Kitfox Static discharge Fire

[ken nougaret]

thoughts here. I know this was done with a funnel. when you go to a fuel pump at an airport where do you ground for fueling? I'm thinking at the fuel tank opening. why? how does the tank ground to the aircraft, even worse to the exhaust on the engine? food for thought

Exactly! All this time i've been grounding at the exhaust. I guess from now on i'll clip the ground to the top of the gas neck. Then move it to the other wing before fueling it.

[aviator79]

The possible downside here is that your plane may have already accumulated quite a charge in flight, and when you touch the bonding clamp to the filler neck, you could jump a spark where a potentially ignitable fuel/air mixture exists. So you may want to touch it to the wing somewhere else (doesn't necessarily need to be metal, charge can still equalize) before touching it to the filler neck.

There are really two hazardous voltage sources:
1) Accumulated charge prior to filling (Airplane moving through air or jug sliding around on your plastic bedliner)

2) Accumulated charge during filling (result of fuel flowage/swirling/sloshing).

[zadwit]

static discharge fires are real common in Alaska due to the dry air.. .one guy put a piece of copper welding rod to the bottom of his red jerry jug of fuel. The top is epoxyed in to preven leakage. Then when refueling the plane, he clips the rod in the red gas jug to the plane and the plane to ground...

IN most every case the person said when he went to install the metal funnel, he heard a pop and funnel blew out. SOmetimes hyou can put hyour hand over the gas cap and the fire will go out.. most of the time the fueler is startled and drops the gas can and fuel goes every where..

Also, when aluminum is exposed to heat like a fire you need to find out what the main spar aluminum is, what the heardness is and then get a hardness tester and check it in the burn area to make sure the fire has not weakened the spar...most hardness testers are a little pointed thing with a dial guage and you press on the metal, the compare the reading to a chart that shows the hardness for the aluminum. Dont want to fly with a weakened spar!!

[Dusty]

Corrosion would be a concern here.Any material that burns leaves a harmful residue,also what was used to put the fire out? If in doubt recover the whole wing, as later corrosion will be hard to detect.
Sad to see the damage but glad the fire was delt to promptly.

[HighWing]

I would suggest earthing the gas tank filler neck rather than the gas caps. You remove the gas caps when refueling. I was thinking that the copper self adhesive tape that is used for ground planes in composite aircraft would be good to use. It is very thin and would not show under the fabric, compared to a wire.

What Jim suggests is exactly what I did. The tape is also used in Leaded glass projects and is where I discovered it. I did it on the second Model IV after fuelling for the 900 hours I put on the first one and every time thinking in my mind that connecting the ground to the exhaust stack was only cosmetic to satisfy the "is the aircraft grounded" question at the pump. What I did is remove the adhesive from a length of the tape with solvent then wrapped it around the filler neck for sizing. I then shortened it a tad to ensure a tight fit and soldered the ends together. The end of the rest of the adhesive backed tape was then soldered to the ring at a 90° angle. The inside of the ring and the filler neck was sanded lightly with a very fine sandpaper to create a good contact surface and the ring was forced onto the neck. The adhesive backed tape was then run to the end of the wing where it was soldered to wire that then led to a bolt to fuselage near the wing. The Aerothane I used on the plane was then carefully brush painted on the neck to create - hopefully - a water tight seal. I check it from time to time with an Ohm meter and it has always shown "0" Ohms from neck to exhaust stacks.

The picture was taken during an annual when I detected a suspected crack in the paint seal.

[efwd]

Odd that this isn't discussed in the build manual. I would think that if I made a small diameter steel cable, looped it around the gas filler neck before removing the cap, ground the cable and then fill the tank, this would suffice. Too late for me to pull off what Lowell did.

[PapuaPilot]

The of lack of bonding has crossed my mind, but I never thought something like this would happen. I am going to check my plane between the airframe and the gas filler neck to see if there is any bonding. If there isn't a proper ground then we need to think of a way to bond our fuel tank necks to the airframe.

On a related subject. Please realize that the use of plastic fuel jugs doesn't guarantee you are free from hazards from sparks. Even though plastic is non-condictive it readily stores static electricity. If a jug is charged it could easily cause a spark between the jug and filler neck. An easy way to take care of this is to wipe plastic jugs with a damp rag or spray/wipe a little water over the jug.

[bholland]

I agree with Phil. I work in the fire service and have been to several calls where people were filling plastic cans in the back of a pick up with a plastic bed liner and a fire was started by static electricity. It is always recommended to fill the plastic cans on the ground not in the bed of the truck. This whole conversation has made me realize that the A240 I sometimes fly has the same problem. Scary stuff

[Av8r3400]

I'm not very smart so help me out here a little.

If the static charge in a plastic can can be dissipated by placing it on the ground by the fuel pump (standard procedure) or grounding through your body to earth with a damp cloth, doesn't the fiberglass fuel tank in the plane ground to the wing spars and the rest of the airframe the same way, if the plane is grounded to the exhaust (standard procedure at all airport fueling pumps)?

Isn't all of this extra grounding to fix an extremely rare occurrence a little over blown?

[jiott]

Maybe someone will put an ohmmeter on a standard Kitfox and measure resistance between the metal filler neck and some point on the fuselage. If its near zero then we are overblowing it.