What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Defuel Rig

RVG8tor

Well Known Member
I am trying not to blow myself up so wondered what you guys think of this. I want to fill my thanks with 10 gal of fuel then immediately drain it out the fuel drain back into the cans. My wings are QB and I have inspected them with a snake camera and found no debris but I want to do this flush to get the big stuff (if there is any) before I start to pump through the system.

I have a barbed fitting that will go where the drain plug is located, attached will be a short section of tube. This will drain into a Mr Funnel which has a wide mouth. In order to keep everything at a common potential I made ground cable to ground the plane to the metal rail on the hanger door (this will be done outside of course). I have another ground to go from the plane to a rod which wraps around the funnel edge into the fuel can (plastic can) this way the ground rod is in the funnel as well as the can. Pictures follow. So have I made a safe as possible way of draining my fuel tank?

I went to all the trouble to make this set up because I figure there may be a reason to drain the tank in the future and I would like to use Mogas in one tank.

Thank you for your inputs.

In this shot you can see the setup, the rod goes from the bottom of the can up around the funnel and down into the bowl of the funnel. I used the eye built into the funnel to hold things. The ground clips are the ones that go from the rod to the plane, another goes to the hanger rail.

o03toj.jpg


This is a shot of the barb fitting and hose. The only place I should have fumes is in the bowl of the funnel and it is a wide area.

25kq5he.jpg
 
When I was calibrating my tanks, I didn't bother going to those lengths. I simply removed the quick drain and let the fuel flow into a funnel, sitting on a five gallon gas can. Of course, my funnel had a micro mesh screen in it.

Since the can is sitting on the ground, it is grounded. You could run your grounding wire from the plane the ground or to the fuel container.

I'm sure someone else will post some comments, I'm just telling you what I did, good or bad. Proceed with caution!
 
I did exactly what Bill said and also no issues except I stuffed up the calibrations and had to do it three times.

Cheers
 
Good to be Cautious

One of the larger maintenance shops here at KPTK had a Seneca on jacks a couple of years ago and the mechanic started to drain fuel. Ground straps were in place. He was wearing a sweater with a nylon jacket over the top. A static spark from his outfit light the fuel. Fortunately, the tower immediately saw smoke billowing out the door, the on field fire department was alerted and they were pumping foam before they came to a stop- they're located about 200 yards away. According to the shop owner, he went thru 2 large extinguishers with no effect, and it took three hits of foam to douse the fire. They were able to rescue three or four other planes in the shop, but the Seneca was a total. Couple of mechanics with minor burns, and the high bay roof was charred pretty good. Investigation determined that all proper practices had been adhered to, but contributing causes were clothing and high static in the air that day.
Terry
 
Draining Tanks

Do not drain tanks on a low humidity day. It can easily flash fire!

Pick a muggy day, use ground straps, and NEVER do it inside the hangar! You may get away with it 9 times, but that tenth time your number may come up!

Those little 5 and 10 pound extinguishers will not make a dent in even a small gasoline fire. Every hangar needs at least one or more 50-75 pound roll-around extinguishers.

It CAN happen to YOU and your RV!
 
Control the vapor and control static. Best to run the tube into the fuel container, the splashing into the funnel will generate vapor. I don't recommend tygon or similar plastic tubing, but there are few options. It you contain the fuel with minimal vapor release, there is little risk of burning up your project.

As far as sources of ignition, the surface of concrete does not offer a ground unless it is wet, so a hard ground is a good plan. Bonding between components as you describe is good. Wear cotton clothing, since it doesn't generate static if there is any humidity, and it doesn't melt to your skin if there is a fire (as nylon or polyester will.)
Most importantly, be sure you stay in contact with and exposed metal surface that is bonded to the fuel and ground. If you walk away, just touch a spot on the plane away from vapor to ground before you grab the funnel or gas can.
 
A jet at my old airport got totaled because someone forgot to open filler caps when draining the fuel. The vacuum crushed the wet wings! Be careful.:eek:
 
One other thought...

Based on your pictures, you are going to remove the quick drain and then screw in the hose fitting, is that correct?

If so, then you will be spilling fuel all over the place while you do that. This makes for a lot of gas vapors. You might want to rethink that part. Maybe add a valve to your hose and install it prior to filling the tanks?

Also, since it is winter time, turn off all heaters and other things that may cause you “issues”.
 
When I calibrated my tanks....three times...after it was done and I was thinking about it, I figured that I was the dumbest person in the world and the luckiest at the same time.

I had fuel all over the place, all over me and my arm and all soaked into the shirt I was wearing. I was a human torch waiting to go off. I broke all the rules, no grounding, did it alone in the hangar with nothing but a wall mounted extinguisher, etc.

Not sure how I will re-calibrate after the panel redo but it won't be the way I did it before!!!

I will be marking this thread for reference...
 
Last edited:
You're doing it the right way Mike.

My own rig is a metal funnel with three attached wires. One is clipped to the airplane. Another is clipped to a good ground....a buried tiedown ring is fine. The third is bare and is dropped down into the fuel container.
 
Fly it to empty?

I want to cal one of my tanks and don't want to do it again as described above or by my (just learned unsafe) messy method.

Couldn't I fly on the tank to cal until I run out of fuel, then switch tanks to keep it running, land at the airport 3000 feet under me and do the dynon two gallon at a time calibration?
 
The only thing I can think of would be to use a bare cable instead of the insulated one. I use an uninsulated braided cable that is clipped to the plane, receptacle, and laying on the ground at all times. I'm just hoping that with all the different points to drain off the static electricity I won't blow myself up.
 
Just in case of a spill, make sure there are no extension cords or trouble lights laying anywhere near by. I've seen three hangars burn down from a fuel spill ignited by an extension cord and or light with incandescent bulb that popped when fuel splashed on it.
 
Just in case of a spill, make sure there are no extension cords or trouble lights laying anywhere near by. I've seen three hangars burn down from a fuel spill ignited by an extension cord and or light with incandescent bulb that popped when fuel splashed on it.

My portable T hangar I'd secured to the ground with stakes. I imagine a ground from the airframe to one of those would be pretty fool proof.... A ramp tiedown hook would work similarly well, as would the metal of a regular T hangar...
 
Back
Top