Tip: Visual Fuel Level Indicator

I saw this suggestion in the 25 Years of RVator and here's how I interpreted the idea. One of Van's guys offered the idea of having some kind of visual indicator of fuel level, so when you look in the cap, you'd know about how much each wing has.

I guessed at 1/4, 1/2, and 3/4. Not too fine, but, distinguishable when looking in a dark tank. I installed AN470-7 rivets thru the next to last outboard tank rib, gently squeezing them for an interference fit in the holes and then sealed the heads in with Proseal to keep them in place.

Anyway, I hope to be able to looking the cap and easily see my fuel level in 1/4 tank increments.

[/IMG]http://img218.imageshack.us/img218/4381/img2798rf4.jpg

Photo of Visual Fuel indicator

Firefox seems to have trouble uploading photos, so here it is thru Explorer.

YOu can see the tips of three rivets sticking out of the rib, they are just aft of the fuel cap.

Glass tube

Hi Bud,
You could also use a glass or plastic tube of small diameter and insert it vertically into the partially filled tank, close the top of the tube with your finger and withdraw it. The fuel level will show how deep it is. If you had incrementally filled the tank, the tube could be calibrated. They sell these for Skyhawks 'n such.

Check either Wentworth Aircraft salvage, or Great Planes aviation for good used engines. Atlanta air salvage is another.

Regards,

That's a great idea - a plane-specific calibrated hand dip gauge. I believe I'll file that one down in my memory banks...

Clear calibrated fuel measuring tube

Spruce sells them. It comes with a calibration chart to allow you to equate units on the tube to gallons of fuel. Also available are tubes already calibrated for specific aircraft such as a C172.

On my 6A I've been disappointed in the use of the tube thru the fuel filler cap because the dihedral causes the fuel to pool toward the fuselage. When measuring with less than 10-12 gals or less in a tank, the depth of the fuel underneath the fueling hole is not very deep. To be really accurate with the fuel tube you need to be on level ground.

A better safety system I've installed and love is the low level fuel light system, the "AE Fuel Guardian - Low Fuel Annunciation".
Spruce also sells this. I have mine set to illumine at 3 gals remaining in each tank. It's hard to miss those lights flashing on the panel.

The problem is...

Even when the fuel level gets all the way down to the bottom of the rib, you will still have about 1/2 tank of fuel because of the slope of the tank.

By the way you could also use an old chop stick and see how wet it gets when you dip it in.

Kent

An Oak Stick

Used a section of oak trim and marked it with a EXTRA FINE SHARPIE.....
These measurements are for a 6A on level ground.

Looking down into the tank, if you just see fuel it is 5 gal.

1 1/8=6 gal 1 1/2=7 1 15/16=8 2 1/8=9 2 1/2=10 2 3/4=11

3 1/8=12 3 9/16=13 3 3/4=14 4 3/16=15 4 5/8=16 5 1/16=17

5 1/2=18 to inside lip= 19 gal. Hold stick to upper edge of filler. Dip it quick.

The fuel will wick up if you wait to read. On my A/C this gauge is within
1/2 gal. The oak is hard enough to not soak up, and will dry in seconds if you wave it. Make a folding "T" for the top of the stick so it won't pass through the filler hole.

Warren

kentb said:

Even when the fuel level gets all the way down to the bottom of the rib, you will still have about 1/2 tank of fuel because of the slope of the tank.

By the way you could also use an old chop stick and see how wet it gets when you dip it in.

Kent

Click to expand...

Kent,
With all of the RV's it is between 1/4 and a 1/3 of a tank when the fuel is just starting to lap up the side of the outboard rib.
On an RV-9A it is between 5 and 6 gallons.

Cheap tube

You don't need to spend $$ on the tube; just a hard, clear plastic tube is good. Spruce version not needed for RV. When the fuel is just wetting the bottom under the cap (on my -7A) I have 5 gallons. It's easy to calibrate and mark with a Sharpie. I don't think I spent more than 1$. Calibrate by adding known quantities, etc. You have to pick a position for the measuring. On mine, I use the most forward portion of the arc of the filler opening. This is really only backup because my GRT EIS is very accurate using Van's float senders.

Low level fuel warning

Vern said:

....
A better safety system I've installed and love is the low level fuel light system, the "AE Fuel Guardian - Low Fuel Annunciation".
Spruce also sells this. I have mine set to illumine at 3 gals remaining in each tank. It's hard to miss those lights flashing on the panel.

Click to expand...

Maybe... but non-one seems to want to buy mine..... it's still for sale.... cheap....

http://www.vansairforce.com/community/showthread.php?t=13777

gil in Tucson

Thank you Warren/gasman for the gallon to inches numbers fuel numbers for the 6A. I use a hollow plastic tube from my C-170A days but only had marked five gallon increments.

On the use of a low fuel warning light....two comments:
I like to see what is in the tank. And I rarely let a tank get down to 3 gals and so the light would only function as an emergency light. Which wouldn't be bad but hopefully never used.
Dale