Kitfox Static discharge Fire

[Dave S]

Amer,

First off - really sorry for your misfortune.

There is so much to consider with this. The repair is one thing; and, preventing this kind of thing is another.

On the repair, it is next to impossible to suggest partial or complete recovering other than in a general way from afar because the need is ability to accurately inspect - only a person on site/hands on can figure that out. One thing regarding fire damage - much of the residue can be a source of corrosion or rot down the road if it isn't all removed and cleaned up. I do know of a local person who had a wing fire not involving fuel on a fabric covered airplane due to misuse of a space heater (put the chimney up against the bottom of the wing) - in that case the mechanic removed the fabric on the entire wing to inspect and do the repair.


I think the incident should reinforce the care we need to take when fueling. 1) Always do it outside, 2) Have an adequate fire extinguisher handy, 3) Have some way of grounding the aircraft......+ other considerations?

One question I have is do you know what the humidity level was in the air at the time? Was it an extremely dry day?

When building our Kitfox, I thought about grounding the fuel cap rings since the rings are insulated from the frame and therefore won't be grounded by the method usually used when fueling, but didn't get it done. I think your idea of doing this has real merit. If anyone has any experience in how to ground the ring, or has done it, that would be very useful information.

Wishing you good luck with the repair - that is a tough deal.

[amerkarim]

Hi Dave,

Many thanks for your thoughts.

It was about midday and it was very hot and dry. There was probably lots of fuel vapour in the air and the wind was blowing, so the wing was probably generating lots of static.

As you are aware, the wing and gas tanks are an insulator and the only metal parts are the gas caps and the lips of the tank. I am sure that earthing the lip of the gas tanks or the gas caps, will help discharge static that builds up over the wing. If anyone was doing a new build, I would advise them to earth both the tanks from inside the wing by riveting an earthing wire from the underside of the gas tank lip on the outside, to the main metal spar or round in the wing.

I am planning to rivet a wire to the gas caps themselves and then pass that through the wing and to a metal earthing point.

Regarding the repair, I am sure I can cut out anything that is fire damaged and do a patch. The plane has already been inspected by an engineer, and he has said it is only fabric damage. He offered to do the repair, but I want to do it myself.

Thanks

[Dave S]

Amer,

Sounds like you are well on your way to getting this solved.

I think the value of a poly tone finish is certainly shown in the case for an easier repair.

Good to know it was just fabric damage.

Dave

[jiott]

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.

[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.

[Slyfox]

first off glad nobody was hurt.

a note on refueling. it scares the bejesus out of me when I see someone using a funnel. I have always used one of those plastic jugs (5gal) with a long spout on them. they are used to refuel 4 wheelers. at least I find them at the motorcycle shops. I always transfer with metal jury cans with a nice neck into this and then into the airplane(touch the steel can spout to the plastic jug). always, I say always let the neck of the jug touch the opening of the airplane fuel tank, that grounds the two together, thus eliminating a static spark. I use this jug to fuel both airplanes, the rv and the kitfox.

onto the repair. you are going to have to remove the wing and rip off all the fabric, then using a heat gun soften the glue and remove the ribs. then start over with new ribs and then refabric the wing.

[dholly]

As you are aware, the wing and gas tanks are an insulator and the only metal parts are the gas caps and the lips of the tank. I am sure that earthing the lip of the gas tanks or the gas caps, will help discharge static that builds up over the wing. If anyone was doing a new build, I would advise them to earth both the tanks from inside the wing by riveting an earthing wire from the underside of the gas tank lip on the outside, to the main metal spar or round in the wing.

I'm confused... the lips of your tanks are metal?

[edit] Sorry, I assume you meant filler neck. I personally like Jim's idea, but stripping the entire wing and removing/replacing ribs etc., not so much. If there is no evidence of adhesive failure and inspector says recover and go, that's exactly what I would do..

[Slyfox]

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