis ground on the pump, which is connected to the retractable bonding cable on the pump. So, one ideally wants to connect the bonding cable between the airframe and fuel filler nozzle, or as close to it electrically as one can get.

bobg56 · #39 08-11-2019, 02:43 PM

When you fill up your car there's no bonding cables used, although nozzle is metal and your usually putting in 20 gallons or more in some cases. There are warnings about static discharge so either its a rare occurance and we're just lucky I guess...

wirejock · #40 08-11-2019, 02:45 PM

I got no skin in this game because I plan to pump but at some point I will be moving fuel to test fuel flow, etc.
Does anyone use racing gas cans? They dump gas really fast. We used them for years refueling the race car. No grounds, no bare hands touching anything. Fully covered with racing gear. Maybe every team was lucky, but I never saw a fire on pit row. Maybe they are made for it?