20 - Fuel Safety

  • Safety Articles

A couple of weeks ago Domenic Romagnoli told me of his worries about our generally poor fuel storage and handling standards at Serpentine, so I promised I would mention his concerns to all our members before the warm weather started and the fuel vapour risk significantly increased.

Since this is Australia, I am sure there are very comprehensive laws governing the subject. I am equally certain that these laws are often impractical. I also do not want to know what they are.

So, what practical measures can we take to make re-fueling our aircraft from Jerry cans and fuel drums as safe as possible?

Our main problems are the flammability of fuel vapours (the fuel itself is not so flammable) and the fact that fuel (petrol, mogas, avgas, call it what you will) does not conduct electricity. This means that, when the fuel flows, it generates a static charge. Flying your aeroplane through the air also builds up a charge on it, and if you are daft enough to wear clothes of man-made fibres when you are flying or working on your aeroplane, they will build up a static charge too.

Your aircraft has rubber tyres, so it retains its charge for a long time. So do you if your shoes have rubber soles (as most do).

The problem comes when one of these charged things (you, the aeroplane or the fuel) comes near to another without them being connected by a low-resistance wire (earthing lead). Then we get a spark. It does not have to be a big one; your spark plugs only have a .020 or .025 inch gap. That's quite enough spark in a cylinder where the pressure is seven or eight times normal atmospheric pressure. One tiny spark and whoomph, the fuel vapour is alight.

If you are level-headed and quick, this need not be the end of you, your aeroplane or your hangar. If you can extinguish the fire before it does any more than burn at the fuel tank neck or the Jerry can nozzle, you can presumably avert disaster. Although John Ball, the only guy I know personally who had this happen, lost his Taylor Monoplane this way. It burnt down to a blob of molten metal (formerly its engine) on the grass.

So, how can you avoid static electricity? I bought a set of ten-dollar jump leads, and split them in half down the middle. I use one half to earth the drum to a bolt in the hangar floor, the other half's croc clips go on the fuel pump and the aeroplane's earthing tab (or the fuel tank neck, or something else connected to the tank). That seems to work for me, and it was nice, cheap, and easy.

When pouring from a Jerry can, I connect one croc clip to the funnel in the tank's filler neck and the other to a bare bit of metal on the can handle. The other lead goes from the tank tab to the floor bolt. Of course, it is most important to connect the leads BEFORE opening the fuel tank or Jerry can cap!

The use of plastic funnels (and, even worse, plastic Jerry cans) makes my hair stand on end (no pun intended). I have long considered the risk involved when fuel flows through plastic, generating static charges, to be the biggest danger of all. And yet, when I enquired about metal funnels in our local Bunnings, the helpful assistant said they didn't sell metal funnels, only plastic ones, because of the risk of static electricity. He clearly slept through his science class when the teacher demonstrated static electricity by rubbing fabric on plastic!

Metal funnels are available. It took me a long time to find a source, but I recently found some smaller ones in FAL, and several sizes in Atom Supply. Previously I read the label on Chris Fowler's one, located the manufacturer in Victoria, phoned and asked for their local distributor, only to discover it was Atkins Carlyle, who ordered a couple for me. The popular American, water-trapping Smart Tech plastic funnels claim to be made out of electro-conductive polypropylene which may be bonded to earth & the airframe (if you believe any American company's claims about their products).

Domenic also suggested we should all have buckets of sand in our hangars to extinguish any fires that do develop. I managed to find seven red plastic buckets at $1.10 apiece in FAL. There is no shortage of sand at Serpentine. I filled the buckets with sand, and now have them distributed around my hangar. I have another galvanised one (the last one left at FAL) on the fuel drum currently in use.

Another point, raised by Graham Hewitt, is that the commonly used twenty litre Jerry cans are painted inside. The paint often flakes off, so he suggests a gauze screen be soldered inside the funnel if it doesn't already come with one.

My old buddy, Neil Thomason, flying our club's Turbulent SAM, had his engine stop just after take-off. The Turb is light, with little momentum, so despite Neil's vast experience on the type (he was then the display team leader) he didn't get his nose down quickly enough, and flicked into a spin, which was stopped abruptly by the ground.

The airframe disintegrated on impact, and Neil was miraculously unhurt, sprinting away from the debris like a 100-metre Olympian. The wreckage did not burst into flames, so he went back to investigate. They had all just refueled from Jerry cans, but there was no funnel available, so they just poured the fuel into their tanks. Opening the fuel cap and peering into the take, he could clearly see a large fleck of paint covering the fuel outlet from the tank!

His was the only Turb without a 'finger' filter sticking up from the outlet.

I know many of you are much more experienced than I am at refueling aeroplanes and fuel safety generally, so I would be delighted to hear your views.

Yours,

Bob Grimstead
SABC Safety Committee