Visual determination of fuel on board

[aldoradave]

Dear Ernie,

Just so I fully understand (given the model year differences) my 73 P337 with 128 gal capacity, should be the same as your 73 in fuel tankage. That is, if I can see fuel below the fuel tube, then I have at least 30 gallons. I will of course confirm this myself, but correct me if I am wrong.

Thanks,

Dave Dillehay

[Ernie Martin]

Yes, if the wing/tank arrangements are the same between your P model and my normally aspirated model, then if you see a thin film of fuel under the filler hole you have 30 gallons, and the tube (after you calibrate it) is used to determine quantity when you have more than just a film (1/4", 3/4", 1.5", etc.). The airplane must be on a level surface for accuracy, and, as mentioned by others, you need to wait until fuel has settled because the fuel SLOWLY feeds down to the inboard part of the tank system.

Filling is important, also. If you're starting from a very low fuel situation, use of the visual-and-tube technique on the first tank/side you fill will give you an inaccurately high reading, because the weight of the fuel on that side (unbalanced by the emptiness of the other side) will make the aircraft tilt in the direction of the tank you are filling, bringing more fuel under the fill port than there would be if the aircraft was level. So, when you just barely see fuel under the port (after waiting for fuel to settle, of course) you won't have 30 gallons, but 28 or 26 or perhaps less. Same with the tube. After calibration, if it shows you have 50 gal, you might have 45. The solution is to go fill the tank on the other wing and then return to the first tank to re-measure and refill as necessary. Generally, this iteration is not needed on the second tank/side, just the first.

Ernie

[rick bell]

shadden, shadden digflo !!! unbelievably accurate all it takes is for the dumbass to reset the computer every time you get gas. on long fligths i would switch to mph. best mpg was 9+ gallons per mile

[rhurt]

Originally Posted by rick bell

shadden, shadden digflo !!! unbelievably accurate all it takes is for the dumbass to reset the computer every time you get gas. on long fligths i would switch to mph. best mpg was 9+ gallons per mile

You might want to lean it a little. (just kidding)

Regaardless the flowmeter, Ernie has a great point about fueling. An impatient line guy with a fast nozzle can leave you five gallons short per side.

[dwbomber]

Hi Dave...congrats on the P337 purchase. Because of a past situation , I will never let a line guy fuel my airplane. I take my time and fuel slowly to the brim. Just remember, many a fine pilot have run a skymaster out of fuel. I have a shadden, and I love it, but time is always been my overriding factor. With 5 1/2 hours of fuel, I never push any legs past the 3 to 3 1/2 hour mark. Yes, when you are fat, dumb, and happy up in the upper teens in your pressurized beast (god, I love skymasters), it will be hard to let her back down. JIM

[Ernie Martin]

I also like to keep my legs to under 4 hours. But sometimes you can't (Miami to Boise RT, Virgin Islands to Miami) and these precautions pay off.

Ernie

[rick bell]

Originally Posted by rhurt

You might want to lean it a little. (just kidding)

Regaardless the flowmeter, Ernie has a great point about fueling. An impatient line guy with a fast nozzle can leave you five gallons short per side.

if you look at the gas pump meter you know how much was put in, so if the line guy is impatient you will know

[stackj]

6 hour fuel range.

3 hour bladder range.

A pretty safe combination!

[Ernie Martin]

Yours or Jenny's?

Ernie