Fuel Tank Tabs

[coyoteheineken]

Hello!

Curious for an answer, does anyone know what these tabs represent in both fuel tanks of our RV8?

There are four tabs, the bottom of which is the "tallest", and it is located facing forward. These tabs are all one piece and this component is hanging from the top of the fuel tank. There are four tabs total with the top tab facing aft and alternating as they extend deeper into the tank. You can also see the reflection of the tabs on the fuel in the tank.

My guess is that since each tank is 21 gallons, that the top of each tab is approximately 5 gallons while the plane is on the ground, with a full top off being slightly above the top tab at 21 gallons, but I am not certain and I don't know whether or not to trust the tank fuel info on the Dynon.

Before I drain a tank and fill it up a few gallons at a time, has anyone seen these before that could give me an accurate answer?

Thanks everyone!

 

[riseric]

Hi !
I don't have tabs in mine.
That must've been added by the builder??
I suggest that you do the calibration of those tabs once you drain the tank.

 

[Ralph Inkster]

Tabs are a custom feature only the original builder would know what values they represent.
If you don't trust the Dynon gauge values, than a re-calibration is in your future, not hard to do. Just note that if you have float type senders, you will show full tanks at about 14 gallons (wing dihedral), if you have capacitance senders the fuel value should be accurate right up to the 21 gallons.

 

[michjor]

Definitely recalibrate for your own peace of mind, even if the previous owner had the fuel tab measurements updated in the POH. I use a custom fuel stick calibrated at 5 gallon increments and manage L/R tank change based on GPH fuel flow.

 

[BillL]

That could be a pretty cool/easy way to know the fuel level!!! Hopefully it works out for you.

I use a .025" X 3/8" dipstick with staggered 1/16" holes every 1/2 gallon. If the L and R tank readings are added, the accuracy is within 1/2 gallon equal to the measured and fuel used totalizer. For a reference my -7 (w/caveats) came to .306"/gal from 7 to 21 at the pump.

When calibrating the tanks, put a jack under the wings so it does not lean during the fill process. I chased a different scale between tanks a while before realizing how sensitive the level reading is to small "roll" changes. Pitch seems to be rather insensitive by comparison.

My stick stops at about 7-8 gallons where fuel level recedes. 20 gal is pretty accurate, but the measurements are non linear from there to the rim.

In all cases YMMV.

 

[Webb]

May I suggest you drain from full instead of fill from empty.

Next time you fuel, only fill one wing.

Drain the full wing a gallon at a time and pour the fuel into the wing you didn’t fuel.

Since you start with a known Qty of 21 gallons, you will quickly find out what quantity each tab represents. You won’t even need a fuel gauge to do this. You only need a gallon milk jug and elbow grease.

 

[PilotjohnS]

Slow

May I suggest you drain from full instead of fill from empty.

Next time you fuel, only fill one wing.

Drain the full wing a gallon at a time and pour the fuel into the wing you didn’t fuel.

Since you start with a known Qty of 21 gallons, you will quickly find out what quantity each tab represents. You won’t even need a fuel gauge to do this. You only need a gallon milk jug and elbow grease.

Ut draining fuel thru the sump valves is slow. Like really slow. I had to drain 10 gals from my tanks for weight and balance and it was painful to sit for what seemed like an hour.

 

[Taltruda]

Ut draining fuel thru the sump valves is slow. Like really slow. I had to drain 10 gals from my tanks for weight and balance and it was painful to sit for what seemed like an hour.

Either of these work pretty quick. Personally, I like the shake hose.. it drains most of the wing, then the drain plug gets the remainder.

 

[andoman]

Removing the sump valves will spill very little fuel.
Some tape off the vent to slow flow but I found that wasn't needed.