SR20 Fill Tabs

Just had the unique instance of having both tanks depleted right to the tabs - exactly (checked it out with a flashlight).

Measured with my dip stick, and compared to gauges.

Gauges said 14 gal in left, 16 gal in right, but right is always 2 gal high.

Dip stick, using my calibrations said about 15 on each side.

All of the above, as we all know, is possibly representative of the inaccuracies of the gauges and certainly my self-calibrated dip stick.

However, I supervised the filling, and it went all the way to the top, and each tank only took 14.0 gallons.

Any other experience on this? I’m wondering if the tabs are off by a gallon.

Andy, how did you make your dipstick?

Did you just grab a plastic rod and spend an hour at the self serve pump one afternoon loading in gas a gallon at a time?

If so, how did you find your “zero” level to calibrate the DS itself? I’ve been reluctant to run a wing dry.

My 22 gauges are still wildly inaccurate (overly conservative) and I’ve had them calibrated twice.

Paul

Andy,

I did the same thing with the Sportys universal stick.

Over a period of 2 months, I put the stick in prior to refueling to top, then noted the difference and calibrated it (slightly different aprroach to what Sporty said, but result should be the same). I found that the resulting curve is slightly non-linear, but that as an estimate, you may conclude that

1 Sporty line represents approx. 10 liters or 2.5 gallons.

The tabs are more or less there where they should be. The dipstick method naturally has some errors (no temperature compensation, indicated height depending on the the vertical speed your hand has while have putting the stick in, stick not exactly vertical, plane on uneven ground, etc.) But I would say that the comparison stick against refueling bill against Fuel gauges per tank is not more than +/- 1 gallon, which is acceptable.

Minimum measurement was in a nearly empty tank (3 gals remaining).

Caution: Don’t let the stick slip out of your hand falling into the tank!! I takes approx 1 hour to fish it out! (Now it has a selfmade collar bigger in diameter than the fuel cap).

Your 14 gals between tabs and max do not surprise me, this equals a hight difference of 4 mm or 0.15 inch only - pretty good for this crude measurement.

AND: if you can refuel only 14 gals from tab to max, then you must also redo the dip stick calibration process. It took me more than 20 repeating attempts to finally get a calibration with an acceptable error envelope.

I hope that everybody flies with at least 45 - 60 mins reserve!!

Timm Preusser N747TG

Just had the unique instance of having both tanks depleted right to the tabs - exactly (checked it out with a flashlight).

Measured with my dip stick, and compared to gauges.

Gauges said 14 gal in left, 16 gal in right, but right is always 2 gal high.

Dip stick, using my calibrations said about 15 on each side.

All of the above, as we all know, is possibly representative of the inaccuracies of the gauges and certainly my self-calibrated dip stick.

However, I supervised the filling, and it went all the way to the top, and each tank only took 14.0 gallons.

Any other experience on this? I’m wondering if the tabs are off by a gallon.

Andy,

The Cirrus sales rep said that the tabs on the SR20 would give 40 gal of fuel. I don’t see how this is possible if its 28 gal (14 x 2) as you say to full tanks from the tabs.

Can you give fuel levels that you are seeing.

Thanks,

…Warren

Just had the unique instance of having both tanks depleted right to the tabs - exactly (checked it out with a flashlight).

Measured with my dip stick, and compared to gauges.

Gauges said 14 gal in left, 16 gal in right, but right is always 2 gal high.

Dip stick, using my calibrations said about 15 on each side.

All of the above, as we all know, is possibly representative of the inaccuracies of the gauges and certainly my self-calibrated dip stick.

However, I supervised the filling, and it went all the way to the top, and each tank only took 14.0 gallons.

Any other experience on this? I’m wondering if the tabs are off by a gallon.

Paul, I purchased the Universal Fuelhawk Fuel Gauge from Sporty’s, and calibrated it according to the instructions.

Basically, that entails correlating lots of dip stick readings with the actual (based on what it took to fill), plotting it on a graph, and deriving a line of best fit.

Implicitly, there’s a projection to the very lowest levels.

Admittedly, not terribly accurate.

Andy

Andy, how did you make your dipstick?

Did you just grab a plastic rod and spend an hour at the self serve pump one afternoon loading in gas a gallon at a time?

If so, how did you find your “zero” level to calibrate the DS itself? I’ve been reluctant to run a wing dry.

My 22 gauges are still wildly inaccurate (overly conservative) and I’ve had them calibrated twice.

Paul

Paul, I purchased the Universal Fuelhawk Fuel Gauge from Sporty’s, and calibrated it according to the instructions.

I think there’s a quicker way. I have a homemade

stick (originally a paint stirring stick) that

I calibrated by filling my tank a gallon at a

time, making unlabeled marks as I went. The

final filling was .5 gallons, so I labeled my

marks 5.5, 6.5, 7.5, etc., up to full. Once

you have that, you can interpolate to any
marking increment you want. Many tanks aren’t

linear, and this method minimizes errors due to

non-linearity.