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Off Boarding Fuel

JonJay

JonJay

Well Known Member
Occasionally draining the tanks is necessary. I have done it with a variety of containers, elevated 5 gallon cans, funnels , etc….
Today, the chore was calibrating fuel level indication for a new EMS. Flofast has a system I have been using to fuel farm vehicles. They make various container sizes but I found the 7.5 gallon units fit perfectly under the RV6 drain. Made the job easier. There is a hand pump and hose that can drain the container in about a minute.
 

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Very good to see the static grounding. I'm using the steel 20 liter jerrycans since that's about the maximum weight my back wants to carry. I run it through my Mr. Funnel to see if I find anything interesting.
 
JonJay said:
Occasionally draining the tanks is necessary. I have done it with a variety of containers, elevated 5 gallon cans, funnels , etc….
Today, the chore was calibrating fuel level indication for a new EMS. Flofast has a system I have been using to fuel farm vehicles. They make various container sizes but I found the 7.5 gallon units fit perfectly under the RV6 drain. Made the job easier. There is a hand pump and hose that can drain the container in about a minute.
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This operation appears to be inside a hangar. Not prudent, if even legal. Even with static ground, it is still quite dangerous.
 
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I too had to calibrate my recently installed G3X. The following method could be used, at your own risk and peril only...

I'm sure most of VAF's avid readers will by now switch their popcorn maker to on, and that sure is a good way to support our farmers.
I find it way more fun to fly around locally on a partially filled tank until the engine starts quitting, switch to the other partially filled tank, return and land. After the calibration, that tank will be full (don't forget to have the tail up for Garmin's dual flight/ground attitude calibration, and please don't even think about asking 🙈), another flight to repeat the procedure and you're done.
The static grounding is not to be kept during the flying portion of the procedure.
 
I calibrated my tanks using water. Much less dangerous and still really accurate even thou water and avgas have different densities. The different desities do not affect the calibration more than 1%( it is the difference in the weight of the float and its bouncy )
 
Mel said:
This operation appears to be inside a hangar. Not prudent, if even legal. Even with static ground, it is still quite dangerous.
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What would you recommend as "best practice" if one has to defuel a tank, other than "burn off as much as you can first"?

One thought I had was to disconnect a fuel line up front, hook up a conductive hose, and use a boost pump (or in my case one of the EFI pumps) to empty the fuel into a larger storage tank, all properly grounded of course.
 
rmartingt said:
What would you recommend as "best practice" if one has to defuel a tank, other than "burn off as much as you can first"?
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I'm sure no Mel, but another way is to use one those wiggle the end hose... bought mine too many moons ago at what was decently called Oshkosh, and still use it from time to time. Quick, and empties most but not all of one's tank contents.
 
rmartingt said:
What would you recommend as "best practice" if one has to defuel a tank, other than "burn off as much as you can first"?
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Roll it into an open area outside of a building. Even the open space between rows of hangars is preferable.

A hangar in Ontario burned to the ground a few years back during a defuelling operation like this, taking i think 7 airplanes with it including some expensive warbirds..
 
rmartingt said:
What would you recommend as "best practice" if one has to defuel a tank, other than "burn off as much as you can first"?

One thought I had was to disconnect a fuel line up front, hook up a conductive hose, and use a boost pump (or in my case one of the EFI pumps) to empty the fuel into a larger storage tank, all properly grounded of course.
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I think what Mel is suggesting is to pull the RV out of the hangar before draining the tanks. I have a stainless welding rod connected to a cable that is clipped to an exhaust stack....the rod is inserted into the can. The entire operation is performed on the ramp in front of the hangar.
 
I recommend merging Tank Calibration with Fuel System Flush and verification of adequate fuel flow.

Disconnect the fuel line on the engine side of the firewall. Make up a temporay hose from the fuel line firewall fitting that includes a cheap clear plastic in line filter. Level the plane (as in flight level) and do the two gallons at a time fuel add to the tank to calibrate the senders. Once you get to the top of the indicating range (perhaps 2/3 to 3/4 full) then use the boost pump to empty the tank into five gallon cans. Measure flow and translate to gallons per minute while doing this. At some point also do the “tail down” fuel flow measurement to verify takeoff fuel flow.

Since you twice filtered the fuel, use the same fuel to do the other side. Repeat as needed if you get anything in either the ship fuel filter or the temporary plastic filter. Once done replace the now clean ship fuel filter.

Side note. I put five gallons or so in each tank a month or so after building them. With the tanks on a bench, I let them sit with the fuel to hopefully find any weeping rivets. Once a month or so I rotate the tanks from resting on the bottom skin, to resting on the top skin, to vertical (resting with the rear baffle down). Here I also drain out the fuel via the plastic inline filter as the initial crud flush. There is a long time between tanks done and mounting the wings on the fusleage so plenty of time to find weeping rivets before the plane is flying and they find you.

Carl
 
Carl Froehlich said:
I recommend merging Tank Calibration with Fuel System Flush and verification of adequate fuel flow.

Disconnect the fuel line on the engine side of the firewall. Make up a temporay hose from the fuel line firewall fitting that includes a cheap clear plastic in line filter. Level the plane (as in flight level) and do the two gallons at a time fuel add to the tank to calibrate the senders. Once you get to the top of the indicating range (perhaps 2/3 to 3/4 full) then use the boost pump to empty the tank into five gallon cans. Measure flow and translate to gallons per minute while doing this. At some point also do the “tail down” fuel flow measurement to verify takeoff fuel flow.

Since you twice filtered the fuel, use the same fuel to do the other side. Repeat as needed if you get anything in either the ship fuel filter or the temporary plastic filter. Once done replace the now clean ship fuel filter.

Side note. I put five gallons or so in each tank a month or so after building them. With the tanks on a bench, I let them sit with the fuel to hopefully find any weeping rivets. Once a month or so I rotate the tanks from resting on the bottom skin, to resting on the top skin, to vertical (resting with the rear baffle down). Here I also drain out the fuel via the plastic inline filter as the initial crud flush. There is a long time between tanks done and mounting the wings on the fusleage so plenty of time to find weeping rivets before the plane is flying and they find you.

Carl
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If one does this, I would recommend using static discharge wires in the fuel receiving tank connected to plane ground. I heard fast flowing fuel generates lots of static electricity.
 
PilotjohnS said:
If one does this, I would recommend using static discharge wires in the fuel receiving tank connected to plane ground. I heard fast flowing fuel generates lots of static electricity.
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It does.
Get a metal funnel. Attach three lengths of wire. One long, with a clip on the end; attach to earth ground. One shorter, again with clip; attach to airframe. Last one is short. Strip a few inches at the free end so the bare copper is exposed. Stick it down into the fuel container.
Everything maintains the same potential. No spark.
 
Thanks for the 3 wire grounding suggestion. FWIW, I machined a fitting that locks onto the tank drain. A vinyl tube slips onto the barbed opposite end . It is like an antenna wire coupling, just push up and twist. Reverse action to disconnect.
Full disclosure , I thought the drain tube touching inside the can was adequate grounding. Improvements are on the way .
 
I would recommend the static ground connect to the airframe, the catch can, and a grounding grid with no less than 2- 10ft ground rods with 15ft of separation. Nitrogen blanket into the tank filler at 6-12cfm. Fabricate a curtain around the catch can sealing to the wing to provide a nitrogen purge. Purge input at the top and CFM based on quality of seal. Then of course an SCBA to provide breathing air while working in the area. And at least 12cal FR clothing. Finally a 30lb class ABC fire extinguisher, and notify the airport fire department so they can be prepared.
 
Jjackh10 said:
I would recommend the static ground connect to the airframe, the catch can, and a grounding grid with no less than 2- 10ft ground rods with 15ft of separation. Nitrogen blanket into the tank filler at 6-12cfm. Fabricate a curtain around the catch can sealing to the wing to provide a nitrogen purge. Purge input at the top and CFM based on quality of seal. Then of course an SCBA to provide breathing air while working in the area. And at least 12cal FR clothing. Finally a 30lb class ABC fire extinguisher, and notify the airport fire department so they can be prepared.
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Only a 30lb extinguisher? I guess some folks are just OK taking risks…

😜
 
DanH said:
It was all lots of fun until lil' Johnny lost an eye...
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Hey' a child hood friend Frank thought it would be cool to smash a 30-06 shell with a sledge hammer. Oops!! it was, But, the primer ended up in his foot and a doctor visit later it was out. Dumb kid tricks.
My luck varies Fixit
 
[email protected] said:
Hey' a child hood friend Frank thought it would be cool to smash a 30-06 shell with a sledge hammer. Oops!! it was, But, the primer ended up in his foot and a doctor visit later it was out. Dumb kid tricks.
My luck varies Fixit
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I hear that. We taped .22 shells to the end of our red riders. Worked pretty good till my buddy caught a little brass in the neck. :LOL:
 
Folks. My original post was about a cool product from Flowfast that some may not be aware of. Check them out. We all know, or should, that off boarding or on boarding fuel is something to take care with.
We taped steel marbles to empty shot gun shells, until someone almost lost an eye from the wad. My uncle made his own shotgun and blew his trigger finger off, and didn’t everyone take a hammer to dad’s primers and smash them on the concrete?
We’re adults. We can assess our risks and benefits. We’re pilots also that operate airplanes, an inherently unforgiving “hobby”.
While I don’t always agree with some of the points folks make, I’ll never argue with a safety concern. I might ignore it, but I won’t argue…..
 
Where does Lower Explosion Limit fit in this discussion ? Compressed air in the tank is theoretically an effective control for combustion potential. That wouldn't totally address the catch can as some grounding is surely prudent. Also, humidity has not been mention for educational purpose. The probability of spark on the Florida coat is lower than Minneapolis at sub zero temps I would think.
 
JonJay said:
Folks. My original post was about a cool product from Flowfast that some may not be aware of. Check them out. We all know, or should, that off boarding or on boarding fuel is something to take care with.
We taped steel marbles to empty shot gun shells, until someone almost lost an eye from the wad. My uncle made his own shotgun and blew his trigger finger off, and didn’t everyone take a hammer to dad’s primers and smash them on the concrete?
We’re adults. We can assess our risks and benefits. We’re pilots also that operate airplanes, an inherently unforgiving “hobby”.
While I don’t always agree with some of the points folks make, I’ll never argue with a safety concern. I might ignore it, but I won’t argue…..
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I agree bud. Cowboys and farmers usually have a great way to get anything done. The Flowfast system is a great example. I apologize for the thread drift.
 
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