Static discharge and grounding plastic airplanes during fueling

[Wayne Hicks]

There have been so many versions and even some contradictions in the

Grounding/Bonding issue. A fellow builder felt compelled to bring to the group a little bit of information in black and white. If you want more info than you can possibly use on this very subject, have a look at this link to an Air Force Technical Order. It's the second file "Grounding/Bonding".

http://www.remotearrow.com/ez/maint/index.htm

 

And from the Cozy FAQs:

21.21 - What are the issues with fueling, static electricity, and grounding the airframe?

 

The issue is with build-up of static electricity on the strake skin surfaces which subsequently discharges and ignites fuel vapors. Static charge is generated at the filler neck by the movement of the fuel through the nozzle into the tank, just like rubbing your shoes on a carpet in low humidity. On a metal airplane this charge is dissipated by the frame to the grounding clamp. Our plastic planes are non-conductive, so the charge has nowhere to go. Fuel is non-conductive too, so dangling a chain or wire into the fuel will not help. Best procedures seem to be to wipe the strakes with a damp towel to dissipate static build-up, touch the fueling nozzle to the fuel cap before removing the cap, provide some method of grounding the fueling receptacle, and never refuel from a plastic container. Sport Aviation addresses this subject in the December 1998 issue, page 55. Reference NFPA 407, Standard for Aircraft Fuel Servicing, for more detailed discussions.

 

============

Wayne Hicks

[marbleturtle]

What about those of us who plan on using auto gas? John said he's going to pump it out of his own tank with rubber tubing. I was thinking about keeping a 60 gallon tank with a small electric pump in the middle of the bed of a pickup truck. (Plastic of course)

 

So is this a bad idea?

[John Slade]

I might be wrong here, but I think that if you ground the vehicle to the fuel cap, put a rubber hose into the tank (so it's pumping directly into the fuel), turn on an electric pump, then there's no point at which the fuel will assume a charge. I think it's the fuel flowing though the air that causes the problem.

[John Slade]

Good news. Harbor Freight have a 12V gasoline pump. It comes with a 15 foot grounded filler nozzel (just like at the gas pump), a big assed filter with fittings for pipe thread inserts, and a gallons indicator. Pumps 15gal / minute. Cost $189. All you need is one of these and a big tank and you're your own gas truck.

 

Bad news. The .astards just opened a store 3 miles from me...

[Jerry Schneider]

Oh John,

 

You poor *astard.

I can't go to the one near me without spending at least $100.

 

I'm in a 12 step program now.... It's called CTA (Cheap Tools Anonymous). Let go.. Let Snap On.

[Cozy1200]

Ok I have a question for you guys that plan to transport auto fuel to the airport.

 

What are you going to do on the flipside of a long trip?

 

Just curious. I haven't figured that out yet.

[John Slade]

There's a web site somewhere that lists all the fields which offer autogas. Worst case I'll burn avgas and keep a spare set of plugs handy.

[TES111]

What about the smart plugs? Don't they let you burn all types of fuels?

[marbleturtle]

John! I need a part number! I can't find it on the HF website.

 

As for going someplace without autogas, I plan on renting a car and making a few trips to the gas station. A little pump and 20 ft of rubber hosing doesn't take up much space.

[John Slade]

Sorry. I don't have a part number. Just looked at it and put it back on the shelf for later.

[chuckthedog]

I ran auto gas in my Long-ez for better than 12 years. In a nut shell. What a pain in the butt. Filling with 5 gal cans before trips. Finding Auto gas at other airports. Finding gas cans. Finding a ride to fill the cans. I could go on, and on. Now to the plugs. Plugs fowel when you idle rich over time, or run rich. keep rich idle to a min. Now Grounding your bird for fueling. I have a peace of copper tubing I stick in the tank Through the the filler hole, and clip the ground clamp on it. To date no earth shattering kaboom. I switched to 100LL this summer when I had to rebuild my 1955 Lycosours. Rebuilt in 1966. checked over in 1989 and run for 1323 hours on auto gas in my long-EZ. Then 0 timed this July and set up to run 100LL. The extra cost of 100LL is worth it just to be rid of all hassel. I am not out to start anything.

PS

I had to plug in my electric coat last week. Can winter be close at hand?

[Jim Sower]

Test111,

<... What about the smart plugs? Don't they let you burn all types of fuels? ...>

If they work and become available, smart plugs will revolutionize a lot of things. Like, we'll be seeing nearly all of the auto conversions converting to Diesel/Jet-A. I am a true believer at this juncture, but skeptical that they will be available in my lifetime. Sort of like being a Zorche (or Red Sox) fan. I went to a couple of their seminars and checked out their web site, and concluded that they are looking more to sell their patent than distribute a product. I've been wrong before, but that's my feeling on those guys.

But it would be nice .... Jim S.

[Cozy1200]

John,

 

You said you'd could run AvGas and then worry about the plugs later.

Can you mix AvGas and Auto gas?

 

I'm guessing you would want to be fairly low on gas before filling up with the different type.

[Jim Sower]

<... you would want to be fairly low on gas before filling up with the different ...>

I can't imagine why. I've been burning a mixture of Avgas and hi-test mogas in my IO-360. It's major heresy in the conventional wisdom to use mogas in any injected engine, but I didn't hear any actual easons for this that sounded more rational than religious. I mix about half and half so as to retain some lead for the valve seats (yes, I know that sounds less rational and more religious), and I put a little 2-stroke oil in the mix as top lube to keep rings, valves, valve guides working. I don't have any hard evidence for 2-stroke top oil doing any good OR the mogas doing any harm. I've only been this for around 50-75 hrs, but it's been good so far. The difference in price is about $1.00 or more per gal, which for me is $13 $15 per hour. Mixing saves me $5 - $7 per hour on average. That's significant for me.

 

I'll more and better information as time goes on.