Originally Posted by
Pilot DAR
Hopefully, the fuel quantity indicators are reasonably accurate to the nearest quarter tank, then assume the weight to the greater quarter tank, and you'll be conservatively safe. Or, fill them right up, and you'll have a pretty accurate idea. If you have a calibrated dipstick, that can help too, though they are variable as to their accuracy, and airplane attitude can affect the reading.
Thanks for the answer.
The common practice is to fill the tanks right up, but with two of us in the cockpit and full tanks Seneca IV goes overweight. So I need to find a way to fill it to an amount that will not make it overweight, say around 200 lbs (mass) below full tank. The bowser has a totalizer in litres, and there is always some fuel left in the tanks, when we start refuelling ... obvuously if the tanks were empty at beginning of refuelling, we could calculate litres to fill it to desired lbs value, but with some fuel left...