Fuel tank dipstick measurements

[201er]

I did just that by draining the plane with the fuel strainer drain until it was empty. I then put two gallons in at a time while measuring with a universal fuel hawk and marking the supplied chart.

Why would you do it by draining from the sump when the real fuel drains down the fuel inlet? The levels would presumably be different and the point at which you'd run out of fuel above your sump point (obviously or else that gunk would always get into the fuel line). I would think a more useful method would be by flying the plane until the engine began to quit (swap tanks obviously) and then do your calibration by filling from that point. The goal is to know how many usable gallons you have rather than actual. Right?

[Lood]

Also use a universal fuel hawk dipstick calibrated on my Mooney. However, I drained the tanks at the fuel strainer on the wing and not the one at the selector. It is incredibly accurate and the only mistake that I made during calibration was to fill the tank 5 gallons at a time. I plan to repeat the exercise, but this time in 2 gallon or 10 liter increments.

[jetdriven]

Why would you do it by draining from the sump when the real fuel drains down the fuel inlet? The levels would presumably be different and the point at which you'd run out of fuel above your sump point (obviously or else that gunk would always get into the fuel line). I would think a more useful method would be by flying the plane until the engine began to quit (swap tanks obviously) and then do your calibration by filling from that point. The goal is to know how many usable gallons you have rather than actual. Right?

Mike, I pulled the drain ring at the fuel selector and drained it there to simulate running a tank dry with the engine. I didn't drain via sump drain

[M20F-1968]

You can purchase plastic pipettes such as used in a scientific lab. They come in various sizes and lengths. I bought a package of them on e-bay for short money.

You can use the markings on the pipette and either number the pipette in gallons or use a calibration card.

Place pipette in tank, put finger over end, withdraw, read level.

John Breda

[tlandrum]

Where is this fuel "ring" or "drain", and where does the fuel come out?

Also do other flyers of m20F's have the same problem of not being able to monitor at all below 1/3 of a tank?

[cliffy]

How come no mention of temperature of the fuel has been brought up as far as "calibration " of  a wooden stick?

Fuel expands quite readily as it heats up   :-) :-)  )its a joke OK?)

Reminds me of my Father's machine shop joke-

Measure with a yardstick, mark with chalk and cut with an axe

[cliffy]

On 7/14/2010 at 11:10 AM, knute said:

My archive has a post I salted away from Rob Hoyle, who graciously provided the measurements and markings from the dipstick he (and the prior owner) calibrated for his 1965 C model, which turns out to work perfectly for my 52 gallon '66E model, verified every time I top up the tanks.  (It also very closely tracks my fuel computer)  I like to stick the tanks before every flight just to make sure I have exactly as much fuel as I think I do.

Hopefully email doesn't screw up the formatting too badly, but distance from the bottom of the stick is on the left (inches) and corresponding gallons is on the right.  Hope that helps or gives you a starting point!  It shouldn't be that hard to calibrate your own paint stick from Home Depot.  The measurements below obviously won't work for an F model with bigger tanks, but for any other C or E model owners with stock 52 gallon tanks, this should come pretty close.

 

9                 26
8 1/2           25
8                 24
7 5/8           23
7 1/4           22
6 7/8           21
6 1/2           20
6 1/16         19
5 3/4           18
5 7/16         17
5 1/16         16
4 13/16       15
4 1/2           14
4 1/8           13
3 7/8           12
3 1/2           11
2 11/16        9
2 3/8            8
2 1/8            7
1 3/4            6

 

 

Good luck!

 

 

Knute
'66 M20E - KSQL (San Carlos, CA)

 

I had one once but I misplaced it.   THX

[cctsurf]

On 1/16/2021 at 12:47 AM, cliffy said:

Measure with a yardstick, mark with chalk and cut with an axe

I grew up with, "Measure it with a micrometer, mark it with a crayon, cut it with an ax."

[Hank]

4 hours ago, cctsurf said:

I grew up with, "Measure it with a micrometer, mark it with a crayon, cut it with an ax."

The one I've always heard and say myself is quite close to that:

Measure with a micrometer, mark with chalk, cut with an ax.

I'll try to remember to get a picture of mine, with a tape measure. On the other hand, it's on a pre-marked Universal dip stick with new numbers engraved into the plastic . . . If I can find the picture I took the last time this came up . . . .

[flyer338]

I made a fuel dipstick for my 1965 C Model with 26 gallons usable per side. I started by running a tank dry. Then I added five gallons and marked my dowel. In order to ensure repeatability of the measurement, I inserted the dowel in the outermost of he three lug positions in the fuel opening. Using a five-gallon interval gave me solid numbers and interpolating between the five-gallon marks turned out to be accurate and consistent.

I dealt with the fuel climbing up the stick by only dipping for a second or less, and then ignoring any runners climbing the fuel stick. I used a knife to carve a line in the Lowe’s purchased dowel (I shopped in the PMA TSO department).

 I made a fuel stick for my recently purchased M20J. I approached this a little differently because I am not (yet) comfortable with running a tank dry with a fuel injected engine.

What I did was sort of a reverse extrapolation. I ran a tank close to dry. Then I added fuel until the fuel just registered on my stick. Then I added fuel five gallons at a time and marked my stick until I filled the tank. By subtracting the fuel added from the fuel necessary to fill the tank, I knew how many gallons were in the tank at the first dip. By adding five gallons for each mark, I know the fuel in the tank at the first mark, and it is easy to interpolate between the five gallon marks. 

I used the fuel cap lug farthest from the fuselage for consistency. 
 

I noted that the float gauges on the wing tanks are reasonably accurate. The electric gauges on the panel are not even consistent from left to right. 
 

It is the responsibility of every pilot to know how much fuel is on board. Sometimes I want to be light and have only the fuel I need (including a reserve) because I plan to depart from a high density altitude airport (Panguitch, Utah; 6700’ and 87 degrees for a density altitude of about 9500’ ft). 
 

I think experience in the plane earned over a long time is critical, and until that experience is validated one should be especially conservative. I do not yet have that experience in my J. I expect that experience will expand or contract my comfort zone and help me to become an old pilot.
 

[carusoam]

Let’s discuss becoming familiar with running a FI’d engine out of fuel...

There is no magic to it...

It isn’t scary...

It can be simulated by dialing out the mixture until all you hear is gliding... 

Whenever you are ready...

If you have a really good GAMI spread... this exercise is fun...

PP thoughts only, not a CFI...

Best regards,

-a-

[cliffy]

Used to run the tanks dry in a Navajo by watching the fuel flow pressure as it would always start to fluctuate just before it ran dry (sucking some air)

Wait for the needle to wiggle and switch tanks  Worked every time. 

[MBDiagMan]

Does the OP’s plane not have 32 gallon tanks?  My 67 F does.