Avgas shrinkage at low temps
This is about 0.1% per degC.
So, let's say I fill right up with avgas from a bowser which has been sitting around all day in Greece, and is say +25C.
Now, I have a flow totaliser, verified accurate at every fillup, to within ~ 0.5% against UK airport pumps (checked by Weights & Measures fairly regularly).
The transducer for this is a Floscan 201 turbine transducer which like just about every liquid flowmeter (short of Coriolis meters) is measuring volume flow, not mass flow.
At FL180, the fuel will eventually cool down to say -25C.
That is a 5% shrinkage in volume. (Not mass, obviously).
So the flowmeter should be reading 5% lower for the same mass flow, yes?
And the engine power derives from mass flow of fuel.
Does any of this actually matter??
The one thing which should matter is that there is a significant difference between uploading fuel at say +5C and +25C - a 2% short-change on the latter and a 2% aircraft range reduction. Why is this not reflected in fuel pricing?
What do they do on big jets? They must work on mass too, not volume flow, even though it is volume that is measured by the flow totalisers (unless they use coriolis meters, or do some kind of fuel temperature compensation).