Guidance for draining tanks

[M20F-1968]

This is a question about how to safely de-fuel the airplane.

My JPI 930 fuel tank gauges need to be recalibrated.  I have Monroy long range tanks and and am using the current production style fuel senders (2 in each tank).  I do have a fuel totalizer connected to the turbine wheel type sender.

The JPI was never properly calibrated.  With the long range tanks, the actual fuel volume is not equally divided for every 1/4 tank increase on the JPI gauges.  I believe the maximum data points allowed by the JPI 930 are five data point, empty, 1/4, 1/2, 3/4 and full.  I wish I could calibrate the JPI with more data points, such as every 5 gallons, but apparently that is not possible.

My plan is to burn off as much fuel as I can in one tank and then empty the remaining fuel into a 5 gallon bucket and put it in the opposite tank.  Once one side is correctly calibrated, then I redo the some procedure on the other side. 

My question for the forum is what are the precautions I should take in draining the one tank and moving fuel to the opposite side?

Thing I recognize are:

1. Ground the airplane.  May use an auto jumper cable with alligator clips on each end, exhaust pipe to steel structure in hanger or electrical conduit.

2. Use a steel bucket to drain fuel into and ground the bucket as well

3. Have no carpets or blankets in the area which could generate static electricity

4. Avoid climbing in/out of plane

5. I plan on using the fuel sump drain to drain the remaining fuel (I know it will take some time) with a wire or string I can access through the pilot's window to pull up on the sump drain.

6. I have a filtered funnel for the other tank which is screened and separates out water as well (as I recall).

7. Perhaps leave the hangar door open to minimize fumes (but it is winter here).

8. Shut off the propane furnace (should I also shut off the pilot flame)?

9. May I leave lights on?

I am obviously worried about the flammability issues while handling fuel.  Is it safe to do this in a T hangar?

Your thoughts are appreciated.

Should I simply but a pump and sealed can rated for fuel?

Or perhaps delegate this to a local mechanic, but I may be thinking more about the problems than a paid mechanic will.

ANY OTHER THOUGHTS ON HOW TO DO THIS WILL BE APPRECIATED.

Another thought may be to full the tank, fly 1/4 tank down at a time and recalibrate one 1/4 tank at a time starting with a full tank.  

The plane needs to be leveled to enter the calibration.  Can the calibration be enter while in level cruise flight in calm air?

John Breda

 

 

[Guest]

When de fueling a plane in the shop I remove the fuel line at the firewall fitting and install a hose to pump fuel into an empty steel engine oil barrel.  Then use the airframe boost pump to pump the fuel out. Be prepared to quickly shut off the pump when the tank is empty.

Drain the last of the fuel by removing the sump drains.

Obvious safety precautions like grounding, sources of ignition in the hangar and on you, no nylon and other synthetics to cause static sparks.

Clarence

[ArtVandelay]

We added measured fuel to get to 1/4, 1/2...it was calibrated on the ground. We used the boost pump to drain the tanks and did not bother draining the unusable fuel, so E means no more fuel for the engine. My 64 gal tanks actually hold 68.


Tom

[takair]

I’ve also added a jumper from the container to the aircraft.  If using smaller container vs barrel, you will get some fumes down low, so best to vent the hangar.  You could fly one tank down to sputtering , as recommended in the older operating manual, but I know that is a contraversial subject....then do one tank at a time.

[Bob_Belville]

John, when we installed add on bladders earlier this year we also added CiES fuel sensors which meant calibrating the 930 fuel quantities. As Clarence indicates the fastest way to drain the tank is to disconnect the fuel line and direct it into a container, we used 5 gallon gas cans, and use the boost pump. With 5 gallon containers it's a 2 person job, one monitoring the fuel flowing into the container and a helper ready to cut off the pump. The JPI calibration process it clear enough. Level the plane and add 1/4 tank at a time and enter the factors into the JPI. We drained the tanks completely in order to install the bladders so when we started the calibration we first added the nominal unusable fuel and set the JPI to zero.    

[201er]

1 hour ago, M20F-1968 said:

My plan is to burn off as much fuel as I can in one tank and then empty the remaining fuel into a 5 gallon bucket and put it in the opposite tank.  Once one side is correctly calibrated, then I redo the some procedure on the other side. 

Should I simply but a pump and sealed can rated for fuel?

Or perhaps delegate this to a local mechanic, but I may be thinking more about the problems than a paid mechanic will.

ANY OTHER THOUGHTS ON HOW TO DO THIS WILL BE APPRECIATE

 

You’re going about it all wrong. You shouldn’t be draining any fuel at all for calibration! You gotta get in that thing and fly it high in cruise until you run a tank dry. No more, no less. That’s the only way to get an accurate zero point for your fuel calibration. If you start draining fuel on the ground, it may not accurately represent the in flight cut off as you get into the unusable fuel.

I suggest you calibrate yourself a dipstick while you’re at it by adding a few known gallons at a time and dipping. Like you said with the extended range tanks it’s not linear so it’s even more important to get this info from an in flight run it dry condition.

[ArtVandelay]

You’re going about it all wrong. You shouldn’t be draining any fuel at all for calibration! You gotta get in that thing and fly it high in cruise until you run a tank dry. No more, no less. That’s the only way to get an accurate zero point for your fuel calibration. If you start draining fuel on the ground, it may not accurately represent the in flight cut off as you get into the unusable fuel.

Why won’t it?
Assuming you use the fuel pump and are level of course.




Tom

[Bob - S50]

The 'legal' definition of zero fuel is what is defined in the POH.  I drained my tanks dry using the gascolator for most of it and then the sump drain for the quart that remained.  I then put the required 5 quarts back in to be 'zero' usable fuel and then calibrated my gauge.

With that said, I also went out and flew around just to run a tank dry and see how long the engine would run after my gauge said zero fuel remaining.  The answer is about 5 to 6 minutes in level flight.  That's almost a gallon of fuel I can burn after my gauge says zero.

I will never plan a flight based on being able to use that gallon (or the one in the other tank) but it's nice to know that it's there in an emergency.

[LANCECASPER]

2 hours ago, M20F-1968 said:

I have Monroy long range tanks and and am using the current production style fuel senders (2 in each tank). 

 

 

Are these the CIES senders? I have the factory senders in my '93 M model and when I go to a JPI 900 or 930 I am going to bite the bullet and do the CIES senders at the same time.

[kortopates]

Emptying the tanks is easy and well addressed above.
But good calibration with long range tanks is a challenge.
Personally IMO trying to do one side alone is an automatic fail. You won’t be able to maintain lateral level as you add weight to only one side. You could consider using jacks outside but that introduces the additional risk of having the plane on jacks exposed to the wind and the challenge of getting the plane level from nose to tail - I can’t do that on my jacks. So that leaves one using addition of equal weight on both sides to help keep the wings level during the calibration process.

Secondly with the long range tanks, I suggest filling only from the outboard side. Fuel will quickly settle inboard from the outside - but not the other way around. When I did it the first time, filling the conventional way, I waited over 5 min for fuel to settle but it wasn’t near long enough. But from the outside it should prove much easier. I plan to redo mine soon too for this reason.



Sent from my iPhone using Tapatalk

[Immelman]

If you need to empty a tank, i.e. for leak work: Tie a rag around your arm, remove the fuel sump drain, it goes pretty quick.

To calibrate your sender... I agree, why not have "0" mean "0" usable. Run that tank dry in cruise. If you're good you'll catch the fuel pressure drop and make the switch before the engine quits with hardly a stumble.

Edited December 30, 2018 by Immelman

[0TreeLemur]

Here's what I did and you can do it too.   Get your wife/girlfriend/signif. other to go up with you after you return from a trip with say less than 10 gallons on each side.  Climb to a few 1000 ft AGL and orbit the field.  Switch to the emptiest tank and ask your passenger to watch the fuel pressure gauge and tell you when it starts to rapidly decrease.    When that happens, switch to the other tank and land.   You can calibrate the senders on that empty tank knowing what zero means.   Then, take it back up and repeat for the other tank.

I've learned that there are two potential issues with removing the sump drain valves.  First, the piece they are screwed into, which is riveted into the tank, might be corroded and can fail.   Second, someone might have attempted to fix it and done a poor job.   Running a tank dry is much easier, and IMHO, fun.

[jaylw314]

You shouldn't need a metal bucket for the fuel, a plastic one is fine as long as it is sitting directly on the ground.  While plastic is less conductive, the surface area is large enough to disperse static.  That's why we can use plastic fuel jugs at the gas station.

It'd be good to have something grounded you can touch nearby.  If you have a grounded appliance with a 3 pronged plug, you can just plug it in and touch its chassis to ground yourself.  Obviously, you want to do this a few feet away, NOT, right next to open fuel 

[EricJ]

3 hours ago, jaylw314 said:

You shouldn't need a metal bucket for the fuel, a plastic one is fine as long as it is sitting directly on the ground.  While plastic is less conductive, the surface area is large enough to disperse static.  That's why we can use plastic fuel jugs at the gas station.

Just make sure the plastic in the bucket isn't soluble in gasoline.  Either test with a little bit of gasoline and make certain is doesn't dissolve or use a plastic that is known insoluble to gasoline (like a red fuel jug).

Learned that the hard way long ago. 

[Bob_Belville]

9 hours ago, kortopates said:

Emptying the tanks is easy and well addressed above.
But good calibration with long range tanks is a challenge.
Personally IMO trying to do one side alone is an automatic fail. You won’t be able to maintain lateral level as you add weight to only one side. You could consider using jacks outside but that introduces the additional risk of having the plane on jacks exposed to the wind and the challenge of getting the plane level from nose to tail - I can’t do that on my jacks. So that leaves one using addition of equal weight on both sides to help keep the wings level during the calibration process.

Secondly with the long range tanks, I suggest filling only from the outboard side. Fuel will quickly settle inboard from the outside - but not the other way around. When I did it the first time, filling the conventional way, I waited over 5 min for fuel to settle but it wasn’t near long enough. But from the outside it should prove much easier. I plan to redo mine soon too for this reason.



Sent from my iPhone using Tapatalk

You do need to use jacks to level and stabilize the plane, even as you add fuel to one wing and even as you move in and out of the plane to enter data to the EDM. But once the weight is on the jacks and not on the mains the plane will not shift even though the tires may be still be touching the floor. In order to level the plane fore/aft you might want to let air out of the nose tire to lower the pitch to level. 

Finally, no one needs to be counting on the accuracy of the empty reading to the precise quart. Only a fool would be operating within 1000 feet of the ground on a tank that might have less than 5gallons (5 is mine, pick your own poison). 

[Guest]

7 hours ago, Immelman said:

If you need to empty a tank, i.e. for leak work: Tie a rag around your arm, remove the fuel sump drain, it goes pretty quick.

To calibrate your sender... I agree, why not have "0" mean "0" usable. Run that tank dry in cruise. If you're good you'll catch the fuel pressure drop and make the switch before the engine quits with hardly a stumble.

 Why do you want to soak your arm in 100LL?  After years of exposure to Avgas I have regular blood testing to monitor my lead levels.

Ever had a hangar fire?  I have, I had my own airplane on fire in my shop caused by static spark. I’ve also seen a large fire ball erupt from a vapour cloud while transferring fuel into a plastic gas can.

 

Clarence

[carusoam]

Since Doc John mentioned it, and Clarence put a highlight on it...

Vapor can be pretty dangerous...

So, yes the heater accross the room.... and its pilot light...

There may be ways of drawing air away from the plane to the outside...

Or for the brief time, do the draining outside where the vapors can’t collect...

Dry air has a way of allowing for large static discharges.... just walking accross the floor, today... 

Best regards,

-a-