We just purchased a1968 Cessna P206C Serial #P2060427, long range 40 gallon tanks.
The stick that came with it seems kind of messed up. Does anyone have accurate measurements for these tanks, to build a reliable accurate measuring stick.
Thanks for the help.

Search on youtube for this video:

How to Make a Fuel Dipstick For Your Airplane

It's pretty easy. Just drain your tanks, then add 5 gallons at a time, dip and mark on a paint stick. Repeat until full.

I have the mechanical gauges in the wing root.
As I added each five gallons, I made a sharpie mark on the gauge itself.

As far as paint sticks, here is an alternative that won't ever crack or splinter:

Universal Fuel Hawk

StillLearning wrote:I have the mechanical gauges in the wing root.
As I added each five gallons, I made a sharpie mark on the gauge itself.

That's a good idea-- wish I'd done that when I went through that exercise to mark my dipper.
Although I rarely pay any attention to those always-in-motion mechanical gauges.

StillLearning wrote:I have the mechanical gauges in the wing root.
As I added each five gallons, I made a sharpie mark on the gauge itself.

I like this idea, very slick

Mapleflt wrote:

StillLearning wrote:I have the mechanical gauges in the wing root.
As I added each five gallons, I made a sharpie mark on the gauge itself.

I like this idea, very slick

Just keep in mind that the accuracy of those gages can deteriorate (rapidly) as the float lever gets bent and distorted...usually by overly aggressive fuel pumps calibrated for filling warbirds, apparently.

Since installing a fuel flow meter I only use my mechanical gages to confirm that there isn't a huge discrepancy with what the meter tells me, and to verify that both tanks are draining. That fuel flow meter represents some of the better money I've spent.

Hammer wrote:

Mapleflt wrote:

StillLearning wrote:I have the mechanical gauges in the wing root.
As I added each five gallons, I made a sharpie mark on the gauge itself.

I like this idea, very slick

Just keep in mind that the accuracy of those gages can deteriorate (rapidly) as the float lever gets bent and distorted...usually by overly aggressive fuel pumps calibrated for filling warbirds, apparently.

Since installing a fuel flow meter I only use my mechanical gages to confirm that there isn't a huge discrepancy with what the meter tells me, and to verify that both tanks are draining. That fuel flow meter represents some of the better money I've spent.

I'm with Hammer. Also, bear in mind that at least with tailwheel airplanes, the reading on the fuel gauges with the airplane at rest will generally be different than the readings while in flight attitude. In some planes, that's not too much, but in many, it's significant.

After I parked a work 185 on a mountainside after the crankshaft broke, our maintenance folks were getting another plane ready for me. The Maintenance Chief called me and asked what equipment I wanted in the panel. My response was "A GPS and a Fuel Computer." Everything else was optional to me.....I LOVE fuel computers.

But, as with any computer, the old adage "Garbage in equals garbage out" applies.

MTV

mtv wrote:

Hammer wrote:

Mapleflt wrote:

StillLearning wrote:I have the mechanical gauges in the wing root.
As I added each five gallons, I made a sharpie mark on the gauge itself.

I like this idea, very slick

Just keep in mind that the accuracy of those gages can deteriorate (rapidly) as the float lever gets bent and distorted...usually by overly aggressive fuel pumps calibrated for filling warbirds, apparently.

Since installing a fuel flow meter I only use my mechanical gages to confirm that there isn't a huge discrepancy with what the meter tells me, and to verify that both tanks are draining. That fuel flow meter represents some of the better money I've spent.

I'm with Hammer. Also, bear in mind that at least with tailwheel airplanes, the reading on the fuel gauges with the airplane at rest will generally be different than the readings while in flight attitude. In some planes, that's not too much, but in many, it's significant.

After I parked a work 185 on a mountainside after the crankshaft broke, our maintenance folks were getting another plane ready for me. The Maintenance Chief called me and asked what equipment I wanted in the panel. My response was "A GPS and a Fuel Computer." Everything else was optional to me.....I LOVE fuel computers.

But, as with any computer, the old adage "Garbage in equals garbage out" applies.

MTV

Sticks go well with the fuel computer. Confirms what the fuel computer is telling you and that someone didn’t borrow fuel from you between flights.

Make a dipstick from 3/8" or 1/2" dowel from the lumber store. Don't coat it with anything, you want the fuel to show up well when the wood gets wet. I don't like the acrylic pipettes anymore because they sink if you fumble it. Wood floats and you can prob fish it out.

Like others said, make one out of wood so that it's easy to see the fuel level. I drained a tank and made fill marks in 1 gal increments for the first 5 gal then every 5 after that until full.

Most important part is either make the stick long enough that when you drop the stick it sits at an angle in the fill hole with the bottom of the stick on the tank floor so that it physically can't drop into the tank. Or, if you want to keep it short, make a T on the top that is wide enough that it won't fit through the hole.

It's really annoying when you have a good calibrated dipstick that is too short and you drop it in the tank, then spend hours fishing it out with a flexible grabber claw and borescope...

People think way, way too hard on this one. Propping the tail up and adding gas one gallon at a time is for people who have a lot of extra time on their hands. It's also like calculating gas mileage by running your car empty, adding a gallon and driving until it's empty again. How do you really calculate the gas mileage on your car? By using a full tank, not an empty one!

Start with a simple (and usually free) paint stick from any home improvement store. It's flat so you can write on it, wood so it shows the amount of gas with a simple dip, and it's too long to lose inside your tank even if you try. Did i mention it's free?

Step one: Fly your airplane. This is the hardest part. Makes no difference how much gas you start with.
Step two: Pull up to the gas pump.
Step three: stick your blank stick in the tank
Step four: pull it out and make a mark with a sharpie pen.
Step five: fill up the tank.
Step six: read the gas pump.
Step seven: Do some math. This is the second hardest part, especially since it's subtraction. Usable fuel capacity - the number on the gas pump = how much gas was in your tank when you stopped.
Step eight: Write that number next to your mark.

If you're lucky (and normal), your tanks will be out of balance which allows you to get two readings every time you land. Added bonus, it makes no difference if you're in a tail dragger because it is automatically accounted for with this method.

Do NOT lift the tail. On a tail dragger the marks will not be linear. The top few gallons will be very close together and the bottom few will be quite far apart. That's how it is regardless of how you decide to make a stick.

Rinse, repeat over several flights, landing with various amounts of fuel on board. I've done it on several planes and it won't take more than 4-5 flights to get a pretty good set of data to make a stick.

Only flew for 0.4? stick the tank
Flew down as far as you're comfortable with? stick the tank.

Pro tip: When you're all done, use your stick to make two more just like it.

All good advice. Why I don't use a fuel stick: Was the aircraft perfectly level (left/right/fore/aft) when you calibrated it? Is the aircraft perfectly level the next time you use the stick? Nose strut/ tailwheel spring displaced due to aircraft loading? Where was the strut/spring when you calibrated the stick? When parked on ANY slope, your stick will be off.
After I put high end senders and fuel computer in my 206, I made two precautionary landings. I was shown a drastic fuel level drop in one tank that did not correspond with predicted fuel burn. I was thinking big fuel leak between tanks and engine. After landing and checking, fuel was there, high end fuel capacity senders no different that old crap ones. Back to "I put this much in, I have flown so many minutes, I should have so much left". Just as my 8,000 hours of commercial 135 flying back in the 80's and 90's taught me.
So far, fuel computer and the above equation have been in agreement.......
Tom

aftCG wrote:People think way, way too hard on this one. Propping the tail up and adding gas one gallon at a time is for people who have a lot of extra time on their hands. It's also like calculating gas mileage by running your car empty, adding a gallon and driving until it's empty again. How do you really calculate the gas mileage on your car? By using a full tank, not an empty one!

Start with a simple (and usually free) paint stick from any home improvement store. It's flat so you can write on it, wood so it shows the amount of gas with a simple dip, and it's too long to lose inside your tank even if you try. Did i mention it's free?

Step one: Fly your airplane. This is the hardest part. Makes no difference how much gas you start with.
Step two: Pull up to the gas pump.
Step three: stick your blank stick in the tank
Step four: pull it out and make a mark with a sharpie pen.
Step five: fill up the tank.
Step six: read the gas pump.
Step seven: Do some math. This is the second hardest part, especially since it's subtraction. Usable fuel capacity - the number on the gas pump = how much gas was in your tank when you stopped.
Step eight: Write that number next to your mark.

If you're lucky (and normal), your tanks will be out of balance which allows you to get two readings every time you land. Added bonus, it makes no difference if you're in a tail dragger because it is automatically accounted for with this method.

Do NOT lift the tail. On a tail dragger the marks will not be linear. The top few gallons will be very close together and the bottom few will be quite far apart. That's how it is regardless of how you decide to make a stick.

Rinse, repeat over several flights, landing with various amounts of fuel on board. I've done it on several planes and it won't take more than 4-5 flights to get a pretty good set of data to make a stick.

Only flew for 0.4? stick the tank
Flew down as far as you're comfortable with? stick the tank.

Pro tip: When you're all done, use your stick to make two more just like it.

Tell me if I’m wrong.
The Only way to know what your usable fuel in a tail dragger is to raise the tail to a level flight attitude.
Drain all fuel, drop the tail back on the ground and start adding fuel to calibrate your stick.
Take landing and takeoff into account depending where your pickup tube is located in your tank.
Working backwards from a full tank assumes your tank will hold what the manufacturer says it will hold?

Tell me if I’m wrong.
The Only way to know what your usable fuel in a tail dragger is to raise the tail to a level flight attitude.
Drain all fuel, drop the tail back on the ground and start adding fuel to calibrate your stick.
Take landing and takeoff into account depending where your pickup tube is located in your tank.
Working backwards from a full tank assumes your tank will hold what the manufacturer says it will hold?

Don't forget the all important definitions when refering to fuel tanks. CAPACITY V.S. USABLE.
In my case the Cessna 150 has a 13GAL Capacity and only 11.5GAL per tank is useable. Many of the commercial dip stick devices already take this into account with a bit of margin to spare. When anybody goes to make the stick, keep this in mind and use your math and markings to account for the actual useable in each tank and not just the capacity!

I prefer to start with drained tanks because that gives you the exact level that YOUR plane holds. There is an AD that lower the manufacturers capacity due to differences in bladder manufacturing. But if you drain the tanks from the gascolator, then start adding, you are starting with the unusable fuel in. Then you know exactly how much fuel your specific plane holds. Maybe being a gallon or 2 off isn't a big deal and you shouldn't be cutting it that close, but if you ever did need it...

I've run each of my tanks dry a few times (with plenty in the other wing!) just to see what my wing-root sight gauges read when the engine stops. Then I switch tanks and land to fill up.

That would be a good method of ensuring you get all but usable out of one wing at a time to calibrate a fuel stick. Can't screw up a cruise attitude in a taildragger if it's flying at cruise.

CamTom12 wrote:I've run each of my tanks dry a few times (with plenty in the other wing!) just to see what my wing-root sight gauges read when the engine stops. Then I switch tanks and land to fill up.

That would be a good method of ensuring you get all but usable out of one wing at a time to calibrate a fuel stick. Can't screw up a cruise attitude in a taildragger if it's flying at cruise.

I do the same. Removes the question of useable completely.

I’ve never seen a need for a dip stick but I can see why Cessna guys would be familiar with them.

In the Luscombe I could eyeball 1/2, 3/4 tank. Both tanks at 1/2 was my personal minimum. The BH has sight gauges in the root. I marked 1/2 tank when on the ground and minimum takeoff.

If I were going to make a stick I would run a tank empty while in cruise and mark the stick as I filled the tank. Just don’t run both tanks dry on the same flight.

Zzz wrote:Make a dipstick from 3/8" or 1/2" dowel from the lumber store. Don't coat it with anything, you want the fuel to show up well when the wood gets wet. I don't like the acrylic pipettes anymore because they sink if you fumble it. Wood floats and you can prob fish it out.

Stirring sticks from the paint store.
Free & easy to hang onto.